Phase adjustment plate, glass plate, and wireless communication system

Abstract

The use of this phase adjustment plate provides a good indoor / outdoor communication environment via the emission of radio waves from an outdoor base station. The phase adjustment plate includes a base body having a first main surface and a second main surface that are opposed to each other; and a conductor pattern provided on the first main surface of the base body. The base body conveys electromagnetic waves introduced from the second main surface to the first main surface. The conductor pattern condenses the introduced electromagnetic waves at a focal point on the first main surface side or on the second main surface side.

Description

Technical Field

[0001] The present invention relates to a phase adjustment plate, a glass plate, and a wireless communication system.

Background Art

[0002] In the fifth-generation (hereinafter simply referred to as "5G") mobile communication standard, in addition to the band less than 6 GHz called "sub-6", the use of radio waves in the "millimeter wave band" is possible. The millimeter wave band generally refers to the frequency band of 30 to 300 GHz, but in the 5G standard, the frequency band of 26 GHz or higher is also called the "millimeter wave band". Since the millimeter wave band has not been used in general mobile communication networks so far, by using the millimeter wave band, the communication band is expanded, and high-speed and large-capacity communication is expected. On the other hand, since the radio waves in the millimeter wave band have strong directivity, the transmission quality is likely to deteriorate due to obstacles. The attenuation due to moisture in the air is also large. The deterioration and attenuation of the transmission quality of millimeter wave band radio waves can occur both outdoors and indoors, and the penetration loss from outdoors to indoors cannot be ignored.

[0003] FIG. 1 is a diagram for explaining the attenuation of radio waves in the millimeter wave band. Generally, radio waves radiated from an outdoor base station enter indoors through the window WDW. The wall of the building BLD becomes an obstacle to the radio waves in the millimeter wave band and does not allow the radio waves to pass through or greatly attenuates them. The radio waves in the millimeter wave band are already attenuated when they reach the building BLD and are further attenuated by the window glass. Since the radio waves transmitted through the window WDW travel straight as they are, the area except within the line of sight (LOS) becomes a dead zone and the radio waves cannot be received. Different from conventional mobile communication systems such as 3G and 4G, it is difficult to create a good communication environment indoors by radiating radio waves from an outdoor base station. For example, Patent Document 1 describes a technique for improving the radio wave permeability by installing a resin layer on the window glass.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] In 5G mobile communication systems, area improvement can be considered by placing customer premise equipment (CPE) and relay equipment such as repeaters near buildings. However, there are many challenges, including construction constraints outdoors, power supply, weather and waterproofing measures, and indoor installation work. Placing CPE and relay equipment indoors is also an option, but the millimeter-wave radio waves that reach indoors are weak, making reception by relay equipment itself difficult. Even if radio waves can be received by indoor relay equipment, significant amplification is required to relay them to each terminal inside the building, increasing power consumption.

[0006] The present invention aims to provide a phase adjustment plate, a glass plate, and a wireless communication system that can create a good indoor and outdoor communication environment by emitting radio waves from an outdoor base station. [Means for solving the problem]

[0007] In one aspect of the present invention, the phase adjustment plate comprises a base having a first main surface and a second main surface facing each other, and a conductive pattern provided on the first main surface of the base, The substrate transmits electromagnetic waves incident from the second main surface to the first main surface. The conductor pattern focuses the incident electromagnetic wave towards a focal point on either the first or second main surface side. [Effects of the Invention]

[0008] Radio waves emitted from outdoor base stations can create a good communication environment both indoors and outdoors. [Brief explanation of the drawing]

[0009] [Figure 1] This diagram illustrates the attenuation of radio waves in the millimeter wave band. [Figure 2] This is a schematic diagram of the wireless communication system according to the first embodiment. [Figure 3] This is a schematic diagram of a glass plate using the phase adjustment plate of the first embodiment. [Figure 4] This is a diagram illustrating the operating principle of the wireless communication system according to the first embodiment. [Figure 5A] This figure shows an example of a conductor pattern provided on the phase adjustment plate of the first embodiment. [Figure 5B] This figure shows an example of a unit cell pattern included in the conductor pattern of Figure 5A. [Figure 6] This is an experimental setup diagram using the phase adjustment plate of the first embodiment. [Figure 7A] Figure 6 shows the measurement results of the relative received signal strength in the x-direction in the setup shown. [Figure 7B] Figure 6 shows the measurement results of the relative received signal strength in the y-direction in the setup shown. [Figure 7C] Figures 5A and 5B show the frequency characteristics of the lens gain for the conductor patterns. [Figure 8] This is a schematic diagram of the wireless communication system according to the second embodiment. [Figure 9A] This is a schematic diagram of a glass plate using the phase adjustment plate of the second embodiment, showing the state with the dielectric plate attached. [Figure 9B] This is a schematic diagram of a glass plate using the phase adjustment plate of the second embodiment, showing the state with the dielectric plate removed. [Figure 10A] This diagram shows the operation of a wireless communication system when a dielectric plate is attached. [Figure 10B] This diagram shows the operation of the wireless communication system when the dielectric plate is removed. [Figure 11A] This figure shows an example of a conductor pattern provided on the phase adjustment plate of the second embodiment. [Figure 11B] This figure shows an example of a unit cell pattern included in the first light-gathering pattern. [Figure 11C] This figure shows an example of a unit cell pattern included in the second light-gathering pattern. [Figure 12] It is a schematic diagram of the wireless communication system of the third embodiment. [Figure 13A] It is a schematic diagram of a glass plate using the phase adjustment plate of the third embodiment, and is a diagram showing a state in which a movable plate is brought close. [Figure 13B] It is a schematic diagram of a glass plate using the phase adjustment plate of the third embodiment, and is a diagram showing a state in which a movable plate is brought close. [Figure 14] It is a model diagram considering the influence of the relative permittivity of the movable plate and the substrate. [Figure 15] It is a diagram for explaining focus switching due to the movement of the movable plate. [Figure 16A] It is a diagram of an example of a conductor pattern provided on the phase adjustment plate of the third embodiment. [Figure 16B] It is a diagram showing an example of a unit cell pattern included in the first condensing pattern. [Figure 16C] It is a diagram showing an example of a unit cell pattern included in the second condensing pattern. [Figure 17A] It is a diagram showing a single focus state by the phase adjustment plate of the fourth embodiment. [Figure 17B] It is a diagram showing a two-focus state by the phase adjustment plate of the fourth embodiment. [Figure 18A] It is an experimental setup diagram when the movable plate is removed (single focus). [Figure 18B] It is an experimental setup diagram of two foci using a movable plate. [Figure 19] It is a diagram showing the relative reception power distribution in the x direction of single focus and two foci. [Figure 20A] It is a diagram showing the relative reception power distribution in the y direction of single focus. [Figure 20B] It is a diagram showing the relative reception power distribution in the y direction when there are two foci. [Figure 21A] It is a diagram showing a modified example of the unit cell pattern. [Figure 21B] It is a diagram showing a modified example of the unit cell pattern. [Figure 21C] It is a diagram showing an example of a mesh. [Figure 22]This is a schematic diagram of the wireless communication system according to the fifth embodiment. [Figure 23A] This figure shows a modified example of a phase adjustment plate. [Figure 23B] This figure shows a modified example of a phase adjustment plate. [Figure 24] This diagram shows a modified example of a wireless communication system. [Modes for carrying out the invention]

