WO2023223896A1 - 反射器 - Google Patents

反射器 Download PDF

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Publication number
WO2023223896A1
WO2023223896A1 PCT/JP2023/017441 JP2023017441W WO2023223896A1 WO 2023223896 A1 WO2023223896 A1 WO 2023223896A1 JP 2023017441 W JP2023017441 W JP 2023017441W WO 2023223896 A1 WO2023223896 A1 WO 2023223896A1
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WO
WIPO (PCT)
Prior art keywords
reflector
reflection
reflecting
length
radio waves
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Ceased
Application number
PCT/JP2023/017441
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English (en)
French (fr)
Japanese (ja)
Inventor
翔 熊谷
裕 宇井
眞平 長江
修 加賀谷
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AGC Inc
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Asahi Glass Co Ltd
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Priority to JP2024521691A priority Critical patent/JPWO2023223896A1/ja
Publication of WO2023223896A1 publication Critical patent/WO2023223896A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/14—Reflecting surfaces; Equivalent structures

Definitions

  • the present disclosure relates to a reflector.
  • a reflecting plate (wave shaping device) has a plurality of reflecting elements, and uses the coupling between the first resonant element and the second resonant element of each reflecting element to shape the radio wave and reflect it. It is described that the direction is adjusted (for example, see Patent Document 1).
  • a reflected wave that is reflected in the direction set as the reflection direction can be obtained in addition to the set reflection.
  • unnecessary reflection may occur in which a reflected wave is generated in an unnecessary direction that is not set as the reflection direction.
  • the reflector according to the embodiment of the present disclosure includes a plurality of reflecting plates each having a first length L1 in the first axial direction and a second length L2 in the second axial direction, and the plurality of reflecting plates an interval between adjacent reflectors of at least some of the plurality of reflectors arranged two-dimensionally along the axial direction and the second axis direction, capable of reflecting radio waves at angles other than specular reflection; is 0.5 ⁇ L1 or more in the first axial direction, or 0.5 ⁇ L2 or more in the second axial direction.
  • FIG. 2 is an explanatory diagram of the operation of the radio wave transmission system 10 in an embodiment of the present disclosure.
  • 1 is a block diagram showing an example of the configuration of a radio wave transmission system 10.
  • FIG. 3 is a diagram showing an example of a state in which the radio wave transmission system 10 is attached to a wall 6.
  • FIG. 1 is a diagram showing an example of the configuration of a reflector 100.
  • FIG. It is a figure showing an example of arrangement of a plurality of cells of reflector 100R.
  • FIG. 3 is a diagram illustrating an example of the principle of adjusting the reflection angle on a reflection plate 100R included in the reflector 100.
  • FIG. 3 is a diagram illustrating an example of the principle of adjusting the reflection angle on a reflection plate 100R included in the reflector 100.
  • FIG. 3 is a diagram showing an example of the configuration of a cell 110.
  • FIG. It is a figure which shows the state of the resonant element 112 in the on state and off state of PIN diode 112C. It is a figure which shows the state of the resonant element 112 in the on state and off state of PIN diode 112C. It is a figure explaining an example of unnecessary reflection in one reflection plate 100R. It is a figure which shows the distribution of ON and OFF when ON and OFF of each cell 110 of 100 R of reflection plates are set in a linear arrangement. It is a figure which shows an example of the simulation result of the angular distribution of the reflected wave of one reflection plate 100R.
  • FIG. 3 is a diagram showing a polar coordinate system used when calculating the radar reflection cross section ⁇ ( ⁇ , ⁇ ). 12 is a diagram showing how to take the angle ⁇ (horizontal angle) of the horizontal axis in FIG. 11.
  • FIG. It is a figure which shows the distribution of ON and OFF when ON and OFF of each cell 110 of 100 R of reflection plates are set in a nonlinear arrangement. It is a figure showing reflector 100 of an embodiment. It is a figure which shows the reflector 1 for comparison. It is a figure which shows the distribution of ON and OFF when ON and OFF of each cell 110 of 4 reflection plates 100R of the reflector 100 of embodiment are set in a nonlinear arrangement.
  • the direction parallel to the X axis (X direction), the direction parallel to the Y axis (Y direction), and the direction parallel to the Z axis (Z direction) are orthogonal to each other.
  • the X direction is an example of a first axis direction
  • the Y direction is an example of a second axis direction
  • the Z direction is an example of a third axis direction.
  • the ⁇ Z direction side may be referred to as the lower side or lower side
  • the +Z direction side may be referred to as the upper side or upper side.
  • planear view refers to viewing in the XY plane.
  • radio wave is a type of electromagnetic wave, and generally, electromagnetic waves of 3 THz or less are called radio waves.
  • electromagnetic waves emitted from outdoor base stations or relay stations will be referred to as “radio waves,” and when referring to electromagnetic waves in general, they will be referred to as “electromagnetic waves.”
  • millimeter wave or millimeter wave band includes not only the frequency band of 30 GHz to 300 GHz, but also the quasi-millimeter wave band of 24 GHz to 30 GHz.
  • the radio waves reflected by the reflector of the embodiment are preferably radio waves in the millimeter wave band of the fifth generation mobile communication system (5G), or in the frequency band of 1 GHz to 40 GHz, including Sub-6. Further, the radio waves reflected by the reflector of the embodiment may be LTE (Long Term Evolution), LTE-A (LTE-Advanced), or UMB (Ultra Mobile Broadband). In addition, the radio waves reflected by the reflector of the embodiment include 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). As the frequency of radio waves increases, propagation loss due to reflection and diffraction increases, and dead zones are more likely to occur. Therefore, the reflector of the embodiment is more suitable for communications that handle relatively high frequencies.
  • FIG. 1 is an explanatory diagram of the operation of a radio wave transmission system 10 according to an embodiment of the present disclosure.
  • the radio wave transmission system 10 of the present disclosure is placed, for example, on a wall or window of an outdoor building BD.
  • the radio wave transmission system 10 includes a reflector 100 (see FIG. 2), and the reflector 100 of the present disclosure is called a RIS (Reconfigurable Intelligent Surface) and can adjust the directivity of a beam. This is a directional control array.
  • the type of building BD in which the radio wave transmission system 10 is placed is arbitrary, it is, for example, a building in an area where there are many high-rise buildings. In areas where there are many high-rise buildings, dead zones (areas or spaces with poor communication environment, also known as ⁇ dead zones'') where radio waves do not reach properly are likely to occur.
  • the radio wave transmission system 10 of the present disclosure transmits radio waves to a dead area by controlling the direction of a reflected radio wave beam.
  • a wireless base station RB may be provided to perform wireless communication.
  • the radio base station RB converts a signal from a network (not shown) such as the Internet into a radio signal, and transmits radio waves R, so that a receiving terminal receives the radio waves R. Further, by receiving radio waves R transmitted by the receiving terminal at the radio base station RB, the receiving terminal can access a network such as the Internet.
  • the radio base station RB may be provided close to the radio wave transmission system 10 by several tens of centimeters to several meters, or may be provided several tens of meters to several kilometers away from the radio wave transmission system 10. Good too.
