Antenna equipment and vehicle antenna equipment

Abstract

[Problem] To facilitate the achievement of a desired antenna gain with a structure in which a connector having a metal member is used to connect a transmission line to an antenna. [Solution] The present invention comprises: an antenna 50 that has a dielectric substrate 52, a radiation plate 56, and a ground conductor plate 54; a connector 70 that is provided to the surface of the ground conductor plate on the reverse side from the radiation plate side, includes a metal member, is fixed to the antenna, and supports a transmission line; and a cover member 95 that faces the surface of the ground conductor plate on the reverse side from the radiation plate side, and is formed from an electrically-grounded conductor. In a front view of the antenna, the position of a power-feeding point on the radiation plate, which is a location where power is supplied from the transmission line, differs from the center of gravity position of the radiation plate, and when the antenna, the connector, and the cover member are viewed along a direction orthogonal to a first straight line connecting the center of gravity and the power-feeding point and to the thickness direction of the dielectric substrate, the antenna and the cover member cover the periphery of the connector.

Description

Technical Field

[0001] The present disclosure relates to an antenna device and a vehicle antenna device.

Background Art

[0002] In recent years, with the increase in the level of autonomous driving, vehicles tend to be equipped with a communication system that realizes V2X (Vehicle to Everything) such as vehicle-to-vehicle communication and vehicle-to-roadside communication. A vehicle equipped with a V2X communication system requires a V2X antenna with an antenna gain and directivity that satisfy the V2X communication standard so that various out-of-vehicle information related to safety can be obtained using, for example, vertically polarized waves in a narrow band in the 5.8 GHz band or 5.9 GHz band.

[0003] In the horizontal plane, the V2X antenna is required to have a directivity that realizes a desired gain, for example, in a range of ±90° (180°) centered on the front (traveling direction) of the vehicle. Such a V2X antenna is not limited in the place where it is arranged as long as a desired antenna gain and directivity can be realized.

[0004] Japanese Patent Application Laid-Open No. 2019-75644 and International Publication No. 2019 / 163521 disclose a configuration in which an antenna device having a radiation surface facing the windshield or the rear glass on the vehicle interior side is used as an in-vehicle antenna for V2X communication In these antenna devices, power is supplied from one end of a transmission line such as a coaxial cable to a radiation plate (radiating conductor), and an ECU (Electrical Control Unit) connected to the other end of the transmission line performs signal control in the antenna device.

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the in-vehicle antenna devices disclosed in Japanese Patent Publication No. 2019-75644 and International Publication No. 2019 / 163521, the coaxial connector for the substrate, which is attached to the housing containing the patch antenna, includes a metal component. This metal component may cause a change in the antenna's directivity, potentially preventing the achievement of the desired antenna gain.

[0006] This disclosure, taking the above facts into consideration, aims to provide an antenna device and a vehicle antenna device that include a structure for connecting a transmission line to an antenna using a connector having a metal member, and that can achieve desired antenna gain and directivity. [Means for solving the problem]

[0007] The antenna device according to this disclosure comprises an antenna having a dielectric substrate, a radiating plate having a radiating surface that radiates radio waves in a predetermined frequency band on a first main surface of the dielectric substrate, and a grounding conductor plate disposed on a second main surface of the dielectric substrate, a connector provided on the side of the grounding conductor plate opposite to the radiating plate side, including a metal member and fixed to the antenna to support a transmission line, and a cover member made of an electrically grounded conductor facing the side of the grounding conductor plate opposite to the radiating plate side, wherein in a front view of the antenna, the position of the feed point on the radiating plate, which is the part to which power is supplied from the transmission line, is different from the position of the center of gravity of the radiating plate, and when the antenna, the connector and the cover member are viewed along a first straight line connecting the center of gravity and the feed point and in a direction perpendicular to the thickness direction of the dielectric substrate, the antenna and the cover member cover the area around the connector. [Effects of the Invention]

[0008] The antenna device and vehicle antenna device according to this disclosure include a structure in which a transmission line is connected to an antenna using a connector having a metal member, and can achieve desired antenna gain and directivity. [Brief explanation of the drawing]

[0009] [Figure 1]This is a plan view from the vertical direction of a vehicle to which the vehicle antenna device according to the embodiment of this disclosure is applied. [Figure 2] These are schematic cross-sectional views of the front and rear of the vehicle. [Figure 3] This is a perspective view of the antenna device, with the second connector and coaxial cable omitted. [Figure 4] This is a front view of the antenna device. [Figure 5] This is a cross-sectional view of the antenna device along the line 5-5 in Figure 3. [Figure 6] Figures 4 and 5 show a cross-sectional view of the antenna device along the line 6-6. [Figure 7] This is a perspective view of the assembly structure of the first connector, the second connector, and the coaxial cable. [Figure 8] This figure shows the measurement results of the directivity of vehicle antenna devices for Example 1, which is an embodiment, and Example 2, which is a comparative example. [Figure 9] This is a rear view of a vehicle antenna device similar to Figure 7, which is a modified example of the present disclosure. [Modes for carrying out the invention]

[0010] The vehicle antenna device 40 according to an embodiment of this disclosure will be described below with reference to the attached drawings. As will be described later, the vehicle antenna device 40 of this embodiment is installed on a vehicle 10. The X-axis, as shown appropriately in each figure, is parallel to the vehicle width direction of the vehicle 10, the Y-axis is parallel to the vehicle's longitudinal direction, and the Z-axis is parallel to the vehicle's vertical direction and is also called the "vertical direction". Furthermore, arrow FR indicates the front in the vehicle's longitudinal direction, arrow UP indicates the upper part in the vehicle's vertical direction, and arrow LF indicates the left side in the vehicle width direction. The XY plane is a plane that passes through the X-axis and Y-axis and is also called the "horizontal plane". That is, in the following description, the vehicle 10 is located on the horizontal plane, the vehicle's vertical direction and the vertical direction coincide, and the XY plane and the horizontal plane coincide, and the vertical direction corresponds to the normal direction to the horizontal plane. Furthermore, the XZ plane is a plane that passes through the X-axis and Z-axis, and the YZ plane is a plane that passes through the Y-axis and Z-axis.