[0010] The following describes specific configuration examples of embodiments with reference to the drawings. In the following description, when "millimeter wave" or "millimeter wave band" is used, it includes the 24GHz to 30GHz quasi-millimeter wave band in addition to the 30GHz to 300GHz frequency band. "Radio waves" are a type of electromagnetic wave, and generally, electromagnetic waves below 3THz are called radio waves. In the following, electromagnetic waves radiated from outdoor base stations or relay stations will be called "radio waves," and when referring to electromagnetic waves in general, the term "electromagnetic waves" will be used. In the drawings, the same elements may be given the same symbols to omit redundant explanations.

[0011] In one embodiment, a phase adjustment plate is installed on the window glass, which is the entry point for electromagnetic waves, and the electromagnetic waves received by the window are concentrated at a single point, thereby improving the reception environment at indoor or outdoor relay equipment and expanding the communication area. In one embodiment, a reflector is used in combination with the phase adjustment plate to more efficiently expand the area indoors or outdoors.

[0012] <First Embodiment> Figure 2 is a schematic diagram of the wireless communication system 1 of the first embodiment. The wireless communication system 1 includes a glass plate 100 and a repeater 50. The glass plate 100 is used in glass windows of buildings, roofs of shelters at bus stops and train station platforms, back glass, etc. The repeater 50 is a CPE, repeater, etc., which receives, amplifies, and radiates radio waves. In the example in Figure 2, the glass plate 100 is used in the window glass of a building BLD, and the repeater 50 is located indoors.

[0013] The glass plate 100 uses a phase adjustment plate, which will be described later. For example, it focuses radio waves radiated from an outdoor base station and incident on the glass plate 100 to a predetermined focal point F. By placing the repeater 50 at or near the focal point F, the repeater 50 can receive radio waves with high energy density. The repeater 50 amplifies the received radio waves and radiates the amplified radio waves at a predetermined radiation angle using an array antenna or the like. Since the energy density of the radio waves received by the repeater 50 is high, it is not necessary to make the amplification factor of the repeater 50 excessively large. The amplified radio waves are radiated from the repeater 50 to a wide area indoors, making it easy for indoor terminals to receive them.

[0014] Figure 3 is a schematic diagram of a glass plate 100 using the phase adjustment plate 10 of the first embodiment. The glass plate 100 has a glass substrate 101 and a phase adjustment plate 10. The phase adjustment plate 10 may be attached to the glass substrate 101 by an adhesive layer 102.

[0015] The phase adjustment plate 10 has a base body 11 having a first main surface 111 and a second main surface 112 facing each other, and a conductor pattern 12 provided on the first main surface 111 of the base body 11. Here, "main surface" refers to a surface perpendicular to the thickness direction of the base body 11. The base body 11 transmits electromagnetic waves incident from the second main surface 112 to the first main surface 111.

[0016] The substrate 11 is made of any material that is transparent to electromagnetic waves at the operating frequency of the wireless communication system 1 and capable of supporting the conductive pattern 12. "Transparent" means that the transmittance is 60% or more, preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. As an example, a resin substrate is used for the substrate 11. As a resin material that satisfies the above conditions, acrylic resins such as polymethyl methacrylate, cycloolefin resins, polycarbonate resins, etc., can be used.

[0017] As will be described later, in the conductive pattern 12, a second pattern larger than the first pattern is formed by repeatedly arranging the first pattern. The repetition of the first pattern generates a periodic structure, making it possible to select a frequency. The second pattern focuses electromagnetic waves of a predetermined frequency, determined by the repetition period of the first pattern, to a predetermined focal point. From the viewpoint of application to a glass plate 100, it is desirable that the conductive pattern 12 be formed of a transparent conductive film such as zinc oxide (ZnO), tin oxide (SnO2), tin-doped indium oxide (ITO), or indium oxide-tin oxide (IZO), but depending on the application, it may be formed of a thin metal film such as copper, nickel, or gold.

[0018] The glass substrate 101 can be any commonly available glass, such as soda-lime glass, alkali-free glass, Pyrex® glass, or quartz glass. The adhesive layer 102 is made of any adhesive material that is transparent to electromagnetic waves at the operating frequency of the wireless communication system 1 and can bond the glass substrate 101 to the substrate 11 of the phase adjustment plate 10. The meaning of "transparent" in the adhesive layer 102 is the same as the meaning of "transparent" in the substrate 11. When the glass plate 100 is used as window glass, the entire glass plate 100 may be transparent to visible light.

[0019] The phase adjustment plate 10 may be formed separately and attached to the glass substrate 101 with an adhesive layer 102. Alternatively, the substrate 11 may be attached to the glass substrate 101 with an adhesive layer 102, a conductive film may be formed on the first main surface 111 of the substrate 11, and the conductive pattern 12 may be formed by photolithography and etching.

[0020] The conductive pattern 12 formed on the first main surface 111 of the substrate 11 forms a metasurface. A "metasurface" refers to an artificial surface that controls the transmission and reflection characteristics of incident electromagnetic waves. By controlling at least one of the phase and amplitude of the electromagnetic waves incident on the conductive pattern, it is possible to realize optical properties that do not exist in nature. The conductive pattern 12 allows incident electromagnetic waves to be transmitted, reflected, or focused in a desired direction.