  • the radio wave transmission system 10 of the present disclosure changes the beam direction of the incident radio wave R, directs the beam in a specific direction and reflects it, or makes it into a multi-beam, thereby achieving a dead zone blocked by the building BD.
  • radio waves are plane waves unless otherwise specified.
  • the radio wave transmission system 10 it is possible to select an outdoor user terminal U1 and an outdoor user terminal U2 to communicate over the Internet. Specifically, for example, a radio wave R transmitted from the wireless base station RB at a certain time is reflected by the radio wave transmission system 10 and received by the user terminal U1 outdoors, thereby establishing wireless communication of the user terminal U1. can. The radio waves R transmitted from the radio base station RB at different times are reflected by the radio wave transmission system 10 and received by the user terminal U2 outdoors, thereby making it possible to establish radio communication with the user terminal U2.
  • FIG. 1 shows an example in which a wireless base station RB is provided in addition to the radio wave transmission system 10, even if the radio waves coming from a wireless relay station etc. are reflected by the reflector 100 of the radio wave transmission system 10, good.
  • FIG. 2 is a block diagram showing an example of the configuration of the radio wave transmission system 10.
  • FIG. 3 is a diagram showing an example of a state in which the radio wave transmission system 10 is attached to the wall 6.
  • FIG. 2 shows a state in which the reflector 100 directly reflects radio waves arriving from the wireless base station RB.
  • the radio wave transmission system 10 includes a reflector 100 and a control section 5.
  • the control unit 5 of the present disclosure is realized by, for example, an MCU (Micro Controller Unit), and includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), input/output Includes interfaces, internal buses, etc.
  • MCU Micro Controller Unit
  • CPU Central Processing Unit
  • RAM Random Access Memory
  • ROM Read Only Memory
  • the control unit 5 receives an incident wave source position (including the direction of arrival of a plane wave by setting it to infinity) and a reflection direction instruction (directivity instruction) from the outside, and controls the reflection angles of the plurality of cells of the reflector 100, respectively. Control. Inputs from outside the control unit 5 are input from, for example, a management computer (not shown) that manages the building BD, a wireless base station RB, and the like. Note that the control unit 5 operates based on a power supply voltage generated by a power generation unit (not shown).
  • the radio wave transmission system 10 (reflector 100 and control unit 5) is provided on the wall 6.
  • the height from the ground is preferably 1 m to 14 m, particularly preferably 2 m to 10 m, from the viewpoint of radio wave efficiency.
  • FIG. 3 shows an example in which the radio wave transmission system 10 is placed on the wall 6, the reflector 100 in the radio wave transmission system 10 may be placed on a window glass.
  • the substrate of the reflecting plate and the resonant element included in the reflector 100 are made of a transparent member having a visible light transmittance of 50% or more.
  • the control unit 5 may be placed at another location apart from the reflector 100, such as a wall adjacent to the window glass or a frame of the window glass. Good too.
  • the radio wave transmission system 10 of the present disclosure may be installed on an indoor wall or window glass. In that case, it contributes to reducing the dead zone indoors.
  • FIG. 4 is a diagram showing an example of the configuration of the reflector 100.
  • the reflector 100 includes, for example, four reflecting plates 100R.
  • the configuration of the four reflectors 100R is the same, and they are arranged at the four corners of a square area A of 2 m x 2 m, for example, with a certain distance between them. That is, the length of the reflector 100 in the X direction and the Y direction is, for example, 2 m in FIG. 4.
  • the length of the reflector 100 in the X direction and the Y direction is preferably 3 m or less, more preferably 2 m or less. For this reason, in FIG. 4, 2 m is shown as an example.
  • the reflector 100 may include a plurality of reflecting plates 100R, and the number of reflecting plates 100R can be any number as long as it is 2 or more. It may be.
  • the plurality of reflecting plates 100R included in the reflector 100 may be arranged with a certain distance between them.
  • Each of the plurality of reflecting plates 100R included in the reflector 100 as a RIS also functions as a RIS, and is a directivity control array that can adjust the directivity of the beam.
  • a configuration in which all the plurality of reflecting plates 100R included in the reflector 100 are arranged with a certain amount of space between each other will be described, but at least one of all the plurality of reflecting plates 100R Some of the reflecting plates 100R may be arranged with a certain distance between them.
  • a fifth reflector 100R may be provided at the center of the four reflectors 100R shown in FIG. 4 or at the center of the upper row.
  • the reflector 100 is a RIS that can reduce reflections in unnecessary directions (unnecessary reflections).
  • the configuration, operation, and unnecessary reflection of a plurality of reflecting plates 100R included in the reflector 100 will be explained.
  • FIG. 5 is a diagram showing an example of the arrangement of a plurality of cells of the reflection plate 100R. In the following, a case will be described in which vertically polarized radio waves are reflected in FIG. 5, but the same applies to horizontally polarized waves.
  • the reflector 100R has a plurality of regularly arranged cells 110.
  • the cells 110 are configured as repeating units, and in FIG. 5, for example, ten cells 110 are arranged in the X direction and the Y direction. This is because if ten cells 110 are arranged in each of the X direction and the Y direction, the reflection angle of the reflected wave can be adjusted.
  • the arrangement of the plurality of cells 110 is not limited to the array shown in FIG. 5, but may be arranged randomly (irregularly) without regularity.
  • Ten or more cells 110 are arranged in the X direction and the Y direction, and the number of cells 110 arranged in the X direction and the Y direction is preferably 130 or less, and more preferably 100 or less.
  • each cell 110 has resonant elements 111 and 112.
  • the cell 110 is an example of a reflective section
  • the resonant element 111 is an example of a first resonant element
  • the resonant element 112 is an example of a second resonant element.
  • the resonant element 111 is a resonant element that can resonate independently at a predetermined resonant frequency.
  • the resonant element 112 includes a switching element that can switch the resonant frequency to the first resonant frequency or the second resonant frequency by electrical control, but this is omitted in FIG. 5. Details of the cell 110 will be described later using FIG. 7.
  • the reflection plate 100R can set the angle at which the incident radio waves are reflected in a desired direction. Details of turning on and off the cell 110 will be described later using FIGS. 7 and 8, but a switching element that can switch the resonant frequency of the resonant element 112 to the first resonant frequency or the second resonant frequency by electrical control is used.
  • a state in which the cell 110 is turned on is a state in which the cell 110 is turned on
  • a state in which the switching element is turned off is a state in which the cell 110 is turned off.
  • FIG. 5 cells 110 that are on are shown in white, and cells that are off are shown as filled dots.
  • the cell may include a passive resonant element that obtains a pre-designed phase of the radio wave upon reflection.
  • FIGS. 6A and 6B are diagrams illustrating an example of the principle of adjusting the reflection angle at the reflection plate 100R included in the reflector 100.
  • the reflector 100R is an array called RIS (Reconfigurable Intelligent Surface: reconfigurable reflector) that can adjust the directivity of the beam.
