antenna

Abstract

The present invention reduces the size of an antenna and increases the angle of directionality.　Provided is an antenna comprising a first conductive plate and a second conductive plate which is disposed inward of the first conductive plate with an interval therebetween, wherein: the first conductive plate includes a first U shape part which is formed in a U shape by a first side surface part, a second side surface part that faces the first side surface part, and a first front surface part that is connected between the first side surface part and the second side surface part; the second conductive plate includes a second U shape part which is formed in a U shape by a third side surface part, a fourth side surface part that faces the third side surface part, and a second front surface part that is connected between the third side surface part and the fourth side surface part; the second front surface part faces the first front surface part; the first front surface part has a slot which divides at least part of the first front surface part into a first surface part and a second surface part; the first surface part has a first feeding point; and the second surface part has a second feeding point.

Description

[Technical field]

[0001] The present disclosure relates to antennas. [Background technology]

[0002] In recent years, there has been a trend toward expanding services that use high-speed, large-capacity wireless communication systems using microwave and millimeter wave frequency bands, such as the transition from 4G LTE to 5G (sub6). The bands in use tend to expand from the 3 GHz band to the 5-6 GHz band. In addition, V2X (Vehicle to Everything) communications, such as vehicle-to-vehicle communications and road-to-vehicle communications, are being deployed in a variety of applications, including short-range communications such as the European Electronic Toll Collection System (ETC), which uses radio waves in the 5.9 GHz band.

[0003] Antennas used in V2X communication may be required to have directivity extending from the vehicle's traveling direction to the vehicle's width direction (±90° with respect to the traveling direction). As an antenna that satisfies such requirements, a vehicle antenna is known that includes a radiating plate facing the vehicle's traveling direction and two elements that are spaced apart on both sides of the radiating plate in the vehicle width direction (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 208453 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, there has been a demand for further miniaturization of antennas having a relatively wide-angle directivity as described above.

[0006] The present disclosure provides an antenna that can achieve miniaturization and wide-angle directivity. [Means for solving the problem]

[0007] In one aspect of the present disclosure, a first conductive plate and a second conductive plate disposed inside the first conductive plate with a gap therebetween; the first conductive plate includes a first U-shaped portion formed in a U-shape by a first side portion, a second side portion opposing the first side portion, and a first front portion connected between the first side portion and the second side portion, the second conductive plate includes a second U-shaped portion formed in a U-shape by a third side portion, a fourth side portion opposing the third side portion, and a second front portion connected between the third side portion and the fourth side portion, The second front portion faces the first front portion, the first front portion has a slot dividing at least a portion of the first front portion into a first surface portion and a second surface portion; the first surface portion has a first feeding point; An antenna is provided, the second surface having a second feed point. Effect of the Invention

[0008] According to the antenna of the present disclosure, it is possible to achieve both miniaturization and wide-angle directivity. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a perspective view showing a configuration example of an antenna in the first embodiment. [Diagram 2] 2 is a cross-sectional view in the ZX plane of an example of the configuration of the antenna in the first embodiment. FIG. [Diagram 3] 4 is a cross-sectional view in the ZX plane of a first modified example of the antenna in the first embodiment. FIG. [Figure 4] 11 is a cross-sectional view in the ZX plane of a second modified example of the antenna in the first embodiment. FIG. [Diagram 5] 13 is a cross-sectional view in the ZX plane of a third modified example of the antenna in the first embodiment. FIG. [Figure 6]13 is a cross-sectional view in the ZX plane of a third modified example of the antenna in the first embodiment. FIG. [Figure 7] FIG. 11 is a perspective view showing a configuration example of an antenna in a second embodiment. [Figure 8] FIG. 11 is a cross-sectional view of an example of the configuration of an antenna in a second embodiment. [Figure 9] FIG. 11 is a perspective view showing a configuration example of an antenna in a third embodiment. [Figure 10] FIG. 11 is a cross-sectional view of a configuration example of an antenna in a third embodiment. [Figure 11] FIG. 13 is a perspective view showing a configuration example of an antenna in a fourth embodiment. [Figure 12] FIG. 13 is a cross-sectional view of an example of the configuration of an antenna in a fourth embodiment. [Figure 13] FIG. 13 is a perspective view showing a configuration example of an antenna in a fifth embodiment. [Figure 14] 1 is a diagram showing an example of mounting an antenna on a vehicle in each embodiment. FIG. [Figure 15] FIG. 13 is a perspective view showing a configuration example of an antenna in a comparative embodiment; [Figure 16] FIG. 13 is a diagram showing an example of a simulation result of antenna directivity in a comparative example. [Figure 17] FIG. 4 is a diagram showing an example of a simulation result of the directivity of the antenna in the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, each embodiment according to the present disclosure will be described with reference to the drawings. For ease of understanding, the scale of each part in the drawings may differ from the actual scale. In directions such as parallel, right angle, orthogonal, horizontal, vertical, up and down, left and right, deviations that do not impair the effects of the embodiments are permitted. The shape of the corners is not limited to right angles, and may be rounded in an arch shape. The X-axis direction, the Y-axis direction, and the Z-axis direction respectively represent directions parallel to the X-axis, the Y-axis direction, and the Z-axis direction. The X-axis direction, the Y-axis direction, and the Z-axis direction are mutually orthogonal. The XY plane, the YZ plane, and the ZX plane respectively represent imaginary planes parallel to the X-axis direction and the Y-axis direction, imaginary planes parallel to the Y-axis direction and the Z-axis direction, and imaginary planes parallel to the Z-axis direction and the X-axis direction.

[0011] The antenna of each embodiment according to the present disclosure is applicable to, for example, a V2X communication system, a fifth generation mobile communication system (so-called 5G), an in-vehicle radar system, and the like, but is not limited to these. An example of a V2X communication system is an ETC system. The antenna of each embodiment according to the present disclosure is suitable for use in a frequency band (sub6) of 6 GHz or less among the frequency bands used in 5G, and is suitable for transmitting and receiving (one or both of transmitting and receiving) radio waves in the 5.8 GHz band or 5.9 GHz band. However, the antenna of each embodiment according to the present disclosure can be used not only in the frequency band (3.3 GHz or more) used in 5G, but also in 4G LTE, millimeter wave band (30 GHz to 300 GHz), and microwave.

