Radio wave reflection device

Abstract

A radio wave reflection device according to an embodiment of the present invention comprises: a radio wave reflection unit that has a radio wave reflection plate in which a plurality of reflection elements are arranged; a rotation mechanism that is attached to the radio wave reflection plate and rotates the radio wave reflection plate on at least one axis; and a control device that controls the rotation of the radio wave reflection plate by the rotation mechanism. According to the present invention, a radio wave reflection device having an improved amplitude can be provided while reducing the number of the reflection elements for which a desired phase cannot be set.

Description

radio wave reflector

[0001] An embodiment of the present invention relates to a radio wave reflecting device.

[0002] A phased array antenna device controls the directivity of a fixed antenna by adjusting the amplitude and phase of a high-frequency signal applied to each of a plurality of antenna elements arranged in a plane. Phased array antenna devices require a phase shifter. Phased array antenna devices using a phase shifter that utilizes a change in the dielectric constant due to the orientation state of liquid crystals have been disclosed (for example, Patent Document 1 and Patent Document 2).

[0003] JP 11-103201 Publication Special Publication No. 2019-530387 Publication

[0004] In a phased array antenna device, if the phase change amount of each antenna element is less than 360°, it may not be possible to set the desired phase for each antenna element. In this case, the amplitude (reflectivity) of the phased array antenna device deteriorates. Therefore, reducing the number of antenna elements for which the desired phase cannot be set leads to an improvement in amplitude. However, there is a trade-off between the phase change amount and the amplitude. Therefore, when an attempt is made to improve the amplitude of a phased array antenna device, the phase change amount of the antenna elements narrows, resulting in a problem that the number of antenna elements for which the desired phase cannot be set increases.

[0005] In view of such problems, one embodiment of the present invention aims to provide a radio wave reflecting device that improves amplitude while reducing the number of reflecting elements that cannot set the desired phase.

[0006] A radio wave reflection device according to one embodiment of the present invention comprises a radio wave reflection unit having a radio wave reflection plate on which a plurality of reflection elements are arranged, a rotation mechanism attached to the radio wave reflection plate and rotating the radio wave reflection plate around at least one axis, and a control device that controls the rotation of the radio wave reflection plate by the rotation mechanism.

[0007] 4 is a diagram showing the configuration of a radio wave reflecting device according to one embodiment of the present invention. FIG. 5 is a diagram showing the configuration of a radio wave reflecting unit according to one embodiment of the present invention. FIG. 6 is a plan view showing the configuration of a radio wave reflecting plate according to one embodiment of the present invention. FIG. 7 is a plan view showing the configuration of a reflecting element corresponding to the inset of FIG. 3. FIG. 8 is a cross-sectional view taken along A1-A2 in FIG. 4. FIG. 9 is a diagram showing a state in which no voltage is applied between the patch electrode and the conductive layer when the radio wave reflecting plate according to one embodiment of the present invention is operating. FIG. 10 is a diagram showing a state in which a control signal is applied to the patch electrode when the radio wave reflecting plate according to one embodiment of the present invention is operating. FIG. 11 is a diagram for explaining the amount of phase shift of the reflecting element. FIG. 12 is a graph showing an example of the amount of phase change of the reflecting element. ０ The radio wave reflector is rotated by the rotation mechanism by θ ０ 1 is a diagram for explaining the phase shift amount of a reflecting element based on a control signal applied to a patch electrode when the reflecting element is rotated by . FIG. 2 is a block diagram showing an example of the configuration of a drive control function according to an embodiment of the present invention. FIG. 3 is a diagram showing an example of calculation of an optimum rotation angle of a radio wave reflecting plate and a corresponding optimum phase shift amount according to an embodiment of the present invention. FIG. 4 is a diagram showing an example of calculation of an optimum rotation angle of a radio wave reflecting plate and a corresponding optimum phase shift amount according to an embodiment of the present invention. FIG. 5 is a diagram showing an example of calculation of an optimum rotation angle of a radio wave reflecting plate and a corresponding optimum phase shift amount according to an embodiment of the present invention. FIG. 6 is a diagram showing an example of calculation of an optimum rotation angle of a radio wave reflecting plate and a corresponding optimum phase shift amount according to an embodiment of the present invention.