  • RIS Reconfigurable Intelligent Surface: reconfigurable reflector
  • d is the pitch between adjacent cells 110 in the X direction.
  • FIGS. 6A and 6B in order to make it easier to understand how radio waves are incident and reflected in adjacent cells 110 on the XZ plane, the positions where the radio waves are incident on the reflective surface (surface on the +Z direction side) of the reflective plate 100R, The position where the light is emitted from the reflective surface is shown separately, shifted in the X direction.
  • the reflecting plate 100R adjusts the propagation direction of the beam, which is the reflected wave, by changing the phase of the radio wave when reflecting the radio wave in each of the plurality of cells 110 arranged in an array.
  • the radio waves are By setting the amount by which the phase is changed (phase change amount) when reflecting radio waves for each cell 110, the direction in which radio waves are reflected by all the cells 110 included in one reflector 100R can be adjusted.
  • the reflection direction is changed by adding a phase to each cell 110. That is, by adding a phase to each location X of the reflector 100R, the direction of reflection of the radio wave can be changed.
  • a radio wave emitted from a point F at coordinates (Xf, Yf, Zf) is incident on a point at coordinates (X, Y, 0) on the reflective surface of the reflector plate 100R, and is reflected.
  • the amount of phase change ⁇ (X, Y) applied to the radio wave on the reflective surface of the reflector plate 100R when reaching the point P of (Xp, Yp, Zp) can be expressed by the following equation (1) .
  • the constant k is 2 ⁇ / ⁇
  • ⁇ is the wavelength of radio waves in free space (free space wavelength).
  • the coordinates (Xp, Yp, Zp) are called a focal point in the sense of a point where radio waves are collected in order to receive them.
  • Equation (1) the distribution of the amount of phase change is nonlinear with respect to the coordinates X and Y on the reflective surface. If point F and point P are sufficiently far from the reflective surface, equation (1) can be approximated as a linear equation with respect to the coordinates X and Y on the reflective surface.
  • FIG. 6B also shows radio waves that are incident on adjacent cells 110 at a pitch d in the X and Y directions at a zenith angle ⁇ in and an azimuth angle ⁇ in, and are reflected by the reflector 100R in the direction of a zenith angle ⁇ out and an azimuth angle ⁇ out.
  • This shows how the radio waves seen in the XZ plane.
  • the zenith angle and the azimuth angle are represented by the zenith angle ⁇ and the azimuth angle ⁇ in FIG. 12A, which will be described later.
  • the radio waves incident on adjacent cells 110 at pitch d are parallel, and the incident angles are both zenith angle ⁇ in and azimuth angle ⁇ in
  • the radio waves reflected by the reflection surface of the reflection plate 100R are also parallel, and the reflection angles are both the zenith angle ⁇ out and the azimuth angle ⁇ out.
  • the phase difference between radio waves incident on adjacent cells 110 at pitch d is, for example, d ⁇ sin ⁇ in ⁇ cos ⁇ in in the X direction
  • the phase difference between radio waves reflected by adjacent cells 110 at pitch d is d ⁇ sin ⁇ out. ⁇ cos ⁇ out.
  • the phase difference between radio waves incident on adjacent cells 110 at pitch d is, for example, d ⁇ sin ⁇ in ⁇ sin ⁇ in in the Y direction
  • the phase difference between radio waves reflected by adjacent cells 110 at pitch d is, for example, d ⁇ sin ⁇ in ⁇ sin ⁇ in.
  • the phase difference is d ⁇ sin ⁇ out ⁇ sin ⁇ out.
  • equation (2) is obtained by approximating equation (1) using the zenith angle ⁇ in and azimuth angle ⁇ in of incidence and the zenith angle ⁇ out and azimuth angle ⁇ out of reflection, and ignoring constant terms that do not depend on X and Y. .
  • phase difference during reflection between the on state and the off state is approximately 180. If the amount of phase change ⁇ (X,Y) is between -90° and 90°, it will be in the off state, and if it is between -180° and -90° or 90° and 180°, it will be in the on state. By taking , the amount of phase change ⁇ (X, Y) can be approximately realized, and as a result, the reflection direction in each cell 110 can be changed. This holds true in both equations (1) and (2).
  • Selection of the on state and the off state from the above-mentioned phase change amount ⁇ (X, Y) is just an example, and it is sufficient to select the on state and the off state within a range of 180 degrees that do not overlap each other. For example, from 20° to 180° or from -180° to -160° may be an off state, and from -160° to 20° may be an on state.
  • the radio wave transmission system 10 can change the direction of the radio waves emitted from a 5G base station, etc., direct the beams in various directions or any desired direction, or make them into multi-beams. You can also.
  • FIGS. 6A and 6B show radio waves reflected within the XZ plane, as described above, the reflector 100 can reflect radio waves within the YZ plane, or Radio waves can be similarly reflected when reflected within a plane having an angle to the YZ plane. Therefore, the reflector 100 becomes a reflector whose reflection angle can be set to an angle other than specular reflection.
  • the on or off state of all the cells 110 changes in the X direction within each row, and 10 cells arranged in the Y direction within each column are shown. 110 is uniformly on or off. This corresponds to determining the on state and off state based on equation (2), and since it is determined based on the linear phase distribution for X and Y, it can be called a linear arrangement. do.
  • the arrangement of the cells 110 in the reflector 100R shown in FIG. 5 is an example, and the number of cells 110 provided in the array may be approximately several tens to several thousand.
  • FIG. 7 is a diagram showing an example of the configuration of the vertically polarized cell 110.
  • the cell 110 has one resonant element 111 and one resonant element 112 adjacent to the one resonant element 111.
  • FIG. 7 shows a substrate 101.
  • the substrate 101 is the substrate 101 of the reflecting plate 100R (see FIG. 4), and one reflecting plate 100R includes one substrate 101.
  • the size of the substrate 101 in plan view is the size shown in FIG. 4 as a reflection plate 100R.
  • a ground layer is provided on the surface of the substrate 101 on the ⁇ Z direction side.
  • the reflector 100R includes a plurality of cells 110.
  • FIG. 7 shows a portion of the entire substrate 101 that corresponds to one cell 110.
  • the cell 110 for horizontal polarization has a configuration obtained by rotating the cell 110 shown in FIG. 7 by 90 degrees clockwise or counterclockwise.
  • one reflecting plate 100R includes one substrate 101
  • a configuration in which one reflecting plate 100R includes a plurality of substrates 101 may be used. That is, one substrate 101 may be provided for one or more cells 110 in one reflecting plate 100R.
  • the substrate 101 is, for example, a rectangular substrate in plan view.
  • the substrate 101 is, for example, a flexible resin-made thin film-like flexible substrate, or a non-flexible rigid substrate. Flexibility is the property of an object to bend without breaking, as can be seen from its appearance.
  • a flexible substrate for example, fluororesin, COP (Cyclo-Olefin Polymer), PET (Polyethylene terephthalate), PEN (Polyethylene Naphthalate), polyimide, Peek (Polyether ether Ketone), LCP (Liquid Crystal Polymer) is used. ), other composite materials, and other flexible resin materials.
