Windowpane with antenna

Abstract

A windowpane (1) with an antenna according to the present disclosure comprises a first glass sheet (11), an antenna substrate (30), and a power feed substrate (40) capable of supplying a high-frequency signal to the antenna substrate (30) in a non-contact manner. The antenna substrate (30) includes a first dielectric substrate (31), a radiating conductor (32), a first power feed line (33), a first matching conductor (34), a first ground conductor (35), and a first pattern conductor (37). The power feed substrate (40) includes a second dielectric substrate (41), a second matching conductor (42), a second power feed line (43), a second ground conductor (44), and a second pattern conductor (46). The first pattern conductor (37) and the second pattern conductor (46) are electromagnetically coupled through the first glass sheet (11), and a high-frequency signal is supplied from the second power feed line (43) to the first power feed line (33). A length corresponding to the distance between the radiating conductor (32) and the first matching conductor (34) in the first power feed line (33) is equal to or greater than the in-tube wavelength λg of the high-frequency signal.

Description

Window glass with an antenna

[0004]

[0001] The present disclosure relates to window glass with an antenna.

[0002] In recent years, in means of transportation such as automobiles, the development of automobiles capable of realizing high-capacity communication using radio waves in the 4G-LTE / 5G frequency band and high-level autonomous driving as infotainment has been accelerating. For this reason, an antenna having a conductor is likely to be mounted on a vehicle in order to transmit and receive radio waves in a predetermined frequency band.

[0003] For example, in order to obtain information in front of the vehicle, mounting such an antenna on a vehicle window glass such as a windshield has also been considered. From the viewpoint of safety, it is legally stipulated that an automotive windshield uses laminated glass in which an intermediate film is sandwiched between two glass plates, and a technique for enclosing an antenna inside such laminated glass is known.

[0004] For example, Patent Document 1 discloses a structure in which an antenna in the band of VHF bands II to V is arranged inside a composite glass plate and is fed by a flat conductor. Further, Patent Document 2 discloses a technique related to an antenna unit having high transparency and capable of radiating radio waves in one direction.

[0005] Japanese Patent Application Laid-Open No. 2014-514836 International Publication No. 2019 / 107514

[0006] When mounting an antenna on a vehicle window glass such as a windshield, as a method of feeding power to the antenna, there are a method of taking out the microstrip line of the antenna substrate from the end of the window glass and directly feeding power to the microstrip line, a method of directly feeding power to the antenna substrate by making a hole in the window glass, a method of non-contact feeding power to the antenna substrate through the window glass, and the like. Among these, considering cost, position accuracy, and feeding efficiency, the method of non-contact feeding power to the antenna substrate through the window glass is optimal.

[0007] When using a non-contact power supply method to the antenna substrate via window glass, for example, the antenna substrate is placed on one main surface of the window glass, and the power supply substrate is placed on the other main surface of the window glass, and the high-frequency signal is supplied non-contact from the power supply substrate to the antenna substrate. Specifically, the high-frequency signal is supplied via the window glass from a power supply line (microstrip line) provided on the power supply substrate to a power supply line (microstrip line) provided on the antenna substrate. The high-frequency signal supplied to the antenna substrate is then supplied to the radiating conductor using the power supply line. At this time, the high-frequency signal may propagate in an unintended direction from the power supply line provided on the antenna substrate, which may reduce the power supply efficiency. For example, this reduction in power supply efficiency can be suppressed by providing a matched conductor on the end of the power supply line opposite to the side where the radiating conductor is located.

[0008] However, if a matching conductor is provided on the antenna substrate, the radiation from the matching conductor and the radiation from the radiating conductor may interfere with each other, potentially reducing the radiation efficiency from the radiating conductor. This can lead to a deterioration in antenna performance.

[0009] In view of the above issues, the purpose of this disclosure is to provide a window glass with an antenna equipped with a non-contact power supply antenna that can suppress the decrease in radiation efficiency.

[0010] An antenna-equipped window glass according to one aspect of this disclosure has the following configuration.

[0011] [1] The antenna comprises a first glass plate, an antenna substrate disposed on the first main surface side of the first glass plate, and a power supply substrate disposed on the second main surface side of the first glass plate opposite to the first main surface, capable of non-contact supplying a high-frequency signal to the antenna substrate, wherein the antenna substrate comprises a first dielectric substrate made of a dielectric material, a radiating conductor disposed on the third main surface of the first dielectric substrate opposite to the side on which the first glass plate is disposed, which radiates radio waves corresponding to the high-frequency signal, a first power supply line for supplying the high-frequency signal to the radiating conductor, a first matching conductor provided adjacent to the first end of the first power supply line opposite to the side on which the radiating conductor is provided, and a first ground conductor disposed on the fourth main surface of the first dielectric substrate opposite to the third main surface, which has a first slot pattern formed at a position corresponding to the first end of the first power supply line when the antenna substrate is viewed in plan, The power supply substrate comprises: a first pattern conductor disposed inside the first slot pattern of the first ground conductor and supplying the high-frequency signal to the first end side of the first power supply line; a second dielectric substrate made of a dielectric material; a second power supply line disposed on the fifth main surface of the second dielectric substrate opposite to the side on which the first glass plate is disposed and supplying the high-frequency signal to the antenna substrate; a second matching conductor provided adjacent to the second end of the second power supply line; a second ground conductor disposed on the sixth main surface of the second dielectric substrate opposite to the fifth main surface, with a second slot pattern formed at a position corresponding to the second end of the second power supply line when the power supply substrate is viewed in plan; and a second pattern conductor disposed inside the second slot pattern of the second ground conductor and supplied with the high-frequency signal from the second end side of the second power supply line. A window glass with an antenna, wherein the first pattern conductor and the second pattern conductor are electromagnetically coupled via the first glass plate, thereby supplying the high-frequency signal from the second power supply line to the first power supply line, and the length corresponding to the distance between the radiating conductor and the first matching conductor in the first power supply line is greater than or equal to the in-tube wavelength λg of the high-frequency signal.

