How to select the interface layer

Abstract

To provide an antenna device that allows for easy selection of the optimal interface layer. [Solution] The interface layer selection method includes an antenna provided on a windowpane and capable of scanning beam angles, an interface layer provided on the windowpane, and a control unit, and is a method for selecting the interface layer of a wireless communication device provided on a window having the windowpane, wherein the control unit scans the beam angle of the antenna to obtain a first angular distribution of the received power of radio waves arriving from a base station with respect to the beam angle, estimates the incident angle of the radio waves based on the first angular distribution, and selects an interface layer according to the estimated result of the incident angle.

Description

Technical Field

[0004] , , , , , ,

[0005] , , , , ,

[0001] This disclosure relates to a method for selecting an interface layer.

Background Art

[0002] Conventionally, there is an antenna device used by being attached to a window glass for a building, which includes an antenna, a waveguide member located on the outdoor side with respect to the antenna, and a conductor located on the indoor side with respect to the antenna. When the distance between the antenna and the waveguide member is a, and the relative permittivity of the medium composed of a dielectric member between the antenna and the waveguide member is εr, a is (2.11×εr - 1.82) mm or more. The antenna device further includes a matching member (for example, see Patent Document 1) that is directly attached to the glass plate of the window glass.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0006] An interface layer selection method according to an embodiment of the present disclosure is a method for selecting the interface layer of a wireless communication device provided in a window having a window glass, comprising an antenna provided in a window glass and capable of scanning a beam angle, an interface layer provided in the window glass, and a control unit, wherein the control unit scans the beam angle of the antenna to obtain a first angular distribution of the received power of radio waves arriving from a base station with respect to the beam angle, estimates the incident angle of the radio waves based on the first angular distribution, and selects an interface layer according to the estimated result of the incident angle. [Effects of the Invention]

[0007] This provides a method for selecting the optimal interface layer, making it easy to choose the most suitable one. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows a plan view of an example of a building with a window that has a wireless communication device installed, which includes an antenna device to which the interface layer selection method of the embodiment is applied. [Figure 2A] This figure shows an example of a wireless communication device and window configuration to which the interface layer selection method of the embodiment can be applied. [Figure 2B] This diagram schematically shows an example of the positional relationship between the window glass, interface layer, and array antenna. [Figure 3] This is a diagram showing an example of the circuit configuration of a wireless device. [Figure 4] This figure shows the elevation angle Θ and azimuth angle Φ when the array antenna is positioned horizontally. [Figure 5] This figure shows examples of the first and second transmission characteristics. [Figure 6] This flowchart illustrates an example of the process performed depending on the selection method of the interface layer. [Figure 7A]This figure shows an example of how the beam angle is scanned in step S1. [Figure 7B] This figure shows an example of the angular distribution P(Θ,Φ) of indoor received power and the angular distribution P0(Θ,Φ) of outdoor received power. [Figure 8] This figure shows an example of the calculation results from a simulation of the attenuation angle distribution A(Θ,Φ), the angle distribution of indoor received power P(Θ,Φ), and the angle distribution of outdoor received power P0(Θ,Φ). [Figure 9] This diagram schematically shows an example of the positional relationship between the window glass, multiple interface layers, and array antenna in a modified embodiment. [Modes for carrying out the invention]

[0009] The following describes embodiments to which the interface layer selection method of this disclosure is applied. In the following, the same number may be used for the same element, and redundant explanations may be omitted.

[0010] In the following, we define and explain the XYZ coordinate system, which is indicated by capital letters. The directions parallel to the X-axis (X direction), the directions parallel to the Y-axis (Y direction), and the directions parallel to the Z-axis (Z direction) are mutually orthogonal. The XYZ coordinate system is an example of a Cartesian coordinate system. In addition, in the following, the length, width, thickness, etc. of each part may be exaggerated to make the configuration easier to understand. Furthermore, the terms parallel, right angle, orthogonal, horizontal, vertical, up and down, etc., should be used with a degree of deviation that does not impair the effect of the embodiment.

[0011] Furthermore, in the following explanation, "radio waves" refer to a type of electromagnetic wave, and generally, electromagnetic waves with a frequency of 3 THz or less are called radio waves. Below, electromagnetic waves with a frequency of 3 THz or less emitted from outdoor base stations or relay stations will be referred to as "radio waves," and when referring to electromagnetic waves in general, the term "electromagnetic wave" will be used.

[0012] The radio wave relayed by the wireless communication device to which the interface layer selection method of the embodiment is applied is preferably a radio wave that assumes beamforming, such as a radio wave in the millimeter wave band of the fifth generation mobile communication system (5G). The wireless communication device functions as a relay that relays radio waves arriving from an outdoor base station or the like indoors.

[0013] Also, the radio wave relayed by the wireless communication device including the antenna device to which the interface layer selection method of the embodiment is applied may be a radio wave in the frequency band of 1 GHz to 6 GHz including Sub-6, LTE (Long Term Evolution), LTE-A (LTE-Advanced), UMB (Ultra Mobile Broadband), or CBRS (Citizens Broadband Radio Service). Further, the radio wave relayed by the wireless communication device of the embodiment may be IEEE802.11 (Wi-Fi (registered trademark)), IEEE802.16 (WiMAX (registered trademark)), IEEE802.20, UWB (Ultra-Wideband), Bluetooth (registered trademark), or LPWA (Low Power Wide Area), etc. Note that beamforming may be performed on the radio wave in the frequency band of 1 GHz to 6 GHz including Sub-6, or the radio wave of Wi-Fi (registered trademark).

[0014] The wireless communication device to which the interface layer selection method of the embodiment is applied can be used as a relay, and has a configuration that enables easy selection of the interface layer at which the power of the radio wave received by the antenna (received power) becomes maximum. The details will be described below. The received power is synonymous with the intensity of the radio wave (received intensity).

[0015] <Embodiment> FIG. 1 is a plan view showing an example of a building 1 in which a window 10 provided with a wireless communication device 200 including an antenna device to which the interface layer selection method of the embodiment is applied is installed. In FIG. 1, in addition to the building 1 and the wireless communication device 200, a base station BS, a personal computer (PC) 50, and a smartphone 60 are shown.

[0016] In addition to detached houses, buildings, or condominiums, etc., Building 1 may also be a commercial facility such as a shopping mall or department store, an airport, a factory, a power facility, a government building, a station (station building), or a bus stop building, etc. Window 10 is used for these Buildings 1. Window 10 includes a window glass and a window frame (window frame on the side of Building 1). The wireless communication device 200 has a function as a repeater.

[0017] The antenna of the wireless communication device 200 is preferably provided on the window glass of Window 10, and the portion other than the antenna may be provided on Window 10 or on the surrounding wall 1A or the frame of the projecting window, etc. Also, the portion other than the antenna may be provided at a location farther from the wall 1A or the frame of the projecting window, etc., as viewed from Window 10. The antenna of the wireless communication device 200 is the antenna of the antenna device included in the wireless communication device 200. Also, the portion other than the antenna of the wireless communication device 200 does not have to be fixed to the surrounding wall 1A, ceiling, or the frame of the projecting window, etc. of Window 10, and for example, it may just be placed on a flat place, etc.

[0018] The millimeter-wave band radio waves radiated from the outdoor base station BS enter the indoor through only the window glass of Window 10 of Building 1, but due to having high directivity, they reach only a part of the indoor area, and a dead zone is likely to occur. The window glass of Window 10 is an entrance of radio waves in Building 1.

[0019] Since it is difficult to create a good communication environment indoors for radio waves in the millimeter-wave band frequency band, a wireless communication device 200 is provided on Window 10 to improve the reception environment and expand the communication area. Here, providing the wireless communication device 200 on Window 10 means that, as described above, the antenna is provided on the window glass, and for the portion other than the antenna, it may be provided on Window 10 or on the surrounding wall 1A or the frame of the projecting window, etc. When relaying radio waves, the wireless communication device 200 receives the radio waves through the window glass of Window 10 with the antenna, amplifies them, and radiates them indoors. In FIG. 1, the wireless communication device 200 is arranged on the indoor side of Window 10, but it may also be arranged on the outdoor side of Window 10.

[0020] When the wireless communication device 200 relays radio waves arriving from outside the window 10, it amplifies the received radio waves and radiates the amplified radio waves indoors at a predetermined radiation angle using an array antenna or the like. Since the amplified radio waves are radiated over a wide area indoors, it becomes easier for indoor terminals to receive the radio waves.

[0021] For example, when relaying radio waves, the wireless communication device 200 may receive, amplify, and radiate radio waves of multiple frequencies. By relaying radio waves of multiple frequencies, the amplified radio waves can be radiated to an even wider area indoors.