[0021] Figure 4 is a diagram illustrating the operating principle of wireless communication system 1. A glass plate 100 is fitted into wall 110. The height direction of wall 110 is the Z direction, the direction from wall 110 toward indoors (IN) is the Y direction, and the direction perpendicular to the Z and Y directions is the X direction. The glass plate 100 is positioned so that the conductor pattern 12 faces indoors (IN).

[0022] Radio waves emitted from an outdoor base station BS are incident on the glass plate 100. The radio waves emitted from the base station BS may be attenuated to a considerable extent by the time they reach the glass plate 100. The incident radio waves pass through the glass plate 100 and, due to the conductive pattern 12 of the first main surface 111, a focal point F is formed at a distance d from the first main surface 111. By placing a repeater 50 such as a CPE near the focal point F, the radio waves, which have been focused and have a high energy density, can be received by the repeater 50.

[0023] Figure 5A shows a focusing pattern 13 included in the conductor pattern 12. The focusing pattern 13 is an example of a second pattern that forms the conductor pattern 12. Figure 5B shows a unit cell pattern 14 included in the focusing pattern 13. The unit cell pattern 14 is an example of a first pattern that forms the conductor pattern 12. The focusing pattern 13 is formed by repeatedly arranging the unit cell pattern 14 in the same orientation. In this example, the unit cell pattern 14 is a cross pattern formed of a solid metal film, but the example is not limited to this example. The size Lunit × Lunit of the unit cell pattern 14 is 3.5 mm × 3.5 mm, and the repeating period of the center C2 is 3.5 mm.

[0024] The size Lunit of the unit cell pattern 14 is determined to match the target frequency. By repeating the unit cell pattern 14 to generate a periodic structure, it acts as a resonator that resonates with electromagnetic waves of the target frequency.

[0025] The focusing pattern 13 in Figure 5A is a Fresnel lens pattern formed by concentric circles 131-1 to 131-n around a center C1. The line width of the concentric circles 131 becomes thinner as you move away from the center C1, and the spacing between adjacent concentric circles 131 becomes narrower. Whether or not to place a unit cell pattern 14 near the boundary of each concentric circle 131 is determined by whether or not the center C2 of the unit cell pattern 14 is contained within the concentric circle 131. Each concentric circle 131 formed by the repetition of the unit cell pattern 14 functions individually as a refractive surface, bending the optical path of the incident electromagnetic wave and focusing it to a predetermined focal point F. In Figure 5A, the concentric circles 131-1 to 131-n, which are planar patterns, realize a lens that is convex in the direction of electromagnetic wave propagation.

[0026] The radius of the nth concentric circle 131-n is r n If the focal length of the focusing pattern 13 is f and the wavelength of the incident electromagnetic wave is λ, r n 2 =nfλ (1) This is the result. The size L1×L1 of the focusing pattern 13 determined from this is larger than 2fλ×2fλ. 2fλ is the diameter of the first concentric circle. Equation (1) is an approximation when the number of rings is small, and when the number of rings can be sufficiently large, use equation (2) as a basis for r n This allows us to determine the following. When n is greater than 2, that is, when a Fresnel annulus of order 5 or higher can be designed, using equation (2) yields higher accuracy.

[0027]

number

[0028] The repeating period of the unit cell pattern 14 and the lens effect of the focusing pattern 13 allow electromagnetic waves of a predetermined frequency to be focused to a desired position. When using the conductor pattern 12 shown in Figures 5A and 5B, the distance d from the glass plate 100 in Figure 4 to the focal point F is approximately 600 mm. The term "approximately" here indicates that an error of ± a few mm due to manufacturing errors, measurement errors, etc., is to be tolerated. Even if "approximately" is not indicated for a numerical value in the following description, this does not mean that tolerances are excluded. By placing the repeater 50 at or near the focal point F, the area can be efficiently deployed indoors.

[0029] Figure 6 is an experimental setup diagram using the phase adjustment plate 10 of the first embodiment. The phase adjustment plate 10 has the conductor pattern 12 shown in Figures 5A and 5B formed on it. A shield 115 is provided on the surface of the wall 110 that holds the phase adjustment plate 10. A transmitting horn antenna is placed at port 1, and a dipole antenna is placed at the focal point F0 as the receiving antenna. The position where the receiving antenna is placed is designated as port 2. The focal point F0 is located 800 mm from the lens formed by the conductor pattern 12 of the phase adjustment plate 10. The receiving antenna is moved in the x and y directions along a straight line (measurement line) including the focal point F0, and the received strength of the radio waves is measured while changing the transmission frequency.

[0030] Figure 7A shows the measurement results of the received power in the x-direction for the setup in Figure 6, and Figure 7B shows the measurement results of the received power in the y-direction for the setup in Figure 6. The horizontal axis represents position, and the vertical axis represents relative received power. The relative received power is normalized to the measurement value when using 4 mm thick soda-lime glass. Figure 7C shows the frequency characteristics of the lens gain of the conductor pattern 12 shown in Figures 5A and 5B. The horizontal axis represents frequency (GHz), and the vertical axis represents lens gain. From Figure 7A, a sharp peak is observed at the center position in the x-direction over the bandwidth from 27.2 GHz to 28.4 GHz.

[0031] In Figure 7B, a slight spread of the received power profile is observed, centered around 800 mm in the y-direction. This means that the receiving margin in the y-direction is large, making it easier to align the receiver. In this respect as well, favorable experimental results have been obtained. In Figure 7C, the 3 dB width is in the range of approximately 1 GHz, from 27.2 GHz to 28.1 GHz. This shows that the light can be focused at a distance of 800 mm from the lens over a wide frequency band. Note that the focal point in the setup in Figure 6 is approximately 800 mm from the lens, which differs from the 600 mm in the design in Figure 4 for the following reason: In the design, the light is focused at a point of 600 mm when a plane wave is incident. On the other hand, in the experimental setup, the wave source is located 200 mm from the phase adjustment plate 10, and a spherical wave is incident on the conductor pattern 12, so the focal length differs from the design.

[0032] <Second embodiment> Figure 8 is a schematic diagram of the wireless communication system 2 of the second embodiment. The wireless communication system 2 includes a glass plate 200 and repeaters 50-1 and 50-2. As will be described later, the phase adjustment plate used in the glass plate 200 includes a removable dielectric plate. Depending on the presence or absence of the dielectric plate, the focal position is switched between the first focal point F1 and the second focal point F2, as indicated by the double-headed arrow SW.

