Antenna device for vehicle

Abstract

This antenna device for a vehicle comprises an antenna, and a dielectric plate having a first surface facing the antenna and a second surface on the opposite side to the first surface, the dielectric plate having a conductive layer provided on the first surface or in an inner layer between the first surface and the second surface and the antenna having a radiation conductor that does not overlap the conductive layer in a plan view of the dielectric plate. In a state resulting from the dielectric plate having been attached to a flange provided on the roof of the vehicle, b is 0.3 × λ to 25 × λ inclusive and e is 0.1 × λ to 25 × λ inclusive, where b is the shortest distance from an end of the flange to the outer edge of the radiation conductor in the plan view, e is the shortest distance from the edge of the conductive layer to the outer edge of the radiation conductor in the plan view, and λ is the wavelength in air of radio waves transmitted or received by the antenna. h is 0.3 × λ to 3 × λ inclusive, where h is the shortest distance from the first surface to the radiation conductor.

Description

Vehicle antenna device

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

[0002] Conventionally, an antenna for transmitting radio waves to an external device through a glass plate of a vehicle or receiving radio waves from an external device through a glass plate of a vehicle has been known (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2002-246817

[0004] A dielectric substrate such as a roof glass is attached to a flange provided on the roof of a vehicle. However, if the dielectric substrate has a conductive layer, the flange and the conductive layer may reduce the gain of an antenna that transmits or receives radio waves via the dielectric substrate.

[0005] The present disclosure provides a vehicle antenna device that can prevent a reduction in antenna characteristics (gain) due to the influence of the edges of the conductive layer and the flange ends on radio waves when a dielectric substrate having a conductive layer is attached to a flange provided on the roof of a vehicle.

[0006] a dielectric plate having a first surface facing the antenna and a second surface opposite the first surface, wherein the dielectric plate has a conductive layer provided on the first surface or on an inner layer between the first surface and the second surface, and the antenna has a radiating conductor that does not overlap with the conductive layer in a planar view of the dielectric plate, wherein, when the dielectric plate is attached to a flange provided on a roof of a vehicle, b is the shortest distance from an end of the flange to an outer edge of the radiating conductor in the planar view, e is the shortest distance from an edge of the conductive layer to the outer edge of the radiating conductor in the planar view, and λ is the wavelength in air of radio waves transmitted or received by the antenna, b is not less than 0.3×λ and not more than 25×λ, and e is not less than 0.1×λ and not more than 25×λ; and h is the shortest distance from the first surface to the radiating conductor, h is not less than 0.3×λ and not more than 3×λ.

[0007] A second aspect is the vehicle antenna device of the first aspect, wherein b may be equal to or greater than 0.4×λ and equal to or less than 25×λ.

[0008] A third aspect is the vehicle antenna device according to the first or second aspect, wherein e may be equal to or greater than 0.3×λ and equal to or less than 25×λ.

[0009] A fourth aspect is the vehicle antenna device according to any one of the first to third aspects, wherein the shortest distance h may be equal to or greater than 0.3×λ and equal to or less than 2×λ.

[0010] A fifth aspect is the vehicle antenna device according to any one of the first to fourth aspects, wherein the conductive layer may have an inner edge that forms an opening that surrounds the radiation conductor in the plan view.

[0011] A sixth aspect is the vehicle antenna device according to the fifth aspect, wherein the size of the opening may be equal to or greater than 1×λ and equal to or less than 25×λ.

[0012] A seventh aspect is the vehicle antenna device according to the sixth aspect, wherein the size of the opening may be equal to or greater than 2×λ and equal to or less than 10×λ.

[0013] An eighth aspect is the vehicle antenna device according to the sixth aspect, wherein the size of the opening may be equal to or greater than 1×λ and equal to or less than 2.5×λ.

[0014] A ninth aspect is the vehicle antenna device according to the eighth aspect, wherein the size of the opening may be equal to or greater than 2×λ and equal to or less than 2.5×λ.

[0015] A tenth aspect is the vehicle antenna device according to any one of the fifth to ninth aspects, wherein, when the shortest distance from the first surface to the radiation conductor is h, h may be equal to or greater than 0.3×λ and equal to or less than 3×λ.

[0016] An eleventh aspect is the vehicle antenna device according to any one of the fifth to ninth aspects, wherein, when the shortest distance from the first surface to the radiation conductor is h, h may be 0.1×λ or more and 0.5×λ or less.

[0017] A twelfth aspect is the vehicle antenna device of the eleventh aspect, wherein h may be equal to or greater than 0.3×λ and equal to or less than 0.5×λ.

[0018] A thirteenth aspect provides a vehicle antenna device comprising: an antenna; and a dielectric plate having a first surface facing the antenna and a second surface opposite the first surface, wherein the dielectric plate has a conductive layer provided on the first surface or on an inner layer between the first surface and the second surface, wherein the antenna has a radiation conductor that does not overlap with the conductive layer in a planar view of the dielectric plate, and the conductive layer has an inner edge that forms an opening that surrounds the radiation conductor in the planar view, wherein, when the dielectric plate is attached to a flange provided on a roof of a vehicle, b is the shortest distance from an end of the flange to the outer edge of the radiation conductor in the planar view, and λ is the wavelength in air of the radio waves transmitted or received by the antenna, b is not less than 0.1×λ and not more than 15×λ, and the size of the opening is not more than 1×λ and not more than 25×λ.

[0019] A fourteenth aspect is a vehicle antenna device according to any one of the first to thirteenth aspects, wherein the conductive layer may include a first conductive layer provided on the first surface, and the radiation conductor may not overlap with the first conductive layer in the planar view.

[0020] A fifteenth aspect is a vehicle antenna device according to any one of the first to thirteenth aspects, wherein the conductive layer may include a second conductive layer provided on the inner layer, and the radiation conductor may not overlap with the second conductive layer in the planar view.

[0021] A sixteenth aspect is the vehicle antenna device according to the fifteenth aspect, in which the conductive layer does not have to be a conductive layer that includes the first conductive layer provided on the first surface.

[0022] A seventeenth aspect is a vehicle antenna device according to any one of the first to thirteenth aspects, wherein the conductive layer may include a first conductive layer provided on the first surface and a second conductive layer provided on the inner layer, and the radiation conductor may not overlap with the first conductive layer and the second conductive layer in the planar view.

[0023] According to the present disclosure, a vehicle antenna device can be provided that can prevent a reduction in antenna characteristics (gain) due to the influence of the edges of the conductive layer and the flange ends on radio waves when a dielectric substrate having a conductive layer is attached to a flange provided on the roof of a vehicle.