[0011] Figure 1 is a plan view of a vehicle to which the vehicle antenna device of this embodiment is attached, as seen from the vertical direction, and Figure 2 is a schematic cross-sectional view of the front and rear of the vehicle. As shown in Figure 1, the vehicle 10 has a body 12 including a metal body, the metal body including, for example, a roof 14, an A-pillar (front pillar) 16, and a C-pillar (rear pillar) 20.

[0012] A roughly rectangular front opening 22 is formed at the front of the vehicle body 12. The upper edge of the front opening 22 is adjacent to the front edge 14A of the roof portion 14, and the left and right side edges of the front opening 22 are adjacent to the left and right A-pillars 16. A windshield (vehicle window glass) 28 is fitted into the front opening 22, and the peripheral edge of the windshield 28 is fixed to the peripheral edge of the front opening 22 with an adhesive such as urethane resin. As shown in Figure 2, the windshield 28 is inclined at an angle θ1 with respect to the XY plane 100, which corresponds to the horizontal plane, such that in a side view (from the X-axis direction), the lower end is located in front of the upper end.

[0013] A roughly rectangular rear opening 24 is formed at the rear of the vehicle body 12. The upper edge of the rear opening 24 is adjacent to the rear edge 14B of the roof portion 14, and the left and right side edges of the rear opening 24 are adjacent to the left and right C pillars 20. A rear glass (vehicle window glass) 34 is fitted into the rear opening 24, and the peripheral edge of the rear glass 34 is fixed to the peripheral edge of the rear opening 24 with an adhesive such as urethane resin. As shown in Figure 2, the rear glass 34 is inclined at an angle θ2 with respect to the XY plane 100, which corresponds to the horizontal plane, such that in a side view (from the X-axis direction), the lower end is located behind the upper end.

[0014] Furthermore, as shown in Figures 1 and 2, a communication antenna 50 is attached to the upper part of the main surface of the windshield 28 in the vehicle's vertical direction via a bracket (not shown). The communication antenna 50 is mounted such that, as shown in Figure 2, the normal vector Dnf of the radiating surface 56C, which extends forward from the radiating surface 56C, passes through the windshield 28. Note that the normal vector Dnf in Figure 2 is the normal to the radiating surface 56C when the inclination angle α, which will be described later, is 0°. Furthermore, as shown in Figure 2, the communication antenna 50 is mounted such that the normal vector Dnr of the radiating surface 56C, which extends rearward from the radiating surface 56C, passes through the rear window 34. Note that the normal vector Dnr in Figure 2 is the normal to the radiating surface 56C when the inclination angle α, which will be described later, is 0°.

[0015] The components of the vehicle antenna device 40 are a vehicle window glass such as a windshield 28 or rear glass 34, a communication antenna 50, a first connector 70, a second connector 80, a coaxial cable (transmission line) 90, and a cover member 95. Furthermore, the components of the antenna device 43 are a communication antenna 50, a first connector 70, a second connector 80, a coaxial cable 90, and a cover member 95. The first connector 70 and the second connector 80 may be constructed as separate components or may be manufactured as a single unit. In this specification, when simply referred to as "connector," it includes both configurations in which the first connector 70 and the second connector 80 are constructed as separate components and configurations in which they are manufactured as a single unit, and refers to a jig that connects the transmission line (coaxial cable 90) and the antenna 50.

[0016] The coaxial cable 90 is an example of a transmission line for transmitting high-frequency signals. Other transmission lines include microstrip lines, strip lines, coplanar waveguide, GCPW (coplanar waveguide with ground plane), coplanar strip, slot line, waveguide, etc. In this specification, unless otherwise specified, the transmission line will be described as a structure including the coaxial cable 90. The communication antenna 50 of this embodiment is a vertical polarization antenna with a higher antenna gain for transmitting and receiving vertical polarization waves compared to horizontal polarization waves. Hereinafter, the V2X antenna to be described is an antenna capable of transmitting and receiving particularly by vertical polarization waves and can utilize radio waves in the 5.8 GHz band or radio waves in the 5.9 GHz band.

[0017] Next, the antenna device 43 and the communication antenna 50 (hereinafter simply referred to as "antenna 50") in the vehicle antenna device 40 according to this embodiment will be described. FIGS. 3 and 4 are a perspective view and a front view of the antenna device 43, respectively. FIG. 5 is a cross-sectional view of the antenna device 43 taken along "5-5" in FIG. 3, and FIG. 6 is a cross-sectional view of the antenna device 43 taken along "6-6" in FIGS. 4 and 5.

[0018] As shown in FIG. 6, the antenna 50 of this embodiment includes a dielectric substrate 52, a first conductor plate 54, a second conductor plate 55, a feeding portion 60, and a connecting conductor 62. Also, as shown in FIGS. 3 and 4, the first conductor plate 54 is a ground conductor plate 54 having a ground potential, and the second conductor plate 55 has a radiation plate 56 and a planar conductive line (transmission line) 57. However, the second conductor plate 55 does not necessarily have to include the planar conductive line 57 and may be only the radiation plate 56. Examples of the materials constituting the first conductor plate 54 and the second conductor plate 55 include, but are not limited to, copper and silver.

[0019] Thus, the antenna 50 of this embodiment is a patch antenna (microstrip antenna). The antenna 50 of this embodiment can be used, for example, as the above V2X antenna, but may also be configured to be able to transmit and receive linearly polarized waves in a frequency band different from these.

[0020] As shown in FIGS. 3 and 6, a radiation plate 56 having a smaller area than the first conductor plate 54 is provided on the main surface 52B of the dielectric substrate 52. The second conductor plate 55 is a planar layer. The front shape of the radiation plate 56 is substantially rectangular (square). That is, the radiation plate 56 has a shape in which a notch 56X is formed at the upper edge of the rectangle in a front view, but the notch 56X may be provided at the lower edge instead of the upper edge of the rectangle. Note that the "front view" in this specification means viewing the antenna 50 along the Y-axis direction (the thickness direction of the dielectric substrate 52).

