Patent ID: 12261367

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the embodiment is described with reference to the drawings. For the ease of understanding, the scales of components illustrated in the drawings may differ from the actual scales. In this specification, three-dimensional Cartesian coordinate system constituted by three axial-directions (an X axis direction, a Y axis direction, and a Z axis direction) is used, in which a width direction of a glass plate is defined as an X axis direction, a thickness direction of the glass plate is defined as a Y axis direction, and a height direction of the glass plate is defined as a Z axis direction. A direction extending from the lower side to the upper side of the glass plate is defined as +Z axis direction, and a direction opposite thereto is defined as a −Z axis direction. In the following explanation, the +Z axis direction may be referred to as upward, and the −Z axis direction may be referred to as downward.

The X-axis direction, the Y-axis direction, and the Z-axis direction represent a direction parallel to the X axis, a direction parallel to the Y axis, and a direction parallel to the Z axis, respectively. The X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to one another. An XY plane is a virtual plane parallel to the X axis direction and the Y axis direction. A YZ plane is a virtual plane parallel to the Y axis direction and the Z axis direction. A ZX plane is a virtual plane parallel to the Z axis direction and the X axis direction.

FIG.2is a cross sectional view schematically illustrating an example of a laminated structure of an antenna unit-attached window glass according to the first embodiment. An antenna unit-attached window glass301as illustrated inFIG.2includes an antenna unit101and window glass201. The antenna unit101is used as being installed to face an interior-side surface of the window glass201for a building.

The window glass201is a glass plate used for window of a building or the like. For example, the window glass201is formed in a rectangular shape as seen in a plan view in the Y axis direction, and includes a first glass surface and a second glass surface. The thickness of the window glass201is set according to the required specifications of a building or the like. In the present embodiment, the first glass surface of the window glass201is an exterior-side surface, and the second glass surface is an interior-side surface. In the present embodiment, the first glass surface and the second glass surface may be collectively simply referred to as a principal surface. In the present embodiment, the rectangular shape includes not only a rectangle and a square but also shapes obtained by rounding the corners of a rectangle and a square. The shape of the window glass201in a plan view is not limited to the rectangular shape, but may be other shapes such as a circle.

The window glass201is not limited to a single plate, and may be laminated glass, insulated glazing, or low-e glass. The low-e glass may also be referred to as low emissivity glass, and may be obtained by coating an interior-side surface of window glass with a coating layer (a transparent conductive film) having a heat ray reflection function. In this case, in order to alleviate a decrease in the electromagnetic wave transmission performance, an opening portion may be provided in the coating layer. The opening portion is preferably provided at a position facing at least a portion of the radiating element10and the wave directing member20. The opening portion may have a patterning. The patterning is, for example, leaving the coating layer in a lattice shape. A portion of the opening portion may have a patterning.

Examples of materials of the window glass201include soda-lime-silica glass, borosilicate glass, aluminosilicate glass, or alkali-free glass.

The thickness of the window glass201is preferably 1.0 to 20 mm. When the thickness of the window glass201is 1.0 mm or more, a sufficient strength for attaching an antenna unit can be provided. Further, when the thickness of the window glass201is equal to or less than 20 mm, the electromagnetic wave transmission performance is high. The thickness of the window glass201is more preferably 3.0 to 15 mm, and is still more preferably 9.0 to 13 mm.

The antenna unit101is a device used by being attached to the interior-side of the window glass201for a building, and transmits and receives electromagnetic waves through the window glass201. For example, the antenna unit101is formed to be able to transmit and receive electromagnetic waves in compliance with wireless communication standards such as 5th generation mobile communication systems (commonly referred to as 5G), Bluetooth (registered trademark), and wireless LAN (Local Area Network) standards such as IEEE 802.11ac. The antenna unit101may be configured to be able to transmit and receive electromagnetic waves in compliance with standards other than the above, or may be configured to be able to transmit and receive electromagnetic waves in multiple different frequencies. The antenna unit101may be used as, for example, a wireless base station used so as to face the window glass201.

In the embodiment as illustrated inFIG.2, the antenna unit101includes a radiating element10, a phase control member80, and a conductor30.

The radiating element10is an antenna conductor formed to be able to transmit and receive electromagnetic waves in a desired frequency band. Examples of desired frequency bands include a UHF (Ultra High Frequency) band with a frequency of 0.3 to 3 GHz, an SHF (Super High Frequency) band with a frequency of 3 to 30 GHz, and an EHF (Extremely High Frequency) band with a frequency of 30 to 300 GHz. The radiating element10functions as a radiating device (radiator). The radiating element10may be a single antenna element, or may include multiple antenna elements of which the feeding points are different from one another.

The phase control member80is provided so as to be situated on the exterior-side with respect to the radiating element10, and in the illustrated configuration, the phase control member80is provided so as to be situated in a specific direction (more specifically, on the negative side in the Y-axis direction) with respect to the radiating element10. The phase control member80according to the present embodiment is provided so as to be situated between the window glass201and the radiating element10. In addition, the wave directing member20configured to control the phase of electromagnetic waves to guide electromagnetic waves radiated from the radiating element10in a specific direction (the negative side in the Y-axis direction in the illustrated case) is provided. That is, with the phase control member80, the directivity of the antenna unit101can be set in any desired direction.

The phase control member80includes a dielectric member41and a wave directing member20. The wave directing member20includes multiple conductor portions.FIG.8illustrates an example of four conductor portions21to24(the details of which are explained later).

The conductor30is provided on the interior-side with respect to the radiating element10, and in the configuration as illustrated inFIG.2, the conductor30is provided on the positive side in the Y-axis direction with respect to the radiating element10.

As explained above, the antenna unit101includes the phase control member80controlling the phase of electromagnetic wave radiated from the radiating element10. The phase control member80has multiple conductor portions in the wave directing member20, and accordingly, can control the phase of the electromagnetic wave radiated from the radiating element10, so that the radiation direction of the electromagnetic wave can be changed. Because the radiation direction of the electromagnetic wave radiated from the radiating element10can be changed, a gain difference between the main lobe and the grating lobe (which may be hereinafter simply referred to as a gain difference) of the antenna unit101can be increased.