[0024] 1 is a partial plan view showing an example of a configuration of a vehicle antenna device of a first embodiment; FIG. 2 is a partial cross-sectional view showing an example of a configuration of a vehicle antenna device of a second embodiment; FIG. 3 is a partial cross-sectional view showing an example of a configuration of a vehicle antenna device of a third embodiment; FIG. 4 is a partial cross-sectional view showing an example of a configuration of a vehicle antenna device of a fourth embodiment; FIG. 5 is a partial plan view showing an example of a configuration of a vehicle antenna device of a fifth embodiment; FIG. 6 is a partial cross-sectional view showing an example of a configuration of a vehicle antenna device of a sixth embodiment; FIG. 7 is a partial cross-sectional view showing an example of a configuration of a vehicle antenna device of a seventh embodiment; FIG. 8 is a partial cross-sectional view showing an example of a configuration of a vehicle antenna device of an eighth embodiment; FIG. 9 is a diagram showing an example of a simulation result of the relationship between distance e and frontal gain for the fourth embodiment; FIG. 10 is a diagram showing an example of a simulation result of the relationship between distance e and frontal gain for the fourth embodiment; FIG. 11 is a partial cross-sectional view showing an example of a configuration of a vehicle antenna device of a first comparative embodiment; FIG. 12 is a diagram showing an example of a simulation result of the relationship between distance b and frontal gain for the first comparative embodiment; 10 is a diagram showing an example of a simulation result of the relationship between the distance b and the front gain for the first comparative embodiment. FIG. 11 is a diagram showing an example of a simulation result of the relationship between the distance e and the front gain for the fourth embodiment. FIG. 12 is a diagram showing an example of a simulation result of the relationship between the distance e and the front gain for the third and fourth embodiments. FIG. 13 is a diagram showing an example of a simulation result of the relationship between the aperture size and the front gain for the eighth embodiment. FIG. 14 is a diagram showing an example of a simulation result of the relationship between the aperture size and the half-value angle for the eighth embodiment. FIG. 15 is a diagram showing an example of a simulation result of the relationship between the aperture size and the half-value angle for the eighth embodiment. FIG. 16 is a diagram showing an example of a simulation result of the relationship between the distance h and the front gain for the eighth embodiment. FIG. 17 is a diagram showing an example of a simulation result of the relationship between the distance h and the half-value angle for the eighth embodiment.FIG. 13 is a diagram showing an example of a result of simulating the relationship between the distance b and the frontal gain for the eighth embodiment. FIG. 14 is a diagram showing an example of a result of simulating the relationship between the distance b and the frontal gain for the eighth embodiment. FIG. 15 is a diagram showing a first modified example of the antenna. FIG. 16 is a diagram showing a second modified example of the antenna. FIG. 17 is a diagram showing an example of a result of simulating the relationship between the distance h and the frontal gain for the fourth embodiment. FIG. 18 is a diagram showing an example of a result of simulating the relationship between the distance h and the frontal gain for the fourth embodiment.

[0025] The present embodiment will be described below with reference to the drawings. For ease of understanding, the scales of the various components in the drawings may differ from the actual scale. Directions such as parallel, right-angled, orthogonal, horizontal, vertical, up, down, left, and right, as well as terms such as identical and equal, are permitted to deviate to the extent that they do not impair the functions and effects of the embodiment. The shape of corners is not limited to right angles and may be rounded like an arch. Overlapping may also mean partially overlapping. The X-axis, Y-axis, and Z-axis directions represent directions parallel to the X-axis, Y-axis, and Z-axis, respectively. The X-axis, Y-axis, and Z-axis directions are mutually orthogonal. The XY plane, YZ plane, and ZX plane represent imaginary planes parallel to the X-axis and Y-axis directions, imaginary planes parallel to the Y-axis and Z-axis directions, and imaginary planes parallel to the Z-axis and X-axis directions, respectively.

[0026] The antenna device of this embodiment is applicable to a wireless communication system called a non-terrestrial network (NTN), which is a communication system that uses non-terrestrial media such as low earth orbit (LEO) satellites, geostationary earth orbit (GEO) satellites, high altitude platform systems (HAPS), or drones.

[0027] The antenna device of this embodiment may be applied to a Satellite Digital Audio Radio Service (SDARS), a Global Navigation Satellite System (GNSS), a Vehicle to Everything (V2X) communication system, a fifth-generation mobile communication system (so-called 5G), an in-vehicle radar system, and the like.

[0028] Systems to which the antenna device of this embodiment can be applied are not limited to these.

[0029] Fig. 1 is a partial plan view showing an example of the configuration of a vehicle antenna device of a first embodiment. Fig. 1 is a plan view of a dielectric plate 10. Fig. 2 is a partial cross-sectional view showing an example of the configuration of a vehicle antenna device of the first embodiment. The antenna device 101 shown in Figs. 1 and 2 is a vehicle antenna device including a dielectric plate 10 having a conductive layer 30 and an antenna 25 that transmits or receives radio waves A through the dielectric plate 10.

[0030] The dielectric plate 10 is attached to a flange 200 provided on the roof of a vehicle. The dielectric plate 10 is applied to, for example, a panoramic roof or a sunroof. The flange 200 is, for example, a conductive frame provided at the edge of the roof of a vehicle.

[0031] The dielectric plate 10 may be a vehicle window glass such as a roof glass attached to the roof of a vehicle, or may be a window glass in which the roof glass is integrated with one or both of a windshield and a rear window.

[0032] The dielectric plate 10 may be a plate other than a glass plate (for example, a resin plate). When the dielectric plate 10 is a resin plate, examples of the material for the resin plate include transparent resins such as polycarbonate or acrylic resin (for example, polymethyl methacrylate). When used for a window, the dielectric plate 10 is a transparent or translucent member. When used for purposes other than a window, the dielectric plate 10 may be opaque.

[0033] The dielectric plate 10 is a plate-shaped dielectric having a principal surface 11 facing in the negative Z-axis direction and a principal surface 12 facing in the opposite direction (positive Z-axis direction) to the principal surface 11. While the principal surfaces 11 and 12 are illustrated parallel to the XY plane, the principal surface 11 or 12 may be curved relative to the XY plane. When the principal surface 11 or 12 is curved relative to the XY plane, i.e., when the dielectric plate 10 has a curved shape, the dielectric plate 10 may have a single curved shape curved in only one of the left-right or up-down directions, or a compound curved shape curved in both the left-right and up-down directions. When the dielectric plate 10 has a curved shape, the radius of curvature may be 2000 to 11000 mm. When the dielectric plate 10 is a glass plate, gravity forming, press forming, roller forming, or the like is used to bend the dielectric plate 10. The principal surface 11 is an example of a first surface facing the antenna. The main surface 12 is an example of a second surface opposite to the first surface.

[0034] When the dielectric plate 10 is attached to the flange 200, the main surface 11 is the surface of the dielectric plate 10 facing the vehicle interior side, and the main surface 12 is the surface of the dielectric plate 10 facing the vehicle exterior side.

[0035] The dielectric plate 10 is, for example, a single-pane window glass, which is a window glass made up of only one glass plate.

[0036] The thickness of the glass plate (dielectric plate 10 in the example of FIG. 2) in the single plate in the Z-axis direction is not particularly limited, but can generally be selected appropriately in the range of 0.5 mm to 10 mm. The thickness of the dielectric plate 10 is preferably 0.5 mm or more, more preferably 0.7 mm or more, even more preferably 1.1 mm or more, and particularly preferably 1.6 mm or more. Furthermore, to prevent the mass from becoming too large, the thickness of the dielectric plate 10 is preferably 7 mm or less, more preferably 5 mm or less, and even more preferably 4 mm or less.

[0037] When the dielectric plate 10 is a laminated glass as described below, the thickness of the dielectric plate 10 in the Z-axis direction is not particularly limited and can be appropriately selected from the range of 0.1 mm to 10 mm. The thickness of the dielectric plate 10 is preferably 0.3 mm or more, more preferably 0.5 mm or more, even more preferably 0.7 mm or more, particularly preferably 1.1 mm or more, and most preferably 1.6 mm or more. Furthermore, to prevent the mass of the laminated glass from becoming too large, the thickness of the dielectric plate 10 is preferably 3.0 mm or less, more preferably 2.6 mm or less, and even more preferably 2.1 mm or less. The thicknesses of the multiple glass plates constituting the dielectric plate 10 may be the same or different.