[0021] The radiation plate 56 shown in FIGS. 3 and 4 is provided with a feeding point 56A1 located near the bottom of the notch 56X. The front shape of the planar conductive line 57 is substantially J-shaped. That is, although the planar conductive line 57 itself is different from the coaxial cable 90, it is a part of the transmission line and is formed on the main surface 52B of the dielectric substrate 52 to electrically supply a high-frequency signal to the feeding point 56A1.

[0022] The planar conductive line 57 has a first portion 57A extending upward from the bottom of the notch 56X of the radiation plate 56, a second portion 57B extending rightward from the upper end of the first portion 57A, and a third portion 57C extending downward from the upper end of the second portion 57B, forming a J shape. A first end portion 57C1 connected to the feeding point 56A1 is provided at the lower end of the first portion 57A, and a second end portion 57C2 is provided at the lower end of the third portion 57C. As shown in FIGS. 3 and 4, in the front view of the antenna 50, the feeding point 56A1 is separated from the center of gravity 56B of the radiation plate 56.

[0023] Also, as shown in FIG. 4, in the front view of the antenna 50, when a first straight line L1 passing through the feeding point 56A1 and the center of gravity 56B is given, the antenna 50 radiates a linearly polarized wave vibrating along the first straight line L1. For example, if the antenna 50 is designed to radiate a linearly polarized wave in the 5.8 GHz band or the 5.9 GHz band, and in the vehicle antenna device 40, if the direction of the linearly polarized wave is the vertical direction, it functions as a V2X antenna for transmitting and receiving vertical polarized waves.

[0024] Furthermore, as shown in Figure 4, the antenna 50 may include one or both of the first element 66 and the second element 68, which are unpowered conductor plates. The first element 66 and the second element 68 are independent conductor plates that are not connected to ground wires such as the signal line 91 and the outer conductor 93, which are internal conductors of the coaxial cable 90. The materials that make up the first element 66 and the second element 68 include, for example, copper and silver, but are not limited to these. In Figure 4, the first element 66 and the second element 68 are rectangular in a front view of the antenna 50, but they may have shapes other than rectangles. However, if the front view shape of the first element 66 and the second element 68 extends in the Z-axis direction, the antenna gain in the X-axis direction (vehicle width direction) can be increased in the vehicle antenna device 40.

[0025] If the antenna 50 has a first element 66 and a second element 68, in the vehicle antenna device 40, these may be separated from each other in the vehicle width direction (horizontal direction) and also separated from the dielectric substrate 52 in the X-axis direction. That is, as shown in Figure 4, in a front view of the antenna 50, the first element 66 and the second element 68 are arranged outside the ground conductor plate 54. In this case, the positions of the first element 66 and the second element 68, which are unpowered conductor plates, may be different from the center of gravity 56B in a front view of the antenna 50. Also, in a front view of the antenna 50, the radiating plate 56 (center of gravity 56B) is located between the first element 66 and the second element 68.

[0026] Furthermore, although not shown in the diagram, when the antenna 50 is viewed along the Z-axis, the first element 66 and the second element 68 are arranged on the same plane as the main surface 52B of the dielectric substrate 52. However, the first element 66 and the second element 68 may be arranged on the opposite side of the main surface 52A from the radiating surface 56C side, or they may be arranged on the same plane as the main surface 52A but in a position that does not contact the grounding conductor plate 54. The main surfaces 52B and 52A of the dielectric substrate 52 are the first main surface and the second main surface of the dielectric substrate 52, respectively. When the first element 66 and the second element 68 are arranged on a plane different from the radiating plate 56 and the grounding conductor plate 54, in a front view of the antenna 50, at least one of the first element 66 and the second element 68 may overlap with part or all of the grounding conductor plate 54, or with part of the radiating plate 56 excluding the centroid 56B.

[0027] The dielectric substrate 52 is a plate-shaped or film-shaped dielectric layer, typically a rectangular parallelepiped dielectric layer. However, "plate-shaped or film-shaped" here may include, for example, convex, concave, or wavy portions. The same applies to the ground conductor plate 54, radiating plate 56, first element 66, and second element 68, but these are typically formed in a planar shape and thinner than the thickness of the dielectric layer. When these components are planar, it becomes easier to predict the antenna gain characteristics of the antenna 50.

[0028] Furthermore, although the front shape of the dielectric substrate 52 shown in Figure 4 is a square, it may also be a rectangle in which the X-axis direction is longer than the Z-axis direction, or any other shape such as a polygon, a circle, or a shape with a curved outer edge. The dielectric substrate 52 has a main surface 52A which is one surface in the thickness direction, and a main surface 52B which is parallel to the main surface 52A. For example, a glass epoxy substrate can be used as the dielectric substrate 52. Note that if the front shape of the dielectric substrate 52 is a rectangle which is longer in the direction perpendicular to the straight line L1 (vehicle width direction), then an area for arranging the first element 66 and the second element 68 can be secured on at least one of the main surfaces 52A and 52B of the dielectric substrate 52.

[0029] Next, we will describe the components arranged on the main surface 52A of the dielectric substrate 52. As shown in Figures 5 and 6, the main surface 52A of the dielectric substrate 52 is provided with a grounding conductor plate 54 and a signal transmission unit 54S. The signal transmission unit 54S is electrically connected to the power supply unit 60 and is also part of the transmission line. As shown in Figure 5, the outer edge of the grounding conductor plate 54 is square-shaped. In addition, a square opening 54X is formed on the inside of the grounding conductor plate 54, and the signal transmission unit 54S is provided on the inside of the inner circumferential surface of the opening 54X. That is, the grounding conductor plate 54 and the signal transmission unit 54S are spaced apart and do not come into contact. Note that the outer edge of the opening 54X is not limited to a square shape, but may be any shape other than a square.