[0012] [2] The window glass with an antenna further comprises a second glass plate arranged opposite to the first glass plate, and an interlayer disposed between the first glass plate and the second glass plate, wherein the antenna substrate is disposed between the first glass plate and the second glass plate, as described in [1].

[0013] [3] The length of the first power supply line is set to satisfy (2n+1)・λg / 4 (where n is an integer of 2 or more), as described in [1] or [2], a window glass with an antenna.

[0014] [4] A window glass with an antenna as described in any one of items [1] to [3], wherein the frequency of the high-frequency signal is 400 MHz or more and 50.0 GHz or less.

[0015] [5] The window glass with an antenna according to any one of items [1] to [4], wherein the thickness of the first glass plate is 0.1 mm or more and 10 mm or less.

[0016] [6] The window glass with antenna according to any one of [1] to [5], wherein an electromagnetic bandgap structure is formed around the first slot pattern of the first ground conductor arranged on the fourth main surface of the antenna substrate.

[0017] [7] The window glass with antenna according to any one of [1] to [6], wherein an electromagnetic bandgap structure is formed around the second slot pattern of the second ground conductor arranged on the sixth main surface of the power supply board.

[0018] [8] The window glass with antenna according to any one of [1] to [7], wherein the length of the first power supply line is set to satisfy (2n+1)・λg / 4 (where n is an integer of 6 or more) when the window glass with antenna is attached to a metal flange.

[0019] [9] The window glass with an antenna according to any one of [1] to [8], wherein when the window glass with an antenna is viewed in plan from the power supply board side, a shielding layer is formed so as to cover the power supply board.

[0020]

[10] The window glass with an antenna according to any one of [1] to [9], wherein the radiating conductor is a patch antenna.

[0021]

[11] The window glass with an antenna according to any one of [1] to

[10] , wherein at least one of the radiating conductor, the first matching conductor, the first feed line, and the first ground conductor is configured in a mesh pattern.

[0022]

[12] The window glass with an antenna according to any one of [1] to

[11] , wherein a plurality of the radiating conductors are arranged in an array on the third main surface of the first glass plate.

[0023] This disclosure makes it possible to provide a window glass with an antenna equipped with a non-contact power supply antenna that can suppress the decrease in radiation efficiency.

[0024] This is a cross-sectional view showing a window glass with an antenna according to an embodiment. This is a plan view showing an example of the configuration of the antenna substrate and feed substrate included in the window glass with an antenna according to an embodiment. This is a graph showing the relationship between the length of the first feed line and the radiation efficiency, glass loss, and average gain. This is a figure showing the simulation results of the radiation directivity of the antenna. This is a cross-sectional view showing a window glass with an antenna according to an embodiment. This is the simulation result of radio waves radiated from the window glass with an antenna. This is a plan view of the antenna substrate included in the window glass with an antenna according to an embodiment. This is a graph showing the relationship between the distance D between the widthwise end of the first matching conductor and the widthwise end of the first ground conductor and the propagation mode in the in-plane direction of the window glass. This is a plan view showing another example of the configuration of the first ground conductor and the second ground conductor. This is a cross-sectional view showing the window glass with an antenna according to an embodiment attached to a metal flange. This is a plan view showing another example of the configuration of the antenna substrate. This is a figure showing the simulation results of the radiation directivity of the array antenna shown in Figure 11.

[0025] The present disclosure will be described below with reference to the drawings. Figure 1 is a cross-sectional view showing a window glass with an antenna according to an embodiment. As shown in Figure 1, the window glass with an antenna 1 according to this embodiment comprises a first glass plate 11, a second glass plate 12, an interlayer 13, an antenna substrate 30, and a power supply substrate 40. The configuration example shown in Figure 1 shows an example in which the window glass with an antenna 1 is made of laminated glass. In other words, the configuration example shown in Figure 1 shows an example in which the interlayer 13 is arranged between the first glass plate 11 and the second glass plate 12, and the antenna substrate 30 is sealed between the first glass plate 11 and the second glass plate 12.

[0026] The window glass with antenna 1 according to this embodiment may be composed of a single glass plate. When the window glass with antenna 1 is composed of a single glass plate, the antenna substrate 30 is placed on one side of the first glass plate 11, and the power supply substrate 40 is placed on the other side (that is, the configuration in Figure 1 does not include the second glass plate 12 and the interlayer 13).

[0027] The window glass with antenna 1 according to this embodiment can typically be used as a windshield of an automobile. In addition to the windshield, the window glass with antenna 1 according to this embodiment can also be used as a rear window, side window, roof window, etc.

[0028] The following describes in detail the window glass with antenna 1 according to this embodiment. As an example, the case where the window glass with antenna 1 is made of laminated glass will be described below. In the following, the window glass with antenna 1 will also be simply referred to as "window glass 1".

[0029] As shown in Figure 1, the window glass 1 comprises a first glass plate 11, a second glass plate 12, and an interlayer 13 disposed between the first glass plate 11 and the second glass plate 12.