[0038] When the dielectric plate 10 is a single-pane glass, the dielectric plate 10 may be either untempered glass or tempered glass. Untempered glass is produced by forming molten glass into a plate shape and slowly cooling it. Tempered glass is produced by forming a compressive stress layer on the surface of untempered glass, and may be either air-cooled tempered glass or chemically tempered glass. When the tempered glass is physically tempered glass (e.g., air-cooled tempered glass), the glass surface may be strengthened by generating a compressive stress layer on the glass surface due to a temperature difference between the glass surface and the interior of the glass through an operation other than slow cooling, such as rapidly cooling a glass plate uniformly heated during bending from a temperature near its softening point. When the tempered glass is chemically tempered glass, the glass surface may be strengthened by generating compressive stress on the glass surface using an ion exchange method or the like after bending. When the dielectric plate 10 is laminated glass as described below, the multiple glass plates constituting the dielectric plate 10 may all be tempered glass, a combination of tempered glass and untempered glass, or all untempered glass.

[0039] The dielectric plate 10 may have a shielding layer (not shown) on its outer periphery. When the dielectric plate 10 is a glass plate, the shielding layer may be a fired product of a dark-colored ceramic paste. The shielding layer may be formed by applying a ceramic color paste containing a fusible glass frit containing a dark-colored pigment such as black to the glass plate and firing it. The shielding layer may also be formed by printing an organic ink or an inorganic ink on the dielectric plate 10. The shielding layer is formed to prevent deterioration of adhesives applied when attaching the dielectric plate 10 to the flange 200 due to ultraviolet rays, and to improve the appearance by preventing the connection between the dielectric plate 10 and the flange 200 from being seen from the outside of the vehicle.

[0040] The conductive layer 30 is provided on the dielectric plate 10. In the example shown in Fig. 2, the conductive layer 30 is provided on the main surface 11 of the dielectric plate 10. The conductive layer 30 may be provided directly on the main surface 11 so as to be in contact with the main surface 11, or may be provided indirectly on the main surface 11 so as to have a predetermined intermediate member interposed between the conductive layer 30 and the main surface 11.

[0041] The conductive layer 30 is a planar conductor disposed on the main surface 11 side of the dielectric plate 10. The conductive layer 30 may be a conductor in contact with the main surface 11, or may be a conductor disposed on the main surface 11 side via a transparent or translucent dielectric (not shown). The conductive layer 30 may be transparent or translucent. Specific examples of the conductive layer 30 include a metal film such as an Ag (silver) film, a metal oxide film such as an ITO (indium tin oxide) film, a resin film containing conductive particles, and a laminate of multiple types of films. The conductive layer 30 may be a resin film such as polyethylene terephthalate coated by vapor deposition or the like. The conductive layer 30 may also be a film formed into a mesh shape by conductive ink or etching.

[0042] The conductive layer 30 may be a conductive film coated on the main surface 11 of the dielectric plate 10. A specific example of the conductive film is a low-emissivity film such as a Low-E (Low Emissivity) film that exhibits low radiation performance.

[0043] Low emissivity refers to reducing heat transfer due to radiation. Low emissivity films such as Low-E films ensure thermal insulation by suppressing heat transfer due to radiation. The low emissivity film may be a general film, for example, a laminated film including a transparent dielectric film, an infrared reflective film, and a transparent dielectric film in this order. Typical transparent dielectric films are metal oxides and metal nitrides. Typical metal oxides are zinc oxide and tin oxide. Typical infrared reflective films are metal films. Typical metal films are silver (Ag). Here, one or more infrared reflective films may be formed between the transparent dielectric films.

[0044] The conductive layer 30 is not limited to a low-emissivity film such as a Low-E film, and may have other functions as long as it is a conductive layer. For example, the conductive layer 30 may have a function of preventing icing or fogging of the dielectric plate 10 such as window glass by generating heat when a voltage is applied.

[0045] The conductive layer 30 may be a conductive film included in a light-controlling film that can actively change the visible light transmittance of the dielectric plate 10 by applying an AC voltage. The light-controlling film has, for example, a molecular layer with optical anisotropy between a pair of opposing resin substrates. A conductive film and an electrode electrically connected to the conductive film are provided on the main surface of each resin substrate. The light-controlling film can be driven by applying a voltage between the pair of conductive layers via the electrodes.

[0046] The resin substrate is made of, for example, a transparent resin. The resin substrate may have, for example, polyethylene terephthalate (PET), polycarbonate (PC), or cycloolefin polymer (COP). Furthermore, a pair of opposing resin substrates may be made of, for example, a combination of the above-mentioned resins. The thickness of the resin substrate is, for example, in the range of 5 μm to 500 μm, preferably in the range of 10 μm to 200 μm, more preferably in the range of 20 μm to 180 μm, and even more preferably in the range of 50 μm to 150 μm.

[0047] The conductive film may include, for example, a transparent conductive oxide, a transparent conductive polymer, a laminated film of a metal layer and a dielectric layer, silver nanowires, a silver or copper metal mesh, etc. The thickness of the conductive film may be, for example, in the range of 5 nm to 2 μm.

[0048] Examples of molecules having optical anisotropy include liquid crystals. That is, for example, a liquid crystal layer may be used as a molecular layer having optical anisotropy. Examples of the liquid crystal layer include polymer dispersed liquid crystal (PDLC), polymer network liquid crystal (PNLC), and guest-host liquid crystal. Alternatively, iodine or the like may be used as a molecule having optical anisotropy. The light control film may have a suspended particle device (SPD) including such a molecular layer.

[0049] The antenna 25 has a radiation conductor 20 facing the main surface 11 and a substrate 22 on which the radiation conductor 20 is provided.

[0050] The radiating conductor 20 is a planar conductor disposed on the surface of the substrate 22. The radiating conductor 20 is, for example, a flat pattern formed by a conductor on the surface of the substrate 22. The shape of the radiating conductor 20 in a planar view is not limited to a rectangle, and may be other shapes (for example, a polygon other than a rectangle, a circle, an ellipse, etc.). The rectangle, polygon, circle, and ellipse may include an approximate rectangle, an approximate polygon, an approximate circle, and an approximate ellipse, respectively.

[0051] The radiation conductor 20 is a radiation element that transmits or receives radio waves A having a frequency included in a predetermined frequency band W through the dielectric plate 10. The radiation conductor 20 is also called a patch conductor.

[0052] The frequency band W is a relatively high band such as the UHF (Ultra High Frequency) band of 300 MHz to 3 GHz, the SHF (Super High Frequency) band of 3 GHz to 30 GHz, or the EHF (Extremely High Frequency) band of 30 GHz to 300 GHz. Specific examples of such high frequency bands include bands used in the fifth generation communication (5G) standard (frequency bands of 6 GHz or less (sub6) and frequency bands of 24 GHz or more (28 GHz band, 39 GHz band, etc.)).

[0053] The substrate 22 is a plate-shaped dielectric having a back surface facing the negative Z-axis direction and a front surface facing the opposite direction (positive Z-axis direction) from the back surface. The front surface of the substrate 22 faces the main surface 11. Although the front surface and back surface are illustrated as being parallel to the XY plane, the front surface or back surface may be curved relative to the XY plane.

[0054] A dielectric layer 110 is present between the radiating conductor 20 and the main surface 11. The dielectric layer 110 may be air or a solid dielectric. The antenna 25 is fixed to the main surface 11 so that the dielectric layer 110 is present between the radiating conductor 20 and the main surface 11.

[0055] 1 , the conductive layer 30 has an edge 31 facing the outer edge 21 of the radiating conductor 20 so that a gap exists between the outer edge 21 and the conductive layer 30 in a plan view of the dielectric plate 10. A distance e indicates the length of the gap in a plan view of the dielectric plate 10. The end of the flange 200 (flange edge 201) and the edge 31 of the conductive layer 30 form an opening 32 that surrounds the radiating conductor 20 in a plan view. The opening 32 functions as a window through which radio waves A transmitted or received by the radiating conductor 20 pass.