[0030] The power supply unit 60 is connected to the signal transmission unit 54S and is also electrically connected to one end 91A of the signal line 91 of the coaxial cable 90. The end of the signal line 91 opposite to end 91A is connected to a control device that controls the signal from the antenna 50, and the end of the outer conductor 93 opposite to end 91A should be grounded.

[0031] As shown in Figure 6, the connecting conductor 62 included in the antenna 50 is a conductive pin provided inside a through-hole that penetrates the dielectric substrate 52 in the direction of its thickness. One end of the connecting conductor 62 is connected to the feed point 60 without contacting the ground conductor plate 54, and the other end is connected to the second end 57C2 of the planar conductive line 57. Also, as shown in Figures 3 and 4, the feed point 56A1, which corresponds to the end of the planar conductive line 57 opposite to the second end 57C2 in a front view, is away from the center of gravity 56B of the radiating plate 56. As shown in Figures 4 and 5, in a front view of the antenna 50, the center of gravity 56B and the center of gravity 54A of the ground conductor plate 54 coincide.

[0032] Figure 7 is a perspective view showing the structure in which the first connector 70, the second connector 80, and the coaxial cable 90 are assembled. As shown in Figures 5 and 6, the first connector (connector) 70 is fixed to the main surface of the ground conductor plate 54 on the side opposite to the second conductor plate 55, with a fixing member 74 in contact with the main surface. The first connector 70 has an insulator 71 and a signal contact (transmission line) (metal member) 72, a ground contact (transmission line) (metal member) 73, and a fixing member (metal member) 74, each of which contains a metal material as a component material. The insulator 71 is made of an insulating material such as resin. The surface of the insulator 71 facing the first conductor plate 54 is a plane parallel to the main surface of the first conductor plate 54.

[0033] In the assembly structure shown in Figure 7, a notch 71A is formed at the lower end of the right end face of the insulator 71. Also, as shown in Figure 5, a recess 71B is formed on the left end face of the insulator 71. Furthermore, as shown in Figures 5 and 6, a groove 71C is formed in the center of the left-right direction of the upper and lower surfaces of the insulator 71. Inside the insulator 71, there is one signal contact 72 and two ground contacts 73, the constituent material of which is metal.

[0034] As shown in Figure 5, in a front view of the antenna 50, the signal contact 72 and the ground contact 73 extend linearly along the X-axis. Furthermore, as shown in Figures 5 to 7, the right ends of the signal contact 72 and the ground contact 73 have tail portions 72A and 73A that are located forward of the rest of the signal contact 72 and the ground contact 73.

[0035] Furthermore, as shown in Figures 5 and 7, fixing members 74, which are metal plates with an L-shaped cross-section, are press-fitted into the upper and lower grooves 71C. The fixing member 74 has a main body portion 74A that is press-fitted into the grooves 71C, and a tail portion 74B that extends from the front end of the main body portion 74A in a direction perpendicular to the main body portion 74A. As shown in Figure 6, the front surface 71f of the insulator 71, the front surface 72Af of the tail portion 72A, the front surface 73Af of the tail portion 73A, and the front surface 74Bf of the tail portion 74B are located on a single plane.

[0036] In the first connector 70, with the insulator 71 and the grounding conductor plate 54 in contact, the tail portions 74B of each fixing member 74 are fixed to the grounding conductor plate 54 with solder or the like, thereby fixing the first connector 70 to the antenna 50. Once the first connector 70 is fixed to the antenna 50, as shown in Figure 6, the tail portions 73A of the two ground contacts 73 are in contact with the grounding conductor plate 54 via solder or the like, and the tail portion 72A of the signal contact 72 is in contact with the signal transmission unit 54S via solder or the like.

[0037] The recess 71B of the first connector 70 has a structure that allows the second connector 80, shown in Figures 5 and 6, to be attached and detached. The second connector 80 has an insulator 81 and a signal contact (transmission line) (metal member) 82 and a ground contact (transmission line) (metal member) 83, the components of which include a metal material. The insulator 81 is made of an insulating material such as resin. The insulator 81 has a main body 81A and a connecting part 81B that protrudes to the right from the right end face of the main body 81A. The second connector 80 has a through hole (not shown) that penetrates the main body 81A and the connecting part 81B in the left-right direction. Inside the insulator 81, there is one signal contact 82 and two ground contacts 83, the components of which include a metal material.

[0038] As shown in Figure 5, in a front view of the antenna 50, the signal contact 82 and the ground contact 83 extend linearly along the X-axis. As mentioned above, the "connector" can connect the coaxial cable 90 and the antenna 50, and may be a single, integrally manufactured fixture rather than a separate configuration like the first connector 70 and the second connector.

[0039] Next, the arrangement of the connector attached to the antenna 50 and supporting the transmission line will be described. Here, as shown in Figure 4, the second straight line L2 is defined as the straight line passing through the centroid 56B in a direction parallel to the X-axis in a front view of the antenna 50. In other words, the second straight line L2 is a straight line passing through the centroid 56B and perpendicular to the first straight line L1 in a front view of the antenna 50. In this case, as shown in Figure 5, in a front view of the antenna 50, the connector is arranged such that the signal contact 72, ground contact 73, fixing member 74, signal contact 82 and ground contact 83 are positioned parallel to the second straight line L2, and the signal contacts 72 and 82 are positioned on the second straight line L2.

[0040] In this context, "parallel" includes the meaning that the signal contact 72, ground contact 73, fixing member 74, signal contact 82, and ground contact 83 are perfectly parallel or nearly parallel to the second line L2. Furthermore, in a front view of the antenna 50, it is desirable that the two fixing members 74 and the two ground contacts 73 be symmetrical with respect to the second line L2, and that the two ground contacts 83 be symmetrical with respect to the second line L2.

[0041] In particular, the two fixing members 74, which are metal members for fixing the connector (first connector 70) and the grounding conductor plate 54, are preferably shaped to extend in a direction approximately perpendicular to the direction of vibration of the linear polarization of the antenna 50 (Z-axis direction), for example, the direction of vibration of the vertical polarization. Furthermore, when the two fixing members 74 are viewed from the front of the antenna 50, they are symmetrical with respect to the second line L2, which makes it easier for the antenna 50 to obtain the desired antenna gain and directivity. When viewed from the front of the antenna 50, the widths (lengths in the Z-axis direction) of the two fixing members 74 may be the same or different, but it is preferable that their widths be the same, as this makes it easier to obtain the above effect.