[0012] FIG. 1 is a perspective view showing a configuration example of an antenna in the first embodiment. FIG. 2 is a cross-sectional view in the ZX plane of the configuration example of the antenna in the first embodiment. The antenna 101 shown in FIGS. 1 and 2 includes an outer conductor plate 10 and an inner conductor plate 20. The conductor plate is not limited to a conductive plate-like member, and may be a conductive film-like member. FIG. 2 is a cross-sectional view of an antenna in which the ends (slot ends 31, 32) in the X-axis direction corresponding to the longitudinal direction of the slot 30 do not extend to the end sides 17, 18. In FIG. 1 and FIG. 2, a dielectric substrate (not shown) may be separately arranged and fixed on the outside of the front part 13 (the side opposite to the front part 23 described later). An example of the dielectric substrate is a PCB (Printed Circuit Board) substrate containing epoxy resin. In particular, when a PCB substrate is provided on the outside of the front portion 13, the front portion 13 formed by the conductor may be planar along the XY plane, and the front portion 13 may be formed on either the first main surface or the second main surface (the surface opposite to the first main surface) of the PCB substrate.

[0013] The external conductor plate 10 is an example of a first conductor plate, and is disposed outside the internal conductor plate 20 with a gap therebetween. The external conductor plate 10 has an outer shape including a U-shaped portion, and in the example shown in FIG. 1, includes a U-shaped portion 14. The outer shape of the external conductor plate 10 may be another shape, such as an H-shape, as long as it includes a U-shaped portion. The U-shaped portion 14 is an example of a first U-shaped portion, and is disposed outside the U-shaped portion 24 of the internal conductor plate 20 with a gap therebetween. In the example shown in FIG. 1, the U-shaped portion 14 has a three-dimensional U-shape that opens on both sides in the Y-axis direction and on the negative side in the Z-axis direction, and in particular, a slot 30 having a narrower opening area than the opening on the negative side in the Z-axis direction is formed to open on the positive side in the Z-axis direction.

[0014] In the example shown in FIG. 1, U-shaped portion 14 is a conductive portion formed in a U-shape by side portion 11, side portion 12 facing side portion 11 in the X-axis direction, and front portion 13 connected between side portion 11 and side portion 12. Side portion 11, side portion 12, and front portion 13 are all conductive plate-like or film-like portions. Side portion 11 is an example of a first side portion. Side portion 12 is an example of a second side portion. Front portion 13 is an example of a first front portion.

[0015] The inner conductor plate 20 is an example of a second conductor plate, and is disposed inside the outer conductor plate 10 with a gap therebetween. The inner conductor plate 20 has an outer shape including a U-shaped portion, and in the example shown in FIG. 1, includes a U-shaped portion 24. The outer shape of the inner conductor plate 20 may be another shape, such as an H-shape, as long as it includes a U-shaped portion. The U-shaped portion 24 is an example of a second U-shaped portion, and is disposed inside the U-shaped portion 14 of the outer conductor plate 10 with a gap therebetween. In the example shown in FIG. 1, the U-shaped portion 24 has a three-dimensional U-shape that opens on both sides in the Y-axis direction and on the negative side in the Z-axis direction. In the example shown in FIG. 1, the inner side means the negative side in the Z-axis direction.

[0016] In the example shown in FIG. 1, the U-shaped portion 24 is a conductive portion formed in a U-shape by a side portion 21, a side portion 22 facing the side portion 21 in the X-axis direction, and a front portion 23 connected between the side portion 21 and the side portion 22. The front portion 23 faces the front portion 13 in the Z-axis direction. The side portion 21, the side portion 22, and the front portion 23 are all conductive plate-like or film-like portions. The side portion 21 is an example of a third side portion. The side portion 22 is an example of a fourth side portion. The front portion 23 is an example of a second front portion.

[0017] The front portion 13 has a slot 30 that divides at least a portion of the front portion 13 into a surface portion 15 and a surface portion 16. The slot 30 is an opening provided at a location corresponding to the bottom of the U-shape of the U-shaped portion 14. The surface portion 15 is an example of a first surface portion, and in the example shown in FIG. 1, is a conductive portion located on the positive side of the slot 30 in the Y-axis direction. The surface portion 16 is an example of a second surface portion, and in the example shown in FIG. 1, is a conductive portion located on the negative side of the slot 30 in the Y-axis direction. The surface portion 15 has a power feed point 41, and the surface portion 16 has a power feed point 42.

[0018] The pair of feed points 41, 42 are points where a feed line such as a coaxial cable or a planar waveguide (not shown in FIG. 1; details will be described later) is electrically connected. Feed point 41 is an example of a first feed point, and is electrically connected, for example, to a ground part of the feed line. Feed point 42 is an example of a second feed point, and is electrically connected, for example, to a signal line of the feed line. Alternatively, feed point 41 may be electrically connected to the signal line of the feed line, in which case feed point 42 is electrically connected to the ground part of the feed line.

[0019] With such a configuration, the antenna 101 has the outer conductor plate 10 functioning as a radiator that radiates radio waves, and the inner conductor plate 20 functioning as a reflector that reflects the radio waves radiated from the outer conductor plate 10. Since the inner conductor plate 20 functioning as a reflector is disposed inside the outer conductor plate 10 functioning as a radiator, the antenna 101 can be made smaller than an antenna (not shown) in which a reflector or director is disposed outside the radiator. In addition, since the pair of side portions 11, 12 extend from both sides of the front portion 13 in which the slot 30 is provided, the radio waves (beam) radiated from the outer conductor plate 10 can be made wider in angle.

[0020] If the shape of the U-shaped portion 14 of the outer conductor plate 10 is symmetrical with respect to the YZ plane, this is advantageous in terms of widening the angle of the directivity of the antenna 101 and stabilizing the antenna gain over a wide angle range. If the shape of the U-shaped portion 24 of the inner conductor plate 20 is symmetrical with respect to the YZ plane, this is advantageous in terms of widening the angle of the directivity of the antenna 101 and stabilizing the antenna gain over a wide angle range. If the overall shape of the U-shaped portion 14 and the U-shaped portion 24 combined with a gap therebetween as illustrated in FIG. 1 is symmetrical with respect to the YZ plane, this is more advantageous in terms of widening the angle of the directivity of the antenna 101 and stabilizing the antenna gain over a wide angle range. If the U-shaped portion 14 and the U-shaped portion 24 are similar, this is advantageous in terms of widening the angle of the directivity of the antenna 101 and stabilizing the antenna gain over a wide angle range.