[0056] The edge 31 is formed parallel to one side of the outer edge 21 of the radiating conductor 20 in a plan view. The edge 31 may be formed parallel to one side of the flange end 201 in a plan view. In the example shown in Fig. 1 , the flange end 201 and the edge 31 form an opening 32 that is completely closed by the conductive layer 30 and the flange 200 in a plan view. However, by cutting out part of the edge 31 or part of the flange end 201, the opening 32 does not have to be completely closed by the conductive layer 30 and the flange 200 in a plan view.

[0057] The conductive layer 30 in the first embodiment is an example of a first conductive layer provided on the first surface facing the antenna. The edge 31 is an example of a first edge that is the edge of the first conductive layer. When the dielectric plate 10 is attached to the flange 200, the radiating conductor 20 does not overlap with the conductive layer 30 in a plan view of the dielectric plate 10.

[0058] Here, the wavelength in air of radio wave A transmitted or received by antenna 25 is λ, and the wavelength shortening rate due to substrate 22 is k. In this case, outer edge 21 of radiation conductor 20 is a polygon with at least one side length of 0.8×k×(λ / 2) to 1.2×k×(λ / 2), a circle with a diameter of 0.8×k×(λ / 2) to 1.2×k×(λ / 2), or an ellipse with a major or minor axis length of 0.8×k×(λ / 2) to 1.2×k×(λ / 2). Hereinafter, this dimensional and shape condition is defined as "Condition C," and the length of one side, the diameter, or the length of the major or minor axis of outer edge 21 is defined as "length c." Figure 1 illustrates an example in which outer edge 21 is square, satisfying Condition C.

[0059] When the outer edge 21 satisfies the condition C, the radiating conductor 20 is formed to have a length c whose median is k × (λ / 2), and the radiating conductor 20 functions as a radiating element of the patch antenna (antenna 25). Therefore, the antenna gain of the antenna device 101 that transmits or receives radio waves A with wavelength λ is improved compared to when the condition C is not satisfied.

[0060] The length c that satisfies condition C is preferably "0.9×k×(λ / 2) or more and 1.1×k×(λ / 2) or less" in terms of improving the antenna gain of antenna 25, and more preferably "0.95×k×(λ / 2) or more and 1.05×k×(λ / 2) or less."

[0061] On the other hand, when the dielectric plate 10 is attached to a flange 200 provided on the roof of a vehicle, the distance from the end of the flange 200 (flange end 201) to the radiating conductor 20 in a planar view is defined as b, and the distance from the edge (edge ​​31) of the conductive layer 30 to the outer edge (outer edge 21) of the radiating conductor 20 in a planar view is defined as e. In this example, distance b represents the shortest distance from the flange end 201 to the outer edge 21 of the radiating conductor 20 in a planar view, and distance e represents the shortest distance from the edge 31 of the conductive layer 30 to the outer edge 21 of the radiating conductor 20 in a planar view. Distance b is equal to or greater than 0.3×λ and equal to or less than 25×λ, and distance e is equal to or greater than 0.1×λ and equal to or less than 25×λ. Hereinafter, this dimensional condition is defined as "Condition B."

[0062] When the dielectric plate 10 is attached to the flange 200, the antenna 25 is positioned to satisfy condition B, thereby improving the gain of the antenna 25 in the positive Z-axis direction compared to when condition B is not satisfied. When condition B is satisfied, the effect of the edge 31 and the flange end 201 on the radio waves A is reduced compared to when condition B is not satisfied, and therefore the opening 32 functions as a radio wave transmission window that can ensure the gain of the antenna 25 in the positive Z-axis direction.

[0063] The distance b that satisfies the condition B is preferably 0.3×λ or more and 25×λ or less, more preferably 0.4×λ or more and 25×λ or less, and even more preferably 0.5×λ or more and 25×λ or less, in terms of improving the gain in the positive Z-axis direction.

[0064] The distance e that satisfies the condition B is preferably 0.3×λ or more and 25×λ or less, and more preferably 0.4×λ or more and 25×λ or less, from the viewpoint of improving the gain in the positive Z-axis direction.

[0065] By making the distance e shorter than the distance b, the conductive layer 30 can be brought closer to the radiation conductor 20 in a plan view, which makes it easier to ensure a desired size of the conductive layer 30. However, the distance e may be the same as the distance b or may be longer than the distance b.

[0066] 2, the shortest distance from the main surface 11 to the radiation conductor 20 is defined as h. In this case, the distance h is equal to or greater than 0.3×λ and equal to or less than 3×λ. Hereinafter, this dimensional condition is defined as "Condition H."

[0067] When the dielectric plate 10 is attached to the flange 200, the antenna 25 is positioned to satisfy condition H, thereby improving the gain of the antenna 25 in the positive Z-axis direction compared to when condition H is not satisfied. When condition H is satisfied, the effect of the edge 31 and the flange end 201 on the radio waves A is reduced compared to when condition H is not satisfied, and therefore the opening 32 functions as a radio wave transmission window that can ensure the gain of the antenna 25 in the positive Z-axis direction.

[0068] Under condition H, when the distance h is less than 0.3 × λ, the antenna 25 is affected by the dielectric plate 10, the flange 200, and the conductive layer 30, causing the electric field distribution of the antenna 25 to change, adversely affecting the characteristics of the antenna 25. Under condition H, when the distance h is 0.3 × λ or greater, the influence of the edge 31 and the flange end 201 on the radio wave A is reduced compared to when the distance h is less than 0.3 × λ, thereby increasing the gain of the antenna 25 in the positive Z-axis direction. Furthermore, when condition H is satisfied, the influence of the edge 31 and the flange end 201 on the half-power angle is reduced compared to when the distance h exceeds 3 × λ, thereby expanding the directivity toward the zenith. For vehicle rooftop installation, it may be highly necessary to place the antenna 25 near the flange 200 from the standpoints of ease of wiring and maintaining aesthetic appeal. Furthermore, the conductive layer 30 may be highly necessary for purposes such as protecting the overhead from heat. However, if the flange 200 and conductive layer 30, which are conductors, are located near the antenna 25, they will interfere with the antenna 25, which is also a conductor, and the performance of the antenna 25 will change. Therefore, satisfying condition B, condition H, or both has the advantageous effect of preventing a reduction in antenna characteristics (e.g., gain) due to the influence of the edge 31 and flange end 201 on radio waves A. Furthermore, under condition H, if the distance h exceeds 3×λ, the vehicle interior space around the occupant's head will be narrowed. Under condition H, if the distance h is 3×λ or less, the vehicle interior space around the occupant's head will be expanded, which is advantageous compared to when the distance h exceeds 3×λ.

[0069] The distance h that satisfies the condition H is preferably 0.3×λ or more and 2×λ or less, and more preferably 0.3×λ or more and 1.5×λ or less, in terms of improving the gain in the positive Z-axis direction.

[0070] The sheet resistance of the radiating conductor 20 (hereinafter also referred to as "sheet resistance R20") is preferably low to improve the radiation efficiency of the antenna, and is preferably lower than the sheet resistance (hereinafter also referred to as "sheet resistance R30") of the conductive layer 30. This improves the radiation characteristics of the radiating conductor 20 and increases the half-value angle of the antenna device 101.

[0071] The sheet resistance R20 is desirably as low as possible to improve the radiation efficiency of the antenna, and is, for example, 0.5 mΩ / sq to 50 mΩ / sq, preferably 1 mΩ / sq to 25 mΩ / sq, and more preferably 3 mΩ / sq to 5 mΩ / sq. The sheet resistance R30 is, for example, 1 mΩ / sq to 200 mΩ / sq, preferably 3 mΩ / sq to 50 mΩ / sq, and more preferably 300 mΩ / sq to 25 mΩ / sq.