Where a distance between the radiating element10and the wave directing member20is denoted as a, and a relative permittivity of a medium constituted by a dielectric member41between the radiating element10and the wave directing member20is denoted as εr, the distance a is preferably equal to or more than (2.11×εr−1.82) mm in order to increase the gain difference. The inventors of the present application have found that the gain difference becomes 0 dB or more by setting the distance a as described above. The gain difference being 0 dB or more means that the gain of the main lobe is equal to or more than the gain of the grating lobe. The upper limit of the distance a is not particularly limited, but the distance a may be 100 mm or less, may be 50 mm or less, may be 30 mm or less, may be 20 mm or less, or may be 10 mm or less. Where the wavelength of the operation frequency of the radiating element10is denoted as λg, the distance a may be 100×λg/85.7 or less, may be 50×λg/85.7 or less, may be 30×λg/85.7 or less, may be 20×λg/85.7 or less, or may be 10×λg/85.7 or less.

Where the operation frequency of the radiating element10is 0.7 to 30 GHz (preferably 1.5 to 6.0 GHz, more preferably 2.5 to 4.5 GHz, still more preferably 3.3 to 3.7 GHz, and particularly preferably 3.5 GHz), the distance a is particularly preferably (2.11×εr−1.82) mm or more in order to increase the gain difference.

A value obtained by dividing the total size of area S of the multiple conductor portions (the wave directing member20) by the size of area of the window glass201is preferably 0.00001 to 0.001. When the value obtained by dividing the total size of area S of the wave directing member20by the size of area of the window glass201is 0.00001 or more, the gain difference increases. The value obtained by dividing the total size of area S of the wave directing member20by the size of area of the window glass201is more preferably 0.00005 or more, still more preferably 0.0001 or more, and particularly preferably 0.0005 or more. When the value obtained by dividing the total size of area S of the wave directing member20by the size of area of the window glass201is 0.001 or less, the wave directing member20is inconspicuous and is aesthetically good. The value obtained by dividing the total size of area S of the wave directing member20by the size of area of the window glass201is more preferably 0.0008 or less, and still more preferably 0.0007 or less.

The gain difference of equal to or more than 3 dB more greatly alleviates, even when there is an obstacle such as window glass facing the antenna unit, the reflection of the electromagnetic wave caused by the obstacle, which is preferable. The gain difference is more preferably equal to or more than 4 dB and still more preferably equal to or more than 5 dB.

Next, the configuration as illustrated inFIG.2is explained in more detail.

The antenna unit101includes a radiating element10, a substrate50, a conductor30, a phase control member80, and a support portion60. The phase control member80includes a wave directing member20and a dielectric member41.

The radiating element10is provided on a first principal surface on the exterior-side of the substrate50. The radiating element10may be formed by printing a metal material so that the metal material overlaps at least a portion of a ceramic layer provided on the first principal surface of the substrate50. Accordingly, the radiating element10is provided on the first principal surface of the substrate50so as to extend across the portion formed with the ceramic layer and a portion other than the portion formed with the ceramic layer.

For example, the radiating element10is a conductor formed in a planar shape. The radiating element10is made of a conductive material such as gold, silver, copper, aluminum, chromium, lead, zinc, nickel, or platinum. The conductive material may be an alloy such as, for example, an alloy of copper and zinc (brass), an alloy of silver and copper, an alloy of silver and aluminum, and the like. The radiating element10may be a thin film. The shape of the radiating element10may be a rectangular or circular shape, but is not limited to these shapes. For example, at least one or more radiating elements10are provided so as to be situated between the wave directing member20and the conductor30, and in the illustrated configuration, the radiating element10may be formed on a surface of the substrate50on the side of the wave directing member20, the substrate50being situated between the wave directing member20and the conductor30. For example, the radiating element10is fed at a feeding point with the conductor30being the ground reference. For example, a patch element (a patch antenna), a dipole element (a dipole antenna), and the like can be used as the radiating element10.

Other materials constituting the radiating element10include fluorinated tin oxide (FTC), indium tin oxide (ITO), and the like.

The above-described ceramic layer can be formed on the first principal surface of the substrate50by printing. When the ceramic layer is provided, wires (not illustrated) attached to the radiating element10can be covered, which improves the aesthetics. In the present embodiment, the ceramic layer does not have to be provided on the first principal surface, and may be provided on a second principal surface on the interior-side of the substrate50. The ceramic layer is preferably provided on the first principal surface of the substrate50because the radiating element10and the ceramic layer can be formed on the substrate50by printing in a same step.

The material of the ceramic layer is glass frit and the like, and the thickness thereof is preferably 1 to 20 μm.

In the present embodiment, the radiating element10is provided on the first principal surface of the substrate50. Alternatively, the radiating element10may be provided in the substrate50. In this case, for example, the radiating element10can be provided as a coil form in the substrate50.

In a case where substrate50is laminated glass including a pair of glass plates and a resin layer provided between the pair of glass plates, the radiating element10may be provided between the glass plate and the resin layer constituting the laminated glass.

The radiating element10may be formed in a planar plate shape. In this case, without using the substrate50, the radiating element10in a planar plate-shape may be directly attached to the support portion60.

Instead of providing the radiating element10on the substrate50, the radiating element10may be provided in the storage container. In this case, for example, the radiating element10in a planar plate-shape may be provided in the above-described storage container. The shape of the storage container is not particularly limited, and may be in a rectangular shape. The substrate50may be a portion of the storage container.

The radiating element10preferably has an optical transparency. The radiating element10may have an optical transparency, so that the aesthetics are improved, and the average solar absorptance can be reduced. The visible light transmittance of the radiating element10is preferably equal to or more than 40%, and is preferably equal to or more than 60% because the function as window glass can be maintained in terms of transparency. Note that the visible light transmittance can be derived according to JIS R 3106(1998).

The radiating element10may be formed in a mesh form to have optical transparency. In this case, “mesh” means a state in which through holes in a form of mesh are formed in the planar surface of the radiating element10.

When the radiating element10is formed in a mesh form, the openings of the mesh may be in a rectangular or rhomboid shape. The line width of the mesh is preferably 5 to 30 μm and more preferably 6 to 15 μm. The line spacing of the mesh is preferably 50 to 500 μm and is more preferably 100 to 300 μm.