[0033] When the first focus F1 is selected, the radio waves are received and relayed by repeater 50-1 located at or near the first focus F1. When the second focus F2 is selected, the radio waves are received and relayed by repeater 50-2 located at or near the second focus F2. It is not necessary to use both repeaters 50-1 and 50-2; a single repeater 50 installed at the selected focus position may be used permanently. The wireless communication system 2 of the second embodiment offers improved system design flexibility.

[0034] Figures 9A and 9B are schematic diagrams of a glass plate 200 using the phase adjustment plate 20 of the second embodiment. Figure 9A shows the state with the dielectric plate 25 attached. Figure 9B shows the state with the dielectric plate 25 removed.

[0035] The glass plate 200 comprises a glass substrate 201 and a phase adjustment plate 20. The phase adjustment plate 20 may be attached to the glass substrate 201 by an adhesive layer 202. The phase adjustment plate 20 includes a substrate 21 having a first main surface 211 and a second main surface 212 facing each other, a conductor pattern 22 provided on the first main surface 211 of the substrate 21, and a removable dielectric plate 25.

[0036] As shown in Figure 9A, when the dielectric plate 25 is attached to the phase adjustment plate 20, the electromagnetic waves incident on the phase adjustment plate 20 from the glass substrate 201 are focused to one of the focal points, for example, the first focal point F1. As shown in Figure 9B, when the dielectric plate 25 is removed from the phase adjustment plate, the incident electromagnetic waves are focused to the other focal point, for example, the second focal point F2.

[0037] The configuration of the glass substrate 201, the adhesive layer 202, and the substrate 21 of the phase adjustment plate 20 is the same as in the first embodiment, and redundant explanations will be omitted. The conductor pattern 22 has a pattern in which the focus switches depending on the presence or absence of the dielectric plate 25. The dielectric plate 25 has a certain degree of difference in relative permittivity with respect to electromagnetic waves of the target frequency. "Transparent" means, as described above, that the transmittance is 60% or more, preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. The difference in relative permittivity between the dielectric plate 25 and respect to to respect to respect to to respect to respect to to respect to respect to to respect to respect to respect to to respect to respect to respect to to respect to respect

[0038] Figure 10A shows the operation of the wireless communication system 2 when the dielectric plate 25 is attached. Figure 10B shows the operation of the wireless communication system 2 when the dielectric plate 25 is removed. The coordinate system in Figures 10A and 10B is the same as the coordinate system in Figure 4. A glass plate 200 is fitted into the wall 110. Separated from the wall 110, there is a base station BS at the outdoor OUT and a repeater 50-1 or 50-2 such as a CPE at the indoor IN. The glass plate 200 is arranged such that, for example, the conductor pattern 22 and the dielectric plate 25 face the indoor IN.

[0039] In Figure 10A, when the dielectric plate 25 is attached, radio waves incident on the glass plate 200 from the outdoors (OUT) are focused at the first focal point F1. The first focal point F1 is located at a distance d1 from the glass plate 200. By placing the repeater 50-1 at or near the first focal point F1, the focused radio waves with increased energy density can be received and relayed by the repeater 50-1.

[0040] In Figure 10B, when the dielectric plate 25 is removed, the radio waves incident on the glass plate 200 from the outdoors (OUT) are focused at the second focal point F2. The second focal point F2 is located at a distance d2 from the glass plate 200. The distance S in the X direction is between the first focal point F1 and the second focal point F2. By placing the repeater 50-2 at or near the second focal point F2, the focused radio waves with increased energy density can be received and relayed by the repeater 50-2.

[0041] The distance d1 from the glass plate 200 to the first focal point F1 and the distance d2 to the second focal point F2 may be the same or different. If d1 and d2 are the same, the first focal point F1 and the second focal point F2 are in the same plane parallel to the wall 110. The positions of the first focal point F1 and the second focal point F2 in the height direction, i.e., in the Z direction, may be the same or different. The positions of the first focal point F1 and the second focal point F2 are controlled by the conductive pattern 22 of the phase adjustment plate 20.

[0042] Figure 11A shows a focusing pattern 23 included in the conductor pattern 22. The focusing pattern 23 is an example of the first pattern that forms the conductor pattern 22. The focusing pattern 23 includes a first focusing pattern 23-1, a second focusing pattern 23-2, and an intersection region 23-3 where the first focusing pattern 23-1 and the second focusing pattern 23-2 intersect.

[0043] The first focusing pattern 23-1 is an example of a first conductive pattern that determines the first focal point F1. The second focusing pattern 23-2 is an example of a second conductive pattern that determines the second focal point F2. The first focusing pattern 23-1 and the second focusing pattern 23-2 are each formed by repeating different unit cell patterns. The intersection region 23-3 of the first focusing pattern 23-1 and the second focusing pattern 23-2 is formed by a solid metal film.

[0044] Figure 11B shows a schematic diagram of the unit cell pattern 24-1 that forms the first focusing pattern 23-1, and Figure 11C shows an example of the unit cell pattern 24-2 that forms the second focusing pattern 23-2. The unit cell pattern 24-1 is a cross pattern formed from a solid metal film. The size Lunit × Lunit of the unit cell pattern 24-1 is 3.0 mm × 3.0 mm. The repeating period of the unit cell pattern 24-1 is 3.0 mm.

[0045] Unit cell pattern 24-2 is formed from a solid metal film. In this example, unit cell pattern 24-2 is an inverted pattern of unit cell pattern 24-1, but is not limited to this example. The size Lunit × Lunit of unit cell pattern 24-2 is 3.0 mm × 3.0 mm.

[0046] The first focusing pattern 23-1 is formed by repeating the unit cell pattern 24-1 with a period of 3.0 mm. The second focusing pattern 23-2 is formed by repeating the unit cell pattern 24-2 with a period of 3.0 mm. Near the boundary of the concentric circles, whether or not a unit cell pattern 24 can be placed is determined by whether or not the center of the unit cell pattern 24 is included in the concentric circle. The size L2×L2 of the focusing pattern 23 determined by the unit cell patterns 24-1 and 24-2 is 800 mm × 800 mm.

[0047] Using the conductor pattern 22 shown in Figures 11A to 11C, in Figures 10A and 10B, the distance d1 to the first focal point F1 and the distance d2 to the second focal point F2 are both 600 mm, and the distance S between the first focal point F1 and the second focal point F2 is 300 mm. By placing repeater 50-1 or 50-2 at the first focal point F1 or the second focal point F2, the area can be efficiently expanded indoors.