[0030] The window glass 1 may be flat or curved. It may also have a shape that includes both a flat and a curved surface. The first glass plate 11 and the second glass plate 12 may each be flat or curved. The curved plate may be a simple curved shape that curves in one direction or a three-dimensional shape that curves in two or more directions. The three-dimensional shape may be, for example, a double curved shape that curves in two orthogonal directions. In the following example, the case in which both the first glass plate 11 and the second glass plate 12 are made of flat plates will be described, but the same description can be applied when at least one of them is made of a curved plate.

[0031] The outer edge shapes of the first glass plate 11 and the second glass plate 12 in plan view can be any shape, but rectangular, trapezoidal, and triangular shapes are preferred, for example. In this embodiment, when the window glass with antenna 1 is installed in a vehicle, the first glass plate 11 is positioned on the inside of the vehicle, and the second glass plate 12 is positioned on the outside of the vehicle.

[0032] The first and second glass plates 11 and 12 can be made of, for example, transparent inorganic glass. For the first and second glass plates 11 and 12, for example, soda-lime glass, aluminosilicate glass, borosilicate glass, alkali-free glass, quartz glass, etc., may be used. The first and second glass plates 11 and 12 are manufactured using, for example, the float method, the fusion method, etc., but are not limited to these methods.

[0033] The thickness of each of the first and second glass plates 11 and 12 is, for example, 0.1 mm to 10 mm, preferably 0.3 mm to 3.0 mm, more preferably 1.1 mm to 2.6 mm, and even more preferably 1.7 mm to 2.1 mm from the viewpoint of resistance to flying stone impact. The thicknesses of the first and second glass plates 11 and 12 may be the same or different. For example, the thickness of the second glass plate 12, which is located on the outside of the vehicle, may be thicker than the thickness of the first glass plate 11, which is located on the inside of the vehicle. When the thickness of the second glass plate 12, which is located on the outside of the vehicle, is increased, the strength of the window glass 1 against objects flying towards the window glass 1 is improved. Also, when the thickness of the first glass plate 11, which is located on the inside of the vehicle, is reduced, power can be efficiently supplied non-contact from the power supply board 40 to the antenna board 30 via the first glass plate 11.

[0034] The interlayer 13 is positioned so as to be sandwiched between the first glass plate 11 and the second glass plate 12. The thickness of the interlayer 13 is not particularly limited, but is preferably 1.10 mm or less. Furthermore, the thickness of the interlayer 13 is preferably 0.50 mm or more, and more preferably 0.70 mm or more. By setting the thickness of the interlayer 13 within this range, the transparency of the window glass 1 can be ensured and the weight of the window glass 1 can be prevented from becoming excessively large.

[0035] The interlayer 13 can be constructed using materials such as polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), cycloolefin polymer, urethane resin, or polyvinylidene fluoride resin (PVDF).

[0036] In this embodiment, when forming the window glass 1, the first glass plate 11, the antenna substrate 30, the interlayer 13, and the second glass plate 12 are stacked in this order and placed in a vacuum bag such as a rubber bag. Then, this vacuum bag is connected to an exhaust system and degassed (degassed) so that the pressure inside the vacuum bag is reduced to a degree of reduced pressure (absolute pressure) of approximately -65 kPa to -100 kPa, and heated and pressurized at a temperature of approximately 70°C to 120°C. Furthermore, by performing a bonding process under conditions of heating and pressurizing at a temperature of approximately 100°C to 140°C and a pressure of 0.6 MPa to 1.3 MPa, a window glass 1 with excellent durability can be obtained. Note that the method of forming the window glass 1 is not limited to this method, and the window glass 1 may be formed using other manufacturing methods.

[0037] As shown in Figure 1, an antenna substrate 30 is positioned on the first main surface 21 side of the first glass plate 11. A power supply substrate 40 is positioned on the second main surface 22 side of the first glass plate 11, opposite to the first main surface 21. For example, the power supply substrate 40 is bonded to the second main surface 22 of the first glass plate 11 using an adhesive layer 48. Here, the first main surface 21 of the first glass plate 11 is the outer surface of the vehicle, and the second main surface 22 is the inner surface of the vehicle. Therefore, the antenna substrate 30 is positioned on the outer surface of the first glass plate 11, and the power supply substrate 40 is positioned on the inner surface of the first glass plate 11. The power supply substrate 40 is configured to non-contact supply high-frequency signals to the antenna substrate 30 via the first glass plate 11. The antenna substrate 30 is configured to transmit and receive radio waves of a predetermined frequency band on the outer surface of the vehicle (upwards on the paper).

[0038] Here, the predetermined frequency band may be from 4G LTE (Long Term Evolution) to 5G, or for example, from 700 MHz to 6 GHz (so-called sub6), but is not limited to these. In other words, the predetermined frequency band may be a frequency band below 700 MHz, or a frequency band above 6 GHz, for example, the 28 GHz band or a frequency band above 30 GHz known as millimeter wave, for example, the 79 GHz band. The antenna (antenna substrate 30 and power supply substrate 40) provided in the window glass 1 with antenna according to this embodiment will be described in detail below.

[0039] Figure 2 is a plan view showing an example of the configuration of the antenna substrate and power supply substrate included in the antenna-equipped window glass according to the embodiment. Figure 2 shows plan views of the top and bottom surfaces of the antenna substrate 30 and the top and bottom surfaces of the power supply substrate 40.

[0040] As shown in Figure 2, the antenna substrate 30 comprises a first dielectric substrate 31, a radiating conductor 32, a first feed line 33, a first matching conductor 34, a first ground conductor 35, and a first pattern conductor 37. As shown in Figure 1, the radiating conductor 32, the first feed line 33, and the first matching conductor 34 are arranged on the side of the first dielectric substrate 31 where the second glass plate 12 is located (the third main surface). The radiating conductor 32, the first feed line 33, and the first matching conductor 34 are formed in the same layer. The first ground conductor 35 and the first pattern conductor 37 are arranged on the side of the first dielectric substrate 31 where the first glass plate 11 is located (the fourth main surface).