[0042] The coaxial cable 90 shown in Figures 5 and 7 has a signal line 91, an insulator 92, an outer conductor 93, and a protective cover 94. A cylindrical insulator 92 is provided on the outer circumference of the signal line 91, which is made up of conductors. One end of the coaxial cable 90 is inserted into the through hole from the left end of the second connector 80. Furthermore, one end of the coaxial cable 90 and the second connector 80 are fixed together by fixing means (not shown). As shown in Figure 5, one end 91A of the signal line 91 is connected to a signal contact 82. In addition, one end of the outer conductor 93 is connected to two ground contacts 83.

[0043] As shown in Figure 5, when the connection portion 81B of the second connector 80 is inserted into the recess 71B of the first connector 70, the second connector 80 becomes integrated with the first connector 70. Furthermore, the signal contact 82 contacts the left end of the signal contact 72, and each ground contact 83 contacts the left end of each ground contact 73.

[0044] As described above, the signal contact 72 included in the first connector 70 is positioned to pass through the centroid 54A in a front view of the antenna 50, but the connector including the first connector 70 is not limited to this arrangement. For example, if the second conductor plate 55 does not include the planar conductive line 57 and the notch 56X, and in a front view of the antenna 50 only includes a square-shaped radiating plate 56, with the feed point 56A1 inside the radiating plate 56, the connector may be fixed to the antenna 50 such that the signal contact 72 is offset from the centroid 54A. The connecting conductor 62 included in the antenna 50 may be provided inside a through-hole that penetrates the dielectric substrate 52 in the thickness direction from the feed point 56A1.

[0045] In other words, even when configuring the second conductor plate 55 in this manner, the tail portion 72A of the signal contact 72 is connected to the signal transmission portion 54S, but the signal transmission portion 54S may be arranged to overlap with the feed point 56A1 of the antenna 50 (see Figure 4) when viewed from the front of the antenna 50. In this case, when viewed from the front of the antenna 50, the antenna 50 may be arranged so that the tail portion 72A of the signal contact 72, the signal transmission portion 54S, the feed point 60, the connecting conductor 62, and the feed point 56A1 overlap.

[0046] Next, the antenna device 43 of this embodiment, including the cover member 95, will be described. As shown in Figures 3, 5, and 6, the antenna device 43 has a cover member 95 fixed to it that protrudes from the ground conductor portion 54 of the antenna 50 on the side opposite to the second conductor plate 55. The cover member 95 is made of a conductor such as copper. In Figure 6, the cover member 95 has a first portion 96, a second portion 97, and a third portion 98, which are flat plates. The second portion 97 and the third portion 98 are shown as rectangular flat plates of the same shape.

[0047] However, the shapes of the first part 96, the second part 97, and the third part 98 may be other than rectangular. Furthermore, the dimensions of the first part 96 in a front view of the antenna 50 may be the same as those of the dielectric substrate 52, or they may be wider or narrower than the dielectric substrate. As shown in Figure 3, if the antenna 50 does not have a first element 66 and a second element 68, the dimensions of the first part 96 in the X-axis direction of the antenna device 43 may be the same as those of the first conductor plate 54 (dielectric substrate 52). On the other hand, as shown in Figure 4, if the antenna 50 has a first element 66 and a second element 68, the cover member 95 of the antenna device 43 should be arranged so as not to overlap with them in a front view of the antenna 50.

[0048] The front end of the second portion 97 of the cover member 95 is connected to the upper edge 54U of the grounding conductor portion 54, and the front end of the third portion 98 is connected to the lower edge 54D of the grounding conductor portion 54. The first portion 96 is parallel to the grounding conductor plate 54. Furthermore, the second portion 97 and the third portion 98 are parallel to each other and perpendicular to the grounding conductor plate 54.

[0049] In a front view of the antenna 50, the cover member 95 fixed to the grounding conductor plate 54 has the upper edge of the first portion 96 and the second portion 97 overlapping with the upper edge 54U of the first conductor plate 54, and the lower edge of the first portion 96 and the third portion 98 overlapping with the lower edge 54D of the first conductor plate 54. In this way, the second portion 97 and the third portion 98 are electrically connected to the grounding conductor plate 54 and also to the first portion 96, and the cover member 95 is grounded. In addition, in a front view of the antenna 50, the first connector 70, the signal contact 82 and the ground contact 83 overlap with the first portion 96. Furthermore, in a front view of the antenna 50, it is preferable that the second portion 97 and the third portion 98 are located on the outer periphery of the radiating plate 56, as this improves the antenna gain and directivity of the antenna device 43.

[0050] Furthermore, when viewing the antenna 50 and cover member 95 along the direction of alignment of the second part 97 and the third part 98 (Z-axis direction), the first connector 70, signal contact 82, and ground contact 83 overlap with the second part 97 and the third part 98. Moreover, as shown in Figure 6, when viewing the antenna 50 and cover member 95 along the X-axis direction, the first connector 70, signal contact 82, and ground contact 83 are located in the space 95S formed between the antenna 50 and the cover member 95. That is, the electrically grounded grounding conductor plate 54 and cover member 95 are arranged to cover the first connector 70 and the second connector 80. Furthermore, when viewing the antenna 50 and cover member 95 along the X-axis direction, the openings at both the left and right ends of the cover member 95 expose the first connector 70.

[0051] The antenna device 43 described above, when mounted on the upper part of the main surface of the windshield 28 via a bracket (not shown), constitutes part of the vehicle antenna device 40. The first straight line L1 passing through the feed point 56A1 and the center of gravity 56B of the antenna 50 of the antenna device 43 is parallel to the Z-axis, as shown in Figure 4. That is, in a front view, the first straight line L1 is parallel to the vibration direction Vd of the vertical polarization that the antenna 50 can transmit and receive. In addition, in the vehicle antenna device 40, the antenna device 43 mounted on the vehicle has the second portion 97 of the cover member 95 positioned above the third portion 98. In particular, in the vehicle antenna device 40, the first portion 96 of the cover member 95 may be mounted approximately parallel to the vertical direction, and the second portion 97 and the third portion 97 may be mounted approximately parallel to the horizontal plane.