  • COP Cyclo-Olefin Polymer
  • PET Polyethylene terephthalate
  • PEN Polyethylene Naphthalate
  • polyimide Polyimide
  • Peek Polyether ether Ketone
  • LCP Liquid Crystal Polymer
  • other composite materials for example, a substrate made of a prepreg made of glass cloth impregnated with an epoxy resin or the like and
  • the substrate 101 may be formed of any material that is transparent to radio waves emitted from an outdoor base station or the like.
  • Transparent means that the transmittance is at least 40% or more, preferably 60% or more, more preferably 70% or more, and still more preferably 80% or more.
  • a transparent resin base material is used for the substrate 101.
  • acrylic resin such as polymethyl methacrylate, COP, polycarbonate resin, PET, etc. can be used.
  • the substrate 101 may be a glass plate.
  • Resonant elements 111 and 112 are formed of metal layers.
  • the metal layer can be formed of a metal thin film such as copper, nickel, or gold, if the substrate 101 is not formed of any material transparent to radio waves.
  • the metal layer may be made of, for example, zinc oxide (ZnO), tin oxide (SnO 2 ), tin-doped indium oxide (ITO), or It is formed of a transparent conductive film such as indium tin oxide (IZO), a metal nitride such as titanium nitride (TiN) or chromium nitride (CrN), or a low-e film for low emissivity glass. is desirable.
  • the metal layer may be made of a mesh-like metal thin film of copper, nickel, gold, or the like, for example.
  • the resonant element 111 is a square conductor in plan view.
  • the resonant element 111 has an end side 111A extending along the X direction on the +Y direction side.
  • a resonant element 112 is parasitic to the resonant element 111 . Since the resonant element 112 is coupled to and parasitic to the resonant element 111 by electromagnetic coupling, the resonant element 111 may be regarded as a main resonant element and the resonant element 112 as a parasitic resonant element.
  • the resonant element 112 includes linear elements 112A and 112B and a PIN (p-intrinsic-n) diode 112C.
  • the PIN diode 112C is an example of a switching element.
  • Linear elements 112A and 112B extend parallel to the X direction.
  • the linear element 112A is arranged on the +Y direction side of the end side 111A of the resonant element 111, and the linear element 112B is arranged on the +Y direction side of the linear element 112A.
  • a PIN diode 112C is provided between the linear elements 112A and 112B.
  • a cathode of a PIN diode is connected to the linear element 112A
  • an anode of a PIN diode 112C is connected to the linear element 112B.
  • RF chokes 113 and 114 are provided at the ends of the linear elements 112A and 112B on the ⁇ X direction side.
  • the RF choke 113 is connected to a ground layer of a ground potential (GND) on the back surface of the substrate 101, and the RF choke 114 is connected to a control terminal to which a control voltage BV is applied.
  • the control voltage BV is applied from the control section 5 (see FIG. 2).
  • the distance between the end side 111A of the resonant element 111 and the linear element 112A is preferably ⁇ e/10 or less, for example. ⁇ e/30 is more preferable. ⁇ e is the electrical length of the wavelength at the frequency of the radio wave reflected by the reflection plate 100R.
  • the length of the region in which the resonant elements 111 and 112 are provided in one cell 110 in the X direction and the Y direction in plan view is 2 ⁇ or less.
  • a square resonant element 111 is shown in FIG. 7, if the dimensions in the X and Y directions are not constant, such as when the resonant element 111 is elliptical, the The maximum length in the X direction and the maximum length in the Y direction in plan view of the region where the resonant elements 111 and 112 are provided need only be 2 ⁇ or less.
  • FIGS. 8A and 8B are diagrams showing the states of the resonant element 112 in the on state and off state of the PIN diode 112C.
  • the linear element 112B is connected to the linear element 112A, so as shown in FIG. 8A, the resonant element 111 Then, the linear elements 112A and 112B of the resonant element 112 are in a coupled state.
  • the state in which the linear elements 112A and 112B of the resonant element 112 are coupled to the resonant element 111 as shown in FIG. 8A has a higher resonance than the state in which only the linear element 112A is coupled to the resonant element 111 as shown in FIG. 8B.
  • the length of the element 112 increases and the shape changes. Therefore, when the PIN diode 112C is turned on as shown in FIG. 8A, the resonant frequency of the resonant element 112 is lowered to the first resonant frequency than when the PIN diode 112C is turned off. On the contrary, when the PIN diode 112C is turned off as shown in FIG.
  • the resonant frequency of the resonant element 112 increases to the second resonant frequency compared to when the PIN diode 112C is on. It is known that when two resonant elements having approximately the same resonant frequency are placed close to each other, their reflection characteristics change due to interaction. When the resonant frequency of the resonant element 111 is approximately the same as either the first resonant frequency or the second resonant frequency of the resonant element 112, the resonant elements 111 and 112 are switched on and off by switching the PIN diode 112C on and off. By changing the overall shape (or length), the reflection characteristics of the cell 110 change.
  • the size of the resonant elements 111 and 112 is set so that the absolute value of the amount of phase change given to the radio wave as an incident wave is approximately 180 degrees when the PIN diode 112C is off and on.
  • linear elements 112A and 112B of the resonant element 112 are set.
  • About 180 degrees means, for example, a value within the range of 180 degrees ⁇ 45 degrees. Since the resonant elements 111 and 112 are made of conductors, there may be errors in the amount of phase change due to manufacturing errors, etc. However, by switching the PIN diode 112C on and off, the amount of phase change can be adjusted to approximately 180 degrees (180 degrees ⁇ 45 degrees).
  • Specular reflection refers to regular reflection, and refers to reflection in a direction in which an equal phase plane is generated by reflection by ordinary metal reflection.
  • the reflection plate 100R can switch the reflection angle (reflection direction) of the incident wave on the reflection plate 100R as a set of all cells 110 by turning on and off the PIN diode 112C of each cell 110. That is, in the reflector 100R, the control unit 5 can control the amount of phase change in a binary manner by switching on and off the PIN diode 112C of each cell 110, and the reflection angle can be changed to an angle other than specular reflection. Adjustable. Note that the reflection angle of the reflection plate 100R can also be adjusted to the angle of specular reflection.
  • the phase change amount of the cell 110 is 30 degrees when the PIN diode 112C is turned off, and the phase change amount of the cell 110 is 210 degrees when the PIN diode 112C is turned on. It can be controlled in a binary manner.
  • the phase change amount of 30 degrees is an example of the first value
  • the phase change amount of 210 degrees is an example of the second value.
  • the difference between the amount of phase change when the PIN diode 112C is off and the amount of phase change when it is on is approximately 180 degrees (180 ⁇ 45 degrees) in absolute value. That is, the difference between the first value and the second value of the amount of phase change is 180 ⁇ 45 degrees in absolute value.
  • the difference in phase change amount of all cells 110 is 0 degree. In reality, there is some variation, so the difference in the amount of phase change is about 0 degrees. This also applies when the PIN diodes 112C of all the cells 110 are turned on.