[0041] The first dielectric substrate 31 is a substrate made of a dielectric material. For example, resin materials or ceramic materials can be used as the dielectric material. In the example configuration shown in Figure 2, the shape of the first dielectric substrate 31 is shown to be rectangular, but the shape of the first dielectric substrate 31 is not limited to rectangular, and can be any shape such as circular or elliptical.

[0042] The radiating conductor 32 is positioned on the side of the first dielectric substrate 31 where the second glass plate 12 is located, and is configured to radiate radio waves corresponding to a high-frequency signal. The radiating conductor 32 is configured to transmit and receive radio waves in a predetermined frequency band to the outside of the vehicle (the side with the second glass plate 12). In this embodiment, the radiating conductor 32 may be configured as a patch antenna. In the configuration example shown in Figure 2, the shape of the radiating conductor 32 is shown to be rectangular, but the shape of the radiating conductor 32 is not limited to rectangular, and can be any shape such as circular or elliptical.

[0043] The first power supply line 33 is configured to supply a high-frequency signal to the radiating conductor 32. As shown in Figure 2, the first power supply line 33 is configured to be directly connected to the radiating conductor 32. The first power supply line 33 extends in a rectangular shape between the radiating conductor 32 and the first matched conductor 34 and functions as a microstrip line (MSL) that supplies a high-frequency signal to the radiating conductor 32.

[0044] The first matching conductor 34 is provided adjacent to an end 38 (first end) on the side opposite to the side where the radiation conductor 32 of the first power supply line 33 is provided. The first matching conductor 34 is provided to suppress the propagation of a high-frequency signal from the first power supply line 33 in an unintended direction. That is, the first matching conductor 34 serves as a stub that suppresses the propagation of the high-frequency signal from the first power supply line 33, and virtually short-circuits the first power supply line 33. In the configuration example shown in FIG. 2, the first matching conductor 34 has a rectangular shape with a recess formed on the end 38 side of the first power supply line 33. The end 38 of the first power supply line 33 on the side of the first matching conductor 34 is disposed in the recess of the first matching conductor 34. In other words, the first matching conductor 34 is formed so as to surround the end 38 of the first power supply line 33. A space is provided between the first power supply line 33 and the first matching conductor 34.

[0045] As shown in FIG. 1, the first ground conductor 35 is disposed on the surface on the side where the first glass plate 11 is disposed. As shown in FIG. 2, the first ground conductor 35 is configured such that when the antenna substrate 30 is viewed in plan, the radiation conductor 32, the first power supply line 33, and the first matching conductor 34 are included in the region where the first ground conductor 35 is formed. Further, when the antenna substrate 30 is viewed in plan, a first slot pattern 36 is formed at a position corresponding to the end 38 of the first power supply line 33 of the first ground conductor 35 (it may also be a position corresponding to the first matching conductor 34). In the configuration example shown in FIG. 2, the first slot pattern 36 is formed in a rectangular shape. The first slot pattern 36 is a portion (opening) of the first ground conductor 35 where no conductor is formed.

[0046] The first pattern conductor 37 is disposed inside the first slot pattern 36 of the first ground conductor 35 and is configured to supply power (slot feeding) to the end 38 side of the first power supply line 33 with a high-frequency signal. Specifically, when the antenna substrate 30 is viewed in plan, at least a part of the first pattern conductor 37 is disposed so as to overlap with the end 38 of the first power supply line 33. By adopting such a configuration, a high-frequency signal can be supplied from the first pattern conductor 37 to the end 38 side of the first power supply line 33.

[0047] The radiation conductor 32, the first power supply line 33, the first matching conductor 34, the first ground conductor 35, and the first pattern conductor 37 can be formed using a metal material having conductivity such as copper or silver.

[0048] As shown in FIG. 2, the power supply substrate 40 includes a second dielectric substrate 41, a second matching conductor 42, a second power supply line 43, a second ground conductor 44, and a second pattern conductor 46. As shown in FIG. 1, the second matching conductor 42 and the second power supply line 43 are disposed on the surface (the fifth main surface) opposite to the surface on which the first glass plate 11 of the second dielectric substrate 41 is disposed. The second matching conductor 42 and the second power supply line 43 are formed in the same layer. Also, the second ground conductor 44 and the second pattern conductor 46 are disposed on the surface (the sixth main surface) on which the first glass plate 11 of the second dielectric substrate 41 is disposed.

[0049] The second dielectric substrate 41 is a substrate made of a dielectric material. For the dielectric material, for example, a resin material or a ceramics material can be used. In the configuration example shown in FIG. 2, the case where the shape of the second dielectric substrate 41 is rectangular is shown, but the shape of the second dielectric substrate 41 is not limited to a rectangular shape, and can be, for example, an arbitrary shape such as a circular shape or an elliptical shape.

[0050] The second power supply line 43 is configured to supply a high-frequency signal to the antenna substrate 30. Specifically, the second power supply line 43 is configured to supply a high-frequency signal to the second pattern conductor 46. As shown in FIG. 2, the second power supply line 43 extends in a rectangular shape and functions as a microstrip line (MSL) that supplies a high-frequency signal to the second pattern conductor 46.