[0021] Edge 17, which is the boundary between front portion 13 and side portion 11, is an example of a first edge between a first front portion and a first side portion, and in the example shown in Fig. 1, side portion 11 is bent at edge 17 relative to front portion 13. Edge 18, which is the boundary between front portion 13 and side portion 12, is an example of a second edge between the first front portion and a second side portion, and in the example shown in Fig. 1, side portion 12 is bent at edge 18 relative to front portion 13.

[0022] Edge 27, which is the boundary between front portion 23 and side portion 21, is an example of a third edge between the second front portion and the third side portion, and in the example shown in Fig. 1, side portion 21 is bent at edge 27 relative to front portion 23. Edge 28, which is the boundary between front portion 23 and side portion 22, is an example of a fourth edge between the second front portion and the fourth side portion, and in the example shown in Fig. 1, side portion 22 is bent at edge 28 relative to front portion 23.

[0023] End side 17 and end side 18 may each include at least one line segment. This allows the directivity of antenna 101 to have a wide angle. In the example shown in Fig. 1, end side 17 is a line segment extending from upper edge 10a of outer conductor plate 10 to lower edge 10b of outer conductor plate 10, and end side 18 is a line segment extending from upper edge 10a of outer conductor plate 10 to lower edge 10b of outer conductor plate 10. End side 17 and end side 18 may each include multiple line segments by bending at one or multiple points, or may be composed of only curved lines.

[0024] 1, the line segment of end side 17 is approximately parallel to the line segment of end side 18. This makes it possible to further widen the angle of the directivity of antenna 101. Note that the line segment of end side 17 does not have to be approximately parallel to the line segment of end side 18. For example, even if front portion 13 of outer conductor plate 10 is a trapezoid (a trapezoid in which upper edge 10a and lower edge 10b are parallel) when viewed from the front, it is possible to widen the angle of the directivity of antenna 101.

[0025] 1, slot 30 extends in a direction intersecting both end side 17 and end side 18. This further improves the antenna gain of antenna 101 in transmitting and receiving radio waves having a plane of polarization perpendicular to the extension direction (longitudinal direction) of slot 30. As shown in FIG. 1, when slot 30 extends in a direction substantially perpendicular to both end side 17 and end side 18, the antenna gain is further improved.

[0026] 1, the front portion 13 is approximately perpendicular to both the side portion 11 and the side portion 12. This allows the directivity of the antenna 101 to be made wider in a plane (in this example, the ZX plane) that is approximately perpendicular to all of the front portion 13, the side portion 11, and the side portion 12. Note that the directivity of the antenna 101 can be made wider even if the front portion 13 is approximately perpendicular to only one of the side portion 11 and the side portion 12. Alternatively, the directivity of the antenna 101 can be made wider even if the front portion 13 is not approximately perpendicular to either the side portion 11 or the side portion 12.

[0027] 1, the front portion 23 is approximately parallel to the front portion 13. This makes it easier to design the directivity pattern of the antenna 101. Note that even if the front portion 23 is not approximately parallel to the front portion 13, it is possible to widen the angle of the directivity of the antenna 101.

[0028] 1, the front portion 23 is approximately perpendicular to both the side portion 21 and the side portion 22. This allows the directivity of the antenna 101 to be made wider in a plane (in this example, the ZX plane) that is approximately perpendicular to all of the front portion 23, the side portion 21, and the side portion 22. Note that the directivity of the antenna 101 can be made wider even if the front portion 23 is approximately perpendicular to only one of the side portion 21 and the side portion 22. Alternatively, the directivity of the antenna 101 can be made wider even if the front portion 23 is not approximately perpendicular to either the side portion 21 or the side portion 22.

[0029] 1, side surface portion 11 is approximately parallel to side surface portion 21 opposite side surface portion 11, and side surface portion 12 is approximately parallel to side surface portion 22 opposite side surface portion 12. This makes it easier to design the directivity pattern of antenna 101. Note that even if side surface portion 11 is not approximately parallel to side surface portion 21, it is possible to widen the angle of directivity of antenna 101, and even if side surface portion 12 is not approximately parallel to side surface portion 22, it is possible to widen the angle of directivity of antenna 101.

[0030] In FIG. 1, the dimension of the outer conductor plate 10 in a direction substantially perpendicular to the longitudinal direction of the slot 30 is L. 1 The dimension of the inner conductor plate 20 in the direction substantially perpendicular to the longitudinal direction of the slot 30 is L 2 In this case, L 2 L 1 It is sufficient if it is 0.75 times or more and 1.5 times or less of L 1 If the distance is 0.9 to 1.25 times the distance L, it is easy to realize a compact antenna 101 and a wide angle of directivity, which is preferable. 2 L 1 If it is less than 0.75 times, the surface area of ​​the inner conductor plate 20 that reflects the radio waves radiated from the outer conductor plate 10 becomes small, so that the antenna gain of the antenna 101 may decrease. 2 L1 If it exceeds 1.5 times, the portion of the inner conductor plate 20 that protrudes from the outer conductor plate 10 in a side view of the outer conductor plate 10 will become large, making it difficult to reduce the size of the antenna 101. There is a trade-off between reducing the size of the antenna 101 and improving the antenna gain, but the antenna 101 that achieves this can be configured according to predetermined specifications.

[0031] In addition, in a side view of the external conductor plate 10, the internal conductor plate 20 may have a portion protruding from the external conductor plate 10. The portion protruding from the external conductor plate 10 may be a portion protruding in the negative Z-axis direction or a portion protruding in the Y-axis direction in Fig. 1. Although this makes it difficult to reduce the size of the antenna 101, the surface area of ​​the internal conductor plate 20 that reflects the radio waves radiated from the external conductor plate 10 becomes larger, and therefore the antenna gain of the antenna 101 is improved.

[0032] Alternatively, in a side view of the outer conductor plate 10, the outer conductor plate 10 may overlap the entire inner conductor plate 20. This allows the inner conductor plate 20 to not protrude from the outer conductor plate 10 in a side view of the outer conductor plate 10, thereby making it possible to reduce the size of the antenna 101.