[0048] When the dielectric plate 25 is attached to the phase adjustment plate 20, the dielectric constant of the dielectric plate 25 causes, for example, the lens function of the focusing pattern 23-1 to be predominantly expressed, and the function of the focusing pattern 23-2 to be suppressed. When the dielectric plate 25 is removed, the dielectric constant of air causes the lens function of the focusing pattern 23-2 to be predominantly expressed, and the function of the focusing pattern 23-1 to be suppressed. Therefore, the first focal point F1 and the second focal point F2 can be switched by attaching and detaching the dielectric plate 25 with the glass plate 200.

[0049] <Third embodiment> Figure 12 is a schematic diagram of a wireless communication system 3 according to a third embodiment. The wireless communication system 3 includes a glass plate 300 and repeaters 50-1 and 50-2. In the third embodiment, a movable plate 35 is used as part of the phase adjustment plate, and the first focal point F1 and the second focal point F2 are switched by changing the position or distance of the movable plate 35 with respect to the first main surface or conductor pattern, as indicated by the bidirectional arrow SW.

[0050] When the first focal point F1 is selected with the movable plate 35 in the first position, the radio waves are received and relayed by the repeater 50-1 located at or near the first focal point F1. When the second focal point F2 is selected with the movable plate 35 in a second position different from the first position, the radio waves are received and relayed by the repeater 50-2 located at or near the second focal point F2. It is not always necessary to use both repeaters 50-1 and 50-2; the movable plate 35 may be fixed in a predetermined position, and the selected focal point may be used permanently. In the wireless communication system 3 of the second embodiment, the focal point can be selected simply by changing the position of the movable plate 35, improving the degree of freedom in system design.

[0051] Figures 13A and 13B are schematic diagrams of a glass plate 300 using the phase adjustment plate 30 of the third embodiment. Figure 13A shows the movable plate 35 in a state close to the conductor pattern 32, and Figure 13B shows the movable plate 35 in a state away from the conductor pattern 32.

[0052] The glass plate 300 includes a glass substrate 301 and a phase adjustment plate 30. The phase adjustment plate 30 may be attached to the glass substrate 301 by an adhesive layer 302. The phase adjustment plate 30 includes a substrate 31 having a first main surface 311 and a second main surface 312 facing each other, a conductor pattern 32 provided on the first main surface 311 of the substrate 31, and a movable plate 35.

[0053] As shown in Figure 13A, when the movable plate 35 is close to the conductive pattern 32, the electromagnetic waves incident on the phase adjustment plate 30 from the glass substrate 301 are focused to one of the focal points, for example, the first focal point F1. As shown in Figure 13B, when the movable plate 35 is moved away from the conductive pattern 32, the incident electromagnetic waves are focused to the other focal point, for example, the second focal point F2. The distance the movable plate 35 moves is, for example, several millimeters to several centimeters. The movable plate 35 may be moved manually or mechanically by an actuator or the like.

[0054] The configuration of the glass substrate 301, the adhesive layer 302, and the substrate 31 of the phase adjustment plate 30 is the same as in the first and second embodiments, and redundant explanations will be omitted. The conductor pattern 32 has a pattern whose focus is switched depending on the position of the movable plate 35 relative to the conductor pattern 32. The average dielectric constant felt by the incident electromagnetic wave changes depending on the position of the movable plate 35. The movable plate 35, like the dielectric plate 25 in the second embodiment, is transparent to radio waves of the target frequency and has a predetermined dielectric constant. As the movable plate 35, optical glass, optical plastic, laminates thereof that satisfy the above conditions can be used.

[0055] Figure 14 is a model diagram considering the influence of the relative permittivity of the movable plate 35 and the substrate 31. A conductive pattern 32 forming a metasurface is formed on the substrate 31. The capacitance component of this system can be considered as a parallel connection of Csub, which is dominated by the relative permittivity of the substrate 31 on which the conductive pattern 32 is formed, and Cmov, a variable capacitance which is dominated by the relative permittivity of air and the movable plate 35 and changes depending on the position of the movable plate 35. The resonant frequency f1 when the movable plate 35 is installed is expressed by equation (3).

[0056]

number

[0057] The resonant frequency f0 when the movable plate 35 is not installed is expressed by equation (4).

[0058]

number

[0059] Therefore, the larger Cmov is relative to Csub, the better the controllability should be. Since the capacitance component is proportional to the respective dielectric constants, if you want to increase the sensitivity depending on the position of the movable plate 35 and design a large change in the resonant frequency, you should lower the dielectric constant of the base 31 and increase the dielectric constant of the movable plate 35. The difference in dielectric constant between the movable plate 35 and the base 31 is preferably 1.0 or more, and more preferably 1.2 or more.

[0060] Figure 15 shows the operation of the wireless communication system 3 when the position of the movable plate 35 relative to the conductor pattern 32 is changed. The coordinate system in Figure 12 is the same as the coordinate system in Figure 4. A glass plate 300 is fitted into the wall 110. Aside from the wall 110, there is a base station BS at the outdoor OUT and a repeater 50-1 or 50-2 such as a CPE installed at the indoor IN. The glass plate 300 is positioned so that the conductor pattern 32 faces indoor IN and the movable plate 35 is located indoor IN.

[0061] When the movable plate 35 is moved in a direction perpendicular to the conductor pattern 32, radio waves incident from the outdoors (OUT) are focused to either the first focal point F1 or the second focal point F2, depending on the position of the movable plate 35. When the first focal point F1 and the second focal point F2 are in the same plane parallel to the glass plate 300, the distance d from the conductor pattern on the glass plate 300 to the focal point is, for example, 300 mm. The distance S between the first focal point F1 and the second focal point F2 is 250 mm. By placing repeater 50-1 at or near the first focal point F1, or by placing repeater 50-2 at or near the second focal point F2, radio waves with increased energy density can be received and relayed.

[0062] Figure 16A shows a focusing pattern 33 included in the conductor pattern 32. The focusing pattern 33 is an example of the first pattern that forms the conductor pattern 32. The focusing pattern 33 includes a first focusing pattern 33-1, a second focusing pattern 33-2, and an intersection region 33-3 where the first focusing pattern 33-1 and the second focusing pattern 33-2 intersect.