[0051] The second matching conductor 42 is provided adjacent to the end 47 (second end) of the second power supply line 43. The second matching conductor 42 is provided to suppress the propagation of high-frequency signals from the second power supply line 43 in unintended directions. In other words, the second matching conductor 42 acts as a stub to suppress the propagation of high-frequency signals from the second power supply line 43, effectively creating a short circuit in the second power supply line 43. In the configuration example shown in Figure 2, the second matching conductor 42 is rectangular in shape with a recess formed on the end 47 side of the second power supply line 43. The end 47 of the second power supply line 43 on the second matching conductor 42 side is positioned in the recess of the second matching conductor 42. In other words, the second matching conductor 42 is formed to surround the end 47 of the second power supply line 43. A space is provided between the second matching conductor 42 and the second power supply line 43.

[0052] The second pattern conductor 46 is positioned inside the second slot pattern 45 of the second ground conductor 44, and is configured to receive high-frequency signals (slot-fed) from the end 47 side of the second power supply line 43. Specifically, when the power supply board 40 is viewed from above, at least a portion of the second pattern conductor 46 is positioned to overlap with the end 47 side of the second power supply line 43. This configuration allows high-frequency signals to be supplied to the second pattern conductor 46 from the end 47 side of the second power supply line 43.

[0053] The second matching conductor 42, the second power supply line 43, the second ground conductor 44, and the second pattern conductor 46 can be constructed using conductive metallic materials such as copper and silver.

[0054] In this embodiment, the first pattern conductor 37 located on the antenna substrate 30 side and the second pattern conductor 46 located on the feed substrate 40 side are electromagnetically coupled via the first glass plate 11, thereby supplying a high-frequency signal from the second feed line 43 to the first feed line 33. That is, the second feed line 43 supplies a high-frequency signal to the second pattern conductor 46. The second pattern conductor 46 is electromagnetically coupled to the first pattern conductor 37 via the first glass plate 11. Therefore, a high-frequency signal is supplied from the second pattern conductor 46 to the first pattern conductor 37 without contact. The first pattern conductor 37 also supplies a high-frequency signal to the end 38 side of the first feed line 33. The high-frequency signal supplied to the first feed line 33 is supplied to the radiating conductor 32, and radio waves corresponding to the high-frequency signal are radiated from the radiating conductor 32.

[0055] In this embodiment, since the first matching conductor 34 is provided on the end 38 side of the first power supply line 33, it is possible to suppress the propagation of high-frequency signals from the first power supply line 33 in an unintended direction. Similarly, since the second matching conductor 42 is provided on the end 47 side of the second power supply line 43, it is possible to suppress the propagation of high-frequency signals from the second power supply line 43 in an unintended direction.

[0056] Furthermore, in this embodiment, as shown in Figure 2, the length L of the first feed line 33, which is arranged between the radiating conductor 32 and the first matching conductor 34, is configured to be greater than or equal to the in-tube wavelength λg of the high-frequency signal. In other words, in this embodiment, the length L corresponding to the distance between the radiating conductor 32 and the first matching conductor 34 in the first feed line 33 is configured to be greater than or equal to the in-tube wavelength λg of the high-frequency signal. With this configuration, it is possible to provide a window glass with an antenna equipped with a non-contact power supply antenna that can suppress a decrease in radiation efficiency.

[0057] In other words, if the first matching conductor 34 is provided on the antenna substrate 30, the radiation from the first matching conductor 34 and the radiation from the radiating conductor 32 may interfere with each other, potentially reducing the radiation efficiency from the radiating conductor 32.

[0058] In contrast, in this embodiment, the length L of the first feed line 33, which is positioned between the radiating conductor 32 and the first matching conductor 34, is configured to be greater than or equal to the in-tube wavelength λg of the high-frequency signal. By making the length L of the first feed line 33 greater than or equal to the in-tube wavelength λg of the high-frequency signal, the radiating conductor 32 and the first matching conductor 34 can be appropriately separated, and interference between the radiation from the first matching conductor 34 and the radiation from the radiating conductor 32 can be suppressed. Therefore, it is possible to provide a window glass with an antenna equipped with a non-contact power supply antenna that can suppress a decrease in radiation efficiency.

[0059] Here, the length L of the first power transmission line 33 corresponds to the distance between the radiating conductor 32 and the first matched conductor 34 shown in Figure 2. In other words, the length L of the first power transmission line 33 corresponds to the distance between the end of the radiating conductor 32 on the first matched conductor 34 side and the end of the first matched conductor 34 on the radiating conductor 32 side.

[0060] In the configuration example shown in Figure 2, the end of the first power supply line 33 on the first matched conductor 34 side is located in the recess of the first matched conductor 34. In this case, the position corresponding to the end of the first matched conductor 34 on the radiating conductor 32 side is defined as one (right) end of the first matched conductor 34. Similarly, the position corresponding to the end of the first matched conductor 34 on the first matched conductor 34 side is defined as the other (left) end of the first matched conductor 34.

[0061] Furthermore, in this embodiment, when an antenna substrate 30 is provided between the first glass plate 11 and the second glass plate 12, the magnitude of the loss in the first glass plate 11 and the second glass plate 12 (hereinafter referred to as glass loss) changes periodically due to multiple reflections between the radiating conductor 32 and the first matching conductor 34.

[0062] Figure 3 is a graph showing the relationship between the length L of the first transmission line and the radiation efficiency, glass loss, and average gain. As shown in Figure 3, the radiation efficiency and glass loss change periodically as the length L of the first transmission line changes. Therefore, the average gain changes periodically.

[0063] In other words, as shown in the equation below, when the length L of the first transmission line approximately coincides with an odd multiple of 1 / 4 wavelength of the electromagnetic wave wavelength λg inside the tube, the radiation efficiency is high. Conversely, when the length L of the first transmission line approximately coincides with an integer multiple of 1 / 2 wavelength of the electromagnetic wave wavelength λg inside the tube, the radiation efficiency is low.