[0033] In addition, in order to match the input impedance of the antenna 101, the slot 30 may be extended until it reaches both the side surface portion 11 and the side surface portion 12. In the example shown in FIG. 1, the slot 30 has a slot end 31 that contacts the side surface portion 11 at an end edge 17, and a slot end 32 that contacts the side surface portion 12 at an end edge 18. The slot 30 can widen the directivity of the antenna 101 even if it does not reach one or both of the side surface portion 11 and the side surface portion 12. In this case, one or both of the slot end 31 and the slot end 32 are located within the front surface portion 13. Alternatively, the slot 30 can widen the directivity of the antenna 101 even if it is extended until it enters one or both of the side surface portion 11 and the side surface portion 12. In this case, the slot end 31 may be located within the side surface portion 11, and the slot end 32 may be located within the side surface portion 12. Furthermore, the slot 30 may be extended to one or both ends of the side portion 11 and the side portion 12 to widen the angle of the directivity of the antenna 101. In this case, the slot end 31 may be located on the end of the side portion 11 (e.g., the side opposite the end 17), and the slot end 32 may be located on the end of the side portion 12 (e.g., the side opposite the end 18).

[0034] In the example shown in FIG. 1, the feed points 41 and 42 are located near the center 35 of the slot 30. This allows the directivity of the antenna 101 to be made wider than in a configuration in which the feed points 41 and 42 are located away from the center 35. The slot 30 has a pair of long sides 33 and 34 extending in the longitudinal direction. When the feed point 41 is located near the center 35 of the long side 33 and the feed point 42 is located near the center 35 of the long side 34, the directivity of the antenna 101 can be made wider. In the example shown in FIG. 1, the center 35 includes a midpoint in the longitudinal direction of the slot 30 from the slot end 31 to the slot end 32. Furthermore, the vicinity of central portion 35 refers to, when an imaginary line is defined that extends from the midpoint in a direction substantially perpendicular to the longitudinal direction of slot 30 and is parallel to front portion 13, the vicinity of the intersection of this imaginary line with long side 33 and the vicinity of the intersection of this imaginary line with long side 34. Note that, for example, when the entire length of slot 30 in the longitudinal direction is taken as 100%, the vicinity of central portion 35 may be in a range of 40% to 60% of the length from slot end 31 (toward slot end 32), or may be in a range of 45% to 55% of the length.

[0035] 1, the front portion 13 is substantially rectangular in a front view of the outer conductor plate 10, and the slot 30 is substantially rectangular in a front view of the outer conductor plate 10. In the outer conductor plate 10 having such a shape, the dimension of the surface portion 15 in a direction substantially perpendicular to the longitudinal direction of the slot 30 is defined as W 1 The dimension of the surface portion 16 in a direction substantially perpendicular to the longitudinal direction of the slot 30 is W 2 In this case, W 2 is W 1 It is sufficient if it is 0.1 times or more and 10 times or less of W 1 Preferably, the value is 0.2 to 9.0 times the value of W 1 More preferably, the ratio is 0.3 to 8.0. 2 But, W 1 If the angle is 0.1 to 10 times the angle of the optical axis, the directivity of the antenna 101 can be made wider.

[0036] The shape of the front portion 13 is substantially rectangular when viewed from the front of the external conductor plate 10, and the dimension of the external conductor plate 10 in a direction substantially perpendicular to the longitudinal direction of the slot 30 is L 1 Let λ be the effective wavelength in the dielectric of the radio wave transmitted and received by the antenna 101. g In this case, L 1 is 0.1×λ g More than 0.6×λ g It is sufficient if it is less than 0.15 × λ g More than 0.55×λ g Less than 0.20×λ is preferable. g More than 0.50×λ g The following is more preferred: 1 But, 0.1×λ g More than 0.6×λ g If it is equal to or less than this, it is possible to achieve both a wide angle of directivity of the antenna 101 and a compact size.

[0037] Effective wavelength λ g represents a wavelength taking into consideration the influence of the dielectric constant of the dielectric materials (such as the case and substrate) surrounding and inside the antenna 101.

[0038] In FIG. 2, the distance between the side surface portion 11 and the side surface portion 21 facing the side surface portion 11 is d 1 The distance between the side surface portion 12 and the side surface portion 22 facing the side surface portion 12 is d 2 Let λ be the effective wavelength in the dielectric of the radio wave transmitted and received by the antenna 101. g In this case, d 1 and d 2 At least one of the following is 0.05×λ g More than 0.5×λ g It is sufficient if it is less than 0.07 × λ g More than 0.4×λ g Less than 0.09×λ is preferable. g More than 0.3×λ g The following is more preferable: d 1 and d 2 At least one of these is 0.05×λ g More than 0.5×λ g If the distance is less than d, the antenna 101 can have a wider angle of directivity and be smaller in size. 1 and d 2 Both are 0.05 × λ g More than 0.5×λ g It is sufficient if it is less than 0.07 × λ g More than 0.4×λ g Less than 0.09×λ is preferable. g More than 0.3×λ g The following is more preferred:

[0039] In FIG. 2, the distance between the front portion 13 and the front portion 23 is d 3 Let λ be the effective wavelength in the dielectric of the radio wave transmitted and received by the antenna 101. g In this case, d 3 is greater than 0 and 0.3×λ g It is sufficient if it is less than 0.02 × λ g More than 0.28×λ g Less than 0.04×λ is preferable. g More than 0.26×λ g The following is more preferable: d 3 is greater than 0 and is 0.3×λ g If it is equal to or less than this, the directivity of the antenna 101 can be made wider.

[0040] Fig. 3 is a cross-sectional view in the ZX plane of a first modified example of the antenna in the first embodiment. Even if one of the front portion 13 and the front portion 23 has a curved portion, the directivity of the antenna 101 can be made wide-angle. In this case, it is preferable that both the front portion 13 and the front portion 23 have a curved portion as shown in Fig. 3, and the directivity of the antenna 101 can be made wide-angle compared to a configuration in which one of the front portions has a curved portion.

[0041] Fig. 4 is a cross-sectional view in the ZX plane of a second modified example of the antenna in the first embodiment. Even if one of the front portion 13 and the front portion 23 has a plurality of planar portions, the directivity of the antenna 101 can be made wide-angle. In this case, it is preferable that both the front portion 13 and the front portion 23 have a plurality of planar portions, and the directivity of the antenna 101 can be made wide-angle compared to a configuration in which one of the front portions has a plurality of planar portions. In the example shown in Fig. 4, both the front portion 13 and the front portion 23 are composed of three planar portions.