[0072] 3 is a partial cross-sectional view showing an example of the configuration of a vehicle antenna device according to a second embodiment. In the second embodiment, the same configuration, operation, and effects as those of the above-described embodiment will not be described by citing the above description. The antenna device 102 shown in FIG. 3 differs from the antenna device 101 in that the dielectric plate 10 includes a plurality of dielectric plates.

[0073] The dielectric plate 10 is, for example, a laminated glass for a vehicle. The dielectric plate 10 includes a glass plate 80, a glass plate 90, and an interlayer film 120. In the example shown in Fig. 3 , the dielectric plate 10 is a laminated glass in which the glass plate 80 disposed on the inside of the vehicle and the glass plate 90 disposed on the outside of the vehicle are bonded together via the interlayer film 120. The interlayer film 120 is sandwiched between the glass plate 80 and the glass plate 90.

[0074] The glass plate 80 and the glass plate 90 are transparent plate-shaped dielectric plates. One or both of the glass plate 80 and the glass plate 90 may be translucent. The glass plate 80 is an example of a first dielectric plate, and the glass plate 90 is an example of a second dielectric plate.

[0075] Glass plate 80 has a main surface 81 facing in the negative Z-axis direction and a main surface 82 facing in the opposite direction (positive Z-axis direction) from main surface 81. Main surface 81 is an example of a first main surface. Glass plate 90 has a main surface 91 facing in the negative Z-axis direction and a main surface 92 facing in the opposite direction (positive Z-axis direction) from main surface 91. Main surface 92 is an example of a second main surface.

[0076] The interlayer film 120 is a dielectric film disposed between the main surface 82 of the glass plate 80 and the main surface 91 of the glass plate 90. The interlayer film 120 is a transparent or semi-transparent dielectric material interposed between the glass plate 80 and the glass plate 90. The glass plate 80 and the glass plate 90 are bonded together by the interlayer film 120. Examples of the interlayer film 120 include thermoplastic polyvinyl butyral (PVB), ethylene vinyl acetate copolymer (EVA), and cycloolefin polymer (COP). The relative dielectric constant of the interlayer film 120 is preferably 2.4 or more and 3.5 or less.

[0077] Like the antenna device 101 of the first embodiment, the antenna device 102 of the second embodiment satisfies condition B, condition H, or both, thereby reducing the effect of the edge 31 and flange end 201 on radio waves A, thereby ensuring the gain of the antenna 25 in the positive Z-axis direction.

[0078] 4 is a partial cross-sectional view showing an example of the configuration of a vehicle antenna device according to a third embodiment. In the third embodiment, the same configurations, functions, and effects as those of the above-described embodiments will not be described again by citing the above descriptions. The antenna device 103 shown in FIG. 4 differs from the antenna device 102 in that the conductive layer 30 is provided on the inner layer of the dielectric plate 10.

[0079] The conductive layer 30 in the third embodiment is an example of a second conductive layer provided on an inner layer between the first surface and the second surface of the dielectric plate. The edge 31 is an example of a second edge that is the edge of the second conductive layer. In the example shown in FIG. 4 , the conductive layer 30 is provided on the main surface 91. However, the conductive layer 30 may be provided on the main surface 82 or between multiple intermediate films 120. The radiation conductor 20 does not overlap with the conductive layer 30 in a plan view of the dielectric plate 10. In the antenna device 103 of the third embodiment, a conductive layer is not provided on the main surface 11.

[0080] Like the antenna devices of the above-mentioned embodiments, the antenna device 103 of the third embodiment satisfies condition B, condition H, or both, thereby reducing the effect of the edge 31 and flange end 201 on radio waves A, thereby ensuring the gain of the antenna 25 in the positive Z-axis direction.

[0081] Fig. 5 is a partial cross-sectional view showing an example of the configuration of an antenna device according to a fourth embodiment. In the fourth embodiment, the description of the configuration, operation, and effects similar to those of the above-described embodiments will be omitted by incorporating the above description. The antenna device 104 shown in Fig. 5 differs from the antenna device 102 or 103 in that the conductive layer 30 includes multiple conductive layers (two conductive layers 60 and 70 in this example).

[0082] The conductive layer 60 in the fourth embodiment is an example of a first conductive layer provided on the first surface facing the antenna. The edge 61 is an example of a first edge that is the edge of the first conductive layer. The conductive layer 70 in the fourth embodiment is an example of a second conductive layer provided on an inner layer between the first surface and the second surface of the dielectric plate. The edge 71 is an example of a second edge that is the edge of the second conductive layer.

[0083] The conductive layer 30 includes a conductive layer 60 provided on the principal surface 11 (principal surface 81) and a conductive layer 70 provided on an inner layer of the dielectric plate 10. The radiation conductor 20 does not overlap with the conductive layer 60 and the conductive layer 70 in a plan view of the dielectric plate 10.

[0084] The edge 71 overlaps with the edge 61 in plan view. However, the edge 71 may be located in the more positive X-axis direction than the edge 61 in plan view. This causes the edge 61 of the conductive layer 60 to have a dominant effect on the radio wave A, and reduces the effect of the edge 71 of the conductive layer 70. Therefore, the half-value angle of the antenna device 104 is larger than when the edge 71 is located in the more negative X-axis direction than the edge 61 in plan view.

[0085] The sheet resistance R20 of the radiating conductor 20 is preferably low to improve the radiation efficiency as an antenna, and is preferably lower than the sheet resistances of the conductive layer 60 (hereinafter also referred to as "sheet resistance R60") and the conductive layer 70 (hereinafter also referred to as "sheet resistance R70"). This improves the radiation characteristics of the radiating conductor 20 and increases the half-value angle of the antenna device 104.

[0086] The sheet resistance R60 is, for example, 1 mΩ / sq or more and 200 Ω / sq or less, preferably 3 mΩ / sq or more and 50 Ω / sq or less, and more preferably 300 mΩ / sq or more and 25 Ω / sq or less. The sheet resistance R70 is, for example, 1 mΩ / sq or more and 200 Ω / sq or less, preferably 3 mΩ / sq or more and 50 Ω / sq or less, and more preferably 300 mΩ / sq or more and 25 Ω / sq or less. However, the sheet resistance R70 of the conductive layer 70 may be lower than the sheet resistance R60 of the conductive layer 60.

[0087] Like the antenna devices of the above-mentioned embodiments, the antenna device 104 of the fourth embodiment satisfies condition B, condition H, or both, thereby reducing the influence of edge 61 or edge 71 and flange end 201 on radio waves A, thereby ensuring the gain of antenna 25 in the positive Z-axis direction.

[0088] Fig. 6 is a partial plan view showing a configuration example of a vehicle antenna device according to a fifth embodiment. Fig. 6 is a plan view of the dielectric plate 10. Fig. 7 is a partial cross-sectional view showing a configuration example of a vehicle antenna device according to the fifth embodiment. In the fifth embodiment, the description above will be used to omit explanations of the configuration, operation, and effects that are similar to those of the above-described embodiments. The antenna device 105 shown in Figs. 6 and 7 differs from the above-described antenna device 101 in that the conductive layer 30 surrounds the radiation conductor 20 in a plan view.

[0089] 6 , the conductive layer 30 has an edge 31, which is an inner edge surrounding the radiating conductor 20, such that a gap exists between the edge 31 and the outer edge 21 of the radiating conductor 20 in a plan view of the dielectric plate 10. A distance e indicates the length of the gap in a plan view of the dielectric plate 10. The edge 31 forms an opening 32 surrounding the radiating conductor 20 in a plan view. The opening 32 functions as a window through which radio waves A transmitted or received by the radiating conductor 20 pass.