[0064]

[0065] Taking this into consideration, in this embodiment, it is preferable to set the length L of the first feed line to satisfy (2n+1)・λg / 4 (where n is an integer of 2 or more). With this configuration, the decrease in the radiation efficiency of the antenna can be suppressed more effectively. Here, "the length L of the first feed line to satisfy (2n+1)・λg / 4" includes the case where the length L of the first feed line is approximately equal to (2n+1)・λg / 4. The length L of the first feed line being approximately equal to (2n+1)・λg / 4 means that L is within ±5% of (2n+1)・λg / 4.

[0066] Figure 4 shows the simulation results of the antenna's radiation directivity. In Figure 4, 0 degrees represents the outside of the vehicle, and 180 degrees represents the inside of the vehicle. As shown in Figure 4, by appropriately setting the length L of the first feed line, radio waves can be efficiently radiated from the radiating conductor 32 to the outside of the vehicle.

[0067] On the other hand, if the length L of the first power transmission line 33 is increased, the radiation efficiency decreases by the amount of loss in the first power transmission line 33. For this reason, in this embodiment, the length L of the first power transmission line 33 is preferably 500 mm or less, more preferably 300 mm or less, and even more preferably 100 mm or less.

[0068] In this embodiment, the frequency of the high-frequency signal can be any frequency within the range described above, but it is particularly suitable to use frequencies between 400 MHz and 50.0 GHz, preferably between 20.0 GHz and 40.0 GHz, and more preferably between 27.0 GHz and 29.5 GHz.

[0069] Furthermore, in this embodiment, the thickness of the first glass plate 11 can be within the range described above, but considering that a non-contact power supply method is used, the thickness of the first glass plate 11 is preferably 0.1 mm or more and 10 mm or less, more preferably 0.3 mm or more and 3.0 mm or less, even more preferably 1.1 mm or more and 2.6 mm or less, and even more preferably 1.7 mm or more and 2.1 mm or less. By setting the thickness of the first glass plate 11 within this range, it is possible to efficiently supply power from the power supply board 40 to the antenna board 30 via the first glass plate 11 in a non-contact manner while maintaining the strength of the first glass plate 11.

[0070] Furthermore, in this embodiment, when an antenna substrate 30 is provided between the first glass plate 11 and the second glass plate 12, there is a mode that propagates between the upper and lower first glass plate 11 and second glass plate 12 with the interlayer 13 in between. Due to this propagation mode, radio waves 25 and 26 are radiated from the end of the antenna-equipped window glass 1 shown in Figure 5 toward the first glass plate 11 or the second glass plate 12. The direction of radiation of the radio waves 25 and 26 at this time changes periodically according to the distance B between the end of the first matching conductor 34 and the end of the window glass 1.

[0071] Figure 6 shows the simulation results of radio waves radiated from a window glass with an antenna. As shown in the upper part of Figure 6, when the distance B is 5.75λg, radio waves 25 are radiated from the edge of the window glass 1 toward the outside of the vehicle (upwards on the paper). On the other hand, as shown in the lower part of Figure 6, when the distance B is 7.31λg, radio waves 26 are radiated from the edge of the window glass 1 toward the inside of the vehicle (downwards on the paper). Thus, the direction of radiation of radio waves 25 and 26, which are radiated due to modes propagating between the first glass plate 11 and the second glass plate 12, changes periodically depending on the distance B between the edge of the first matching conductor 34 and the edge of the window glass 1. Note that the simulation results shown in Figure 6 are for a high-frequency signal with a frequency of 28 GHz.

[0072] For example, if radio waves 25 are radiated from the edge of the window glass 1 toward the outside of the vehicle (above the plane of the paper), there is a risk of interference with radio waves radiated from the radiating conductor 32 toward the outside of the vehicle (above the plane of the paper). Taking this into consideration, in this embodiment, it is preferable to set the distance B between the edge of the window glass 1 and the edge of the first matching conductor 34 such that the direction of radiation of radio waves radiated from the edge of the window glass 1, in the mode propagating between the first glass plate 11 and the second glass plate 12, is toward the second main surface 22 side of the first glass plate 11.

[0073] For example, if the frequency of the high-frequency signal is 28 GHz and the thickness of the window glass 1 is 4.76 mm (that is, if the thickness of the first glass plate 11 is 2 mm, the thickness of the second glass plate 12 is 2 mm, and the thickness of the interlayer is 0.76 mm), there is a mode that propagates between the first glass plate 11 and the second glass plate 12 with a period of 18 to 20 mm. In this case, by setting the distance B between the edge of the window glass 1 and the edge of the first matching conductor 34 to a period length of 18 to 20 mm, the direction of the radio waves radiated from the edge of the window glass 1 can be directed towards the inside of the vehicle (radio waves 26).

[0074] Figure 7 is a plan view of the antenna substrate of the window glass with an antenna according to the embodiment. The mode propagating between the first glass plate 11 and the second glass plate 12, that is, the mode propagating in the in-plane direction of the window glass 1, changes according to the distance D between the end of the first matching conductor 34 in the width direction (a direction perpendicular to the direction in which the first feed line 33 extends) and the end of the first ground conductor 35 in the width direction (see Figure 2).

[0075] Figure 8 is a graph showing the relationship between the distance D between the widthwise end of the first matched conductor and the widthwise end of the first ground conductor, and the propagation mode in the in-plane direction of the window glass. In the graph shown in Figure 8, the vertical axis represents the magnitude of the mode propagating in the in-plane direction of the window glass 1. Figure 8 shows the simulation results when the widthwise length of the first matched conductor 34 is 6.45 mm and the frequency of the high-frequency signal is 28 GHz.