[0022] Furthermore, when millimeter-wave radio waves pass through window glass, the radio waves are attenuated. To suppress radio wave attenuation (loss), it is preferable to use an interface layer. By using an interface layer, when the wireless communication device 200 relays radio waves, the loss can be reduced by adjusting the electrical length of the radio waves before or after they pass through the window glass to match the impedance.

[0023] <Configuration of wireless communication device 200 and window 10> Figure 2A shows an example of the configuration of the wireless communication device 200 and the window 10. The wireless communication device 200 includes an antenna device 100 and is mounted on the window 10. The window 10 includes a window pane 11 and a window frame 12.

[0024] Here, we will describe the configuration of the window 10, the configuration of the wireless communication device 200 and its mounting structure to the window 10, and the configuration of the antenna device 100 in that order.

[0025] <Configuration of Window 10> In the following description, we will explain an example in which window 10 is a fixed window, but it may also be a sliding window that can be opened and closed, or a casement window, etc. Also, the window glass 11 held by the window frame may be one pane or multiple panes.

[0026] The window glass 11 has an indoor main surface 11A and an outdoor main surface (not shown). The window glass 11 can be made of commonly available glass, such as soda-lime glass, alkali-free glass, Pyrex® glass, or quartz glass. Furthermore, the window glass 11 is not limited to glass plates and may be made of resin materials such as polycarbonate or acrylic. The outdoor main surface of the window glass 11 is the main surface opposite to the indoor main surface 11A.

[0027] The window frame 12 is a frame-like component that surrounds the edge of the window glass 11, and is made of a metal such as aluminum, or a resin or the like. Below, an example of a window frame 12 made of metal will be described.

[0028] The window pane 11 and window frame 12 of the window 10 are installed on a wall 1A perpendicular to the horizontal plane. The main indoor surface 11A of the window pane 11 is parallel to the indoor surface 12A of the window frame 12, and the thickness (thickness in the Z direction) of the window pane 11 and window frame 12 is constant.

[0029] <Configuration of wireless communication device 200 and mounting structure to window 10> The wireless communication device 200 includes an antenna device 100, a waveguide 150, a wireless device 210, and a bracket 220. The waveguide 150 is an example of a transmission path. The bracket 220 is an example of a mounting device. The wireless communication device 200 is installed, for example, on the indoor side of building 1 (see Figure 1). The wireless communication device 200 is a separated-type repeater in which the antenna device 100 and the wireless device 210 are separated and connected by the waveguide 150.

[0030] Here, as an example, a configuration in which the wireless communication device 200 includes a waveguide 150 is described, but the following transmission lines may be used instead of the waveguide 150. For example, an FPC (Flexible Printed Circuits) transmission line having transmission lines such as microstrip lines (MSL) or coplanar waveguides (CPW) formed on a flexible substrate made of polyimide or the like may be used. An FPC transmission line is an example of a transmission line having a flexible substrate and transmission lines such as MSL or CPW formed on the flexible substrate. In addition, a coaxial cable may be used instead of the waveguide 150.

[0031] Here, the XYZ coordinate system is defined with respect to the indoor surface 12A of the window frame 12 to which the wireless device 210 is attached. The X-axis is an example of the first axis, the Y-axis is an example of the second axis, and the Z-axis is an example of the third axis. The X-direction is an example of the first axis direction, the Y-direction is an example of the second axis direction, and the Z-direction is an example of the third axis direction.

[0032] The indoor surface 12A of the window frame 12 is a surface that includes the X and Y directions. Surface 12A is parallel to the XY plane and is an example of a first surface. The Z direction is the direction perpendicular to and away from surface 12A, and is the direction of the normal to surface 12A. The +Z side of surface 12A is the indoor side. In such an XYZ coordinate system, the Y direction is the direction connecting the wireless device 210 and the window glass 11. The X direction is the direction in which the window frame 12 extends along the outer edge 11E of the window glass 11 at the fixing position of the wireless device 210 to the window frame 12. The fixing position of the wireless device 210 to the window frame 12 is the position where the two brackets 220 of the frame-shaped window frame 12 are attached, and in Figure 2A, it is the part of the window frame 12 that is on the +Y direction side relative to the window glass 11 and extends in the X direction. The outer edge 11E of the window glass 11 is the outer edge when the window glass 11 is viewed in the XY plane (plan view). The outer edge 11E of the window glass 11 at the fixing position of the wireless device 210 to the window frame 12 is the portion of the outer edge 11E of the window glass 11 that is on the +Y side relative to the window glass 11 and extends in the X direction. Here, we describe a configuration in which the window glass 11 is rectangular in plan view and the window frame 12 is frame-shaped (rectangular) in plan view. However, the window glass 11 is not limited to a rectangular shape in plan view; for example, it may be circular or elliptical, and its outer edge 11E may be curved. In this case, the window frame 12 can be any frame-shaped member that surrounds the window glass 11 having such a curved outer edge 11E.

[0033] In Figure 2A, the X and Z directions are horizontal, and the XZ plane is parallel to the horizontal plane. The Y direction is vertical, with the +Y direction being vertically upward and the -Y direction being vertically downward. In the following explanation, the +Y direction will be referred to as the upper side and the -Y direction as the lower side.

[0034] Two waveguides 150 are provided between the antenna device 100 and the radio device 210. The two waveguides 150 are spaced apart in the X direction, arranged parallel to each other, and have equal lengths. The relative position of the antenna device 100 and the radio device 210 in the X direction is defined by the two waveguides 150. As an example, it may be configured to guide two systems of radio waves (high-frequency signals), one horizontally polarized and the other vertically polarized.

[0035] Waveguide 150 has an end 151 connected to the array antenna 110 of the antenna device 100 and an end (not shown) connected to the wireless device 210, and guides the radio waves received by the antenna device 100. Here, as an example, a configuration in which the wireless communication device 200 includes two waveguides 150 is described, but the number of waveguides 150 may be one or three or more. Even when there is only one waveguide 150, the relative position of the antenna device 100 and the wireless device 210 does not need to be adjusted in the X direction, so the relative position of the antenna device 100 and the wireless device 210 in the X direction is determined by the single waveguide 150.

[0036] As mentioned above, it is possible to use an FPC transmission line instead of the waveguide 150. In this case, for example, RF components such as an amplifier may be mounted on the transparent antenna device 100. Furthermore, the relative position of the antenna device 100 and the wireless device 210 in the X direction is defined by the FPC transmission line.

[0037] Waveguide 150 is, for example, a bendable waveguide, extending from the +Z side to the +Z side of the holder 130 that holds the array antenna 110 of the antenna device 100, and bent in the +Y direction to extend to the lower end of the radio device 210. Waveguide 150 hardly expands or contracts, but is bendable at any position between the end 151 and the end connected to the radio device 210. As such a bendable waveguide 150, for example, a flexible waveguide can be used.

[0038] The wireless device 210 is fixed to two brackets 220 attached to the indoor surface 12A of the window frame 12 by screws 240. That is, the wireless device 210 is attached to the indoor surface 12A of the window frame 12 by two screws 240 and two brackets 220. The screws 240 are an example of a projection that protrudes in the X direction from the housing 231 of the wireless device 210. Alternatively, a projection that is integrally formed with the housing 231 and protrudes in the X direction may be provided instead of the screws 240.

[0039] The wireless device 210 includes an array antenna 210A, a heat dissipation unit 210B, a housing 231, and a wireless communication unit. The array antenna 210A, the heat dissipation unit 210B, and the wireless communication unit are located inside the housing 231. The housing 231 is, for example, a rectangular parallelepiped-shaped resin case. The housing 231 is fixed to the bracket 220 by screws 240. The array antenna 210A is located on the +Z side of the housing 231, and the heat dissipation unit 210B is located on the -Z side of the housing 231. The wireless communication unit is omitted here. The wireless communication unit will be described later using Figure 3.

[0040] The wireless communication unit is connected to the end of the waveguide 150 (the end connected to the wireless device 210) and performs processes such as amplifying the radio waves received from the antenna device 100 via the waveguide 150 and outputting them to the array antenna 210A, and controlling the radiation direction of the radio waves emitted by the array antenna 210A. For this reason, the wireless communication unit includes an amplifier, a microcomputer, etc. The wireless communication unit is also connected to the heat dissipation unit 210B in a heat conduction manner and dissipates heat through the heat dissipation unit 210B.

[0041] The heat dissipation section 210B faces the indoor surface 12A of the window frame 12 when the wireless device 210 is attached to the window frame 12 by the bracket 220. Therefore, the heat generated by the wireless communication unit can be dissipated from the heat dissipation section 210B to the window frame 12. A material with high thermal conductivity may be provided between the heat dissipation section 210B and the window frame 12.