[0063] The first focusing pattern 33-1 is an example of a first conductive pattern that determines the first focal point F1. The second focusing pattern 33-2 is an example of a second conductive pattern that determines the second focal point F2. The first focusing pattern 33-1 and the second focusing pattern 33-2 are each formed by repeating different unit cell patterns. The intersection region 33-3 of the first focusing pattern 33-1 and the second focusing pattern 33-2 is a solid metal film.

[0064] Figure 16B shows a schematic diagram of the unit cell pattern 34-1 that forms the first focusing pattern 33-1, and Figure 16C shows an example of the unit cell pattern 34-2 that forms the second focusing pattern 33-2. The unit cell pattern 34-1 is a cross pattern formed from a solid metal film. The size Lunit × Lunit of the unit cell pattern 34-1 is 3.1 mm × 3.1 mm. The repeating period of the unit cell pattern 34-1 is 3.1 mm.

[0065] Unit cell pattern 34-2 is formed from a solid metal film and, in this example, is an inverted pattern of unit cell pattern 34-1, but is not limited to this example. The size Lunit × Lunit of unit cell pattern 34-2 is 3.1 mm × 3.1 mm.

[0066] The first focusing pattern 33-1 is formed by repeating the unit cell pattern 34-1 with a period of 3.1 mm. The second focusing pattern 33-2 is formed by repeating the unit cell pattern 34-2 with a period of 3.1 mm. Near the boundary of the concentric circles, whether or not a unit cell pattern 24 is placed is determined by whether or not the center of the unit cell pattern 34 is included in the concentric circle. The size L3×L3 of the focusing pattern 33 determined by the unit cell patterns 34-1 and 34-2 is 500 mm × 500 mm.

[0067] When the movable plate 35 is close to the conductor pattern 32, the dielectric constant of the movable plate 35 causes, for example, the lens function of the focusing pattern 33-1 to be predominantly expressed, and the function of the focusing pattern 33-2 to be suppressed. When the movable plate 35 is away from the conductor pattern 32, the dielectric constant of air causes the lens function of the focusing pattern 33-2 to be predominantly expressed, and the function of the focusing pattern 33-1 to be suppressed. The first focal point fF and the second focal point F2 can be switched by changing the position of the movable plate 35 relative to the conductor pattern 32 using the glass plate 300.

[0068] In the configuration of the third embodiment, by placing repeater 50-1 or 50-2 at the first focal point F1 or the second focal point F2, the area can be efficiently expanded indoors.

[0069] <Fourth Embodiment> In the fourth embodiment, single focus and multiple focus are switched by changing the attachment or detachment of the movable plate. Figure 17A shows the single focus state using the phase adjustment plate 40 in the wireless communication system 4. Figure 17B shows the two-focus state using the phase adjustment plate 40 in the wireless communication system 4. The phase adjustment plate 40 includes a base body 41 on which a conductor pattern 42 is formed, and a movable plate 45. The phase adjustment plate 40 may also be fixed to a glass base body 401 and used as a glass plate 400. The conductor pattern 42 provided on the base body 41 is designed to switch between single focus and multiple focus depending on the change in the dielectric constant of the radio wave propagation plate chamber. The basic shape of the conductor pattern 42 may be similar to the conductor pattern 32 of the third embodiment. The presence or absence of the movable plate 45 switches between single focus and multiple focus. In particular, multiple focus is achieved by setting the position of the movable plate 45 to an "intermediate state" where it does not contact the conductor pattern 42.

[0070] In Figure 17A, the movable plate 45 is removed. As the radio wave propagation medium, the dielectric constant of air is dominant, and a single focal point F1 is formed at a predetermined distance in the normal direction from the lens formed by the conductive pattern 42. In single-focus mode, a repeater 50-1 may be placed at focal point F1.

[0071] In Figure 17B, by using the movable plate 45, focal points F2 and F3 are formed at a predetermined distance in the normal direction from the lens formed by the conductive pattern 42. By using the movable plate 45, the dielectric constant of the radio wave propagation medium changes, altering the state in which the lens function of the conductive pattern 42 is expressed, and the two focal points F2 and F3 are formed. When there are two focal points, repeaters 50-2 and 50-3 may be placed at the positions of focal points F2 and F3, respectively.

[0072] Figure 18A shows the experimental setup for a single-focus antenna with the movable plate 45 removed, and Figure 18B shows the experimental setup for a two-focus antenna with the movable plate 45. In Figures 18A and 18B, a shield 115 is provided on the surface of the wall 110 that holds the phase adjustment plate 40. A transmitting horn antenna is placed at port 1. A dipole antenna is placed at port 2 as the receiving antenna. The receiving antenna is moved in the x and y directions along the measurement lines shown by the dotted lines, and the received power of the radio waves is measured.

[0073] Figure 19 shows the received power of the receiving antenna in the x-direction. The horizontal axis represents the position in the x-direction, and the vertical axis represents the relative received power. The relative received power is normalized to the measurement value when using 4 mm thick soda-lime glass. The position in the y-direction is fixed at a position 300 mm from the lens formed by the conductive pattern 42.

[0074] In the intermediate state where the movable plate 45 is used away from the conductive pattern 42, peaks of similar received power are observed at positions 75 mm and 410 mm in the x-direction. When multiple peaks are observed, the point within 3 dB of the relative received power of the maximum peak is called the "focal point." In Figure 19, it can be seen that focal points F2 and F3 are connected at the positions of the two peaks of similar received power.

[0075] On the other hand, with the movable plate 45 removed, a steep peak (first peak) is observed at 410 mm in the x-direction. This peak is 4 dB higher than the intermediate state peak at the same x-position. There is a low, wide peak (second peak) at 80 mm in the x-direction, but the relative received power of the second peak is 6 dB lower than the intermediate state peak power at the same point and 10 dB lower than the first peak at 410 mm, so it is not considered a "focal point". It can be seen that removing the movable plate 45 results in the formation of a single focal point F1.

[0076] Figure 20A shows the relative received power distribution in the y-direction when the movable plate 45 is removed, and Figure 20B shows the relative received power distribution in the y-direction in an intermediate state. In Figures 20A and 20B, the solid line represents the relative received power in the y-direction when the x-direction position is fixed at 410 mm, and the dotted line represents the relative received power in the y-direction when the x-direction position is fixed at 80 mm. In Figure 20A, the receiving margin in the y-direction is wide near 410 mm, making alignment easier. In Figure 20B, the margin in the y-direction is wide at both the first and second peak positions, making alignment in the y-direction easier.