The opening rate of the radiating element10is preferably equal to or more than 80%, and more preferably equal to or more than 90%. The opening rate of the radiating element10is a ratio of the size of area of the opening portions to the total size of area of the radiating element10including the opening portions formed in the radiating element10. The visible light transmittance of the radiating element10increases in accordance with an increase in the opening rate of the radiating element10.

The thickness of the radiating element10is preferably equal to or less than 400 nm and more preferably equal to or less than 300 nm. Although the lower limit of the thickness of the radiating element10is not particularly limited, the thickness of the radiating element10may be equal to or more than 2 nm, may be equal to or more than 10 nm, or may be equal to or more than 30 nm.

When the radiating element10is formed in in a mesh form, the thickness of the radiating element10may be 2 to 40 μm. When the radiating element10is formed in a mesh form, the visible light transmittance can be increased, even if the radiating element10is thick.

For example, the substrate50is a substrate provided in parallel with the window glass201. For example, the substrate50is formed in the rectangular shape in a plan view, and includes a first principal surface and a second principal surface. The first principal surface of the substrate50is provided to face the exterior-side, and in the form as illustrated inFIG.2, the first principal surface of the substrate50is provided to face the second glass surface on the interior-side of the window glass201. The second principal surface of the substrate50is provided to face the interior-side, and in the form as illustrated inFIG.2, the second principal surface of the substrate50is provided to face the same direction as the second glass surface on the interior-side of the window glass201.

The substrate50may be provided with a predetermined angle with reference to the window glass201. The antenna unit101may radiate electromagnetic waves in such a state that (a direction normal to) the substrate50on which the radiating element10is provided is inclined with reference to (a direction normal to) the window glass201. This is, for example, a case where the antenna unit101is provided at a location, such as window glass or the like of a building, higher than the ground surface, and radiates electromagnetic waves toward the ground surface to form an area on the ground surface. The inclination angle between the substrate50and the window glass201may be equal to or more than 0 degrees, may be equal to or more than 5 degrees, or may be equal to or more than 10 degrees, because the propagation direction of the electromagnetic waves can be made changed preferably. Also, in order to transmit electromagnetic wave to the outdoors, the inclination angle between the substrate50and the window glass201may be equal to or less than 50 degrees, may be equal to or less than 30 degrees, or may be equal to or less than 20 degrees.

The material constituting the substrate50is designed according to the antenna performance such as the power and directivity required for the radiating element10, and may be, for example, dielectric such as glass and resin, metal, or a complex thereof. The substrate50may be constituted by resin or the like to have an optical transparency. When the substrate50is constituted by a material having an optical transparency, the scenery as seen through the window glass201is less likely to be blocked by the substrate50.

In a case where glass is used as the substrate50, examples of materials of the substrate50include soda-lime-silica glass, borosilicate glass, aluminosilicate glass, or alkali-free glass.

The glass plate used as the substrate50can be manufactured by a conventional manufacturing process such as float process, fusion process, redraw process, press forming process, Fourcault process, or the like. As the method for manufacturing the glass plate, it is preferable to use the float process, because it is advantageous in productivity and cost.

In the plan view, the glass plate is formed in a rectangular shape. For example, the method for cutting the glass plate may be a method for cutting the glass plate by emitting laser light onto the surface of the glass plate and moving the emission area of the laser light on the surface of the glass plate, or a mechanical cutting method with a cuter wheel or the like.

In the present embodiment, the rectangular shape includes not only a rectangle and a square but also shapes obtained by rounding the corners of a rectangle and a square. The shape of the glass plate in a plan view is not limited to the rectangular shape, but may be other shapes such as a circle. The glass plate is not limited to a single plate, and may be laminated glass or insulated glazing.

In a case where resin is used as the substrate50, the resin is preferably transparent resin, and may be liquid crystal polymer (LCP), polyimide (PI), polyphenylene ether (PPE), polycarbonate, acrylic resin, fluorine resin, or the like. Fluorine resin is preferable because it has a low dielectric constant.

Fluorine resins include ethylene-tetrafluoroethylene-based copolymer (which may be hereinafter also referred to as “ETFE”), hexafluoropropylene-tetrafluoroethylene-based copolymer (which may be hereinafter also referred to as “FEP”), tetrafluoroethylene-propylene copolymer, tetrafluoroethylene-hexafluoropropylene-propylene copolymer, perfluoro (alkyl vinyl ether)-tetrafluoroethylene-based copolymer (which may be hereinafter also referred to as “PFA”), tetrafluoroethylene-hexa fluoropropylene-vinylidene fluoride System copolymer (which may be hereinafter also referred to as “THV”), polyvinylidene fluoride (which may be hereinafter also referred to as “PVDF”), vinylidene fluoride-hexafluoropropylene-based copolymer, polyvinyl fluoride, chlorotrifluoroethylene-based polymer, ethylene-chlorotrifluoroethylene-based copolymer (which may be hereinafter also referred to as “ECTFE”) or polytetrafluoroethylene, or the like. Any one of the above fluorine resins may be used alone, or two or more of the above fluorine resins may be used in combination.

The fluorine resin is preferably at least one selected from the group comprising ETFE, FEP, PFA, PVDF, ECTFE, and THV. ETFE is particularly preferable because ETFE has a high transparency, workability, and weather resistance.

Further, as the fluorine resin, “Fluon ETFE FILM” (registered trademark “AFLEX” in Japan) may be used. A thickness d of the substrate50is preferably 25 μm to 10 mm. The thickness d of the substrate50can be designed as desired according to the location where the radiating element10is provided. Where the thickness of the substrate50(or a distance between the radiating element10and the conductor30) is denoted as d, and a wavelength of the operation frequency of the radiating element10is denoted as λg, the thickness d is preferably equal to or less than λg/4, in order to increase the gain difference.

In a case where the substrate50is resin, the resin is preferably formed in a film or sheet shape. The thickness of the film or the sheet is preferably 25 to 1000 μm, more preferably 100 to 800 μm, and particularly preferably 100 to 500 μm, in order to achieve a high strength for holding the antenna.