[0042] As an example, the bracket 220 is fixed to the indoor surface 12A of the window frame 12 via double-sided tape, as shown in Figure 2A. The bracket 220 is made of resin or metal, etc. One bracket 220 is provided on the +X side and one on the -X side of the housing 231 of the wireless device 210, and one is positioned to sandwich the ±X side ends of the wireless device 210. The bracket 220 may also be fixed to the window frame 12 with screws or the like. In particular, fixing with screws is effective when the surface 12A of the window frame 12 is not a flat surface or when it is difficult to fix with double-sided tape due to the material.

[0043] The bracket 220 has a flat plate portion 220P, a rib 220R, and a guide groove 221. The guide groove 221 is an example of a guide portion. The flat plate portion 220P is a flat plate-shaped portion that is substantially parallel to the YZ plane. The flat plate portion 220P has a substantially trapezoidal shape when viewed from the YZ plane. An X-shaped guide groove 221 is formed in the flat plate portion 220P when viewed from the YZ plane. The rib 220R is formed around the flat plate portion 220P that is substantially parallel to the YZ plane and in the vicinity of the guide groove 221 for reinforcement.

[0044] The guide groove 221 is an X-shaped groove that penetrates the flat plate portion 220P in the X direction. The X-shape of the guide groove 221 extends in four directions that form a 45-degree angle with respect to the Y and Z axes when viewed in the YZ plane.

[0045] When installing the wireless communication device 200 in the window 10, placing it on the indoor side of the building 1 (see Figure 1) makes it easier to protect it from wind, rain, dust, etc., and allows for stable operation over a long period of time. For this reason, the wireless communication device 200 is placed indoors.

[0046] Furthermore, when the wireless communication device 200 is attached to the window 10, it is preferable to install the antenna device 100 in a portion that overlaps with the window glass 11 in order to efficiently receive radio waves that pass through the window glass 11. For this reason, in one embodiment, each part of the antenna device 100 is made transparent, and the antenna device 100 is attached to the window glass 11, thereby achieving efficient reception of radio waves propagating from outdoors and suppressing interference with the view through the window glass 11.

[0047] On the other hand, the wireless device 210 generates heat due to amplification processing and control of the array antenna 210A, including the amplifier and microcomputer. Therefore, if it is attached to the window glass 11, the heat may cause damage or breakage to the window glass 11. Furthermore, it is difficult to make the wireless device 210 itself transparent to light. For these reasons, it is more convenient to attach the wireless device 210 to the window frame 12. In particular, if the window frame 12 is made of metal, the heat generated by the wireless device 210 can be dissipated through the window frame 12.

[0048] For the reasons stated above, in this embodiment, the antenna device 100 is attached to the window glass 11 and the wireless device 210 is attached to the window frame 12. Here, as an example, a configuration in which the antenna device 100 and the wireless device 210 are attached to the upper side (+Y direction side) of the window glass 11 and the window frame 12, respectively, will be described. However, the same applies to configurations in which the antenna device 100 and the wireless device 210 are attached to the lower side (-Y direction side) or the side (+X direction side or -X direction side) of the window glass 11 and the window frame 12, respectively.

[0049] <Configuration of antenna device 100> The antenna device 100 includes an array antenna 110, an interface layer 120, and a holder 130. Here, as an example, a configuration including an array antenna 110, which is capable of beamforming, will be described. The array antenna 110 has multiple antenna elements arranged two-dimensionally in the XY plane for beamforming. The array antenna 110 is an example of an antenna capable of scanning the beam angle. The interface layer 120 is an example of an interface layer provided on the window glass 11. A phase shifter that adjusts the phase of radio waves is connected to each antenna element. The antenna device 100 includes a phase shifter, which will be described later using Figure 3.

[0050] The holder 130, which holds the array antenna 110 and the interface layer 120, is, for example, attached to the main surface 11A on the indoor side of the window glass 11 using double-sided tape. In this configuration, for example, the antenna device 100 is positioned on the indoor side of the window glass 11. The phase shifter is also held by the holder 130.

[0051] <Array Antenna 110> The array antenna 110 is positioned on the indoor side of the window glass 11 and spaced apart from the window glass 11. The array antenna 110 is held together with the interface layer 120 and the phase shifter by the holder 130, thus spaced apart from the window glass 11.

[0052] The array antenna 110 is connected to the wireless device 210. The array antenna 110 and the wireless device 210 can be connected by a transmission path capable of transmitting radio waves, for example, by a waveguide 150. In addition, a cable is provided between the array antenna 110 and the wireless device 210 for the wireless device 210 to transmit control signals, etc. to the array antenna 110, but the cable is not shown in the diagram.

[0053] The array antenna 110 receives radio waves that have passed through the window glass 11 and the interface layer 120. The radio waves emitted by the array antenna 110 are transmitted to the outside of building 1 through the interface layer 120 and the window glass 11.

[0054] The array antenna 110 receives radio waves radiated from an outdoor base station BS, etc. The array antenna 110 is formed, for example, on the -Z-direction surface of the substrate 111. The substrate is preferably transparent. Here, transparency means transparency to visible light.

[0055] The array antenna 110 is preferably placed near the window glass 11. This is because radio waves are easier to receive when it is closer to the window glass 11. The distance in the Z direction between the array antenna 110 and the main surface 11A on the indoor side of the window glass 11 is preferably about 2 mm to 50 mm, and more preferably 5 mm to 15 mm.

[0056] The substrate 111 is made of any material that is transparent to radio waves radiated from an outdoor base station and capable of supporting the array antenna 110. "Transparent" means that the visible transmittance is at least 40%, preferably 60%, more preferably 70%, and even more preferably 80%. As an example, a resin substrate is used for the substrate 111. As a resin material that satisfies the above conditions, acrylic resins such as polymethyl methacrylate, cycloolefin resins, polycarbonate resins, polyethylene terephthalate (PET), etc. can be used. Alternatively, the substrate 111 may be a glass plate.

[0057] The array antenna 110 is made of a conductor. Since the antenna device 100 is positioned in overlap with the window 10, it is preferable that the array antenna 110 be made of a transparent conductive film such as zinc oxide (ZnO), tin oxide (SnO2), tin-doped indium oxide (ITO), indium oxide-tin oxide (IZO), a metal nitride such as titanium nitride (TiN) or chromium nitride (CrN), or a Low-e film for Low-e (low emissivity) glass. However, the array antenna 110 may also be made of a thin metal film such as copper, nickel, or gold. In the case of a thin metal film, it is preferable to make it mesh-like from the viewpoint of visibility.

[0058] <Interface layer 120> The interface layer 120 is a plate-shaped member held by a holder 130 attached to the indoor side of the window glass 11. For example, the upper and lower ends of the interface layer 120 are held by the holder 130.

[0059] The interface layer 120 may be held by the holder 130 and positioned in close contact with the window glass 11, or it may be positioned between the window glass 11 and the array antenna 110.

[0060] The interface layer 120 is provided to adjust the electrical length of the radio waves incident on the array antenna 110 and match the impedance. The interface layer 120 can be made from polycarbonate, acrylic, COP (cycloolefin polymer), PET (polyethylene terephthalate), polystyrene, or glass, etc.

[0061] The interface layer 120 preferably has a thickness of 1 mm or more from the viewpoint of suppressing the occurrence of bending. This is because if the interface layer 120 bends, the characteristics of adjusting the electrical length of radio waves become non-uniform in the XY plane, which may cause variations in the degree of impedance matching.

[0062] The thickness of the interface layer 120 in the Z direction is, for example, constant throughout. From the viewpoint of increasing the visible transmittance, the thickness of the interface layer 120 is preferably 20 mm or less, and more preferably 15 mm or less. Furthermore, the thickness of the interface layer 120 is even more preferably 1 mm to 12 mm. The interface layer 120 may be a single layer, or it may be a configuration of multiple layers stacked on top of each other, or a configuration of multiple layers arranged with gaps in between.

[0063] The interface layer 120 has different effective thicknesses depending on the relative permittivity in order to adjust the electrical length of the radio waves incident on the array antenna 110. This is because the degree of wavelength shortening effect of the radio waves differs depending on the relative permittivity. Therefore, from the standpoint of matching the impedance of the radio waves, the effective thickness of the interface layer 120 should be set to an appropriate effective thickness that allows for impedance matching.