[0077] The number of focal points in the intermediate state is not limited to two. For example, the number of focal points may be set to three or more by changing the position of the movable plate 45 in the intermediate state to a first intermediate position, a second intermediate position, etc., depending on the distance from the lens. In this case, it becomes possible to switch between single focal length and three focal lengths, or between two focal lengths and three focal lengths. As described above, the y-direction alignment margin is wide and y-direction alignment is easy, but the accuracy of y-direction alignment at the intermediate position may be improved by adding a low dielectric constant layer to the movable plate 45.

[0078] <Variations of unit cell patterns> Figures 21A and 21B show modified examples of the unit cell pattern. In the embodiments described above, the unit cell pattern was formed with a solid metal film, but a mesh pattern may be used instead of the solid film. The mesh pattern 64-1 in Figure 21A may be used as the unit cell pattern 14 in the first embodiment, the unit cell pattern 24-1 in the second embodiment, and the unit cell pattern 34-1 in the third embodiment.

[0079] When using a conductor pattern with switchable focus, the mesh pattern 64-2 shown in Figure 21B may be used as the unit cell pattern used in the unit cell pattern 24-2 of the second embodiment, the unit cell pattern 34-2 of the third embodiment, and the conductor pattern 42 of the fourth embodiment.

[0080] Figure 21C shows an example of a mesh. The mesh line width W is 10 μm and the mesh pitch P is 300 μm, but this is not an exhaustive example. The mesh line width can be appropriately selected within the range of 1 μm to 20 μm. The mesh pitch P should preferably be λ / 15 or less of the frequency or wavelength λ used in the wireless communication system.

[0081] In the second to fourth embodiments, when a mesh pattern is used for the conductor pattern 22, 32, or 42, the intersection region where the first focusing pattern and the second focusing pattern intersect may be filled with mesh. When mesh patterns 64-1 and 64-2 are used, the first focal point F1 and the second focal point F2 can be switched depending on the presence or absence of the dielectric plate 25 or the position of the movable plate 35. In the fourth embodiment, single focal point and multiple focal points can be switched depending on the presence or absence of the movable plate 45 or its intermediate position.

[0082] <Variations of wireless communication systems> Figure 22 is a schematic diagram of the wireless communication system 5. In the wireless communication system 4, reflectors 61 are placed indoors to further improve the indoor area.

[0083] For example, there are areas A1 to A4 where radio waves from repeater 50-1 or 50-2 have difficulty reaching due to shadows from indoor installations. Even if the radio waves are amplified by repeater 50-1 or 50-2, it is difficult for millimeter waves to penetrate these installations.

[0084] By positioning reflectors 61a to 61c at an appropriate angle in the range of the repeater 50-1 or the radio waves from 50-1, the radio waves are directed towards areas A1 to A4, thereby improving the coverage area. The first focal point F1 and the second focal point F2 of the incident electromagnetic wave can be switched by attaching or detaching the dielectric plate 25 or by changing the position of the movable plate 35, as described in the second and third embodiments. Furthermore, as in the fourth embodiment, it is possible to switch between a single focal point and two focal points by attaching or detaching the movable plate 45 or by switching its intermediate position.

[0085] <Other variations> In the second and third embodiments, two Fresnel lens patterns of the same shape were used to form the first focal point F1 and the second focal point F2 at the same distance d, i.e., in a plane parallel to the glass plate, but the invention is not limited to this example. The first focal point F1 and the second focal point F2 may be formed at different positions in the depth direction, i.e., in the Y direction, or they may be formed at different positions in the height direction, i.e., in the Z direction, or in the horizontal direction, i.e., in the X direction, within the same plane.

[0086] As shown in Figure 23A, the distance d2 of the second focal point F2 may be made larger than the distance d1 of the first focal point F1. For example, the conductive pattern 72A of the phase adjustment plate 70A used in the glass plate 700A may be made into a lens pattern with different focal lengths in the depth direction, i.e., in the Y direction. The change in the spacing of the concentric circles of the second focusing pattern 23-2 shown in Figure 11A may be made more gradual than the change in the spacing of the concentric circles of the first focusing pattern 23-1. This makes it possible to make the focal length of the plane Fresnel lens realized with the second focusing pattern 23-2 longer than the focal length of the plane Fresnel lens realized with the first focusing pattern 23-1.

[0087] The configuration in which the positions of the first focal point F1 and the second focal point F2 are different in the Y direction is also applicable to the third embodiment. The focal position can be switched in the Y direction by attaching, detaching, or moving the adjustment plate 75 provided on the phase adjustment plate 70A. The adjustment plate 75 may be a dielectric plate as in the second embodiment, or a movable plate as in the third or fourth embodiment.

[0088] As shown in Figure 23B, at least one of the first focal point F1 and the second focal point F2 may be positioned outside the LOS (the area enclosed by the two horizontal dotted lines) of the glass plate 700. The distance d1 to the first focal point F1 and the distance d2 to the second focal point F2 may be the same or different.

[0089] For example, the conductive pattern 42B of the phase adjustment plate 70B used in the glass plate 700B is made into a lens pattern that increases refraction towards the outside of the line of sight (LOS). By forming a planar lens with multiple annular patterns that are asymmetrical with respect to the center, rather than concentric circles, the first focal point F1 or the second focal point F2 can be formed outside or inside the LOS.

[0090] The configuration that shifts the positions of the first focal point F1 and the second focal point F2 outward or inward from the line of sight (LOS) is also applicable to the second to fourth embodiments. The focal position can be switched in the X direction by attaching, detaching, or moving the adjustment plate 75 provided on the phase adjustment plate 70B. The adjustment plate 75 may be a dielectric plate as in the second embodiment, or a movable plate as in the third or fourth embodiment.

[0091] Two focusing patterns, sensitive to electromagnetic waves of different frequencies, may be formed as the conductor pattern. For example, a first focusing pattern with a unit cell pattern resonance frequency tuned to 28 GHz and a second focusing pattern with a unit cell pattern resonance frequency tuned to 50 GHz may be formed. Either frequency may be selectable by the presence or absence of the dielectric plate 25 or by changing the position of the movable plate 35.