In a case where the substrate50is glass, the thickness of the substrate50is preferably 1.0 to 10 mm, in order to achieve a high strength for holding the antenna.

An arithmetic mean roughness Ra on the first principal surface on the exterior-side of the substrate50is preferably equal to or less than 1.2 μm. This is because, when the arithmetic mean roughness Ra of the first principal surface is equal to or less than 1.2 μm, air is likely to flow in a space formed between the substrate50and the window glass201. The arithmetic mean roughness Ra of the first principal surface is more preferably equal to or less than 0.6 μm and still more preferably equal to or less than 0.3 μm. The lower limit of the arithmetic mean roughness Ra is not particularly limited, and, for example, equal to or more than 0.001 μm.

The arithmetic mean roughness Ra can be measured based on Japanese Industrial Standards (JIS) B0601:2001.

The size of area of the substrate50is preferably 0.01 to 4 m2. When the size of area of the substrate50is equal to or more than 0.01 m2, the radiating element10, the conductor30, and the like can be formed without difficulty. When the size of area of the substrate50is equal to or less than 4 m2, the antenna unit is inconspicuous and aesthetically good. The size of area of the substrate50is more preferably 0.05 to 2 m2.

The antenna unit101may have the conductor30provided on the second principal surface of the substrate50on the opposite side from the window glass201. The conductor30is provided on the interior-side with respect to the radiating element10, but the conductor30does not have to provided. The conductor30may be a portion that functions as an electromagnetic shielding layer capable of reducing the electromagnetic waves interference with electromagnetic waves radiated from the radiating element10and electromagnetic waves that occur from indoor electronic devices. The conductor30may be constituted by a single layer, or may be constituted by multiple layers. The conductor30may be constituted by a conventional material, and may be constituted by, for example, a metal film such as copper and tungsten, a transparent substrate using a transparent conductive film, or the like.

The transparent conductive film may be constituted by, for example, indium tin oxide (ITO), fluorinated tin oxide (FTC)), indium zinc oxide (IZO), indium tin oxide including silicon oxide (ITSO), zinc oxide (ZnO), or a conductive material with translucency, such as Si compounds containing phosphorous (P) and boron (B).

The conductor30is, for example, a conductor plane formed in a planar shape. The shape of the conductor30may be a rectangular shape or a circular shape, but is not limited to these shapes. For example, at least one or more conductors30are provided on the opposite side of the radiating element10from the wave directing member20, and in the illustrated embodiment, formed on a surface of the substrate50on the opposite side from a surface of the substrate50on the side of the wave directing member20.

The conductor30is preferably formed in a mesh form so as to have an optical transparency. In this case, “mesh” means a state in which through holes in a form of mesh are formed in the planar surface of the conductor30. When the conductor30is formed in a mesh form, the openings of the mesh may be in a rectangular or rhomboid shape. The line width of the mesh is preferably 5 to 30 Tim and more preferably 6 to 15 μm. The line spacing of the mesh is preferably 50 to 500 μm and is more preferably 100 to 300 μm.

The method for forming the conductor30may be a conventional method, and may be, for example, a sputtering method, a deposition method, or the like.

The surface resistivity of the conductor30is preferably equal to or less than 20 Ω/sq, more preferably equal to or less than 10 Ω/sq, and still more preferably equal to or less than 5 S)/sq. The size of the conductor30is preferably equal to or more than the size of the substrate50. When the conductor30is provided on the second principal surface on the interior-side of the substrate50, transmission of electromagnetic waves to indoors can be alleviated. The surface resistivity of the conductor30depends on the thickness, the material, and the opening rate of the conductor30. The opening rate is a ratio of the size of area of the opening portions to the total size of area of the conductor30including the opening portions formed in the conductor30.

In order to improve the aesthetics, the visible light transmittance of the conductor30is preferably equal to or more than 40%, and more preferably equal to or more than 60%. In order to alleviate transmission of electromagnetic waves to indoors, the visible light transmittance of the conductor30is preferably equal to or less than 90% and more preferably equal to or less than 80°.

The visible light transmittance increases in accordance with an increase in the opening rate of the conductor30. The opening rate of the conductor30is preferably equal to or more than 80%, and is more preferably equal to or more than 90%. In order to alleviate transmission of electromagnetic waves to indoors, the opening rate of the conductor30is preferably equal to or less than 95%.

The thickness of the conductor30is preferably equal to or less than 400 nm, and more preferably equal to or less than 300 nm. The lower limit of the thickness of the conductor30is not particularly limited, but may be equal to or more than 2 nm, equal to or more than 10 nm, or equal to or more than 30 nm.

When the conductor30is formed in a mesh form, the thickness of the conductor30may be 2 to 40 μm. When the conductor30is formed in a mesh form, the visible light transmittance can be increased, even if the conductor30is thick.

The antenna unit101according to the present embodiment has a configuration in which the substrate50is sandwiched between the radiating element10and the conductor30so as to form a microstrip antenna, i.e., a type of planar antenna. Alternatively, a plurality of radiating elements10may be arranged on the surface of the substrate50on the side of the wave directing member20so as to form an array antenna.

For example, the wave directing member20is a conductor formed in a planar shape. The wave directing member20is made of a conductive material such as gold, silver, copper, aluminum, chromium, lead, zinc, nickel, or platinum. The conductive material may be an alloy such as, for example, an alloy of copper and zinc (brass), an alloy of silver and copper, an alloy of silver and aluminum, and the like. For example, the wave directing member20may be formed by attaching a conductive material to a glass substrate or a resin substrate. The wave directing member20may be a thin film.

Multiple conductor portions used for the wave directing member20may be a line-shaped or belt-shaped conductor element, and may be in a straight shape or a curved shape. Also, the plurality of conductor portions may have a rectangular shape or a circular shape.

Multiple conductor portions used for the wave directing member20may be formed in a mesh form to have optical transparency. In this case, “mesh” means a state in which through holes in a form of mesh are formed in the planar surface of the conductor portions. The visible light transmittance of multiple conductor portions used for the wave directing member20is preferably equal to or more than 40%, and is preferably equal to or more than 60% in order to maintain the function as the window glass in terms of transparency.