  • the amount of phase change of all the cells 110 (for example, 30 degrees and 210 degrees) The difference is 180 degrees. In reality, since there is some variation, the difference in the amount of phase change is about 180 degrees.
  • the resonant element 111 has a square shape and the resonant element 112 has a PIN diode 112C between two linear elements 112A and 112B.
  • the shape of the resonant element 111 is not limited to a square shape, and may have any planar shape as long as it can reflect radio waves.
  • the resonant element 112 may have any configuration as long as its shape and length can be changed by being switched by the control unit 5.
  • the diode 112C is not limited to the PIN diode 112C, and may be a transistor such as a MEMS (Micro Electro Mechanical Systems) switch, a varactor, or a FET (Field Effect Transistor).
  • FIG. 9 is a diagram illustrating an example of unnecessary reflection on one reflecting plate 100R.
  • FIG. 10 is a diagram showing the distribution of on and off states when the on and off states of each cell 110 of the reflector plate 100R are set in a linear arrangement.
  • FIG. 10 shows, as an example, the on/off distribution in the reflection plate 100R including 40 cells 110 in the X direction and the Y direction, for a total of 1600 cells.
  • FIG. 10 shows the distribution of ON and OFF in a linear arrangement, and in FIG. 10, ON is shown in white and OFF is shown in black for simplification.
  • the amount of phase change that the cell 110 that is on adds to the reflected wave is 180 degrees
  • the amount of phase change that the cell 110 that is off adds to the reflected wave is 0 degrees.
  • FIG. 9 shows 1600 cells 110 arranged in the X direction and 40 in the Y direction as shown in FIG. 10, which are turned on and off in a linear arrangement. This shows the reflected wave obtained for the incident wave when .
  • a predetermined reflection direction set in advance on the reflection plate 100R will be referred to as a set reflection direction.
  • the radio waves When unnecessary reflection occurs, the radio waves are also reflected in a direction different from the set reflection direction, so the radio waves may be reflected toward an unexpected user terminal, wireless relay station, or wireless base station. Also, since unnecessary reflections occur in the direction opposite to the set reflection direction with respect to the direction of the incident wave, if the set reflection direction is set in the direction of unnecessary reflections in FIG. The relationship is such that the directions of unnecessary reflections are exchanged, and unnecessary reflections occur in the set reflection direction in FIG. For this reason, a situation may arise in which it becomes difficult to distinguish between set reflections and unnecessary reflections.
  • the azimuth angles ⁇ in, ⁇ out, and ⁇ out,set can all be considered to be zero.
  • the reflection angle ⁇ out of the reflected wave is expressed as the following equation (3).
  • ⁇ in is the incident angle
  • ⁇ out,set is the reflection angle representing the set reflection direction.
  • the set incident angle was set to be equal to the incident angle.
  • Equation (3) shows that when the incident angle is ⁇ in, the reflection angle of set reflection is ⁇ out,set, and the reflection angle of unnecessary reflection is arcsin[sin ⁇ out,set+2sin ⁇ in].
  • FIG. 11 is a diagram showing an example of a simulation result of the angular distribution of reflected waves of one reflecting plate 100R.
  • the horizontal axis represents the reflection angle (degrees)
  • the vertical axis represents RCS (radar reflection cross section) (dBm 2 ).
  • the reflective plate 100R used in the simulation was arranged so that the reflective surface of the cell 110 was in the XY plane.
  • the cells 110 of the reflector 100R have a length of dX in the X direction and dY in the Y direction.
  • NX cells 110 are arranged at equal intervals of dX in the X direction
  • NY cells 110 are arranged at equal intervals of dY in the Y direction. That is, the number of cells 110 is NX ⁇ NY, the length of the reflecting plate 100R in the X direction is NX ⁇ dX, and the length in the Y direction is NY ⁇ dY.
  • the row number of the cell 110 in the X direction as n
  • the column number of the cell 110 in the Y direction as m
  • the number of the cell 110 can be specified by n and m.
  • the radar reflection cross section ⁇ ( ⁇ , ⁇ ) was determined using the following equation (4).
  • a polar coordinate system shown in FIG. 12A was used.
  • FIG. 12A is a diagram showing a polar coordinate system used when calculating the radar reflection cross section ⁇ ( ⁇ , ⁇ ).
  • the center of the reflective surface of the reflective plate 100R is located at the origin of the XYZ coordinates.
  • the zenith angle ⁇ is an angle with respect to the +Z direction, and the angle downward from the +Z direction as shown by the arrow is positive.
  • the azimuth angle ⁇ is an azimuth angle with respect to the +X direction in the XY plane, and the angle from the +X direction to the +Y direction as shown by the arrow is positive.
  • r is the radius vector.
  • FIG. 12A shows reception point G.
  • a receiving point G represents the position of a receiving terminal that receives radio waves from the reflector 100R.
  • the receiving terminal is a user terminal or the like.
  • r is the distance (m) from the reflection plate 100R to the receiving point G, and is the vector radius in the polar coordinate system.
  • P0 is the power density (W/m 2 ) of a radio wave (incident wave) that is incident on the reflection plate 100R.
  • Pr is the power density (W/m 2 ) at the reception point G.
  • the electric field E at the point (X, Y) of the radius vector r can be calculated using the following equation (5).
  • A is the distribution of the complex electric field immediately after being reflected from the RIS
  • s is the distance between the position on the reflection plate 100R and the receiving point
  • Q is the electric field reflection intensity distribution for each reflection direction of the cell. Note that RIS means that integration is performed over the entire reflection plate 100R.
  • Equation (5) the size of the cell 110 is used for discretization, and the position of the cell 110 is specified using n and m.
  • the radar reflection cross section ⁇ ( ⁇ , ⁇ ) expressed by equation (4) can be determined.
  • the radar reflection cross section ⁇ ( ⁇ , ⁇ ) as shown in FIG. 11 consider the incidence and output of radio waves in the XZ plane as an example, and the angle ⁇ in the polar coordinate system shown in FIG. 12B. was used.
  • calculations are performed at a distance r (1000 m in this example), which is very large relative to the size of the reflector.
  • FIG. 12B is a diagram showing how to take the angle ⁇ (horizontal angle) of the horizontal axis in FIG. 11.
  • the angle ⁇ is an angle with respect to the +Z direction in the Represents direction as a negative angle. Note that the method of determining the vector radius r is the same as the method of determining the vector radius r in FIG. 12A.
  • the radar reflection cross section ⁇ ( ⁇ , ⁇ ) calculated according to equation (4) with respect to the angle ⁇ is obtained using the angle ⁇ shown in FIG. 12B
  • the angular distribution shown in FIG. 11 is obtained.
  • the radar reflection cross section ⁇ ( ⁇ , ⁇ ) is shown as RCS.
  • each cell 110 is set on and off in a linear arrangement and the amount of phase change is controlled in a binary manner, unnecessary reflections will occur that are equivalent to the intensity of the set reflected radio waves.
  • the reflector 100 of the embodiment can reduce such unnecessary reflections.