[0090] The edge 31 is formed so as to surround the radiation conductor 20 in plan view. In the example shown in Fig. 6 , the edge 31 forms an opening 32 that is completely closed by the conductive layer 30 in plan view. However, by cutting out a portion of the edge 31, the opening 32 does not have to be completely closed by the conductive layer 30 in plan view.

[0091] The edge 31 according to the fifth embodiment is a polygon with at least one side having a length of 1×λ or more and 25×λ or less, a circle with a diameter of 1×λ or more and 25×λ or less, or an ellipse with a major axis or a minor axis having a length of 1×λ or more and 25×λ or less. Hereinafter, this dimensional and shape condition is defined as "Condition D," and the length of one side, the diameter, or the length of the major axis or the minor axis of the edge 31 is defined as the "size d of the opening 32." The size d represents the length. Figure 6 illustrates an example in which the edge 31 that satisfies Condition D is a square.

[0092] When condition D is satisfied, the influence of edge 31 and flange end 201 on radio waves A is reduced compared to when condition D is not satisfied, and therefore opening 32 functions as a radio wave transmission window that can ensure gain in the positive Z-axis direction of antenna 25.

[0093] The size d that satisfies the condition D may be 1×λ or more and 8×λ or less, 1×λ or more and 6×λ or less, or 1×λ or more and 4×λ or less, in terms of improving the gain in the positive Z-axis direction.

[0094] When the size d that satisfies condition D is 2×λ or more and 10×λ or less, the half-power angle of the antenna device 105 increases. On the other hand, when the size d that satisfies condition D is 1×λ or more and 2.5×λ or less, the gain in the positive Z-axis direction increases. Therefore, when the size d is 2×λ or more and 2.5×λ or less, the half-power angle increases and the gain in the positive Z-axis direction improves.

[0095] When the conductive layer 30 has an edge 31 that surrounds the entire periphery of the radiation conductor 20 in plan view, the distance b may be 0.1×λ or more and 15×λ or less in terms of improving the gain in the positive Z-axis direction. Hereinafter, this dimensional condition is defined as "Condition BB."

[0096] When the dielectric plate 10 is attached to the flange 200, by positioning the antenna 25 so as to satisfy condition BB, the gain of the antenna 25 in the positive Z-axis direction is improved compared to when condition BB is not satisfied. When condition BB is satisfied, the effect of the edge 31 and the flange end 201 on the radio wave A is reduced compared to when condition BB is not satisfied, so the opening 32 functions as a radio wave transmission window that can ensure the gain of the antenna 25 in the positive Z-axis direction.

[0097] The distance b that satisfies the condition BB is preferably 0.15×λ or more and 15×λ or less, and more preferably 0.2×λ or more and 15×λ or less, from the viewpoint of improving the gain in the positive Z-axis direction.

[0098] The antenna device 105 of the fifth embodiment satisfies at least one of conditions D, H, and BB, thereby reducing the influence of the edge 31 and flange end 201 on radio waves A, thereby ensuring the gain of the antenna 25 in the positive Z-axis direction.

[0099] Fig. 8 is a partial cross-sectional view showing an example of the configuration of a vehicle antenna device according to a sixth embodiment. In the sixth embodiment, the same configurations, actions, and effects as those of the above-described embodiments will not be described by citing the above descriptions. The antenna device 106 shown in Fig. 8 differs from the antenna device 105 in that the dielectric plate 10 includes a plurality of dielectric plates. The configuration of the inner layer of the dielectric plate 10 according to the sixth embodiment may be the same as the configuration of the inner layer of the dielectric plate 10 according to the second embodiment.

[0100] Fig. 9 is a partial cross-sectional view showing an example of the configuration of a vehicle antenna device according to the seventh embodiment. In the seventh embodiment, the same configurations, actions, and effects as those of the above-described embodiments will not be described by citing the above descriptions. The antenna device 107 shown in Fig. 9 differs from the above-described antenna device 106 in that the conductive layer 30 is provided on the inner layer of the dielectric plate 10. The configuration of the inner layer of the dielectric plate 10 according to the seventh embodiment may be the same as the configuration of the inner layer of the dielectric plate 10 according to the third embodiment.

[0101] FIG. 10 is a partial cross-sectional view showing an example configuration of an antenna device according to an eighth embodiment. In the eighth embodiment, the same configurations, operations, and effects as those of the above-described embodiments will not be described further by citing the above descriptions. The antenna device 108 shown in FIG. 10 differs from the antenna device 106 or 107 in that the conductive layer 30 includes multiple conductive layers (two conductive layers 60 and 70 in this example). The configuration of the conductive layer 30 according to the eighth embodiment may be the same as the configuration of the conductive layer 30 according to the fourth embodiment.

[0102] The edge 71 overlaps with the edge 61 in plan view. However, the edge 71 may be located outside the edge 61 in the direction along the XY plane in plan view. This makes the influence of the edge 61 of the conductive layer 60 on the radio wave A the main influence, and reduces the influence of the edge 71 of the conductive layer 70. Therefore, the half-value angle of the antenna device 108 is larger than when the edge 71 is located inside the edge 61 in plan view.

[0103] The antenna 25 in each embodiment may be an antenna other than a patch antenna, and the shape of the radiation conductor 20 may be a shape other than a patch. Other examples of the antenna 25 include a single-layer antenna (dipole type, monopole type) without a metal layer on the back surface of the substrate, an inverted F antenna, an inverted L antenna, etc.

[0104] 27 is a diagram showing a first modified example of an antenna. Antenna 25A is an example of a planar dipole antenna. A dipole-shaped radiating conductor 20 is printed on the surface of a substrate 22, for example. Distance b is defined by the shortest distance from the flange end 201 to the outer edge 21 of the radiating portion 23 of the radiating conductor 20 in a planar view. Distance e is defined by the shortest distance from the edge 31 of the conductive layer 30 to the outer edge 21 of the radiating portion 23 of the radiating conductor 20 in a planar view. Distance h is defined by the shortest distance from the main surface 11 of the dielectric plate 10 to the radiating portion 23 of the radiating conductor 20.

[0105] 28 is a diagram showing a second modified example of an antenna. Antenna 25B is an example of an inverted-F antenna. The inverted-F-shaped radiating conductor 20 is provided, for example, on the surface of a substrate 22 having a ground plane 24 formed on the back surface. Distance b is defined by the shortest distance from the flange end 201 to the outer edge 21 of the radiating conductor 20 in a planar view. Distance e is defined by the shortest distance from the edge 31 of the conductive layer 30 to the outer edge 21 of the radiating conductor 20 in a planar view. Distance h is defined by the shortest distance from the main surface 11 of the dielectric plate 10 to the top surface of the radiating conductor 20.

[0106] Next, some examples of the results of simulations of the antenna devices of the respective embodiments will be shown.

[0107] 11 and 12 are diagrams showing an example of the results of a simulation of the relationship between the distance e and the front gain for the antenna device 104 ( FIG. 5 ) of the fourth embodiment. In FIGS. 11 and 12 , a negative distance e represents the area where the radiation conductor 20 overlaps with the conductive layer 30 in a planar view. The front gain on the vertical axis represents the antenna gain in the positive Z-axis direction. FIG. 11 shows a case where the polarization direction of the antenna 25 is in the X-axis direction, which is parallel to the direction in which the distance e is changed. FIG. 12 shows a case where the polarization direction of the antenna 25 is in the Y-axis direction, which is perpendicular to the direction in which the distance e is changed.

[0108] 11 and 12, when the distance e is equal to or greater than 0.1×λ and equal to or less than 25×λ, the frontal gain of the antenna device 104 is improved compared to the frontal gain of the antenna 25 alone. 11 and 12, when the distance e is equal to or greater than 0.1×λ and equal to or less than 25×λ, the frontal gain of the antenna device 104 is improved compared to when the distance e is less than 0.1×λ.