When the conductor portions are formed in a mesh form, the openings of the mesh may be in a rectangular or rhomboid shape. When the openings of the mesh are formed in a rectangular shape, the openings of the mesh are preferably in a square shape. When the openings of the mesh are in a square shape, the aesthetics are improved. Alternatively, the openings of the mesh may be in directed self-assembly random shapes. Such random shapes can prevent the forming of a moiré pattern. The line width of the mesh is preferably 5 to 30 μm, and more preferably 6 to 15 μm. The line spacing of the mesh is preferably 50 to 500 μm, and more preferably 100 to 300 μm. Where the wavelength of the operation frequency of the radiating element10is denoted as λ, the line spacing of the mesh is preferably equal to or less than 0.5λ, more preferably equal to or less than 0.1λ, and still more preferably equal to or less than 0.01λ. When the line spacing of the mesh is 0.5λ or less, the performance of the antenna is high. Also, the line spacing of the mesh may be 0.001λ or more.

The dielectric member41is a medium between the radiating element10and the wave directing member20. In the present embodiment, the wave directing member20is provided on the dielectric member41, and more specifically, the wave directing member20is provided on an exterior-side surface of the dielectric member41. The dielectric member41is supported by the substrate50in such a manner that the interior-side surface of the dielectric member41is in contact with the radiating element10. For example, the dielectric member41is a dielectric substrate having a dielectric as its main component with a relative permittivity of larger than 1 and equal to or less than 15 (preferably 7 or less, more preferably 5 or less, and particularly preferably 2.2 or less). Examples of the dielectric member41include fluororesin, COC (cycloolefin copolymer), COP (cycloolefin polymer), PET (polyethylene terephthalate), polyimide, ceramic, sapphire, and a glass substrate. When the dielectric member41is formed of a glass substrate, examples of materials of the glass substrate include alkali-free glass, quartz glass, soda lime glass, borosilicate glass, alkali borosilicate glass, and aluminosilicate glass. For example, the relative permittivity is measured by the cavity resonator.

The dielectric member41has an optical transparency of transmission of visible light, so that the scenery as seen through the window glass201is less likely to be blocked by the dielectric member41.

The support portion60is a portion that supports the antenna unit101on the window glass201. In the present embodiment, the support portion60supports the antenna unit101so as to form a space between the window glass201and the wave directing member20. The support portion60may be a spacer that secures a space between the window glass201and the substrate50or may be a housing of the antenna unit101. The support portion60is formed by a dielectric substrate. Examples of materials of the support portion60include conventional resins such as silicone resin, polysulfide resin, and acrylic resin. Alternatively, a metal such as aluminum may be used.

The distance D between the window glass201and the radiating element10is preferably 0 to 3λ, where the wavelength at the resonance frequency of the radiating element10is denoted as λ. When the distance D between the window glass201and the radiating element10is 0 to 3λ, the reflection of electromagnetic waves at the glass interface can be alleviated. The distance D between the window glass201and the radiating element10is more preferably equal to or more than 0.1λ, and still more preferably equal to or more than 0.2λ. The distance D between the window glass201and the radiating element10is more preferably equal to or less than 2λ, still more preferably equal to or less than A, and particularly preferably equal to or less than 0.6λ.

A value obtained by dividing the total size of area S of multiple conductor portions (the wave directing member20) by the size of area of the substrate50is preferably 0.0001 to 0.01. When the value obtained by dividing the total size of area S of the wave directing member20by the size of area of the substrate50is equal to or more than 0.0001, the gain difference increases. The value obtained by dividing the total size of area S of the wave directing member20by the size of area of the substrate50is more preferably equal to or more than 0.0005, still more preferably equal to or more than 0.001, particularly preferably equal to or more than 0.0013. When the value obtained by dividing the total size of area S of the wave directing member20by the size of area of the substrate50is equal to or less than 0.01, the wave directing member20is inconspicuous and is aesthetically good. The value obtained by dividing the total size of area S of the wave directing member20by the size of area of the substrate50is more preferably equal to or less than 0.005 and still more preferably equal to or less than 0.002.

It should be noted that the wave directing member20may be provided so as to be in contact with the interior-side surface of the window glass201. In this case, the dielectric member41may be provided, or does not have to be provided, and the relative permittivity of the medium between the radiating element10and the wave directing member20is preferably less than the relative permittivity of the window glass201. The relative permittivity of the window glass201may be 10 or less, may be 9 or less, may be 7 or less, or may be 5 or less.

FIG.3is a cross sectional view schematically illustrating an example of a laminated structure of an antenna unit-attached window glass according to a second embodiment. Description about the configurations and effects substantially the same as the above embodiment is omitted or simplified by incorporating the above description by reference. An antenna unit-attached window glass302includes an antenna unit102and a window glass201. The antenna unit102is attached to the interior-side surface of the window glass201for a building.

Similar to the above-described embodiment, the antenna unit102includes a phase control member80provided between the window glass201and the radiating element10, and therefore the gain difference increases.

In the antenna unit102, a dielectric member41is supported by a spacer61on a substrate50, so that the interior-side surface of the dielectric member41is not in contact with the radiating element10. Specifically, the dielectric member41is situated so that a space42is formed between the radiating element10and the dielectric member41. The medium between the radiating element10and the wave directing member20includes both of the dielectric member41and the space42. Air is present in the space42, but gas other than air may be used. The space42may be a vacuum. Because the radiating element10is not in contact with the dielectric member41, the resonance frequency is unlikely to be affected by the dielectric member41, and therefore, the gain difference increases.

Because the dielectric member41is situated so that the space42is formed between the radiating element10and the dielectric member41, the distance a of the antenna unit102is preferably 2.1 mm or more in order to increase the gain difference. The distance a is determined by the effective relative permittivities of the dielectric member41and the space42. The inventors of the present application have found that, when the dielectric member41is situated so that the space42is formed between the radiating element10and the dielectric member41, the gain difference can attain 0 dB or more when the distance a is set as described above.

FIG.4is a cross sectional view schematically illustrating an example of a laminated structure of an antenna unit-attached window glass according to a third embodiment. Description about the configurations and effects substantially the same as the above embodiment is omitted or simplified by incorporating the above description by reference. An antenna unit-attached window glass303includes an antenna unit103and window glass201. The antenna unit103is attached to the interior-side surface of the window glass201for a building.