  • This embodiment provides a reflector 100 (see FIG. 4) that can reduce unnecessary reflections while controlling the phase change amount of the cell 110 in a binary manner. A method for reducing unnecessary reflections will be described below.
  • a state in which the reflector 100 forms a plane wave is a state in which the cell arrangement is determined by equation (2)
  • a state in which the reflector 100 is a plane wave is a state in which the cell arrangement is determined by equation (1).
  • FIG. 13 shows the on/off distribution when the on/off states of each cell 110 of the reflector plate 100R are set in a nonlinear arrangement so that an incident wave with ⁇ of 0 degrees is reflected at ⁇ of 25 degrees. It is a diagram.
  • a non-linear arrangement means that when determining whether cells 110 are on or off based on formula (1), the number of cells 110 that matches the number of cells 110 when determining whether cells 110 are on or off based on formula (2) is This is the arrangement that makes up 90% or less of the total.
  • FIG. 13 shows, as an example, the on/off distribution in the reflector plate 100R including 40 cells 110 in the X direction and the Y direction, for a total of 1600 cells 110.
  • ON is shown in white and OFF is shown in black.
  • the amount of phase change that the cell 110 that is on adds to the reflected wave is 180 degrees
  • the amount of phase change that the cell 110 that is off adds to the reflected wave is 0 degrees.
  • each cell 110 shown in FIG. 13 compared to the on and off distribution shown in FIG.
  • the boundary between the area with many on and the area with many off is curved into an arc.
  • an arcuate boundary appears as the boundary between an area with many ons and an area with many offs when the ons and offs are arranged in a nonlinear manner. be.
  • each cell 110 of the reflector 100R shown in FIG. 10 is turned on and off when the focal length is 100 m, and the cells are set in a linear arrangement, so that the reflected waves are plane waves.
  • the focal length of the reflected wave is, for example, 10 m. Note that FIG. 13 shows a form in which the boundary between on and off is curved in an arc shape.
  • the azimuth angle ⁇ of the incident wave is 0 degrees
  • the zenith angle ⁇ is 0 degrees
  • the azimuth of the reflected wave is If the angle ⁇ is 45 degrees and the zenith angle ⁇ is 40 degrees, it may not be possible to recognize the boundary between on and off as a clear arc, but even in such a case, it is not a linear arrangement. There is something called a nonlinear arrangement.
  • each cell 110 of the reflector 100R shown in FIG. 10 is set in a linear arrangement, the angle ⁇ will be +25 degrees and -25 degrees as shown in FIG. 11 with respect to the incident wave from the +Z direction. Since reflected waves occur in two directions, if you look only at the reflected waves without knowing the set reflection direction, you cannot distinguish which is the set reflection and which is the unnecessary reflection. On the other hand, as shown in FIG. 13, if each cell 110 is turned on and off in a nonlinear arrangement, a reflected wave with an angle ⁇ of +25 degrees is obtained with respect to the incident wave from the +Z direction, and - Reflected waves (unnecessary reflections) in the 25 degree direction are suppressed.
  • FIG. 14A is a diagram showing the reflector 100 of the embodiment.
  • FIG. 14B is a diagram showing the reflector 1 for comparison.
  • the reflector 100 shown in FIG. 14A is the same as the reflector 100 shown in FIG. 4, and includes four reflecting plates 100R as an example.
  • the four reflecting plates 100R are arranged with a certain distance Dw between them in the X direction and the Y direction.
  • the length L1 in the X direction of each reflecting plate 100R is, for example, 40 cm or less
  • the length L2 in the Y direction is, for example, 40 cm or less.
  • the length L1 and the length L2 are preferably within the range of 10 cm to 40 cm.
  • the length of the cell 110 in the X direction and the Y direction in plan view is 0.5 ⁇ , and there are 40 cells 110 in each of the X direction and the Y direction. If they are arranged, the length L1 and the length L2 will be about 20 cm.
  • the state in which a certain distance Dw is left between each other means that the distance Dw between adjacent reflecting plates 100R is, for example, 0.5 ⁇ L1 or more in the X direction and 0.5 ⁇ L2 or more in the Y direction. It means that.
  • the comparative reflector 1 shown in FIG. 14B includes four reflectors 100R like the embodiment reflector 100 shown in FIG. This differs from the reflector 100 of the embodiment in that the reflectors 100 are arranged closely spaced without leaving an interval Dw between them.
  • FIG. 15A is a diagram showing the on/off distribution when the on/off states of each cell 110 of the four reflecting plates 100R of the reflector 100 of the embodiment are set in a nonlinear arrangement.
  • FIG. 15B is a diagram showing the on/off distribution when the on/off states of each cell 110 of the four reflecting plates 100R of the comparative reflector 1 are set in a nonlinear arrangement.
  • each cell 110 of the four reflectors 100R are set so that the boundaries between areas with many ON states and areas with many OFF states are distributed along a plurality of circular arcs C1, C2, and C3.
  • the boundary between the area with many ON and the area with many OFF may be located on the arcs C1, C2, and C3, or may be slightly deviated from the arcs C1, C2, and C3.
  • the arcs C1, C2, and C3 are concentric circles, they may not be concentric circles.
  • the ON and OFF states of each cell 110 of the four reflecting plates 100R of the comparative reflector 1 are distributed along the curved boundaries C11 and C12 between the area with many ON and the area with many OFF.
  • the on and off distributions are close to linear, so the center of the circle including the boundaries C11 and C12 is set to +X of the four reflectors 100R. It is difficult to tell whether it is on the direction side or the -X direction side.
  • a near-linear distribution means that when compared with the arrangement determined based on equation (2), there is a high proportion of cells in each position whose on and off states are the same.
  • FIG. 16 is a diagram showing an example of the calculation results of the RCS of the set reflection and unnecessary reflection in the reflector 100 of the embodiment and the comparative reflector 1.
  • the above-mentioned equation (4) is transformed as shown in the following equation (7).
  • the radar reflection cross section ⁇ (r, ⁇ , ⁇ ) as the near-field RCS was determined according to equation (7).
  • the near-field RCS coincides with the RCS defined by equation (4) when observed at a sufficiently far distance.
  • Equation (7) shows that the point where the distance r (radius r) from the reflector 100R to the receiving point G (see FIG. 12A) is set to the distance to the place that receives the reflected wave from the reflector, such as the user terminal, is the distance. This is different from equation (4), which sets r to infinity ( ⁇ ). Equation (7) eliminates the influence of distance attenuation due to radio wave propagation, and is convenient for comparing the effect of the reflector in the intensity of radio waves received by the user terminal.
  • FIG. 16 shows the near-field RCS of the set reflection and unnecessary reflection in the reflector 100 of the embodiment and the comparative reflector 1, and the ratio of the near-field RCS of the set reflection and unnecessary reflection.
  • the frequency of the radio waves was set to 28 GHz, as an example.
  • Dw was set to 400 mm (2 ⁇ L1).
  • the distance D from the reflector 1 to the terminal is the distance from the center of the four reflecting plates 100R included in the reflector 1 to the focal point of the reflected wave.