[0052] Next, the elevation and depression angles of the vehicle antenna device 40 will be described. As shown in Figure 2, when the front of the vehicle 10 is viewed from the side (from the X-axis direction), it is preferable that the vehicle antenna device 40 be installed such that the inclination angle α of the radiating surface 56C of the radiating plate 56 with respect to the vertical direction 101 is within the range of ±15°. Also, as shown by the solid line in Figure 2, when the radiating surface 56C is located behind the vertical direction 101, the value of the inclination angle α is positive. On the other hand, as shown by the dashed line in Figure 2, when the radiating surface 56C is located in front of the vertical direction 101, the value of the inclination angle α is negative. In other words, when the inclination angle α is greater than 0°, the elevation angle between the normal direction of the radiating surface 56C of the radiating plate 56 and the horizontal plane is greater than 0° and less than or equal to +15°.

[0053] Next, Example 1, which is an embodiment of the above-described model, will be explained in comparison with Example 2, which is a comparative example. In Example 1, the antenna device 43 is attached to the windshield 28, and the conditions θ1 = 22.5° and α = 0° are assumed. The comparative example vehicle antenna device (not shown) has the same structure as the antenna device 43 except that it does not have a cover member 95.

[0054] Figure 8 shows the measurement results illustrating the directivity of the antenna device 43 in Example 1 and the antenna device in Example 2. These are simulation results of the antenna gain in the 5.9 GHz band in each direction in the horizontal plane. 0° represents the front side in the vehicle's longitudinal direction, 90° represents the right side in the vehicle's width direction, 180° represents the rear side in the vehicle's longitudinal direction, and 270° represents the left side in the vehicle's width direction. The dotted line in Figure 8 represents the directivity of Example 1, and the solid line represents the directivity of Example 2. The unit of antenna gain in Figure 8 is [dBi].

[0055] In Figures 4 to 6, the dimensions (in mm) of each part of the antenna device 43 in Example 1 and the antenna device in Example 2, represented by the symbols L20, L21, L50, L51, L53, L55, L60, L62, L97, and L98, are as follows. The directivity in Figure 8 is the result when each part is designed with these values. Note that L55 is the distance in the Y-axis direction between the first element 66 and the second element 68 and the radiating surface 56C. Furthermore, the cover member 95 has a second part 97 and a third part that are orthogonal to the first part 96, and in a front view of the antenna 50, the first part 96 has the same shape as the grounding conductor plate 54 (L53 × L60). L20:13 L21:13 L50:19 L51:1.5 L53:20 L55:2 L60:20 L62:1 L97:11 L98:11

[0056] Furthermore, in Example 1 and Example 2, the first connector 70 and the second connector 80 are arranged so as shown in Figure 5, with respect to a straight line (second straight line L2) passing through the centroid 54A of the grounding conductor plate 54 (in the X-axis direction), with respect to each metal member. Specifically, the signal contacts 72 and 82 are positioned on the second straight line L2, and the two fixing members 74 and the two ground contacts 73 and 83 are arranged so as to be symmetrical with respect to the second straight line L2.

[0057] As is clear from Figure 8, the antenna gain of the antenna device 43 in Example 1 in the ranges of 0° to +90° and 0° to 270° (-90°) was better than that of the antenna device in Example 2 in the ranges of 0° to +90° and 0° to 270° (-90°). Furthermore, in the ranges of +90° to 120° and 270° to 240° (-90° to -120°), the antenna gain of the antenna device 43 in Example 1 was also better than that of the antenna device in Example 2.

[0058] As described above, the first connector 70 of the antenna device 43 in this embodiment has a metal signal contact 72, a ground contact 73, and a fixing member 74, and the second connector 80 has a metal signal contact 82 and a ground contact 83. These metal members can easily change the antenna gain and directivity of the antenna device 43. However, in the antenna device 43 of this embodiment, when viewed along the X-axis direction, the first conductor plate 54 and the cover member 95 cover the area around the connectors (first connector 70 and second connector 80). Therefore, the antenna device 43 of this embodiment, which is an example, can more easily obtain the desired antenna gain and directivity than the comparative example antenna device which does not have the cover member 95.

[0059] Furthermore, in a front view of the antenna 50, the signal contacts 72 and 82 of the antenna device 43 are located on the second line L2. Therefore, in the antenna device 43 of Example 1, the reduction in antenna gain and distortion of directivity caused by the signal contacts 72 and 82 are less likely to occur with respect to the vertical polarization transmitted and received by the antenna 50. Furthermore, in a front view of the antenna 50, the two ground contacts 73 are symmetrical with respect to the second line L2, and the two ground contacts 83 are symmetrical with respect to the second line L2. Therefore, compared to the case where the two ground contacts 73 and 83 are not symmetrical, each ground contact 73 and 83 in this embodiment is less likely to cause a reduction in antenna gain and distortion of directivity of the vertical polarization transmitted and received by the antenna 50. Therefore, the antenna device 43 of this embodiment makes it easier to obtain the desired antenna gain and directivity.

[0060] In a front view of the antenna 50, the widths (lengths in the Z-axis direction) of the two ground contacts 73 and 83 in the antenna device 43 may be the same or different. It is preferable that the widths of the two ground contacts 73 and 83 are the same, as they are symmetrical with respect to the second line L2, thus achieving the above-mentioned effect. Also, the width (length in the Z-axis direction) of the signal contact 72 and the widths of the ground contacts 73 and 83 may be the same or different, as long as they are symmetrical with respect to the line L2.

[0061] While embodiments of this disclosure have been described above, this disclosure is not limited to these embodiments.