[0064] Furthermore, the interface layer 120 has a size that can face the array antenna 110 in the XY plane view. A size that can face the array antenna 110 in the XY plane view means that it is larger than the array antenna 110 in the XY plane view and can cover the region of radio waves emitted from the array antenna 110 where the radiation intensity is equal to or greater than the intensity required for wireless communication.

[0065] <Holder 130> The holder 130 is attached to the main surface 11A on the indoor side of the window glass 11, and, for example, holds the upper and lower ends of the interface layer 120. The holder 130 is made of transparent glass or resin. Transparent here means transparent to visible light. Note that the holder 130 is not limited to a configuration that holds the upper and lower ends of the interface layer 120, but may also be configured to hold, for example, the +X direction side and the -X direction side.

[0066] The holder 130 holds the array antenna 110 and the interface layer 120. The holder 130 has a configuration that allows the interface layer 120 to be inserted and removed (attached and removed), and multiple types of interface layers 120 can be attached to the holder 130 while replacing them one by one.

[0067] <Positional relationship between window glass 11, interface layer 120, and array antenna 110> Figure 2B is a schematic diagram illustrating an example of the positional relationship between the window glass 11, the interface layer 120, and the array antenna 110. Figure 2B shows the main surface 11B of the window glass 11, which is opposite to the main surface 11A on the indoor side. Main surface 11B is the main surface of the window glass 11 on the outdoor side. The holder 130 is omitted in Figure 2B.

[0068] The interface layer 120 is positioned on the indoor side (+Z direction side) of the window glass 11. The interface layer 120 may be held by the holder 130 and be in close contact with the main surface 11B of the window glass 11, or it may be positioned spaced apart from the main surface 11A as shown in Figure 2B. Close contact means that the surface of the interface layer 120 on the -Z direction side is in contact (surface contact) with the main surface 11B. The interface layer 120 may be attached to the main surface 11B with double-sided tape or adhesive, but it is not required. For example, the state in which the interface layer 120 is stuck to the main surface 11B by static electricity is also included in close contact.

[0069] The array antenna 110, held by the holder 130, is positioned away from the interface layer 120 and on the -Z side of the interface layer 120.

[0070] The array antenna 110 and interface layer 120 are positioned on the indoor side of the window glass 11 by a holder 130, which is not shown in Figure 2B. Since the interface layer 120 is removable from the holder 130, the received power of radio waves at the array antenna 110 can be measured by the PC 50 while replacing multiple types of interface layers 120 one by one.

[0071] <Wireless device 210> The wireless device 210 will be explained using Figure 3 in addition to Figure 2A. Figure 3 is a diagram showing an example of the circuit configuration of the wireless device 210. Figure 3 shows the configuration of a part of the overall configuration of the wireless device 210 that corresponds to one array antenna 110. Each of the multiple antenna elements of the array antenna 110 is connected to the wireless device 210 via a phase shifter 140. The phase shifter 140 is a collection of multiple phase shifters connected to each antenna element of the array antenna 110, which is a collection of multiple antenna elements.

[0072] If the distance between the array antenna 110 and the wireless device 210 is long, the transmission loss of radio waves between the array antenna 110 and the wireless device 210 increases. For this reason, in order to reduce the transmission loss of radio waves, it is preferable to mount the wireless device 210 on the window glass 11, or on the wall 1A or ceiling surrounding the window 10.

[0073] Furthermore, in order to reduce the transmission loss of radio waves between the array antenna 110 and the wireless device 210, a bendable waveguide 150 is used as the transmission path connecting the array antenna 110 and the wireless device 210, as an example. By using a bendable waveguide 150, radio waves can be efficiently propagated between the array antenna 110 and the wireless device 210 with minimal transmission loss.

[0074] The wireless device 210 includes a wireless module 211, a switch 212, an LNA (Low Noise Amplifier) ​​213, a mixer 214, an ADC (Analog to Digital Converter) 215, a DAC (Digital to Analog Converter) 216, a mixer 217, and a PA (Power Amplifier) ​​218. Wireless modules 211 to PA 218 are an example of the wireless communication section of the wireless device 210.

[0075] The wireless module 211 is, for example, composed of an MCU (Micro Controller Unit) and has a control unit 211A, a relay unit 211B that performs relay processing, and a memory 211C. The control unit 211A and the relay unit 211B are functional blocks that represent the functions performed by the MCU. The memory 211C functionally represents the memory of the MCU. The memory 211C is an example of a storage unit. In the wireless communication device 200, the antenna device 100 and the wireless device 210 are separated and connected by a waveguide 150 and a cable (not shown). The antenna device 100 has an array antenna 110, and the wireless device 210 has a wireless module 211, and the wireless module 211 has a control unit 211A. The array antenna 110 and the control unit 211A are arranged separately and connected by a cable (not shown). The separation of the array antenna 110 and the control unit 211A means, for example, that the antenna device 100 having the array antenna 110 is placed on the window glass 11, and the wireless device 210 including the control unit 211A is placed on the window frame 12, so that the array antenna 110 and the control unit 211A are placed in separate locations.

[0076] When the control unit 211A receives radio waves with the array antenna 110, it switches the 3-terminal switch 212 to connect the array antenna 110 and the LNA 213. When the control unit 211A transmits radio waves with the array antenna 110, it switches the 3-terminal switch 212 to connect the array antenna 110 and the PA 218.

[0077] Furthermore, when the array antenna 110 receives radio waves and when the array antenna 110 transmits radio waves, the control unit 211A controls the amount of phase change that the phase shifter 140 uses to change the phase of the radio waves, thereby controlling the beam angle. At this time, the control unit 211A transmits a control signal to the phase shifter 140 via a cable (not shown) to control the amount of phase change. Controlling the beam angle is synonymous with controlling the direction of the beam.

[0078] Furthermore, when selecting the optimal interface layer 120, the control unit 211A performs the following processing: The control unit 211A scans the beam angle of the array antenna 110 and obtains a first angular distribution of the received power of the radio waves arriving from the base station BS with respect to the beam angle.

[0079] Furthermore, based on the acquired first angle distribution and the first transmission characteristics stored in the memory 211C, the control unit 211A estimates a second angle distribution with respect to the beam angle of the received power of the radio waves arriving from the base station BS in the absence of the window glass 11, and uses the second angle distribution to estimate the incident angle of the radio waves. The first transmission characteristics will be described later.

[0080] Furthermore, the control unit 211A selects the optimal interface layer 120 based on the estimated incidence angle and the second transmission characteristic stored in the memory 211C. The second transmission characteristic will be described later.

[0081] Thus, the control unit 211A estimates the incident angle of the radio waves using the second angle distribution and selects the optimal interface layer 120 based on the estimated incident angle. In other words, the control unit 211A estimates the incident angle of the radio waves based on the first angle distribution and selects the interface layer 120 according to the estimated incident angle.

[0082] The relay unit 211B includes, for example, a Wi-Fi (registered trademark) communication unit and is connected to the array antenna 210A. It transmits the digital signal input from the ADC 215 through the array antenna 210A into the building 1. By transmitting the signal into the building 1 via the array antenna 210A, the radio waves received by the array antenna 110 from the base station BS are relayed, and the radio waves are radiated into the building 1 where the wireless communication device 200 is located. As a result, radio waves are radiated over a wide area inside the building 1, making it easier for terminals such as smartphones 60 located indoors to receive the radio waves. Note that the communication unit that radiates the radio waves relayed indoors by the relay unit 211B is not limited to Wi-Fi; it may also be Bluetooth (registered trademark), etc.

[0083] Memory 211C stores a first transmission characteristic that associates the type of window glass 11, the angle of incidence on the window glass 11, and the transmittance of the radio waves passing through the window glass 11. Memory 211C also stores a second transmission characteristic that associates the types of window glass 11 and interface layer 120, the angle of incidence on the window glass 11, and the transmittance of the radio waves passing through the window glass 11 and interface layer 120.

[0084] The LNA213 is located between the switch 212 and the mixer 214, and amplifies the radio waves received by the array antenna 110, outputting them while preventing degradation of the signal-to-noise ratio.

[0085] Mixer 214 mixes the radio waves output from LNA213 with the local signal (Lo), demodulates them, and outputs an IF (Intermediate Frequency) signal. Converting to an IF signal makes digital conversion by ADC215 easy.

[0086] The ADC215 digitally converts the IF signal output from the mixer 214 and outputs it to the wireless module 211.

[0087] When the wireless communication device 200 transmits a signal from the array antenna 110, the DAC 216 performs analog conversion on the signal output by the wireless module 211 and outputs an IF signal to the mixer 217.

[0088] The mixer 217 mixes and modulates the IF signal with the local signal (Lo) and outputs it to the PA 218.

[0089] The PA 218 amplifies the signal output from the mixer 217 and outputs it to the array antenna 110 via the switch 212.