Similar to the above-described embodiment, the antenna unit103includes a phase control member81provided between the window glass201and a radiating element10, and therefore the gain difference increases. The phase control member81includes: a wave directing member20having multiple conductor portions; and a dielectric member41situated on the side of the window glass201with reference to the wave directing member20, and has the same function as the phase control member80of the above-described embodiment.

In the antenna unit103, the dielectric member41is supported by a spacer61on a substrate50, so that the wave directing member20formed on the interior-side surface of the dielectric member41is not in contact with the radiating element10. In other words, the antenna unit103includes the dielectric member41, i.e., an example of dielectric situated on the opposite side of the wave directing member20from the radiating element10. The wave directing member20is situated between the dielectric member41and the radiating element10. The wave directing member20provided on the interior-side surface of the dielectric member41is situated so that the space42is formed between the wave directing member20and the radiating element10, and the medium between the radiating element10and the wave directing member20includes only the space42. Air is present in the space42, but gas other than air may be used. The space42may be a vacuum. Because the radiating element10is not in contact with the dielectric member41, and the medium between the radiating element10and the wave directing member20includes only the space42, the resonance frequency is unlikely to be affected by the dielectric member41, and therefore, the gain difference increases.

Because the medium between the radiating element10and the wave directing member20includes only the space42, the distance a of the antenna unit103is preferably 2.3 mm or more in order to increase the gain difference. The inventors of the present application have found that, when the medium between the radiating element10and the wave directing member20includes only the space42, the gain difference can attain 0 dB or more when the distance a is set as described above.

Although the dielectric member41is supported on the substrate50by the spacer61, the dielectric member41may be supported by the support portion60. Also, the dielectric member41does not have to be provided, and merely space may exist between the wave directing member20and the window glass201. In a case where nothing but space exists between the wave directing member20and the window glass201, the wave directing member20is supported by, for example, the support portion60or the spacer61.

FIG.5is a cross sectional view schematically illustrating an example of a laminated structure of an antenna unit-attached window glass according to a fourth embodiment. Description about the configurations and effects substantially the same as the above embodiment is omitted or simplified by incorporating the above description by reference. An antenna unit-attached window glass304includes an antenna unit104and window glass201. The antenna unit104is attached to the interior-side surface of the window glass201for a building.

Similar to the above-described embodiment, the antenna unit104includes a phase control member82provided between the window glass201and the radiating element10, and therefore, the gain difference increases. The phase control member82includes: a wave directing member20having multiple conductor portions; and a support wall62that is a dielectric situated on the side of the window glass201with reference to the wave directing member20, and has the same function as the phase control member80of the above-described embodiment.

In the antenna unit104, the wave directing member20is formed on a support wall62of a support portion60on the side of the window glass201, the wave directing member20being formed on an inner wall surface of the support wall62facing the interior-side, so that the wave directing member20does not come into contact with the radiating element10. In other words, the antenna unit104includes (the support wall62of) the support portion60, i.e., an example of dielectric situated on the opposite side of the wave directing member20from the radiating element10. The wave directing member20is situated between the support wall62and the radiating element10. The wave directing member20provided on the support wall62of the support portion60is situated so that the space42is formed between the wave directing member20and the radiating element10, and the medium between the radiating element10and the wave directing member20includes only the space42. Air is present in the space42, but gas other than air may be used. The space42may be a vacuum. Because the medium between the radiating element10and the wave directing member20includes only the space42, the gain difference increases.

Because the medium between the radiating element10and the wave directing member20includes only the space42, the distance a of the antenna unit104is preferably 2.3 mm or more in order to increase the gain difference.

FIG.6is a cross sectional view schematically illustrating an example of a laminated structure of an antenna unit-attached window glass according to a fifth embodiment. Description about the configurations and effects substantially the same as the above embodiment is omitted or simplified by incorporating the above description by reference. An antenna unit-attached window glass305includes an antenna unit105and window glass201. The antenna unit105is attached to an exterior-side surface of window glass201for a building.

The antenna unit105has the same laminated structure as the antenna unit101(seeFIG.2). However, the antenna unit105is different from the antenna unit101in that the radiating element10is situated between the window glass201and the wave directing member20.

Because, in the antenna unit105, the wave directing member20is arranged on the opposite side (i.e., the exterior-side) of the radiating element10from the window glass201situated on the interior-side in this manner, the phase of the electromagnetic waves radiated from the radiating element10toward exterior-side can be controlled by the phase control member80, and the reflection of the electromagnetic waves at the interface of the window glass201situated at the interior-side of the radiating element10can be reduced, and therefore, the gain difference increases. As a result, the gain of the electromagnetic waves incident in a direction normal to the surface of the window glass201increases, and the reflection to the back (interior-side) of the radiating element10decreases, so that the gain difference increases. Also, the distance a is preferably (2.11×εr−1.82) mm or more in order to increase the gain difference.

It should be noted that the antenna unit attached to the exterior-side of the window glass201is not limited to the antenna unit105ofFIG.6. For example, an antenna unit having the same laminated structure as the antenna unit102ofFIG.3, the antenna unit103ofFIG.4, or the antenna unit104ofFIG.5may be attached to the exterior-side of the window glass201.

FIG.7is a cross sectional view schematically illustrating an example of a laminated structure of an antenna unit-attached window glass according to a sixth embodiment. Description about the configurations and effects substantially the same as the above embodiment is omitted or simplified by incorporating the above description by reference. An antenna unit-attached window glass403includes an antenna unit503and window glass201. The antenna unit503is attached to the interior-side surface of the window glass201for a building. The antenna unit503has the same laminated structure as the antenna unit103(seeFIG.4). Specifically, the antenna unit503is used by being attached to the window glass201so that a matching member70is interposed between the window glass201and a wave directing member20.

The matching member70is an example of a matching body for matching the mismatch of the impedance between the window glass201and the medium existing between the radiating element10and the window glass201. Because the mismatch of the impedance is adjusted, the electromagnetic waves radiated from the radiating element10to the window glass201are suppressed from being reflected by the interface of the window glass201, and therefore, the gain difference increases.