[0092] Figure 24 shows wireless communication system 6 as yet another modified example of the wireless communication system. In wireless communication systems 1 to 5, radio waves incident from outdoors are focused indoors by a phase adjustment plate, and received and amplified by an indoor repeater 50. In wireless communication system 6 of Figure 24, radio waves incident from outdoors are focused outdoors by a glass plate 100 having a phase adjustment plate, and received and amplified by an outdoor repeater 50.

[0093] In the wireless communication system 6, the phase adjustment plate 10 (see Figure 3) functions as an electromagnetic wave shield. The glass plate 100 is positioned so that the conductive pattern 12 faces indoors. Radio waves that pass through the glass substrate 101, adhesive layer 102, and substrate 11 and enter the conductive pattern 12 are reflected by the conductive pattern 12 and focused at the outdoor focal point F. By placing a repeater 50 at or near the focal point F, the focused radio waves with increased energy density are received and amplified by the repeater 50 and radiated outdoors.

[0094] As the conductive pattern 12 that reflects the incident radio waves, a planar pattern that realizes a light-concentrating reflector can be formed. The configuration in Figure 24 can prevent radio waves from entering indoors and effectively utilize the reflected radio waves outdoors, thereby improving the outdoor area.

[0095] The configuration shown in Figure 24 may be combined with the focus switching configurations of the second to fourth embodiments. In this case, the dielectric plate or movable plate may be placed on the indoor side. The presence or absence of the dielectric plate or movable plate, or the movement of the movable plate, reflects the incident radio waves to different focal points outdoors.

[0096] Although the present invention has been described above based on specific configuration examples, the present invention is not limited to the examples described above. The unit cell pattern is not limited to a cross pattern or its inverted pattern. As long as a periodic structure is obtained by repeating the pattern, any suitable pattern such as a crescent pattern, circular pattern, or wave pattern can be used. If a detachable dielectric plate is used, the dielectric plate may be detachably attached to the glass plate with a latch or the like. If a movable plate is used, it may be possible to switch between a first position close to the conductor pattern and a second position away from the conductor pattern using a switch or the like. When reflecting and focusing incident electromagnetic waves outdoors, a reflector may be placed at an appropriate location outdoors. In any case, a good indoor and outdoor communication environment can be established by radiating radio waves from an outdoor base station.

[0097] This application is based on the priority of Patent Application No. 2020-217939, filed with the Japan Patent Office on 25 December 2020, and Patent Application No. 2021-094723, filed with the Japan Patent Office on 4 June 2021, and incorporates, by reference, the entire contents thereof. [Explanation of symbols]

[0098] 1, 2, 3, 4, 5, 6 Wireless communication systems 10, 20, 30, 40, 70A, 70B Phase Adjustment Plate 11, 21, 31, 41 Base Conductor patterns 12, 22, 32, 42, 72A, 72B 13, 23, 33 Light-gathering pattern (second pattern) 23-1, 33-1 First focusing pattern (first conducting pattern) 23-2, 33-2 Second focusing pattern (second conducting pattern) 23-3, 33-3 Cross-sectional area 14 Unit Cell Pattern (Pattern 1) 24-1, 34-1 Unit Cell Pattern (First Unit Pattern) 24-2, 34-2 Unit Cell Pattern (Second Unit Pattern) 44-1, 44-2, 64-1, 64-2 Mesh Pattern 25 Dielectric Plate 35, 45 Movable plate 75 Adjustment plate 50, 50-1, 50-2 Repeater 100, 200, 300, 400, 700A, 700B glass plates 111, 211, 311 First main surface 112, 212, 312 Second main surface

Claims

1. A substrate having a first principal surface and a second principal surface facing each other, A conductive pattern provided on the first main surface of the substrate, A dielectric plate is detachably provided on the first main surface, It has, The substrate transmits electromagnetic waves incident from the second main surface to the first main surface. The conductor pattern focuses the incident electromagnetic wave towards a focal point on either the first or second main surface side. A phase adjustment plate in which the position of the focal point differs when the dielectric plate is attached and when the dielectric plate is removed.

2. A substrate having a first principal surface and a second principal surface facing each other, A conductive pattern provided on the first main surface of the substrate, A movable plate whose position relative to the conductor pattern is variable, It has, The substrate transmits electromagnetic waves incident from the second main surface to the first main surface. The conductor pattern focuses the incident electromagnetic wave towards a focal point on either the first or second main surface side. A phase adjustment plate in which the position of the focal point differs when the movable plate is in a first position relative to the conductor pattern and when it is in a second position different from the first position.

3. The phase adjustment plate according to claim 1 or 2, wherein the conductor pattern has a first pattern that is repeated at a predetermined period and a second pattern formed by the repetition of the first pattern.

4. The first pattern is a pattern of a size corresponding to the wavelength of the electromagnetic wave, The second pattern is an annular pattern formed by repeating the first pattern. The phase adjustment plate according to claim 3.

5. The phase adjustment plate according to any one of claims 1 to 4, wherein the conductor pattern includes a first conductor pattern that focuses the incident electromagnetic wave to a first focal point and a second conductor pattern that focuses the electromagnetic wave to a second focal point different from the first focal point.

6. The phase adjustment plate according to claim 5, wherein the first conductor pattern is formed by repeating a first unit pattern, and the second conductor pattern is formed by repeating a second unit pattern different from the first unit pattern.

7. The first unit pattern is the inverse pattern of the second unit pattern. The phase adjustment plate according to claim 6.

8. The phase adjustment plate according to claim 5, wherein the first conductor pattern focuses the electromagnetic wave of a first frequency to the first focal point, and the second conductor pattern focuses the electromagnetic wave of a second frequency different from the first frequency to the second focal point.

9. The substrate is a resin film. A phase adjustment plate according to any one of claims 1 to 8.

10. A phase adjustment plate according to any one of claims 1 to 9, A glass substrate supporting the phase adjustment plate, A glass plate having [something].

11. A window pane using the glass plate described in claim 10, A relay unit located on the indoor or outdoor side of the aforementioned window glass, A wireless communication system comprising a conductor pattern positioned on the indoor side, which collects radio waves radiated from an outdoor base station and incident on the window glass to the repeater.

12. A reflector that reflects radio waves emitted from the relay in a predetermined direction. The wireless communication system according to claim 11, further comprising:

13. The aforementioned radio waves are in the millimeter wave band. The wireless communication system according to claim 11 or 12.

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