[0062] For example, when viewing the antenna device along the X-axis direction, the cover member 95 may have a different shape from that of the above embodiment, as long as it is possible to cover the area around the first connector 70 and the second connector 80 with the grounding conductor plate 54 and the cover member 95. For example, the modified antenna device 43A shown in Figure 9 includes a cover member 95A. The vehicle antenna device 40A of this modified example includes a windshield 28 (not shown in Figure 9) and an antenna device 43A. This cover member 95A includes a first part 96A, a second part 97A, and a third part 98A. The first part 96A is a flat plate shape parallel or substantially parallel to the first conductor plate 54. When viewing the antenna device 43A along the X-axis direction, the first part 96A faces the first conductor plate 54 in the Y-axis direction. When viewing the antenna device 43A along the X-axis direction, the second part 97A and the third part 98A are substantially arc-shaped. The front end of the second part 97A is soldered to the upper edge 54U of the grounding conductor plate 54, and the front end of the third part 98A is soldered to the lower edge 54D of the grounding conductor plate 54. The rear ends of the second part 97A and the third part 98A of the cover member 95 are connected to the upper and lower ends of the first part 96A, respectively. The antenna 50 of the antenna device 43A also makes it easier to obtain the desired antenna gain and directivity than the antenna of the comparative example antenna device.

[0063] Furthermore, in antenna devices 43 and 43A, the cover members 95 and 95A are open at both ends in the direction of extension of the signal contact 72, but at least a portion of both ends of the cover members 95 and 95A in that direction of extension may be closed. For example, in antenna devices 43 and 43A, the right end of the cover member 95 in the above embodiment may be completely closed, and only the left end may be open. Alternatively, for example, in antenna devices 43 and 43A, a portion of the right end of the cover member 95 may be closed, and the entire left end may be closed. In Figure 5, the members that close at least a portion of the right end and left end of the cover member 95 can be arbitrarily selected, and may be conductors or dielectrics, and may have a plate-like shape or a shape with irregularities.

[0064] The antenna device 43 does not need to have the second portion 97 and the third portion 98 of the cover member 95 perpendicular to the grounding conductor plate 54 when viewed along the X-axis. For example, the angle that the second portion 97 and the third portion 98 of the antenna device 43 make with respect to the grounding conductor plate 54 may be an angle other than 90°, for example, any angle in the range of 90° ± 20°. In this case, when viewed along the X-axis, the antenna device 43 may be configured with shapes including trapezoids and parallelograms, as the grounding conductor plate 54, the first portion 96, the second portion 97, and the third portion 98.

[0065] Furthermore, in a front view of the antenna 50, the second portion 97 of the antenna device 43 may be located below the upper edge 54U of the grounding conductor plate 54, and the third portion 98 may be located above the lower edge 54D of the grounding conductor plate 54. In addition, in a front view of the antenna 50, the front end of the second portion 97A of the antenna device 43 may be located below the upper edge 54U of the grounding conductor plate 54, and the front end of the third portion 98A may be located above the lower edge 54D of the grounding conductor plate 54.

[0066] Furthermore, the front end of the second portion 97 of the cover member 95 may not be soldered to the grounding conductor plate 54 and may be separated from the grounding conductor plate 54. However, in this case, the distance between the grounding conductor plate 54 and the front end of the second portion 97 must be set to a distance sufficient for high-frequency signals (electrical signals) to be transmitted between them. Similarly, if high-frequency signals are transmitted between the grounding conductor plate 54 and the cover member 95, at least one front end of the third portion 98 of the cover member 95, the second portion 97A of the cover member 95A, and the third portion 98A of the cover member 95A may not be soldered to the grounding conductor plate 54 and may be separated from the grounding conductor plate 54.

[0067] The antenna device 43, which has an antenna 50, a first connector 70, a second connector 80, a coaxial cable 90, and a cover member 95, may have a structure that is symmetrical to the shape shown in Figure 5. That is, in the antenna device 43 shown in Figure 5, the third part 57C of the planar transmission line 57 may be located to the left of the radiating plate 56, the second connector 80 and the coaxial cable 90 may be located to the right of the first connector 70, and the tail parts 72A and 73A may be located to the left of the insulator 71. Furthermore, the connectors constituting the antenna device 43 only need to be able to bring the ground wire of the transmission line, such as the coaxial cable 90, and the grounding conductor plate 54 to the same potential as ground. In this case, the two ground contacts 73 and 83 are not essential, and the ground wire may be connected to any point on the grounding conductor plate 54. However, if the antenna device 43 has two ground contacts 73 and 83 parallel to the signal contacts 72 and 73, the transmitted and received signals can be transmitted stably.

[0068] As shown in Figures 1 and 2, an antenna device 43 or antenna device 43A may be attached to the upper part of the main surface (front) on the interior side of the rear window (vehicle window glass) 34 in the vehicle vertical direction, via a bracket (not shown).

[0069] When an antenna device 43 or antenna device 43A is installed on the rear window 34 of the vehicle 10, the antenna device 43 or antenna device 43A may or may not be installed on the windshield 28 of the vehicle 10. In the configuration shown in Figure 1, when an antenna device 43 or antenna device 43A is installed on the windshield 28 and an antenna device 43 or antenna device 43A is installed on the rear window 34, the desired antenna gain can be achieved in the range of 0° to 360° in the horizontal plane by the combined value of the antenna gains of the front antenna 50 and the rear antenna 50.

[0070] Furthermore, the antenna 50 may be a horizontally polarized antenna, which has a higher antenna gain when transmitting and receiving horizontally polarized signals compared to vertically polarized signals. In this case, it is preferable to mount the antenna device 43 or antenna device 43A on the vehicle 10 such that, in a front view, the first straight line L1 is parallel to the X-axis direction.

[0071] If the antenna devices 43 and 43A are vertically polarized antennas, the antenna devices 43 and 43A may be installed on the vehicle 10 such that the angle between the straight line L1 and the vertical direction in a front view of the antenna 50 is 15° or less, thereby configuring the vehicle antenna device 40. Alternatively, if the antenna devices 43 and 43A are horizontally polarized antennas, the antenna devices 43 and 43A may be installed on the vehicle 10 such that the angle between the straight line L2 and the vertical direction in a front view is 15° or less, thereby configuring the vehicle antenna device 40.