[0090] The phase shifter 140 is a set of a plurality of phase shifters connected to each antenna element of the array antenna 110, which is a set of a plurality of antenna elements. The amount of phase change applied by the phase shifter 140 to the radio wave is controlled by the control unit 211A. The phase shifter 140 can be made of LC (Liquid Crystal) as an example.

[0091] In practice, corresponding to the plurality of phase shifters 140, which is the same number as the plurality of antenna elements of the array antenna 110, the switch 212 and the plurality of phase shifters 140 are connected via a distributor or the like. When the array antenna 110 performs beamforming of radio waves in two polarization directions, two sets of the combination of the array antenna 110, the distributor, the ADC 215, the DAC 216, the switch 212, the LNA 213, the mixer 214, the mixer 217, and the PA 218 are connected in parallel.

[0092] <Measurement of Received Power at PC50> PC50 (see Figure 1) is connected to the wireless device 210 to measure the received power of the array antenna 110. For example, PC50 measures the strength of the digital signal output from ADC215 (see Figure 3) to the wireless module 211. The digital signal output from ADC215 is a signal obtained by digitally converting the IF signal output from mixer 214, and the strength of this digital signal corresponds to the received power of the radio waves at the array antenna 110. Therefore, by measuring the strength of the digital signal with PC50, the received power of the radio waves at the array antenna 110 can be measured.

[0093] Furthermore, since multiple types of interface layers 120 can be attached to the holder 130 one by one, by measuring the received power of the array antenna 110 with the PC 50 when each interface layer 120 is attached to the holder 130, the interface layer 120 that maximizes the received power can be found. The interface layer 120 that maximizes the received power is the optimal interface layer 120.

[0094] By selecting the optimal interface layer 120 and attaching it to the holder 130, the wireless communication device 200 can relay outdoor radio waves indoors in a state optimized by the optimal interface layer 120. After selecting the optimal interface layer 120 and attaching it to the holder 130, the PC 50 may be removed from the wireless communication device 200. This is because the PC 50 is connected to the wireless communication device 200 to measure the received power of the array antenna 110 when selecting the optimal interface layer 120. From thereafter, the wireless communication device 200 optimized by the optimal interface layer 120 can be used. Here, we describe a configuration in which the received power of radio waves is measured with the PC 50 to select the optimal interface layer 120, but this can also be done with a smartphone 60 instead of the PC 50. For example, an application program for selecting the optimal interface layer 120 can be installed on the smartphone 60, and the application program can execute a process to select the optimal interface layer 120.

[0095] <Elevation angle Θ and azimuth angle Φ for array antenna 110> Figure 4 shows the elevation angle Θ and azimuth angle Φ when the array antenna 110 is positioned horizontally. In Figure 4, we will use the xyz coordinate system shown in lowercase letters. The +x direction corresponds to the -X direction in Figure 2A, the +y direction corresponds to the +Y direction in Figure 2A, and the +z direction corresponds to the -Z direction in Figure 2A. The XYZ coordinate system shown in Figure 2A is based on the indoor surface 12A of the window frame 12, whereas the xyz coordinate system in Figure 4 is based on the transmitting and receiving surface of the array antenna 110. The transmitting and receiving surface of the array antenna 110 is a virtual plane in which the multiple antenna elements of the array antenna 110 are arranged and the array antenna 110 transmits and receives radio waves.

[0096] In Figure 4, the xz plane is the horizontal plane. In Figure 4, the origin of the xyz coordinate system is the center of the transmitting and receiving surface of the array antenna 110, and the transmitting and receiving surface of the array antenna 110 is located on the xy plane. Orienting the array antenna 110 horizontally means that the normal to the transmitting and receiving surface of the array antenna 110 is oriented horizontally, which corresponds to the state in which the array antenna 110 is attached to the window glass 11 as shown in Figure 2A.

[0097] Here, the incidence angle of radio waves on the array antenna 110 is explained using the transmission point G. The transmission point G is a point located in the direction of arrival of radio waves incident toward the center of the transmitting and receiving surface of the array antenna 110 (the origin of the xyz coordinate system).

[0098] The elevation angle Θ and azimuth angle Φ are as shown in Figure 4. Specifically, the elevation angle Θ is the angle of elevation of the transmitting point G relative to the horizontal plane (xz plane) within a plane α that contains the transmitting point G and the origin of the xyz coordinate system and is perpendicular to the horizontal plane (xz plane). The azimuth angle Φ is the angle that the plane α, which contains the transmitting point G and the origin of the xyz coordinate system and is perpendicular to the horizontal plane (xz plane), makes with the +z direction in the xz plane view (horizontal view).

[0099] The incident angle of the radio waves incident on the array antenna 110 can be expressed in terms of the elevation angle Θ and the azimuth angle Φ.

[0100] <First transmission characteristics and second transmission characteristics> Figure 5 shows an example of the first and second transmission characteristics. The first transmission characteristic, shown by the solid line, is the characteristic of the transmittance of radio waves that pass only through the window glass 11 with respect to the angle of incidence. The second transmission characteristic is the characteristic of the transmittance of radio waves that pass through both the window glass 11 and the interface layer 120 with respect to the angle of incidence. The second transmission characteristic, shown by the dashed line, is an example of the second transmission characteristic when the thickness of the interface layer 120 is 4 mm, and the second transmission characteristic, shown by the dashed line, is an example of the second transmission characteristic when the thickness of the interface layer 120 is 2 mm.

[0101] In Figure 5, the horizontal axis represents the angle of incidence, and the vertical axis represents the gain (dB) of the radio waves transmitted through the window glass 11, or the gain (dB) of the radio waves transmitted through both the window glass 11 and the interface layer 120. The gain (dB) of the transmitted radio waves corresponds to the transmittance. In Figure 5, the value on the vertical axis corresponding to the transmittance is shown as the value converted to gain. When the gain is 0 dB, the transmittance is 100%.

[0102] The angle of incidence (degrees) on the horizontal axis is either the elevation angle Θ or the azimuth angle Φ, and here we will explain assuming it is the azimuth angle Φ. The direction in which the elevation angle Θ and azimuth angle Φ are 0 degrees is the +z direction in Figure 4. Furthermore, since the first and second transmission characteristics exhibit symmetrical characteristics in the positive and negative angle ranges with respect to the direction in which the angle of incidence is 0 degrees, Figure 5 shows the positive angle range from 0 degrees to 70 degrees. Also, due to the symmetry of the window glass 11 in the XY plane view, the first transmission characteristic exhibits symmetrical characteristics in the positive and negative angle ranges of the elevation angle Θ. Similarly, the second transmission characteristic exhibits symmetrical characteristics in the positive and negative angle ranges of the elevation angle Θ. For this reason, Figure 5 shows only the positive angle range from 0 degrees to 70 degrees for the azimuth angle Φ of the first and second transmission characteristics.

[0103] In Figure 5, the first transmission characteristic (solid line) is the characteristic of the transmittance of radio waves passing only through the window glass 11 as a function of the incident angle, showing that at an incident angle of 0 degrees, a loss of approximately 1.2 dB occurs when converted to gain. The first transmission characteristic decreases gradually as the incident angle increases, and the rate of decrease becomes large when the incident angle exceeds approximately 30 degrees.

[0104] Furthermore, for example, the second transmission characteristic (dashed line) when the interface layer 120 is 4 mm thick shows a slightly higher gain than the first transmission characteristic (solid line) at an incident angle of 0 degrees, and the decrease in gain is relatively small up to an incident angle of around 40 degrees. Also, for example, the second transmission characteristic (dashed line) when the interface layer 120 is 4 mm thick shows a decrease compared to the second transmission characteristic (dotted line) when the interface layer 120 is 2 mm thick when the incident angle is approximately 52 degrees or more.

[0105] Furthermore, when the interface layer 120 has a thickness of 2 mm, the second transmission characteristic (dotted line) shows, for example, a slightly lower gain than the first transmission characteristic (solid line) at an incident angle of 0 degrees. The decrease in gain with increasing incident angle is gradual, but at incident angles of approximately 43 degrees or less, the gain is lower than the first transmission characteristic (solid line). When the interface layer 120 has a thickness of 2 mm, the second transmission characteristic (dotted line) shows, for example, a lower gain than the second transmission characteristic (dashed line) when the interface layer 120 has a thickness of 4 mm at incident angles of approximately 52 degrees or less. However, when the incident angle exceeds approximately 52 degrees, the gain is higher than the second transmission characteristic (dashed line) when the interface layer 120 has a thickness of 4 mm.