Where the relative permittivity of the window glass201is denoted as εr1, the relative permittivity of the matching member70is denoted as εr2, and the relative permittivity of the medium between the matching member70and the radiating element10is denoted as εr3, it is preferable that εr1 be larger than εr2 and εr2 be larger than εr3. Accordingly, the electromagnetic waves radiated from the radiating element10propagate, with reduction in the reflection loss, through the medium between the matching member70and the radiating element10, through the matching member70, and then through the window glass201, and therefore the gain difference increases.

The matching member70is provided on the window glass201. In the present embodiment, the matching member70is provided on the interior-side surface of the window glass201. The antenna unit503is attached to the interior-side surface of the window glass201via the matching member70.

The dielectric member41is an example of the medium between the matching member70and the radiating element10. In the antenna unit-attached window glass403, the matching member70and the dielectric member41are not in contact with each other, but the matching member70and the dielectric member41may be in contact with each other.

Similar to the above-described embodiment, the distance a is preferably equal to or more than (2.11×εr−1.82) mm in order to increase the gain difference.

It should be noted that the antenna unit attached to the interior-side of the window glass201via the matching member70is not limited to the antenna unit503of FIG. V. For example, the antenna unit having the same laminated structure as the antenna unit101ofFIG.2, the antenna unit102ofFIG.3, or the antenna unit104ofFIG.5may be attached to the interior-side of the window glass201via the matching member70.

In the antenna unit-attached window glass as illustrated inFIG.7, a conductor may be provided between the matching member70and the window glass201. When a conductor is provided between the matching member70and the window glass201, the thickness of the matching member70can be reduced. For example, the conductor provided between the matching member70and the window glass201is a conductor pattern having a Frequency Selective Surface (FSS) formed with a mesh or slit pattern and the like to pass electromagnetic waves in a predetermined frequency range. The conductor provided between the matching member70and the window glass201may be a meta-surface. The conductor does not have to be provided between the matching member70and the window glass201.

FIG.8is a perspective view illustrating a specific example of configuration of an antenna unit according to the present embodiment. A radiating element10is fed at a feeding point11. In the form as illustrated inFIG.8, the wave directing member20includes multiple conductor portions21to24arranged parallel to one another. The number of conductor portions is not limited to four. Multiple conductor portions may be line-shaped or belt-shaped conductor elements, and may be in a straight shape or a curved shape.

In order to increase the gain difference, the shape of each of the conductor portions may be changed, or the relationship in position between the radiating element10and each of the conductor portions may be changed. The multiple conductor portions may have the same shape as one another as illustrated inFIG.8. Among the multiple conductor portions, conductor portions of a first group (in the case ofFIG.8, the conductor portions21,22) and conductor portions of a second group (in the case ofFIG.8, the conductor portions23,24) may be arranged symmetrically about the radiating element10as illustrated inFIG.8. In the form as illustrated inFIG.8, the multiple conductor portions21to24are on the same plane (on the ZX plane), and the lengths of the multiple conductor portions21to24are the same as one another in the polarization direction (the Z axis direction) of the radiating element10.

The multiple conductor portions do not have to be on the same plane. The phases of currents induced in the respective conductor portions provided in different planes are different from one another, and therefore, the gain difference increases.

FIG.9is a plan view illustrating a specific example of an antenna unit according to the present embodiment.FIG.10is a plan view illustrating a configuration of a microstrip array antenna of the antenna unit as illustrated inFIG.9.FIG.11is a plan view illustrating a configuration of a phase control member of the antenna unit as illustrated inFIG.9. In the antenna unit1as illustrated inFIG.9, a microstrip array antenna14(FIG.10) in which the radiating element10is constituted by multiple patch elements10A to10D and a phase control member80(FIG.11) including multiple conductor portions21to23provided on the dielectric member41are laminated. The laminated structure is the same as inFIG.3. Multiple patch elements10A to10D arranged in an array manner on the substrate50are fed by a transmission line12.

The multiple conductor portions may include conductor portions in different shapes as illustrated inFIG.9. The phases of currents induced in the respective conductor portions different in shape are different from one another, and accordingly, the gain difference increases. In the case ofFIG.9, the conductor portions22and23are in the same shape as one another, but the conductor portion21is in a shape different from the conductor portions22and23. Among the multiple conductor portions, conductor portions of a first group (in the case ofFIG.9, the conductor portion21) and conductor portions of a second group (in the case ofFIG.9, the conductor portions22and23) may be arranged asymmetrically about the radiating element10as illustrated inFIG.9. The phases of currents induced in the respective conductor portions that are arranged asymmetrically are different, accordingly, the gain difference increases.

The multiple conductor portions may include conductor portions of different lengths in the polarization direction (the Z axis direction) of the radiating element10as illustrated inFIG.9. Due to the difference in the lengths in the polarization direction of the radiating element10, the phases of currents inducted in the respective conductor portions of different lengths are different from one another, and accordingly, the gain difference increases. In the case ofFIG.9, the conductor portions22and23are of the same length, i.e., a length B, but a length A of the conductor portion21is different from the length B of the conductor portions22and23.

When the lengths A and B in the polarization direction of the radiating element10are different, the phase of the current inducted in the conductor portion21and the phases of the currents inducted in the conductor portions22and23are different, and therefore, the gain difference increases. In order to increase the gain difference, a ratio A/B is preferably equal to or more than 1.1 and equal to or less than 2.0.

As illustrated inFIG.9, when multiple conductor portions21to23are situated along the outer edge of the patch element10A in a plan view, the gain of the microstrip array antenna14improves. Likewise, when multiple conductor portions are situated along the outer edges of the patch elements10B to10D in a plan view, the gain of the microstrip array antenna14improves. More preferably, the multiple conductor portions are situated along the outer edge extending in the polarization direction of the radiating element (patch element) in order to improve the gain of the microstrip array antenna14.