  • the centers of the four reflectors 100R are located at the centers of the four reflectors 100R shown in FIG. 4 in the XY plane, and are located at the same position as the reflective surfaces of the four reflectors 100R in the Z direction. Further, the focal length Df of the reflector 100 and the reflector 1 was set to 40 m. This is a setting for propagating radio waves to a terminal where the distance D from the reflector 1 to the terminal is 40 m.
  • the focal length Df of the reflector 100 is the distance from the center of the four reflecting plates 100R included in the reflector 100 to the focal point of the reflected wave.
  • the focal length Df of the reflector 1 is the distance from the center of the four reflecting plates 100R included in the reflector 1 to the focal point of the reflected wave.
  • the near field RCS of the set reflections of the reflector 100 of the embodiment and the comparative reflector 1 were both 29.7 dBm 2 .
  • the near-field RCS of unnecessary reflection of the reflector 100 of the embodiment was 27.7 dBm 2
  • the near-field RCS of unnecessary reflection of the comparative reflector 1 was 29.4 dBm 2 .
  • a lower value was obtained for the near-field RCS of the unnecessary reflection of the reflector 100 of the embodiment, and the ratio to the near-field RCS of the set reflection was 2 dB.
  • the near-field RCS of the unnecessary reflection of the comparative reflector 1 had a value equivalent to the RCS of the set reflection of the comparative reflector 1, and the ratio was 0.3 dB.
  • the ratio of the set reflection to the unnecessary reflection can be maintained at 1 dB or more up to a distance D of 60 m from the reflector 1 to the terminal.
  • the reflector 100 of the embodiment in which the spacing between adjacent reflectors 100R is set to 0.5 ⁇ L1 or more in the X direction and 0.5 ⁇ L2 or more in the Y direction the reflectors 100R are arranged closely together. It was found that unnecessary reflections can be reduced compared to the comparative reflector 1.
  • W is the length of the reflector 100R in the X direction
  • Dw is the distance between two adjacent reflectors 100R in the X direction
  • ds be the distance representing the position of the boundary between the far field and the near field in
  • dr be the distance representing the position of the boundary between the far field and the near field between the reflector 100 and the receiving terminal.
  • the length W of the reflection plate 100R in the X direction is the same as the length L1 described above.
  • the relationship between the size of the reflector 100 and the maximum distance at which the reflector 100 can create a focal point satisfies the following equation (8).
  • the size of the reflector 100 in the case of the reflector 100 including four reflecting plates 100R as shown in FIG. 4, the length in the X direction is 2W+Dw.
  • the length in the X direction of the size of the reflector 100 will be explained, but the same applies to the length in the Y direction.
  • the lengths of each reflecting plate 100R in the X direction and the Y direction are equal, and the intervals between two adjacent reflecting plates 100R in the X direction and the Y direction are also equal, so the length in the Y direction is also equal. It is 2W+Dw.
  • the distance dr determined by equation (8) represents the position of the boundary between the far field and the near field in the reflection direction (+Z direction) of the reflector 100, so it is a distance that becomes a guideline for unnecessary reflections to become indistinguishable from set reflections. be.
  • An area within the distance dr from the reflector 100 in the Z direction is a near field, and is an area where the focus of the reflector 100 can be set.
  • An area farther from the reflector 100 than the distance dr is a far field, and is an area where the focus of the reflector 100 cannot be set.
  • the distance dr for the comparative reflector 1 is approximately 27 m.
  • the distance dr for the reflector 100 of the embodiment is about 108 m.
  • the distance dr (108 m) of the reflector 100 of the embodiment is longer than the focal length Df (40 m), and the distance dr (27 m) of the comparative reflector 1 is shorter than the focal length Df (40 m). Under these conditions, it was found that the reflector 100 of the embodiment reduces unnecessary reflections more than the comparative reflector 1.
  • unnecessary reflections are considered to have been reduced because the focal length Df was under the condition of entering the near field (Df ⁇ dr). In other words, it is considered that unnecessary reflections were reduced because the focal length Df was shorter than the distance dr.
  • the set focal length Df was a condition for entering the far field, and it is considered that unnecessary reflections were not reduced because the focal length Df was longer than the distance dr.
  • the reflector 100 can reduce unnecessary reflections by arranging the four reflectors 100R with a certain distance Dw between them in the X direction and the Y direction.
  • both the incident angle ⁇ in and the reflection angle ⁇ out are 60 degrees or less, which represents the position of the boundary between the far field and the near field between the reflector 100 and the receiving terminal.
  • the distance dr is 200 m.
  • the length (2W+Dw) of the reflector 100 in the X and Y directions is 3 m.
  • the interval is not too large, and specifically, it is preferably 3 m or less, and more preferably 2 m or less. For this reason, in FIG. 4, the distance is indicated as 2 m.
  • the four reflectors 100R function similarly to Fresnel zones of a Fresnel lens.
  • the focal length Df may be set so as to satisfy Df ⁇ 2X1 2 / ⁇ .
  • FIG. 17 is a diagram showing an example of calculation results of near-field RCS of set reflections and unnecessary reflections in the reflector 100 of the embodiment and the comparative reflector 1.
  • FIG. 17 shows an example of calculation results under the calculation conditions of part 2.
  • the calculation conditions for part 2 are the calculation conditions for part 1, except that the focal length Df of reflector 100 and reflector 1 is changed from 40 m to 20 m.
  • the conditions other than the focal length Df are the same as the calculation conditions in Part 1.
  • the RCS of the set reflection of the reflector 100 of the embodiment was 29.3 dBm2
  • the near-field RCS of the set reflection of the comparative reflector 1 was 29.7 dBm2 .
  • the RCS of the set reflection of the reflector 100 of the embodiment was a slightly lower value, it was approximately the same value.
  • the near-field RCS of unnecessary reflection of the reflector 100 of the embodiment was 25.3 dBm2, and the near-field RCS of unnecessary reflection of the comparative reflector 1 was 29.3 dBm2.
  • a lower value was obtained for the RCS of the unnecessary reflection of the reflector 100 of the embodiment, and the ratio to the RCS of the set reflection was 4 dBm 2 .
  • the near-field RCS of the unnecessary reflection of the comparative reflector 1 had a value equivalent to the near-field RCS of the set reflection of the comparative reflector 1, and the ratio was 0.4 dBm2 .
  • the distance dr (108 m) of the reflector 100 of the embodiment is longer than the focal length Df (20 m), and the distance dr (27 m) of the reflector 1 for comparison is the focal length Df (20 m). ), it was found that the reflector 100 of the embodiment reduces unnecessary reflections more than the comparative reflector 1.
  • Unwanted reflections are significantly reduced compared to the simulation results in Part 1, and it is thought that unnecessary reflections are further reduced compared to the simulation results in Part 1 because the focal length Df is sufficiently short compared to the distance dr. . In other words, it is considered that unnecessary reflections were effectively reduced because the focal length Df was sufficiently shorter than the distance dr.