[0076] As shown in Figure 8, increasing the distance D between the widthwise end of the first matching conductor 34 and the widthwise end of the first ground conductor 35 reduces the magnitude of modes propagating in the in-plane direction of the window glass 1. Therefore, in this embodiment, increasing the distance D between the widthwise end of the first matching conductor 34 and the widthwise end of the first ground conductor 35 by a predetermined length can suppress the generation of modes propagating in the in-plane direction of the window glass 1. In other words, increasing the width of the first ground conductor 35 (the length in the direction perpendicular to the direction in which the first feed line 33 extends) can suppress the generation of modes propagating in the in-plane direction of the window glass 1. Thus, the feeding performance from the feed board 40 to the antenna board 30 can be improved. In the example shown in Figure 8, setting the distance D to 3 mm effectively suppresses the generation of modes propagating in the in-plane direction of the window glass 1.

[0077] Figure 9 is a plan view showing other configuration examples of the first and second ground conductors. In this embodiment, as shown in the upper part of Figure 9, electromagnetic bandgap structures (EBG (Electromagnetic Bandgap) structures) 52 and 53 may be formed around the first slot pattern 36 of the first ground conductor 35a, which is located on the lower surface of the antenna substrate 30. In the configuration example shown in Figure 9, electromagnetic bandgap structures 52 and 53 are formed on both sides (up and down directions on the paper) in the width direction of the first slot pattern 36 of the first ground conductor 35a. Also, as shown in the lower part of Figure 9, electromagnetic bandgap structures 62 and 63 may be formed around the second slot pattern 45 of the second ground conductor 44a, which is located on the upper surface of the power supply substrate 40. In the configuration example shown in Figure 9, electromagnetic bandgap structures 62 and 63 are formed on both sides (up and down directions on the paper) in the width direction of the second slot pattern 45 of the second ground conductor 44a.

[0078] In this way, by providing the electromagnetic bandgap structures 52, 53, 62, and 63, the generation of modes propagating in the in-plane direction of the window glass 1 can be effectively suppressed (see Figure 8), and the power supply performance from the power supply board 40 to the antenna board 30 can be improved.

[0079] The electromagnetic bandgap structure has a periodic structure in which one or more unit cells, composed of conductors or the like, are arranged periodically. In the example configuration shown in Figure 9, the electromagnetic bandgap structures 52, 53, 62, and 63 have a periodic structure in which multiple cross-shaped unit cells, composed of conductors or the like, are arranged periodically. In Figure 9, a cross shape is shown as an example of the shape of the conductor pattern of the unit cell, but the shape of the conductor pattern of the unit cell may be other than a cross shape, for example, a square or a circle. Furthermore, the size of the unit cell and the period in which it is arranged can be determined according to the frequency of the high-frequency signal supplied from the power supply board 40 to the antenna board 30.

[0080] The electromagnetic bandgap structure may be provided on both the first ground conductor 35a and the second ground conductor 44a, or on only one of them. Considering the need to effectively suppress the generation of modes propagating in the in-plane direction of the window glass 1, it is preferable to provide the electromagnetic bandgap structure on both the first ground conductor 35a and the second ground conductor 44a.

[0081] Figure 10 is a cross-sectional view showing the antenna-equipped window glass according to the embodiment attached to a metal flange. As shown in Figure 10, the antenna-equipped window glass 1 may be attached to a metal flange (body flange) 70 using an adhesive 71 such as polyurethane. In the configuration example shown in Figure 10, in order to make the power supply board 40 less conspicuous when viewed from inside the vehicle, a shielding layer 49 is formed on the antenna-equipped window glass 1 so as to cover the power supply board 40 when viewed from the power supply board 40 side. The shielding layer 49 can be made using, for example, black ceramics.

[0082] Furthermore, when the window glass 1 is viewed from above, the first matching conductor 34 of the antenna substrate 30 may be configured to overlap with the shielding layer 49. This configuration makes the first matching conductor 34 of the antenna substrate 30 less conspicuous when viewed from inside the vehicle. In addition, the radiating conductor 32 may be formed in a mesh shape. By making the radiating conductor 32 in a mesh shape in this way, the radiating conductor 32 can be made less conspicuous. Furthermore, the first feed line 33, the first matching conductor 34, and a part of the first ground conductor 35 may be made in a mesh shape. That is, when the window glass 1 with the antenna is viewed from above from the feed board 40 side, the components that do not overlap with the shielding layer 49 can be made in a mesh shape, making the components constituting the antenna less conspicuous.

[0083] Furthermore, in the configuration example shown in Figure 10, the window glass with antenna 1 is attached to the metal flange 70, so the antenna may be affected by the metal flange 70. Taking this into consideration, in this embodiment, when the window glass with antenna 1 is attached to the metal flange 70, the length of the first feed line 33 may be set to satisfy (2n+1)・λg / 4 (where n is an integer of 6 or more). By setting the length of the first feed line 33 in this way, the influence of the metal flange 70 on the antenna can be suppressed.

[0084] Figure 11 is a plan view showing another example of the antenna substrate configuration. In this embodiment, multiple radiating conductors 72 may be arranged in an array, as shown in the antenna substrate 30a in Figure 11. In the configuration example shown in Figure 11, an example in which 13 radiating conductors 72 are arranged in an array is shown, but the number of radiating conductors 72 to be arranged can be arbitrarily determined. Multiple radiating conductors 72 are connected to each other using conductors 75.