[0042] 3 and 4, side surface portion 11 and side surface portion 12 are two-dimensional flat surfaces, but even if at least one of side surface portion 11 and side surface portion 12 has a curved surface, the directivity of antenna 101 can be made wide-angle. Similarly, side surface portion 21 and side surface portion 22 are two-dimensional flat surfaces, but even if at least one of side surface portion 21 and side surface portion 22 has a curved surface, the directivity of antenna 101 can be made wide-angle.

[0043] 5 is a cross-sectional view in the ZX plane of a third modified example of the antenna in the first embodiment. Even if one of the U-shaped portion 14 and the U-shaped portion 24 is arc-shaped, the directivity of the antenna 101 can be made wide-angle. In this case, it is preferable that both the U-shaped portion 14 and the U-shaped portion 24 are arc-shaped, and the directivity of the antenna 101 can be made wide-angle compared to a case where one of them is arc-shaped.

[0044] When the U-shaped portion 14 has an arc shape, for example, the front portion 13 may be defined as an arc portion of the U-shaped portion 14 from the slot end 31 to the slot end 32 in a plan view of the U-shaped portion 14 (as viewed from the Y-axis direction). The side portion 11 may be defined as an arc portion of the U-shaped portion 14 on the opposite side of the front portion 13 with respect to the slot end 31 in a plan view of the U-shaped portion 14. The side portion 12 may be defined as an arc portion of the U-shaped portion 14 on the opposite side of the front portion 13 with respect to the slot end 32 in a plan view of the U-shaped portion 14.

[0045] When the U-shaped portion 24 is an arc shape, for example, the front portion 23 may be defined as an arc portion of the U-shaped portion 24 from the intersection 58 to the intersection 59 in a plan view of the U-shaped portion 24 (viewpoint seen from the Y-axis direction). The intersection 58 refers to a point where a straight line 54 perpendicular to a tangent line passing through the slot end 31 intersects with the U-shaped portion 24, and the intersection 59 refers to a point where a straight line 55 perpendicular to a tangent line passing through the slot end 32 intersects with the U-shaped portion 24. The side portion 21 may be defined as an arc portion of the U-shaped portion 24 on the opposite side of the intersection 58 from the front portion 23 in a plan view of the U-shaped portion 24. The side portion 22 may be defined as an arc portion of the U-shaped portion 24 on the opposite side of the intersection 59 from the front portion 23 in a plan view of the U-shaped portion 24.

[0046] FIG. 6 is a cross-sectional view of the third modified example of the antenna in the first embodiment in the ZX plane, similar to FIG. 5. When the U-shaped portion 14 is an arc shape, the definitions of the front portion 13, the side portion 11, and the side portion 12 may be different from the above definitions. The angle at which the tangent 51 at the junction 56 of the U-shaped portion 14 and the tangent 52 at the junction 57 of the U-shaped portion 14 intersect with the tangent 53 with the bottom point 50 of the U-shaped portion 14 as a junction is defined as θ. In this case, the front portion 13 may be defined as the arc portion of the U-shaped portion 14 from the junction 56 to the junction 57, where θ is 0° or more and 45° or less (in absolute value), in the plan view of the U-shaped portion 14. The side portion 11 may be defined as the arc portion of the U-shaped portion 14 on the opposite side of the front portion 13 with respect to the junction 56, in the plan view of the U-shaped portion 14. The side surface portion 12 may be defined as a circular arc portion of the U-shaped portion 14 on the opposite side to the front surface portion 13 with respect to the contact point 57 in a plan view of the U-shaped portion 14 .

[0047] When the U-shaped portion 24 is an arc-shaped portion, the front portion 23 may be defined as an arc portion of the U-shaped portion 24 from the intersection 58 to the intersection 59 in a plan view of the U-shaped portion 24. The intersection 58 refers to a point where a straight line 54 perpendicular to a tangent 51 passing through a contact point 56 intersects with the U-shaped portion 24, and the intersection 59 refers to a point where a straight line 55 perpendicular to a tangent 52 passing through a contact point 57 intersects with the U-shaped portion 24. The side portion 21 may be defined as an arc portion of the U-shaped portion 24 on the opposite side of the intersection 58 from the front portion 23 in a plan view of the U-shaped portion 24. The side portion 22 may be defined as an arc portion of the U-shaped portion 24 on the opposite side of the intersection 59 from the front portion 23 in a plan view of the U-shaped portion 24.

[0048] As shown in FIGS. 1 to 6, when the front portion 23 has a conductor surface at the location where the power feed points 41 and 42 are projected when the outer conductor plate 10 is viewed from the front, the directivity of the antenna 101 can be made to have a wide angle.

[0049] In addition, the inner conductor plate 20 may be a grounded conductor or a parasitic conductor that is neither grounded nor powered, and can effectively function as a reflector to widen the directivity of the antenna 101.

[0050] Fig. 7 is a perspective view showing a configuration example of an antenna in the second embodiment. Fig. 8 is a cross-sectional view of the configuration example of an antenna in the second embodiment. In the second embodiment, the description of the configuration and effects similar to those of the above-mentioned embodiments will be omitted by citing the above description.

[0051] 7 and 8 includes a coaxial cable 60 electrically connected to the feed point 41 and the feed point 42. The coaxial cable 60 is an example of a feed line. In the example shown in Figs. 7 and 8, an outer conductor 61, which is a ground portion of the coaxial cable 60, is electrically connected to the feed point 41, and an inner conductor 62, which is a signal line of the coaxial cable 60, is electrically connected to the feed point 42.

[0052] When a part of the coaxial cable 60 passes between the front portion 13 and the front portion 23, the robustness of the directivity of the antenna 102 with respect to the coaxial cable 60 is improved, as compared with, for example, a form not shown in which a part of the coaxial cable 60 passes on the positive side in the Z-axis direction with respect to the front portion 13. In order to widen the angle of the directivity of the antenna 102, it is preferable that the coaxial cable 60 is wired such that its tip portion enters the gap between the front portion 13 and the front portion 23 from the positive side in the Y-axis direction to the negative side or from the negative side in the Y-axis direction to the positive side. The coaxial cable 60 may be wired such that its tip portion enters the gap between the side portion 11 and the side portion 21 from the negative side in the Z-axis direction to the positive side.