InFIG.9, the radiating element10includes multiple antenna elements (in this example, four patch elements10A to10D) connected to the single transmission line12. The multiple conductor portions21to23are provided for each of the multiple antenna elements. In the example as illustrated inFIG.9, three conductor portions21to23are provided for the single patch element10A, three conductor portions21to23are provided for the single patch element10B, three conductor portions21to23are provided for the single patch element10C, and three conductor portions21to23are provided for the single patch element10D. For a single antenna element, a single conductor portion may be provided, or multiple conductor portions may be provided. However, when multiple conductor portions are provided, the phase of the electromagnetic wave radiated from the radiating element10can be adjusted to be larger. The multiple antenna elements may have the same number of conductor portions or may have different numbers of conductor portions. A single or multiple conductor portions provided for a single antenna element are provided in proximity to the antenna element.

As illustrated inFIGS.9and10, the antenna unit may include a least one passive element13in proximity to at least one conductor portion of the multiple conductor portions. The passive element13can change the direction of the main lobe, and the gain difference can be increased. The passive element13as illustrated inFIGS.9and10is provided on the same plane as the radiating element10(the patch element10A), and is provided along the outer edge of the patch element10A at such a distance that the passive element13can be coupled with the patch element10A and the conductor portions22and23. Passive elements13may be provided in proximity to the patch elements10B and the like in a similar manner. In a plan view, in the arrangement, the passive elements13may overlap with at least portions of the multiple conductor portions, or may not overlap therewith as illustrated inFIG.9. The gain difference can be adjusted by adjusting the positions of the passive elements13with respect to the radiating elements10.

FIG.12is a drawing illustrating an example of simulation of a gain difference obtained with out-of-phase feeding where the ratio A/B was 1.0 in the antenna unit as illustrated inFIG.9.FIG.13is a drawing illustrating an example of simulation of a relationship between the gain difference and the ratio A/B obtained with out-of-phase feeding in the antenna unit as illustrated inFIG.9.

InFIGS.12and13, the antenna unit1was installed such that the patch elements10A and10C were on the upper side in the vertical direction, and the patch elements10B and10D were on the lower side in the vertical direction, and it is assumed that the patch elements10A and10C and the patch elements10B and10D were fed out-of-phase. InFIG.12, the horizontal axis denotes an inclination angle θ of the main lobe (the grating lobe) with reference to the horizontal plane. The main lobe represents the gain radiated in the downward direction with reference to the horizontal plane. The grating lobe represents the gain radiated in the upward direction with reference to the horizontal plane.

During the simulation ofFIGS.12and13, the simulation conditions such as the dimensions of components as illustrated inFIGS.9and10were as follows.A: VariableB: 22.5 mm (fixed)L1: 212 mmL2: 850 mmL3: 24.5 mmL4: 55.5 mmL5: 18.2 mmL6: 60.0 mmThickness of substrate50: 3.3 mmRelative permittivity of substrate50: 4.4Thickness of dielectric member41: 1.1 mmRelative permittivity of dielectric member41: 4.4Distance between radiating element10and phase control member80: 7.5 mmDistance between radiating element10and window glass201: 15 mm

As illustrated inFIG.13, the gain difference improved in accordance with an increase in the ratio A/B, and when the ratio A/B was equal to or more than 0.9, the gain difference increased more greatly.

FIG.14is a drawing illustrating an example of simulation of a gain difference obtained with phase difference feeding where the ratio A/B was 1.0 in the antenna unit as illustrated inFIG.9.FIG.15is a drawing illustrating an example of simulation of a relationship between the gain difference and the ratio A/B obtained with phase difference feeding in the antenna unit as illustrated inFIG.9.

InFIGS.14and15, the antenna unit1was installed such that the patch elements10A and10C were on the upper side in the vertical direction, and the patch elements10B and10D were on the lower side in the vertical direction, and it is assumed that the phases were set so that the inclination angle θ of the main lobe became 20 degrees (the gain was maximized at 20 degrees). The conditions during simulation ofFIGS.14and15were the same as the above-described conditions during the simulation ofFIGS.12and13.

As illustrated inFIG.15, the gain difference improved in accordance with an increase in the ratio A/B, and when the ratio A/B became equal to or more than 1.1, the gain difference increased.

FIG.16is a drawing illustrating the antenna unit1that faces window glass201including insulated glass plates211,211.FIG.17is a drawing illustrating an example of simulation of a gain obtained with phase difference feeding where the ratio A/B was 1.0 in a case where the phase control member80was provided in the antenna unit1ofFIG.16.FIG.18is a drawing illustrating an example of simulation of a gain obtained with phase difference feeding where the ratio A/B was 1.0 in a case where the phase control member80was not provided in the antenna unit1ofFIG.16.

InFIGS.17and18, the antenna unit1was installed as inFIG.16such that the patch elements10A and10C were on the upper side in the vertical direction, and the patch elements10B and10D were on the lower side in the vertical direction, and it is assumed that the phases were set so that the inclination angle θ of the main lobe became 20 degrees (the gain was maximized at 20 degrees).

During the simulation ofFIGS.17and18, the conditions were as follows.

Distance between the radiating element10and the window glass201: 15 mm

Thickness of each of the glass plates211,212: 4.7 mm

Thickness of an air layer213between the glass plate211and the glass plate212: 6.0 mm

The remaining conditions were the same as the above-described conditions during the simulation ofFIGS.12and13.

In a case where the phase control member80was provided (FIG.17), the gain became 11.5 dBi when the inclination angle θ was 20 degrees, and in a case where the phase control member80was not provided (FIG.18), the gain became 8.1 dBi when the inclination angle θ was 20 degrees. In this manner, when the phase control member80was provided, the reflection by the window glass201was alleviated.

Although the antenna unit and the window glass have been described above with reference to the embodiments, the present invention is not limited to the above-described embodiments. Various modifications and improvements such as combinations and replacements with some or all of other embodiments can be made within the subject matters of the present invention.

For example, the antenna unit does not have to be fixed to the window glass. The antenna unit may be hung from the ceiling so that the antenna unit is installed and used so as to face the window glass, or the antenna unit can be fixed to a protrusion (for example, a window frame, a window sash, or the like for holding the outer edge of the window glass) that is present around the window glass. The antenna unit may be installed so as to be in contact with the window glass, or may be installed in proximity thereto without being in contact with the window glass.

The phase control member does not have to have multiple conductor portions, and may have only one conductor portion.