[0072] Furthermore, the antenna 50 may be configured to transmit and receive circularly polarized or elliptically polarized waves.

[0073] Furthermore, multiple antenna devices 43, 43A may be attached to the windshield 28. Similarly, multiple antenna devices 43, 43A may be attached to the rear glass 34.

[0074] Furthermore, a rear window 34 may be provided in a back door (not shown) that opens and closes an opening at the rear of the vehicle 10.

[0075] The disclosure of Japanese Patent Application No. 2021-214890, filed on 28 December 2021, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference. [Explanation of symbols]

[0076] 10 vehicles 28. Windshield (vehicle window glass) 34. Rear window (vehicle window glass) 40 40A Vehicle Antenna Device 43 43A Antenna equipment 50 Communication Antenna (Antenna) 52 Dielectric Substrate 54 Grounding conductor plate 56 Radiation plate 56A1 Power supply point 56B Center of gravity 56C Radiation surface 57 Planar conductive lines (transmission lines) 57C1 1st end 57C2 2nd end 66. First element (unpowered conductor plate) 68. Second element (unpowered conductor plate) 70. First connector (connector) 72. Signal Contacts (Metal Components) (Transmission Lines) 73. Ground Contact (Metal Components) (Transmission Lines) 74 Fixing members (metal members) 80 Second connector (connector) 82. Signal Contacts (Metal Components) (Transmission Lines) 83 Ground Contact (Metal Components) (Transmission Lines) 90 Coaxial cable (transmission line) 95 95A Cover component 96 96A Part 1 97 97A 2nd part 98 98A Part 3 L1, first straight line L2, second straight line

Claims

1. Dielectric substrate and An antenna comprising: a radiating plate having a radiating surface for emitting radio waves in a predetermined frequency band on the first main surface of the dielectric substrate; and a grounding conductor plate disposed on the second main surface of the dielectric substrate; A connector is provided on the side of the grounding conductor plate opposite to the radiating plate side, includes a metal member, is fixed to the antenna, and is connected to a transmission line. A cover member made of a conductor that is electrically grounded and faces the side of the grounding conductor plate opposite to the side of the radiating plate, Equipped with, In a front view of the antenna, the position of the feed point on the radiating plate and the position of the center of gravity of the radiating plate are different. An antenna device in which, when the antenna, the connector, and the cover member are viewed from a direction perpendicular to the first straight line connecting the center of gravity and the feed point and the thickness direction of the dielectric substrate, the antenna and the cover member cover the area around the connector, and when viewed from the thickness direction of the grounding conductor plate, the connector is contained within the area of ​​the grounding conductor plate.

2. The antenna device according to claim 1, wherein, in a front view of the antenna, a part of the cover member is located on the outer periphery side of the peripheral edge of the radiating plate.

3. The antenna device according to claim 1 or 2, wherein the antenna comprises at least one passive conductor plate whose position, when viewed from the thickness direction of the dielectric substrate, is different from the center of gravity of the radiating plate.

4. The antenna comprises two unpowered conductor plates located on the radiating plate side of the ground conductor plate, The antenna device according to claim 3, wherein, in a front view of the antenna, the radiating plate is positioned between the two passive conductor plates.

5. The antenna device according to claim 4, wherein, in a front view of the antenna, the two unpowered conductor plates are located outward from each other than the ground conductor plate.

6. The cover member has a first portion that faces the ground conductor plate and the connector in the thickness direction of the dielectric substrate and is parallel to the radiating plate, and a second portion and a third portion that electrically connect the first portion and the ground conductor plate. The antenna device according to claim 1 or 2, wherein the connector is located between the second portion and the third portion.

7. The antenna device according to claim 6, wherein the second portion and the third portion are connected to both ends of the grounding conductor plate, respectively, and are parallel to each other.

8. The antenna device according to claim 7, wherein the second and third portions are orthogonal to the first portion.

9. The antenna device according to claim 1 or 2, wherein when the antenna, the connector, and the cover member are viewed from a direction perpendicular to the first straight line and the thickness direction of the dielectric substrate, the cover member exposes the space formed between the cover member and the ground conductor plate.

10. The antenna device according to claim 9, wherein, in a plan view of the antenna, the pair of metal members provided on the connector are arranged perpendicular to the first straight line and parallel to the second straight line passing through the center of gravity.

11. The antenna device according to claim 10, wherein the pair of metal members provided on the connector are fixing members fixed to the ground conductor plate, and the pair of fixing members are symmetrical with respect to the second straight line.

12. The antenna device according to claim 10, wherein at least a portion of the transmission line is parallel to the second straight line and the transmission line is connected to the connector such that it overlaps with the second straight line.

13. The antenna device according to claim 12, wherein the signal contact of the transmission line extends in conjunction with the second straight line.

14. The antenna device according to claim 13, wherein the pair of ground contacts of the transmission line are symmetrical with respect to the second straight line.

15. The antenna has a planar conductive line located on the plane in which the radiating surface is located, The planar conductive line has a first end connected to the power supply point and a second end located on a second straight line perpendicular to the first straight line and passing through the centroid. The antenna device according to claim 1 or 2, wherein the first end is electrically connected to a signal line of the transmission line.

16. Vehicle window glass installed in a vehicle, The antenna device according to claim 1 or 2, wherein the radiating surface is arranged to face the vehicle window glass, Equipped with, A vehicle antenna device in which the angle between the radiating surface and the vertical direction of the vehicle is within the range of ±15°.

17. The cover member has a first portion that faces the grounding conductor plate and the connector in the thickness direction and is parallel to the radiating plate, and a second portion and a third portion that are separated from each other in a direction parallel to the first straight line and are connected to the first portion. The vehicle antenna device according to claim 16, wherein one of the second portion and the third portion is located above the other.

18. The vehicle antenna device according to claim 16, wherein the antenna is a V2X antenna.

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