[0053] The external conductor 61 is electrically connected to the inner surface of the front portion 23 side of the surface portion 15. The internal conductor 62 crosses the slot 30 in the Y-axis direction when the external conductor plate 10 is viewed from the front, and is electrically connected to the inner surface of the front portion 23 side of the surface portion 16.

[0054] Fig. 9 is a perspective view showing a configuration example of an antenna in the third embodiment. Fig. 10 is a cross-sectional view of the configuration example of an antenna in the third embodiment. In the third embodiment, the description of the configuration and effects similar to those of the above-mentioned embodiments will be omitted by citing the above description.

[0055] 9 and 10 includes a coaxial cable 60 electrically connected to the feed point 41 and the feed point 42. The coaxial cable 60 is an example of a feed line. In the example shown in Figs. 9 and 10, an outer conductor 61 which is a ground portion of the coaxial cable 60 is electrically connected to the feed point 41, and an inner conductor 62 which is a signal line of the coaxial cable 60 is electrically connected to the feed point 42.

[0056] As in the second embodiment described above, a portion of the coaxial cable 60 passes between the front portion 13 and the front portion 23. In the example shown in Figs. 9 and 10, the front portion 23 has an opening 29 through which the coaxial cable 60 passes. By passing the coaxial cable 60 through the opening 29, a portion of the coaxial cable 60 can be wired inside the inner conductor plate 20, so that the effect of the coaxial cable 60 on the antenna 103 can be suppressed and the directivity can be stabilized.

[0057] When the opening 29 is positioned at the center of gravity of the front portion 23, the effect of the coaxial cable 60 on the antenna 103 can be further suppressed, and the directivity becomes more stable.

[0058] The tip of the coaxial cable 60 contacts the inner surface of the front portion 23 side of the surface portion 15. The outer conductor 61 is electrically connected to the surface portion 15. The inner conductor 62 crosses the slot 30 in the Y-axis direction when viewed from the front of the outer conductor plate 10, and is electrically connected to the outer surface of the surface portion 16 opposite to the front portion 23.

[0059] Fig. 11 is a perspective view showing a configuration example of an antenna in the fourth embodiment. Fig. 12 is a cross-sectional view showing a configuration example of an antenna in the fourth embodiment. In the fourth embodiment, the description of the same configuration and effects as those of the above-mentioned embodiments will be omitted by citing the above description.

[0060] 11 and 12 includes a coplanar line 63 electrically connected to the feed point 41 and the feed point 42. The coplanar line 63 is an example of a feed line, and more specifically, an example of a planar waveguide. In the example shown in FIGS. 11 and 12, the coplanar line 63 has a dielectric substrate 64 on which a strip conductor 65 and ground planes 66a and 66b are formed. The dielectric substrate 64 is disposed parallel to the ZX plane so as to be located between a pair of long sides 33 and 34 of the slot 30 when the external conductor plate 10 is viewed from the front.

[0061] The strip conductor 65 is a signal line formed on the surface of the dielectric substrate 64 on the positive side in the Y-axis direction. The strip conductor 65 has one end electrically connected to the inner conductor of the coaxial cable 60 and the other end electrically connected to the feeding point 41 via a connecting conductor 67c. The connecting conductor 67c is a conductor piece extending in the Y-axis direction.

[0062] The ground planes 66a and 66b are grounding parts formed on the surface of the positive side in the Y-axis direction of the dielectric substrate 64, and are formed with a gap on both sides of the strip conductor 65. The ground plane 66a has one end electrically connected to the outer conductor of the coaxial cable 60 and the other end electrically connected to the first feeding portion 42a of the feeding point 42 via a connecting conductor 67a. The ground plane 66b has one end electrically connected to the outer conductor of the coaxial cable 60 and the other end electrically connected to the second feeding portion 42b of the feeding point 42 via a connecting conductor 67b. The connecting conductors 67a and 67b are conductor pieces extending in the Y-axis direction on both sides of the connecting conductor 67c in the X-axis direction.

[0063] A part of the coplanar line 63 passes between the front portion 13 and the front portion 23, as in the second and third embodiments described above. In the example shown in Figs. 11 and 12, the dielectric substrate 64 is a U-shaped substrate installed in the space between the outer conductor plate 10 and the inner conductor plate 20, and is arranged parallel to the ZX plane. The inner conductor plate 20 may be a grounded conductor grounded to the ground surface 66a, or a parasitic conductor that is neither grounded nor fed, and can effectively function as a reflector to widen the directivity of the antenna 104.

[0064] The planar waveguide is not limited to a coplanar line, but may be another type of transmission line such as a microstrip line.

[0065] 13 is a perspective view showing a configuration example of an antenna in the fifth embodiment. In the fifth embodiment, the description of the configuration and effects similar to those of the above-mentioned embodiments will be omitted by citing the above description.

[0066] The antenna 105 shown in FIG. 13 may include a matching circuit 68 that matches the impedance between the feeding point 42 to which the inner conductor 62, which is the signal line of the coaxial cable 60, is connected and the feeding point 41 to which the outer conductor 61, which is the ground part of the coaxial cable 60, is connected. The matching circuit 68 has at least one impedance element Z (e.g., an inductor or a capacitor). The antenna in each of the above-mentioned embodiments may also include the matching circuit 68. Note that a dielectric substrate (not shown) can be separately arranged on the outside of the front part 13 in FIG. 13 (the side opposite to the front part 23), and a PCB substrate containing an epoxy resin may be used as the dielectric substrate. For example, the front part 13 of the outer conductor plate 10 of the antenna 105 shown in FIG. 13 may be formed by a conductor provided on the first main surface of the PCB substrate, and the matching circuit 68 may include an element such as an inductance or a capacitor arranged on the second main surface (the side opposite to the first main surface) of the PCB substrate. 13, the front portion 13 and the matching circuit 68 of the external conductor 10 may both be disposed on the first main surface of the PCB. When the PCB is provided on the outside of the front portion 13, the front portion 13 may be flat along the XY plane.

[0067] Fig. 14 is a diagram showing an example of mounting an antenna in each embodiment on a vehicle. The antenna system 100 shown in Fig. 14 includes a windshield 71, a rear windshield 72, a front antenna 111 attached to the windshield 71, and a rear antenna 112 attached to the rear windshield 72. The windshield 71 and the rear windshield 72 are each an example of a window glass of a vehicle. The front antenna 111 and the rear antenna 112 are each an example of an antenna in each embodiment such as the antenna 101.