[0109] 11 and 12, the conditions for each part in the simulation are as follows: Antenna 25: 10 GHz stack patch antenna b=0.6×λ h=0.4×λ Thickness of glass plate 80: 2 mm Thickness of glass plate 90: 2 mm Thickness of interlayer 120: 0.76 mm Material of interlayer 120: PVB The distance e on the horizontal axis is a value normalized by the wavelength λ.

[0110] 13 is a partial cross-sectional view showing a configuration example of a vehicle antenna device of a first comparative example. The antenna device 100 shown in FIG. 13 differs from the antenna device 102 described above in that it does not have the conductive layer 30.

[0111] Fig. 14 shows an example of the results of a simulation of the relationship between the distance b and the front gain for the antenna device 100 of the first comparative embodiment (Fig. 13). The front gain on the vertical axis represents the antenna gain in the positive Z-axis direction. Fig. 14 shows the results of a simulation of how close the antenna 25 can be to the flange 200 without the conductive layer 30, using the antenna device 100 of the first comparative embodiment, when the polarization direction of the antenna 25 is in the X-axis direction, which is parallel to the direction in which the distance b is changed.

[0112] If it is allowed that the front gain is reduced to about 1.2 dB below the value of antenna 25 alone, and the polarization direction of antenna 25 is parallel to the direction of distance b, distance b should be 0.3×λ or more and 25×λ or less.

[0113] The conditions for each part during the simulation in FIG. 14 are the same as those described above for FIGS. 11 and 12 (except for the distance b).

[0114] Fig. 15 is a diagram showing an example of the results of a simulation of the relationship between the distance e and the front gain for the antenna device 104 of the fourth embodiment (Fig. 5). Fig. 15 shows the results of a simulation of how close the conductive layer 30 can be to the antenna 25, with the distance b fixed to the preferable minimum value of 0.3 × λ obtained in Fig. 14. The conditions for each part during the simulation in Fig. 15 are the same as those described above for Figs. 11 and 12 (except for the distance b and the distance e).

[0115] 15, the front gain does not reach its maximum value when the distance e is equal to the distance b (=0.3×λ), but reaches its maximum value when the distance e is 0.7×λ. If the front gain is allowed to fall to about 1.2 dB below the maximum value, then when the polarization direction of antenna 25 is parallel to the direction of distance e, the distance e should be between 0.3×λ and 25×λ in terms of improving the front gain.

[0116] Fig. 16 shows an example of the results of a simulation of the relationship between the distance b and the front gain for the antenna device 100 of the first comparative embodiment (Fig. 13). The front gain on the vertical axis represents the antenna gain in the positive Z-axis direction. Fig. 16 shows the results of a simulation of how close the antenna 25 can be to the flange 200 without the conductive layer 30, using the antenna device 100 of the first comparative embodiment, when the polarization direction of the antenna 25 is in the Y-axis direction, which is perpendicular to the direction in which the distance b is changed.

[0117] If it is allowed that the front gain is reduced to about 1.2 dB below the value of antenna 25 alone, and the polarization direction of antenna 25 is perpendicular to the direction of distance b, distance b should be 0.2×λ or more and 3×λ or less.

[0118] The conditions for each part during the simulation in FIG. 16 are the same as those described above for FIGS. 11 and 12 (except for the distance b).

[0119] Fig. 17 is a diagram showing an example of the results of a simulation of the relationship between the distance e and the front gain for the antenna device 104 of the fourth embodiment (Fig. 5). Fig. 17 shows the results of a simulation of how close the conductive layer 30 can be to the antenna 25, with the distance b fixed at 0.3 × λ, which is within the preferred range obtained in Fig. 16. The conditions for each part in the simulation in Fig. 17 are the same as those described above for Figs. 11 and 12 (except for the distance b and the distance e).

[0120] 17, the front gain does not reach its maximum value when the distance e is equal to the distance b (=0.3×λ), but reaches its maximum value when the distance e is 0.8×λ. When the polarization direction of the antenna 25 is perpendicular to the direction of the distance e, the front gain improves when the distance e is 0.2×λ or more and 25×λ or less. However, in order to improve the front gain compared to when the antenna 25 is used alone, the distance e may be 0.3×λ or more and 25×λ or less.

[0121] Fig. 18 is a diagram showing an example of the results of a simulation of the relationship between the distance e and the front gain for the antenna device 103 of the third embodiment (Fig. 4) and the antenna device 104 of the fourth embodiment (Fig. 5). The conditions for each part during the simulation in Fig. 18 are the same as those described above for Figs. 11 and 12 (however, the distance b = 0.3 × λ).

[0122] 18, the distance e at which the front gain reaches its maximum value is shorter by about 0.1×λ in the case of antenna device 103, which has only the inner conductive layer, than in the case of antenna device 104, which has two conductive layers. In other words, in the case of antenna device 103, the conductive layer 30 can be brought closer to the antenna 25 than in the case of antenna device 104, making it easier to ensure the desired area of ​​the conductive layer 30. Note that the results for antenna device 102, which has a conductive layer on main surface 11, are equivalent to the results for antenna device 104.

[0123] Fig. 19 is a diagram showing an example of the results of a simulation of the relationship between the size d of the aperture 32 and the front gain for the antenna device 108 of the eighth embodiment (Fig. 10). The conditions for each part in the simulation in Fig. 19 are the same as those described above for Figs. 11 and 12 (however, the distance h = 0.5 × λ).

[0124] 19, when the size d is 1×λ or more and 25×λ or less, the front gain is improved. In terms of improving the gain in the positive Z-axis direction, the size d may be 1×λ or more and 10×λ or less, 1×λ or more and 8×λ or less, 1×λ or more and 6×λ or less, or 1×λ or more and 4×λ or less.

[0125] 20 and 21 are diagrams showing an example of the results of a simulation of the relationship between the size d of the aperture 32 and the half-power angle for the antenna device 108 of the eighth embodiment (FIG. 10). In FIGS. 20 and 21, the half-power angle on the vertical axis represents the angle between the azimuth direction at which the gain of the antenna 25 is reduced by 3 dB in power compared to the gain in the main axis direction. FIG. 20 shows the half-power angle of the directivity in the E plane (ZX plane) parallel to the electric field vector. FIG. 21 shows the half-power angle of the directivity in the H plane (YZ plane) parallel to the magnetic field vector. The conditions for each part in the simulations of FIGS. 20 and 21 are the same as those for FIGS. 11 and 12 (except that the distance h = 0.5 × λ).

[0126] According to FIGS. 20 and 21, when the size d is 2×λ or more and 25×λ or less, a half-value angle equivalent to that of the antenna 25 alone can be obtained.

[0127] Fig. 22 is a diagram showing an example of the results of a simulation of the relationship between the distance h and the front gain for the antenna device 108 of the eighth embodiment (Fig. 10). The front gain on the vertical axis represents the antenna gain in the positive Z-axis direction. The conditions for each part in the simulation of Fig. 22 are the same as those described above for Figs. 11 and 12 (except for the size d = 2 × λ).

[0128] 22, when the distance h is 0.3×λ or more and 3×λ or less, a frontal gain equivalent to that of the antenna 25 alone can be obtained. From the viewpoint of improving the frontal gain, the distance h is preferably 0.3×λ or more and 2×λ or less, and more preferably 0.3×λ or more and 1.5×λ or less.