[0085] Figure 12 shows the simulation results of the radiation directivity of the array antenna shown in Figure 11. The left figure in Figure 12 shows the simulation results of the radiation directivity on a plane perpendicular to the direction in which the first feed line 33 extends, and the right figure shows the simulation results of the radiation directivity on a plane tilted at θ = 60 degrees with respect to a plane parallel to the direction in which the first feed line 33 extends. As shown in Figure 12, beam tilt is possible by changing the length of the conductor 75 that connects the multiple radiation conductors 72. Furthermore, beamforming is possible by arranging multiple radiation conductors 72 in parallel and changing the phase of the supplied high-frequency signal.

[0086] Although the present invention has been described above in accordance with the above embodiments, the present invention is not limited to the configuration of the above embodiments, and of course includes various modifications, alterations, and combinations that can be made by a person skilled in the art within the scope of the claims of the present patent application.

[0087] This application claims priority based on Japanese Patent Application No. 2025-5060, filed on 14 January 2025, and incorporates all of its disclosures herein.

[0088] 1 Window glass with antenna 11 First glass plate 12 Second glass plate 13 Interlayer 30 Antenna substrate 31 First dielectric substrate 32 Radiating conductor 33 First feed line 34 First matched conductor 35, 35a First ground conductor 37 First pattern conductor 40 Feed substrate 41 Second dielectric substrate 42 Second matched conductor 43 Second feed line 44, 44a Second ground conductor 46 Second pattern conductor 48 Adhesive layer 49 Shielding layer 52, 53, 62, 63 Electromagnetic bandgap structure 72 Radiating conductor 75 Conductor

Claims

1. The antenna comprises a first glass plate, an antenna substrate disposed on the first main surface side of the first glass plate, and a power supply substrate disposed on the second main surface side opposite to the first main surface of the first glass plate, capable of non-contact supplying a high-frequency signal to the antenna substrate, wherein the antenna substrate comprises a first dielectric substrate made of a dielectric material, a radiating conductor disposed on the third main surface of the first dielectric substrate opposite to the side on which the first glass plate is disposed, which radiates radio waves corresponding to the high-frequency signal, a first power supply line for supplying the high-frequency signal to the radiating conductor, a first matching conductor provided adjacent to the first end of the first power supply line opposite to the side on which the radiating conductor is provided, and a first ground conductor disposed on the fourth main surface of the first dielectric substrate opposite to the third main surface, which has a first slot pattern formed at a position corresponding to the first end of the first power supply line when the antenna substrate is viewed in plan view, The power supply substrate comprises: a first pattern conductor disposed inside the first slot pattern of the first ground conductor and supplying the high-frequency signal to the first end side of the first power supply line; a second dielectric substrate made of a dielectric material; a second power supply line disposed on the fifth main surface of the second dielectric substrate opposite to the side on which the first glass plate is disposed and supplying the high-frequency signal to the antenna substrate; a second matching conductor provided adjacent to the second end of the second power supply line; a second ground conductor disposed on the sixth main surface of the second dielectric substrate opposite to the fifth main surface, with a second slot pattern formed at a position corresponding to the second end of the second power supply line when the power supply substrate is viewed in plan; and a second pattern conductor disposed inside the second slot pattern of the second ground conductor and supplied with the high-frequency signal from the second end side of the second power supply line. A window glass with an antenna, wherein the first pattern conductor and the second pattern conductor are electromagnetically coupled via the first glass plate, thereby supplying the high-frequency signal from the second power supply line to the first power supply line, and the length corresponding to the distance between the radiating conductor and the first matching conductor in the first power supply line is greater than or equal to the in-tube wavelength λg of the high-frequency signal.

2. The window glass with an antenna further comprises a second glass plate arranged opposite to the first glass plate, and an interlayer disposed between the first glass plate and the second glass plate, wherein the antenna substrate is disposed between the first glass plate and the second glass plate, as described in claim 1.

3. The window glass with antenna according to claim 1 or 2, wherein the length of the first power supply line is set to satisfy (2n+1)・λg / 4 (where n is an integer of 2 or more).

4. The window glass with an antenna according to claim 1 or 2, wherein the frequency of the high-frequency signal is 400 MHz or more and 50.0 GHz or less.

5. The window glass with an antenna according to claim 1 or 2, wherein the thickness of the first glass plate is 0.1 mm or more and 10 mm or less.

6. The window glass with antenna according to claim 1 or 2, wherein an electromagnetic bandgap structure is formed around the first slot pattern of the first ground conductor arranged on the fourth main surface of the antenna substrate.

7. The window glass with antenna according to claim 6, wherein an electromagnetic bandgap structure is formed around the second slot pattern of the second ground conductor arranged on the sixth main surface of the power supply board.

8. The window glass with antenna according to claim 1 or 2, wherein, when the window glass with antenna is attached to a metal flange, the length of the first power supply line is set to satisfy (2n+1)・λg / 4 (where n is an integer of 6 or more).

9. The window glass with an antenna according to claim 1 or 2, wherein, when the window glass with an antenna is viewed in plan view from the power supply board side, a shielding layer is formed so as to cover the power supply board.

10. The window glass with antenna according to claim 1 or 2, wherein the radiating conductor is composed of a patch antenna.

11. The window glass with antenna according to claim 1 or 2, wherein at least one of the radiating conductor, the first matching conductor, the first feed line, and the first ground conductor is configured in a mesh pattern.

12. The window glass with an antenna according to claim 1 or 2, wherein a plurality of the radiating conductors are arranged in an array on the third main surface of the first glass plate.

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