[0068] It is preferable that the front portion 13 of the front antenna 111 is installed at an inclination (inclination angle β) of ±15° or less with respect to the vertical plane 91 perpendicular to the horizontal plane 90. This improves the antenna gain of the front antenna 111 in a direction parallel to the horizontal plane 90 (toward the front of the vehicle), and since the side portions 11 and 12 are arranged apart from each other on both sides in the vehicle width direction, the antenna gain in the vehicle width direction is improved. On the other hand, if the front portion 13 of the front antenna 111 is installed at an angle of more than ±15° with respect to the vertical plane 91 perpendicular to the horizontal plane 90, the balance of the antenna gain in the direction parallel to the horizontal plane 90 is lost, that is, there is a risk that the difference between the gain in the vehicle's traveling direction and the gain in the vehicle width direction will become large.

[0069] Similarly, it is preferable that the front portion 13 of the rear antenna 112 is installed at an inclination (inclination angle β) of ±15° or less with respect to the vertical plane 91 perpendicular to the horizontal plane 90. This improves the antenna gain of the rear antenna 112 in a direction parallel to the horizontal plane 90 (toward the rear of the vehicle), and since the side portions 11 and 12 are arranged apart from each other on both sides in the vehicle width direction, the antenna gain in the vehicle width direction is improved. On the other hand, if the front portion 13 of the rear antenna 112 is installed at an angle of more than ±15° with respect to the vertical plane 91 perpendicular to the horizontal plane 90, the balance of the antenna gain in the direction parallel to the horizontal plane 90 is lost, that is, there is a risk that the difference between the gain in the vehicle's traveling direction and the gain in the vehicle width direction will become large.

[0070] The front part 13 of the front antenna 111 is preferably installed at an inclination of ±10° or less with respect to the vertical plane 91 perpendicular to the horizontal plane 90, and more preferably at an inclination of ±5° or less. Similarly, the front part 13 of the rear antenna 112 is preferably installed at an inclination of ±10° or less with respect to the vertical plane 91 perpendicular to the horizontal plane 90, and more preferably at an inclination of ±5° or less.

[0071] The front antenna 111 may be attached directly or indirectly to the windshield 71 so that the front portion 13 is located on the vehicle front side relative to the front portion 23, and the rear antenna 112 may be attached directly or indirectly to the rear windshield 72 so that the front portion 13 is located on the vehicle rear side relative to the front portion 23. In this way, the front antenna 111 improves the antenna gain in the region extending from the front of the vehicle in the vehicle width direction, and the rear antenna 112 improves the antenna gain in the region extending from the rear of the vehicle in the vehicle width direction. Thus, the antenna gain in 360° directions centered on the vehicle 80 can be improved.

[0072] Moreover, it is preferable that the front portion 23 of the front antenna 111 is installed at an inclination (inclination angle α) of ±15° or less with respect to the vertical plane 91 perpendicular to the horizontal plane 90. This improves the antenna gain of the front antenna 111 in a direction parallel to the horizontal plane 90 (toward the front of the vehicle), and since the above-mentioned side portions 21 and 22 are arranged apart from each other on both sides in the vehicle width direction, the antenna gain in the vehicle width direction is improved. The same applies to the inclination angle α of the front portion 23 of the rear antenna 112.

[0073] Note that being installed at 0° with respect to the vertical plane 91 means being installed parallel to the vertical plane 91.

[0074] 14, vehicle antennas are attached directly or indirectly to the windshield 71 and the rear window 72. However, the antenna system 100 may include at least two window panes of the windshield 71, the rear window 72, and the side window 73, and at least one antenna attached directly or indirectly to each of the at least two window panes.

[0075] Fig. 15 is a perspective view showing a configuration example of an antenna in a comparative embodiment. The antenna shown in Fig. 15 includes two conductor plates 210 and 220 spaced apart from each other, and conductor plate 210 has a slot 230. This antenna is fed at feeding points 241 and 242 on either side of slot 230.

[0076] Fig. 16 is a diagram showing an example of a simulation result of the directivity in the ZX plane of the antenna in the comparative embodiment shown in Fig. 15 under the condition of vertical polarization with a frequency of 5.9 GHz. The half-width of the antenna shown in Fig. 15 was 52.5°, which was relatively narrow.

[0077] In the simulation of FIG. 16, the dimensions of each part of the antenna in FIG. 15 are as follows, in mm units: D 11 :20 D 12 :27 D 13 :45 D 14 :45 D 15 :2 D 16 :17 D 17 :13 It was.

[0078] On the other hand, Fig. 17 is a diagram showing an example of a simulation result of the directivity in the ZX plane of the antenna 101 in the first embodiment shown in Figs. 1 and 2 under the condition of vertically polarized waves with a frequency of 5.9 GHz. The half-width of the antenna 101 was 138.0°, which was wider than that of the antenna of a comparative embodiment (the antenna shown in Fig. 15). In other words, a wider angle of the antenna directivity was achieved.

[0079] In the simulation of FIG. 17, the dimensions of each part of the antenna 101 are as follows, in mm: L 1 :20 L 2 :20 D 1 :2 D 2 :14 D 3 :17 D 4 :10 D 5 :3 At this time, the length D of the slot 30 in the longitudinal direction 3 was set to coincide with the distance between end edge 17 and end edge 18 of front portion 13.