[0106] As shown in Figure 5, the first transmission characteristics (solid line) and the two second transmission characteristics (dashed and dashed lines) indicate that when the incident angle is approximately 52 degrees or less, the interface layer 120 with a thickness of 4 mm is the optimal interface layer 120, and when the incident angle exceeds approximately 52 degrees, the interface layer 120 with a thickness of 2 mm is the optimal interface layer 120.

[0107] <Estimation of received power when window glass 11 is absent> Since building 1 has a window 10 with a glass pane 11, it is difficult to measure the received power of the radio waves arriving at window 10 from the base station BS in the array antenna 110 when the glass pane 11 is not present.

[0108] However, it is possible to estimate the received power of the array antenna 110 for radio waves arriving at window 10 from base station BS in the absence of window glass 11 by following the procedure below. In the absence of window glass 11, the received power of the array antenna 110 for radio waves arriving at window 10 from base station BS corresponds to the received power of radio waves incident on the main surface 11B (see Figure 2B) on the outdoor side of window glass 11.

[0109] The received power of radio waves transmitted only through the window glass 11 can be measured by the PC 50 when the interface layer 120 is not inserted into the holder 130 that holds the interface layer 120 in a removable manner. When the interface layer 120 is not inserted into the holder 130, the control unit 211A controls the phase change amount of the phase shifter 140 to scan the beam angle received by the array antenna 110, thereby determining the angular distribution of the received power of radio waves transmitted only through the window glass 11.

[0110] Furthermore, using the first transmission characteristic shown by the solid line in Figure 5, the received power in the absence of the window glass 11 can be estimated by adding the gain reduction when the radio waves pass through the window glass 11 to the received power of the radio waves that pass through only the window glass 11. By adding the gain reduction for all incident angles in the angular distribution of the received power of the radio waves that pass through only the window glass 11, the angular distribution of the received power with respect to the incident angle in the absence of the window glass 11 can be estimated. The angular distribution of the received power with respect to the incident angle in the absence of the window glass 11 is the angular distribution of the power of the radio waves incident on the main surface 11B on the outdoor side of the window glass 11 (see Figure 2B).

[0111] Furthermore, in the angular distribution of received power with respect to the incident angle when the window glass 11 is absent, the incident angle that yields the largest received power can be estimated as the incident angle of the radio waves on the window glass 11 and the array antenna 110.

[0112] Furthermore, by using the second transmission characteristics of multiple interface layers 120, the interface layer 120 that yields the largest received power for the estimated radio wave incidence angle can be selected as the optimal interface layer 120.

[0113] Thus, to select the optimal interface layer 120, data representing the first transparency characteristics shown in Figure 5 and the second transparency characteristics when multiple types of interface layers 120 are used should be stored in the memory 211C.

[0114] Here, let P(Θ,Φ) be the angular distribution of the received power of the radio waves transmitted only through the window glass 11, A(Θ,Φ) be the angular distribution of the gain reduction obtained by converting the first transmission characteristic into a gain reduction, and P0(Θ,Φ) be the angular distribution of the received power with respect to the incident angle when the window glass 11 is absent.

[0115] P(Θ,Φ) is the angular distribution of received power measured on the indoor side of the window glass 11, and therefore may be referred to as the indoor received power angular distribution P(Θ,Φ) below. The indoor received power angular distribution P(Θ,Φ) is an example of the first angular distribution of received power with respect to the beam angle of radio waves arriving from the base station BS.

[0116] The angle distribution A(Θ,Φ) for gain reduction is the angle distribution of the power attenuation (loss) when passing through the window glass 11, and therefore may be referred to as the attenuation angle distribution A(Θ,Φ) below. The attenuation angle distribution A(Θ,Φ) is an example of the first transmission characteristic and is stored in memory 211C. In the angle distribution A(Θ,Φ) for gain reduction, the power attenuation (loss) when passing through the window glass 11 is expressed as gain (dB).

[0117] Furthermore, since P0(Θ,Φ) is the angular distribution of power of radio waves incident on the main surface 11B (see Figure 2B) on the outdoor side of the window glass 11, it may be referred to as the angular distribution of outdoor received power P0(Θ,Φ) below. The angular distribution of outdoor received power P0(Θ,Φ) is an estimated value. The angular distribution of outdoor received power P0(Θ,Φ) is an example of the second angular distribution of received power with respect to the beam angle of radio waves arriving from the base station BS in the absence of the window glass 11.

[0118] <Flowchart> Figure 6 is a flowchart illustrating an example of the process performed depending on the selection method of the interface layer.

[0119] First, the control unit 211A acquires the angular distribution P(Θ,Φ) of the indoor received power (step S1). More specifically, with the interface layer 120 not inserted into the holder 130, the control unit 211A controls the phase change amount of the phase shifter 140 to scan the beam angle received by the array antenna 110, and has the PC 50 measure the received power, thereby acquiring the angular distribution (P(Θ,Φ)) of the received power of the radio waves that have passed only through the window glass 11.

[0120] Next, the control unit 211A reads the attenuation angle distribution A(Θ,Φ) (first transmission characteristic) from the memory 211C and calculates the angle distribution P0(Θ,Φ) of the outdoor received power based on the angle distribution P(Θ,Φ) of the indoor received power obtained in step S1 and the attenuation angle distribution A(Θ,Φ) (step S2). That is, by adding the attenuation angle distribution A(Θ,Φ), which is the gain reduction, to the attenuation angle distribution A(Θ,Φ) obtained in step S1, the control unit 211A calculates the angle distribution (P0(Θ,Φ)) of the received power with respect to the incident angle when the window glass 11 is not present.

[0121] The angular distribution P0(Θ,Φ) can be calculated using the angular distribution P(Θ,Φ) of the indoor received power and the attenuation angular distribution A(Θ,Φ) by the following equation (1).

[0122] P0(Θ,Φ)=P(Θ,Φ)-A(Θ,Φ) (1)

[0123] In equation (1), the attenuation angle distribution A(Θ,Φ) is subtracted from the indoor received power angle distribution P(Θ,Φ) because P(Θ,Φ) and the attenuation angle distribution A(Θ,Φ) are expressed as negative values ​​in decibels. By subtracting according to equation (1), the attenuation angle distribution A(Θ,Φ), which is the gain reduction, is added to the attenuation angle distribution A(Θ,Φ) obtained in step S1. Equation (1) allows us to estimate the outdoor received power angle distribution P0(Θ,Φ).

[0124] Next, the control unit 211A determines the incident angle of the maximum received power in the angular distribution P0(Θ,Φ) of the outdoor received power (step S3). The incident angle of the maximum received power in the angular distribution P0(Θ,Φ) of the outdoor received power can be determined by searching for the incident angle that gives the maximum value among all the received powers included in the angular distribution P0(Θ,Φ) of the outdoor received power. In this way, the incident angle of the radio waves on the window glass 11 and the array antenna 110 can be estimated.

[0125] Next, the control unit 211A reads the second transmission characteristics for multiple interface layers 120 from the memory 211C and selects the interface layer 120 that can obtain the largest received power at the radio wave incidence angle estimated in step S3 (step S4). Step S4 allows for the selection of the optimal interface layer 120.

[0126] <An example of how to specifically determine the angular distribution P(Θ,Φ) of indoor received power and the angular distribution P0(Θ,Φ) of outdoor received power> Figure 7A shows an example of the beam angle scanning process in step S1. By scanning the beam angle of the array antenna 110 placed on the indoor side of the window glass 11, the angular distribution P(Θ,Φ) of the indoor received power can be determined. In this case, the beam angle is scanned without providing an interface layer 120 on the holder 130.

[0127] Figure 7B shows an example of the angular distribution P(Θ,Φ) of indoor received power and the angular distribution P0(Θ,Φ) of outdoor received power.

[0128] By substituting the angular distribution P(Θ,Φ) of the indoor received power obtained in step S1 and the attenuation angular distribution A(Θ,Φ) into equation (1), the angular distribution P0(Θ,Φ) of the outdoor received power shown in the lower part of Figure 7B can be obtained from the angular distribution P(Θ,Φ) of the indoor received power shown in the upper part of Figure 7B.

[0129] As shown in Figure 5, the transmittance of the first transmission characteristic decreases as the incident angle increases, so the gain represented by the attenuation angle distribution A(Θ,Φ) decreases as the incident angle increases. For this reason, the incident angle at which the maximum value of the received power is obtained in the indoor received power angle distribution P(Θ,Φ) shown in the upper part of Figure 7B may be different from the incident angle (Θa,Φa) at which the maximum value of the received power is obtained in the outdoor received power angle distribution P0(Θ,Φ) shown in the lower part of Figure 7B.