[0129] 23 and 24 are diagrams showing an example of the results of a simulation of the relationship between the distance h and the half-power angle for the antenna device 108 of the eighth embodiment (FIG. 10). In FIGS. 23 and 24, the half-power angle on the vertical axis represents the angle between the azimuth direction at which the gain of the antenna 25 is 3 dB lower in power than the gain in the main axis direction. FIG. 23 shows the half-power angle in the direction of directivity in the E plane (ZX plane) parallel to the electric field vector. FIG. 24 shows the half-power angle in the direction of directivity in the H plane (YZ plane) parallel to the magnetic field vector. The conditions for each part in the simulations of FIGS. 23 and 24 are the same as those for FIGS. 11 and 12 (except that the size d = 2 × λ).

[0130] According to FIGS. 23 and 24, when the distance h is 0.1×λ or more and 0.5×λ or less, a half-value angle equivalent to that of the antenna 25 alone is obtained.

[0131] Combining the results of FIGS. 22, 23 and 24, when the distance h is 0.3×λ or more and 0.5×λ or less, both the front gain and the half-value angle can be ensured.

[0132] Figures 25 and 26 are diagrams showing an example of the results of a simulation of the relationship between the distance b and the front gain for the antenna device 108 of the eighth embodiment (Figure 10). In Figures 25 and 26, the front gain on the vertical axis represents the antenna gain in the positive Z-axis direction. Figure 25 shows a case where the polarization direction of the antenna 25 is in the X-axis direction, parallel to the direction in which the distance b is changed. Figure 26 shows a case where the polarization direction of the antenna 25 is in the Y-axis direction, perpendicular to the direction in which the distance b is changed. The conditions for each part in the simulations of Figures 25 and 26 are the same as those described above for Figures 11 and 12 (however, size d = 2 × λ).

[0133] 25 and 26, when the distance b is 0.1×λ or more and 15×λ or less, a higher frontal gain can be obtained than with the antenna 25 alone. In terms of improving the frontal gain, the distance b may be 0.1×λ or more and 3×λ or less, preferably 0.15×λ or more and 1×λ or less, and more preferably 0.2×λ or more and 0.8×λ or less.

[0134] 29 and 30 are diagrams showing an example of the results of a simulation of the relationship between the distance h and the front gain for the antenna device 104 (FIG. 5) of the fourth embodiment. The front gain on the vertical axis represents the antenna gain in the positive Z-axis direction. FIG. 29 shows the case where the polarization direction of the antenna 25 is in the Y-axis direction, which is perpendicular to the plane of FIG. 5. FIG. 30 shows the case where the polarization direction of the antenna 25 is in the X-axis direction, which is parallel to the plane of FIG. 5. The simulation conditions for FIGS. 29 and 30 are the same as those for FIGS. 11 and 12 (wherein, however, the distance e = 2 × λ, b = 6.7 × λ, and h = 0 to 3 × λ). The distance h on the horizontal axis is a value normalized by the wavelength λ.

[0135] 29 and 30, when the distance h is 0.3×λ or more and 3×λ or less, the antenna device 104 can obtain a substantially constant frontal gain with a slight drop within an allowable range with respect to the frontal gain of the antenna 25 alone. 29 and 30, when the distance h is 0.3×λ or more and 3×λ or less, the frontal gain of the antenna device 104 is improved compared to when the distance h is less than 0.2×λ.

[0136] Although the embodiments have been described above, they are presented as examples and the present invention is not limited to the above embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims.

[0137] This international application claims priority based on Japanese Patent Application No. 2024-021860, filed on February 16, 2024, the entire contents of which are incorporated herein by reference.

[0138] REFERENCE SIGNS LIST 10 Dielectric plate 11, 12 Main surface 20 Radiating conductor 21 Outer edge 22 Substrate 23 Radiating portion 24 Ground plane 25, 25A, 25B Antenna 30 Conductive layer 31 Edge 32 Opening 60 Conductive layer 61 Edge 70 Conductive layer 71 Edge 80, 90 Glass plate 100-108 Antenna device 110 Dielectric layer 120 Interlayer

Claims

1. A vehicle antenna device comprising: an antenna; and a dielectric plate having a first surface facing the antenna and a second surface opposite the first surface, wherein the dielectric plate has a conductive layer provided on the first surface or on an inner layer between the first and second surfaces, and the antenna has a radiating conductor that does not overlap with the conductive layer in a planar view of the dielectric plate, wherein, when the dielectric plate is attached to a flange provided on a roof of a vehicle, b is the shortest distance from an edge of the flange to the outer edge of the radiating conductor in the planar view, e is the shortest distance from the edge of the conductive layer to the outer edge of the radiating conductor in the planar view, and λ is the wavelength in air of radio waves transmitted or received by the antenna, b is between 0.3×λ and 25×λ and e is between 0.1×λ and 25×λ, and h is the shortest distance from the first surface to the radiating conductor, h is between 0.3×λ and 3×λ.

2. The vehicle antenna device according to claim 1, wherein b is equal to or greater than 0.4×λ and equal to or less than 25×λ.

3. The vehicle antenna device according to claim 2, wherein e is equal to or greater than 0.3×λ and equal to or less than 25×λ.

4. The vehicle antenna device according to claim 1, wherein the shortest distance h is equal to or greater than 0.3×λ and equal to or less than 2×λ.

5. The vehicle antenna device according to claim 1, wherein the conductive layer has an inner edge that forms an opening that surrounds the radiation conductor in the plan view.

6. The vehicle antenna device according to claim 5, wherein the size of the opening is not less than 1×λ and not more than 25×λ.

7. The vehicle antenna device according to claim 6, wherein the size of the opening is not less than 2×λ and not more than 10×λ.

8. The vehicle antenna device according to claim 6, wherein the size of the opening is not less than 1×λ and not more than 2.5×λ.

9. The vehicle antenna device according to claim 8, wherein the size of the opening is equal to or greater than 2×λ and equal to or less than 2.5×λ.

10. The vehicle antenna device according to claim 5, wherein h is the shortest distance from the first surface to the radiation conductor, and h is equal to or greater than 0.3×λ and equal to or less than 3×λ.

11. The vehicle antenna device according to claim 5, wherein h is the shortest distance from the first surface to the radiation conductor, and h is equal to or greater than 0.1×λ and equal to or less than 0.5×λ.

12. The vehicle antenna device according to claim 11, wherein h is equal to or greater than 0.3×λ and equal to or less than 0.5×λ.

13. A vehicle antenna device comprising: an antenna; and a dielectric plate having a first surface facing the antenna and a second surface opposite the first surface, wherein the dielectric plate has a conductive layer provided on the first surface or on an inner layer between the first surface and the second surface, wherein the antenna has a radiation conductor that does not overlap with the conductive layer in a planar view of the dielectric plate, and the conductive layer has an inner edge that forms an opening that surrounds the radiation conductor in the planar view, wherein, when the dielectric plate is attached to a flange provided on the roof of a vehicle, b is the shortest distance from the edge of the flange to the outer edge of the radiation conductor in the planar view, and λ is the wavelength in air of the radio waves transmitted or received by the antenna, b is between 0.1×λ and 15×λ, and the size of the opening is between 1×λ and 25×λ.

14. A vehicle antenna device as described in any one of claims 1 to 13, wherein the conductive layer includes a first conductive layer provided on the first surface, and the radiation conductor does not overlap with the first conductive layer in the planar view.

15. A vehicle antenna device as described in any one of claims 1 to 13, wherein the conductive layer includes a second conductive layer provided on the inner layer, and the radiation conductor does not overlap with the second conductive layer in the planar view.

16. The vehicle antenna device according to claim 15, wherein the conductive layer is not a conductive layer that includes a first conductive layer provided on the first surface.

17. A vehicle antenna device as described in any one of claims 1 to 13, wherein the conductive layer includes a first conductive layer provided on the first surface and a second conductive layer provided on the inner layer, and the radiation conductor does not overlap with the first conductive layer and the second conductive layer in the planar view.

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