[0080] Although the embodiments have been described above, the technology of the present disclosure is not limited to the above-described embodiments. Various modifications and improvements, such as combinations with or substitutions for part or all of other embodiments, are possible. The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2020-204527, filed on December 9, 2020, are hereby incorporated by reference as the disclosure of the present invention. [Explanation of symbols]

[0081] 10 Outer conductor plate 10a Upper edge 10b Lower edge 11,12,21,22 Side part 13,23 Front 14,24 U-shaped part 15,16 Surface part 17,18,27,28 Edge 20 Inner conductor plate 20a top end 20b bottom end 29 Aperture 30 Slots 31,32 Slot end 33,34 Long side 35 Central part 41,42 Power supply point 50 bottom point 56,57 Contacts 51,52,53 tangent 54,55 straight line 58,59 intersection 60 Coaxial Cable 61 Outer conductor 62 Inner conductor 63 Coplanar Line 64 Dielectric Substrate 65 Strip conductor 66a,66b Ground plane 67a, 67b, 67c Connecting conductor 68 Matching circuit 71 Windshield 72 Rear window 73 Side glass 80 vehicles 90 horizontal plane 91 Vertical Plane 100 Antenna System 101 Antenna 111 Front Antenna 112 Rear antenna 210,220 Conductor plate 230 Slots 241,242 Power supply point

Claims

1. a first conductive plate and a second conductive plate disposed inside the first conductive plate with a gap therebetween; the first conductive plate includes a first U-shaped portion formed in a U-shape by a first side portion, a second side portion opposing the first side portion, and a first front portion connected between the first side portion and the second side portion, the second conductive plate includes a second U-shaped portion formed into a U-shape by a third side portion, a fourth side portion opposing the third side portion, and a second front portion connected between the third side portion and the fourth side portion, The second front portion faces the first front portion, the first front portion has a slot dividing at least a portion of the first front portion into a first surface portion and a second surface portion; The first surface portion has a first power supply point, The second surface portion has a second feed point.

2. The antenna according to claim 1 , wherein a first side between the first front portion and the first side portion and a second side between the first front portion and the second side portion each include at least one line segment.

3. The antenna of claim 2 , wherein the line segment of the first side is substantially parallel to the line segment of the second side.

4. The antenna according to claim 2 or 3, wherein the slot extends in a direction intersecting both the first side and the second side.

5. The antenna of claim 4 , wherein the slot extends in a direction substantially perpendicular to both the first side and the second side.

6. The antenna according to claim 1 , wherein the first front portion is substantially orthogonal to both the first side portion and the second side portion.

7. The antenna according to claim 1 , wherein the second front portion is substantially parallel to the first front portion.

8. The antenna according to claim 1 , wherein the second front portion is substantially orthogonal to both the third side portion and the fourth side portion.

9. the first side surface portion is substantially parallel to the third side surface portion opposed to the first side surface portion, The antenna according to claim 1 , wherein the second side portion is substantially parallel to the fourth side portion opposite the second side portion.

10. The dimension of the first conductor plate in a direction substantially perpendicular to the longitudinal direction of the slot is defined as L. １ and the dimension of the second conductor plate in a direction substantially perpendicular to the longitudinal direction of the slot is L ２ Then, L ２ L １ The antenna according to claim 1 , wherein the θ is 0.75 to 1.5 times greater than the θ.

11. The antenna according to claim 1 , wherein, in a side view of the first conductive plate, the second conductive plate has a portion that protrudes from the first conductive plate.

12. The antenna according to claim 1 , wherein the first conductive plate overlaps the entire second conductive plate in a side view of the first conductive plate.

13. 13. An antenna as claimed in any preceding claim, wherein the slot extends at least to both the first side portion and the second side portion.

14. 14. An antenna as claimed in any one of claims 1 to 13, wherein the first feed point and the second feed point are located near a centre of the slot.

15. The first front portion is substantially rectangular in a front view of the first conductor plate, The slot has a substantially rectangular shape when viewed from the front of the first conductive plate, The dimension of the first surface portion in a direction substantially perpendicular to the longitudinal direction of the slot is W １ and the dimension of the second surface portion in a direction substantially perpendicular to the longitudinal direction of the slot is W ２ Then, W ２ , W １ The antenna according to claim 1 , wherein the θ is 0.1 to 10 times greater than the θ.

16. The dimension of the first conductor plate in a direction substantially perpendicular to the longitudinal direction of the slot is defined as L. １ Let λ be the effective wavelength of the radio waves in the dielectric body to be transmitted and received. ｇ Then, L １ is 0.1 × λ ｇ More than 0.6×λ ｇ 16. The antenna of claim 15, wherein:

17. The distance between the first side surface portion and the third side surface portion facing the first side surface portion is defined as d １ The distance between the second side portion and the fourth side portion facing the second side portion is d ２ Let λ be the effective wavelength of the radio waves in the dielectric body to be transmitted and received. ｇ Then, d １ and ２ At least one of the following is 0.05×λ ｇ More than 0.5×λ ｇ 17. An antenna according to any one of claims 1 to 16, wherein:

18. The distance between the first front portion and the second front portion is d ３ Let λ be the effective wavelength of the radio waves in the dielectric body to be transmitted and received. ｇ Then, d ３ is greater than 0 and 0.3×λ ｇ 18. An antenna according to any one of claims 1 to 17, wherein:

19. a feed line electrically connected to the first feed point and the second feed point; The antenna according to claim 1 , wherein the second front portion has an opening through which the feed line passes.

20. 20. The antenna of claim 19, wherein the opening is located at the center of gravity of the second front portion.

21. 21. An antenna according to claim 19 or 20, wherein the feed line is a coaxial cable.

22. The antenna according to claim 1 , wherein the second front portion has a conductor surface at a position where the first feed point and the second feed point are projected in a front view of the first conductor plate.

23. a feed line electrically connected to the first feed point and the second feed point; 23. The antenna of claim 22, wherein a portion of the feed line passes between the first front portion and the second front portion.

24. 24. The antenna of claim 23, wherein the feed line is a coaxial cable.

25. 25. The antenna according to claim 1, wherein the second conductive plate is a parasitic conductor.

26. a planar waveguide electrically connected to the first feed point and the second feed point; 19. An antenna as claimed in any one of claims 1 to 18, wherein a portion of the planar waveguide passes between the first front portion and the second front portion.

27. 27. The antenna of claim 26, wherein the second conductive plate is a parasitic conductor.

28. 27. The antenna of claim 26, wherein the planar waveguide has a ground portion electrically connected to the second conductor plate.

29. 29. An antenna as claimed in any one of claims 26 to 28, wherein the planar waveguide is a coplanar line.

30. 30. The antenna according to claim 1, which transmits and receives radio waves having a frequency of 3.3 GHz or more and 6 GHz or less.

31. 31. The antenna according to claim 1, wherein the antenna is installed on a vehicle such that the first front portion and the second front portion are inclined within ±15° with respect to a vertical plane perpendicular to a horizontal plane.

32. 32. An antenna as claimed in any one of claims 1 to 31 arranged on the inside of at least one of a front windshield and a rear windshield of a vehicle.

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