[0130] The incident angle (Θa,Φa) obtained in this way is the incident angle of the radio wave that yields the maximum received power when the window glass 11 is not present.

[0131] Therefore, in step S4, in the second transmission characteristics of the multiple interface layers 120, it is sufficient to select the interface layer 120 that provides the maximum received power at the incidence angle (Θa, Φa) estimated in step S3.

[0132] <Example of calculating the angular distribution P0(Θ,Φ) of outdoor received power and method for selecting interface layer 120> Figure 8 shows an example of the calculation results from a simulation of the attenuation angle distribution A(Θ,Φ), the angle distribution of indoor received power P(Θ,Φ), and the angle distribution of outdoor received power P0(Θ,Φ). Figure 8 shows the calculation results in the range of incident angles from 0 to 60 degrees. If the incident angle is too large, the attenuation of transmittance when radio waves pass through the window glass 11 and interface layer 120 becomes very large. For this reason, the upper limit of the incident angle is, for example, about 60 to 70 degrees in absolute value for both the elevation angle Θ and the azimuth angle Φ.

[0133] Here, for the sake of simplicity, the incident angle is shown as the value of the azimuth angle Φ, one of the two values ​​of the elevation angle Θ and azimuth angle Φ. However, for the angular distribution P(Θ,Φ) of indoor received power and the angular distribution P0(Θ,Φ) of outdoor received power, calculations were performed by varying both the elevation angle Θ and the azimuth angle Φ in 10-degree increments from 0 to 60 degrees. Note that the interval for shifting the incident angle when calculating the angular distribution P(Θ,Φ) of indoor received power and the angular distribution P0(Θ,Φ) of outdoor received power is not limited to 10 degrees; for example, it may be set to 3 degrees, 5 degrees, 15 degrees, etc.

[0134] When the attenuation angle distribution A(Θ,Φ) was calculated by varying both the elevation angle Θ and the azimuth angle Φ from 0 to 60 degrees in 10-degree increments, the values ​​were -4(dBm), -4(dBm), -4(dBm), -4(dBm), -5(dBm), -6(dBm), and -8(dBm). The gain (dB) of the attenuation angle distribution A(Θ,Φ) decreased with increasing incidence angle. Such an attenuation angle distribution A(Θ,Φ) can be calculated using electromagnetic field simulation. Alternatively, the attenuation angle distribution A(Θ,Φ) may be based on measured values.

[0135] Furthermore, for the angular distribution P(Θ,Φ) of the indoor received power, values ​​such as -120(dBm), -90(dBm), -95(dBm), -100(dBm), -100(dBm), -85(dBm), and -85(dBm) were used as examples.

[0136] In these cases, the angular distribution P0(Θ,Φ) of the outdoor received power was determined to be -116 (dBm), -86 (dBm), -91 (dBm), -96 (dBm), -95 (dBm), -79 (dBm), and -77 (dBm).

[0137] From these results, it can be seen that a maximum value of -77 (dBm) is obtained when the incident angle is 60 degrees. Based on these results, the interface layer 120 to be selected is as follows, using the two second transmission characteristics (dashed line and dashed line) shown in Figure 5. In Figure 5, when the incident angle is 60 degrees, the gain of the second transmission characteristic of the 2 mm thick interface layer 120 shown by the dashed line is greater than the gain of the second transmission characteristic of the 4 mm thick interface layer 120 shown by the dashed line, so the 2 mm thick interface layer 120 is selected.

[0138] Comparing the first transmission characteristic (attenuation angle distribution A(Θ,Φ)) shown by the solid line in Figure 5 with the second transmission characteristic shown by the dashed line, when the incident angle is 60 degrees, the gain of the second transmission characteristic shown by the dashed line is approximately 3 dB greater. Therefore, by inserting the 2 mm thick interface layer 120 into the holder 130, the received power of the array antenna 110 can be increased by 3 dB.

[0139] Once the optimal position for the interface layer 120 is determined, it can be inserted into the holder 130, and the wireless communication device 200, including the antenna device 100, can be used as a repeater.

[0140] <Effects> The interface layer selection method includes an array antenna 110 provided on a window glass 11 and capable of scanning beam angles, an interface layer 120 provided on the window glass 11, and a control unit 211A, and is used to select the interface layer 120 of a wireless communication device 200 attached to a window 10 having a window glass 11. The method involves the control unit 211A scanning the beam angle of the array antenna 110 to obtain a first angular distribution of the received power of radio waves arriving from a base station BS with respect to the beam angle, estimating the incident angle of the radio waves based on the first angular distribution, and selecting the interface layer 120 according to the estimated incident angle. In this way, the interface layer 120 is selected according to the incident angle of the radio waves estimated based on the first angular distribution.

[0141] Therefore, a method for selecting the optimal interface layer 120 can be provided.

[0142] Furthermore, the control unit 211A is installed in the window 10 which has a window pane 11. Therefore, in a wireless communication device 200 in which the control unit 211A is installed in the window 10, a method for selecting the optimal interface layer 120 can be provided.

[0143] Furthermore, the wireless communication device 200 further includes a memory 211C that stores a first transmission characteristic relating the type of window glass 11, the angle of incidence to the window glass 11, and the transmittance of the radio waves passing through the window glass 11. The control unit 211A estimates a second angular distribution with respect to the beam angle of the received power of the radio waves arriving from the base station BS in the absence of window glass 11, based on the first angular distribution and the first transmission characteristic, and estimates the angle of incidence of the radio waves using the second angular distribution. As a result, the angle of incidence of the radio waves can be estimated using the second angular distribution of received power in the absence of window glass 11, and a method for selecting an interface layer that allows easy selection of the optimal interface layer 120 according to the angle of incidence in the absence of window glass 11 can be provided.

[0144] Furthermore, the memory 211C stores a second transmission characteristic that associates the type of interface layer 120 with the angle of incidence to the window glass 11 and the transmittance of radio waves passing through the window glass 11 and the interface layer 120. The control unit 211A then selects the interface layer 120 based on the estimated angle of incidence and the second transmission characteristic. This provides an interface layer selection method that allows for easy selection of the optimal interface layer 120 by considering the transmission characteristics of multiple types of interface layers 120.

[0145] Furthermore, the second transmission characteristic is a transmission characteristic that relates the type of window glass 11 and interface layer 120, the angle of incidence to the window glass 11, and the transmittance of radio waves passing through the window glass 11 and interface layer 120. Therefore, by considering the transmission characteristics of the window glass 11 in addition to the transmission characteristics of multiple types of interface layers 120, it is possible to provide an interface layer selection method that allows for easy selection of the optimal interface layer 120.

[0146] Furthermore, the second transmission characteristic is the transmission characteristic when the interface layer 120 is a first interface layer that is in close contact with the window glass 11, or a first interface layer that is located on the window glass 11 side. The control unit 211A selects the first interface layer based on the estimated incident angle and the second transmission characteristic. Therefore, by using the second transmission characteristic when the interface layer 120 is in close contact with the window glass 11 or located on the window glass 11 side, a method for selecting the optimal interface layer 120 can be provided.

[0147] Furthermore, the second transmission characteristic is a transmission characteristic that relates the incident angle to the window glass 11 with the transmittance of radio waves passing through the window glass 11 and the interface layer 120 for multiple interface layers 120 with different thicknesses or dielectric constants. Therefore, it is possible to provide an interface layer selection method that allows for easy selection of the optimal interface layer 120 by considering the thickness or dielectric constant of multiple types of interface layers 120.

[0148] Furthermore, the control unit 211A estimates the incident angle at which the received power of the radio waves is maximized in the second angle distribution as the incident angle of the radio waves. Therefore, it is possible to estimate the direction of the maximum received power as the incident angle when the window glass 11 is absent, and based on the incident angle estimated in this way, it is possible to provide an interface layer selection method that allows for easy selection of the optimal interface layer 120.

[0149] Furthermore, since the radio waves are in the millimeter-wave band, it is possible to provide an interface layer selection method that allows for easy selection of the optimal interface layer 120 usable by a wireless communication device acting as a relay for millimeter-wave band radio waves.

[0150] The array antenna 110 and the control unit 211A are separated and connected via a cable (not shown). Therefore, in a separated wireless communication device 200 in which the array antenna 110 and the control unit 211A are separated and easy to install in a window 10, a method for selecting the optimal interface layer 120 can be provided.