  • the set focal length Df is a condition that is almost the boundary between the near field and the far field, and the distance dr is almost the same as the focal length Df, so the amount of reduction of unnecessary reflections is It is thought that the amount was small.
  • the reflector 100 can reduce unnecessary reflections by arranging the four reflectors 100R with a certain distance Dw between them in the X direction and the Y direction. Do you get it.
  • the reflector 100 includes a plurality of reflection plates 100R having a length L1 in the X direction and a length L2 in the Y direction, and the plurality of reflection plates 100R are two-dimensionally arranged along the X direction and the Y direction, Radio waves can be reflected at angles other than specular reflection, and the interval between adjacent reflectors of at least some of the plurality of reflectors 100R is 0.5 ⁇ L1 or more in the X direction and 0 in the Y direction. .5 ⁇ L2 or more. In this way, unnecessary reflections in the reflector 100 can be reduced by arranging at least some of the plurality of reflection plates 100R with a certain distance between them.
  • the distance between adjacent reflectors is such that the distance between adjacent reflectors of at least some of the plurality of reflectors 100R is 0.5 ⁇ L1 or more in the X direction, and the distance between at least some of the reflectors is 0.5 ⁇ L1 or more in the X direction. It is preferable that the interval between adjacent ones is 0.5 ⁇ L2 or more in the Y direction. In such a case, unnecessary reflections can be reduced in both the X direction and the Y direction.
  • the distance between adjacent reflectors should be 0.5 ⁇ L1 or more in the X direction and 0.5 ⁇ L2 or more in the Y direction for at least some of the reflectors. preferable. In this case, unnecessary reflections in the X and Y directions can be reduced with a relatively small number of reflecting plates.
  • the distance between adjacent reflectors 100R should be 0.5 ⁇ L1 or more in the X direction and 0.5 ⁇ L2 or more in the Y direction for all the reflectors 100R. More preferred. In this case, unnecessary reflections in the X direction and the Y direction can be reduced with an even smaller number of reflecting plates 100R.
  • each reflector 100R has a plurality of cells 110 that can change the phase of the radio wave when reflecting the radio wave, and in each reflector 100R, the plurality of cells 110 have a phase change that changes the phase of the radio wave.
  • the difference in amount is 0 degrees or 180 degrees. Therefore, by controlling the amount of phase change in a binary manner, the reflection angle can be adjusted to an angle other than specular reflection.
  • each reflector 100R since the plurality of cells 110 in each reflector 100R are arranged in the X direction in 10 or more and in the Y direction in 10 or more, it is possible to more reliably add a phase change amount to the radio wave when reflecting it. This allows the reflected waves to be more reliably reflected in the set reflection direction.
  • the length of the cell 110 in the X direction and the length of the cell 110 in the Y direction are both 2 ⁇ or less. It is possible to reliably add a phase change amount to radio waves, and the reflected waves can be reliably reflected in the set reflection direction.
  • each reflector 100R since the lengths L1 and L2 of each reflector 100R are 40 ⁇ or less, where ⁇ is the free space wavelength of radio waves, it is possible to reduce the size of the radio waves while ensuring the amount of phase change in the radio waves when reflecting. The reflected wave can be reliably reflected in the set reflection direction.
  • the amount of phase change by which each cell 110 of each reflector 100R changes the phase of the radio wave is a binary value of a first value or a second value
  • the plurality of reflectors 100R is a plurality of cells in each reflector 100R.
  • the reflection angle can be adjusted to reflect the mirror surface. Can be adjusted to angles other than reflection.
  • the distance dr is The size of the reflector 100 can be determined in consideration of the distance, which is about 200 m, that the reflector 100 communicates with a receiving terminal, a base station, etc. in the real world. Thereby, it is possible to reliably add a phase change amount to the radio wave when reflecting it while ensuring a realistic communication distance, and it is possible to reliably reflect the reflected wave in the set reflection direction while reducing unnecessary reflections.
  • the length of the reflector 100 in the X direction and the length of the reflector 100 in the Y direction are 3 m or less, considering the distance that the reflector 100 communicates with a receiving terminal, base station, etc. in the real world.
  • the distance dr can be set to about 200 m.
  • the cell 110 includes a resonant element 111, a resonant element 112, and a switching element that can switch the resonant frequency of the resonant element 112 to a first resonant frequency or a second resonant frequency by electrical control.
  • a switching element that can switch the resonant frequency of the resonant element 112 to a first resonant frequency or a second resonant frequency by electrical control.
  • a PIN diode, MEMS switch, varactor, or transistor is a PIN diode, MEMS switch, varactor, or transistor. Therefore, the amount of phase change can be reliably controlled in a binary manner, and the reflected wave can be reliably reflected in the set reflection direction while reducing unnecessary reflections.
  • radio waves are in the millimeter wave band, when reflecting radio waves in frequency bands such as the fifth generation mobile communication system (5G) and Sub-6, it is possible to reduce unnecessary reflections and adjust the direction of reflection. It is possible to provide a reflector 100 that can reliably reflect reflected waves.
  • 5G fifth generation mobile communication system
  • Sub-6 it is possible to reduce unnecessary reflections and adjust the direction of reflection. It is possible to provide a reflector 100 that can reliably reflect reflected waves.
  • the reflector 100 is directed toward the receiving terminal.
  • the focal length Df when reflecting radio waves satisfies Df ⁇ dr. Therefore, the reflected wave can be reliably reflected in the set reflection direction while effectively reducing unnecessary reflections.
  • the focal length Df satisfies Df ⁇ 2X1 2 / ⁇ , so the reflected waves can be reliably focused on the focal point at the focal length Df, and the radio waves can be It is possible to provide a reflector 100 that has a high focusing effect and can reliably reflect reflected waves in a set reflection direction while reducing unnecessary reflections.
  • Control unit 10 Radio wave transmission system 100 Reflector 100R Reflector 110 Cell 111 Resonant element 112 Resonant element 112A, 112B Linear element 112C PIN diode

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013115756A (ja) * 2011-11-30 2013-06-10 Ntt Docomo Inc リフレクトアレー
JP2021175054A (ja) * 2020-04-22 2021-11-01 Kddi株式会社 メタサーフェス反射板アレイ
WO2022092029A1 (ja) * 2020-10-30 2022-05-05 電気興業株式会社 可変リフレクトアレーおよび可変リフレクトアレーの設計方法
WO2022244676A1 (ja) * 2021-05-17 2022-11-24 株式会社ジャパンディスプレイ 電波反射板および電波反射装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013115756A (ja) * 2011-11-30 2013-06-10 Ntt Docomo Inc リフレクトアレー
JP2021175054A (ja) * 2020-04-22 2021-11-01 Kddi株式会社 メタサーフェス反射板アレイ
WO2022092029A1 (ja) * 2020-10-30 2022-05-05 電気興業株式会社 可変リフレクトアレーおよび可変リフレクトアレーの設計方法
WO2022244676A1 (ja) * 2021-05-17 2022-11-24 株式会社ジャパンディスプレイ 電波反射板および電波反射装置

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