[0151] <Variation> Figure 9 is a schematic diagram showing an example of the positional relationship between the window glass 11, interface layers 120A and 120B, and the array antenna 110 in a modified embodiment. Interface layer 120A is an example of a first interface layer, and interface layer 120B is an example of a second interface layer. Interface layers 120A and 120B are provided to adjust the electrical length of the radio waves incident on the array antenna 110 and match the impedance, similar to interface layer 120 shown in Figure 2B, and can be manufactured from the same material as interface layer 120 shown in Figure 2B. Interface layers 120A and 120B may be of the same type, or they may be different types of interface layers. Interface layers of the same type are interface layers with the same thickness and dielectric constant, while different types of interface layers are interface layers with different thicknesses or dielectric constants.

[0152] Interface layer 120A is in close contact with the window glass 11, and interface layer 120B is located closer to the array antenna 110 than interface layer 120A. Note that interface layer 120A is not limited to being in close contact with the window glass 11; it may also be located on the side of the window glass 11. When interface layer 120A is located on the side of the window glass 11, it means that interface layer 120A is not in close contact with the window glass 11 but is located closer to the window glass 11 than interface layer 120B.

[0153] Thus, the wireless communication device 200 may include multiple interface layers 120A and 120B. In such cases, the second transmission characteristic may be the transmission characteristic for two interface layers, interface layer 120A and interface layer 120B. The second transmission characteristic includes the transmission characteristics for multiple types of interface layers 120A and multiple types of interface layers 120B.

[0154] The control unit 211A can select the optimal interface layers 120A and 120B based on the estimated incident angle and the second transmission characteristics of the two interface layers 120A and 120B. In this case, the second transmission characteristics of interface layer 120A and the second transmission characteristics of interface layer 120B may be separate data, or they may represent a single integrated second transmission characteristic for the two interface layers 120A and 120B.

[0155] Therefore, by considering the second transparency characteristics of multiple types of interface layers 120A and 120B, a method for selecting the optimal interface layer 120 can be provided. Although Figure 9 describes a configuration in which the wireless communication device 200 includes two interface layers 120A and 120B, it may also include three or more interface layers.

[0156] While exemplary antenna devices of this disclosure have been described above, this disclosure is not limited to the specifically disclosed embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0157] The following additional information is disclosed regarding the embodiments described above. (Note 1) A method for selecting an interface layer for a wireless communication device provided in a window having a window, comprising an antenna provided in the window glass and capable of scanning beam angles, an interface layer provided in the window glass, and a control unit, wherein the interface layer is provided in the window glass. The control unit, The beam angle of the antenna is scanned to obtain a first angular distribution of the received power of the radio waves arriving from the base station with respect to the beam angle. Based on the first angular distribution, the incident angle of the radio wave is estimated. A method for selecting an interface layer, which selects an interface layer according to the estimation result of the incident angle. (Note 2) The method for selecting the interface layer according to Appendix 1, wherein the control unit is provided in the window having the window glass or in the wall surrounding the window. (Note 3) The wireless communication device further includes a storage unit for storing a first transmission characteristic relating the type of window glass, the angle of incidence to the window glass, and the transmittance of radio waves passing through the window glass. Based on the first angular distribution and the first transmission characteristics, the control unit estimates a second angular distribution of the received power of the radio waves arriving from the base station with respect to the beam angle in the absence of the window glass. A method for selecting an interface layer as described in Appendix 1, wherein the incidence angle of the radio waves is estimated using the second angular distribution. (Note 4) The storage unit further stores a second transmission characteristic relating the type of interface layer, the angle of incidence to the window glass, and the transmittance of radio waves passing through the window glass and the interface layer. The method for selecting an interface layer according to Appendix 3, wherein the control unit selects the interface layer based on the estimated incidence angle and the second transmission characteristics. (Note 5) The method for selecting an interface layer as described in Appendix 4, wherein the second transmission characteristic is a transmission characteristic relating the type of window glass and the interface layer, the angle of incidence to the window glass, and the transmittance of radio waves passing through the window glass and the interface layer. (Note 6) The second transmission characteristic is the transmission characteristic when the interface layer is a first interface layer that is in close contact with the window glass, or a first interface layer that is located on the window glass side. The method for selecting an interface layer according to Appendix 4, wherein the control unit selects the first interface layer based on the estimated incidence angle and the second transmission characteristics. (Note 7) The second transmission characteristic is the transmission characteristic when the interface layer consists of two interface layers: a first interface layer that is in close contact with the window glass, or a first interface layer that is located on the window glass side and a second interface layer that is located on the antenna side of the first interface layer. The method for selecting interface layers according to Appendix 4, wherein the control unit selects the first interface layer and the second interface layer based on the estimated incidence angle and the second transmission characteristics. (Note 8) The method for selecting an interface layer as described in Appendix 4, wherein the second transmission characteristic is a transmission characteristic obtained by relating the angle of incidence to the window glass with the transmittance of radio waves passing through the window glass and the interface layer for a plurality of interface layers with different thicknesses or dielectric constants of the interface layer. (Note 9) The method for selecting an interface layer according to any one of Appendix 3 to 8, wherein the control unit estimates the incident angle at which the received power of the radio wave is maximized in the second angle distribution as the incident angle of the radio wave. (Note 10) The aforementioned radio waves are in the millimeter-wave band, and the method for selecting the interface layer described in any one of the appendices 1 to 9. (Note 11) The method for selecting an interface layer according to any one of the appendices 1 to 10, wherein the antenna and the control unit are separated and connected via a transmission line. [Explanation of Symbols]

[0158] 1. Building 1A Wall 10 windows 11 Windowpanes 12 Window frames 100 Antenna equipment 110 Array Antenna 120, 120A, 120B Interface Layer 121 Matching section 122 Wall 130 Holder 140 Phase shifter 150 Waveguides (an example of a transmission line) 200 Wireless communication devices 210 Radio equipment 211A Control Unit 211B Relay Unit 211C Memory (Example of a storage unit)

Claims

1. A method for selecting an interface layer for a wireless communication device, which includes an antenna provided on a windowpane and capable of scanning beam angles, an interface layer provided on the windowpane, and a control unit, The control unit, The beam angle of the antenna is scanned to obtain a first angular distribution of the received power of the radio waves arriving from the base station with respect to the beam angle. Based on the first angular distribution, the incident angle of the radio wave is estimated. A method for selecting an interface layer, which selects an interface layer according to the estimation result of the incident angle.

2. The method for selecting an interface layer according to claim 1, wherein the control unit is provided in the window having the window glass or in the wall surrounding the window.

3. The wireless communication device further includes a storage unit for storing a first transmission characteristic relating the type of window glass, the angle of incidence to the window glass, and the transmittance of radio waves passing through the window glass. Based on the first angular distribution and the first transmission characteristics, the control unit estimates a second angular distribution of the received power of the radio waves arriving from the base station with respect to the beam angle in the absence of the window glass. A method for selecting an interface layer according to claim 1, wherein the incidence angle of the radio wave is estimated using the second angle distribution.

4. The storage unit further stores a second transmission characteristic relating the type of interface layer, the angle of incidence to the window glass, and the transmittance of radio waves passing through the window glass and the interface layer. The method for selecting an interface layer according to claim 3, wherein the control unit selects the interface layer based on the estimated incidence angle and the second transmission characteristic.

5. The method for selecting an interface layer according to claim 4, wherein the second transmission characteristic is a transmission characteristic relating the type of window glass and the interface layer, the angle of incidence to the window glass, and the transmittance of radio waves passing through the window glass and the interface layer.

6. The second transmission characteristic is the transmission characteristic when the interface layer is a first interface layer that is in close contact with the window glass, or a first interface layer that is arranged on the window glass side. The method for selecting an interface layer according to claim 4, wherein the control unit selects the first interface layer based on the estimated incidence angle and the second transmission characteristics.

7. The second transmission characteristic is the transmission characteristic when the interface layer consists of two interface layers: a first interface layer that is in close contact with the window glass, or a first interface layer that is located on the window glass side and a second interface layer that is located on the antenna side of the first interface layer. The method for selecting interface layers according to claim 4, wherein the control unit selects the first interface layer and the second interface layer based on the estimated incidence angle and the second transmission characteristics.

8. The method for selecting an interface layer according to claim 4, wherein the second transmission characteristic is a transmission characteristic obtained by relating the angle of incidence to the window glass and the transmittance of radio waves passing through the window glass and the interface layer for a plurality of interface layers with different thicknesses or dielectric constants of the interface layer.

9. The method for selecting an interface layer according to claim 3, wherein the control unit estimates the incident angle at which the received power of the radio wave is maximized in the second angle distribution as the incident angle of the radio wave.

10. The method for selecting an interface layer according to claim 1, wherein the radio waves are in the millimeter wave band.

11. The method for selecting an interface layer according to claim 1, wherein the antenna and the control unit are separated and connected via a transmission line.

Images