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention can be implemented in many different forms, and should not be construed as being limited to the description of the following exemplary embodiments. For clarity of explanation, the drawings may show schematic representations of the width, thickness, shape, etc. of each part compared to the actual form. However, these are merely examples and are not intended to limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements similar to those previously described with reference to the preceding drawings may be designated by the same reference numerals (or reference numerals with a, b, etc. suffixed thereto) and redundant explanations may be omitted. Furthermore, the letters "first" and "second" attached to each element are convenient labels used to distinguish each element and have no further meaning unless otherwise specified.

[0009] In this specification, when a component or region is referred to as being "on (or under)" another component or region, unless otherwise specified, this includes not only the case where it is directly above (or directly under) the other component or region, but also the case where it is above (or under) the other component or region, i.e., the case where another component is included between the component or region and above (or under) the other component or region.

[0010] The radio wave reflector of the present invention has a rotation mechanism on the back surface of the radio wave reflector, which is located opposite to the radio wave incident surface where radio waves are incident. By tilting the radio wave reflector by a predetermined angle using this rotation mechanism, the incident angle of the radio waves incident on the radio wave reflector can be adjusted to a desired angle. As a result, the number of reflecting elements that cannot be set to the desired phase can be reduced, and the amplitude of the radio wave reflector can be improved.

[0011] 1 is a diagram showing the configuration of a radio wave reflecting device 10 according to one embodiment of the present invention. The radio wave reflecting device 10 has a radio wave reflecting unit 100, a rotation mechanism 200, and a control device 300. The radio wave reflecting unit 100 and the rotation mechanism 200 are connected to the control device 300 by wire or wirelessly.

[0012] [Radio Wave Reflecting Unit] Fig. 2 is a diagram showing the configuration of a radio wave reflecting unit 100 according to one embodiment of the present invention. The radio wave reflecting unit 100 has a radio wave reflecting plate 120. A rotation mechanism 200 is attached to the radio wave reflecting unit 100. The radio wave reflecting plate 120 has a radio wave incident surface 120a and a back surface 120b. The radio wave reflecting surface 120a is the surface onto which radio waves are incident, and the back surface 120b is the surface located opposite the radio wave incident surface 120a. The rotation mechanism 200 is attached to the back surface 120b side.

[0013] [Radio Wave Reflector] The configuration of the radio wave reflector 120 of the radio wave reflecting unit 100 will be described. FIG. 3 is a plan view showing the configuration of the radio wave reflector 120 according to one embodiment of the present invention. The radio wave reflector 120 is composed of a plurality of reflecting elements (antenna elements) 102. The plurality of reflecting elements 102 are arranged, for example, in a first direction (e.g., a column direction) and a second direction (e.g., a row direction) different from the first direction. The reflecting elements 102 are arranged so that a plurality of patch electrodes 108 (described later) face the radio wave incident surface. The radio wave reflector 120 is flat, and within the flat surface, the plurality of patch electrodes 108 of each reflecting element 102 are arranged in a matrix along the first and second directions.

[0014] The radio wave reflecting unit 100 has a structure in which a plurality of reflecting elements 102 are integrated on a single dielectric substrate (dielectric layer) 104. As shown in FIG. 3 , the radio wave reflecting unit 100 has a structure in which a dielectric substrate (dielectric layer) 104 on which a plurality of patch electrodes 108 (described later) are arranged and a counter substrate 106 on which a conductive layer 110 is provided are overlapped such that the patch electrodes 108 and the conductive layer 110 face each other, and a liquid crystal layer (not shown) is provided between the two substrates. The radio wave reflector 120 is formed in a region where the plurality of patch electrodes 108 and the conductive layer 110 overlap. The dielectric substrate (dielectric layer) 104 and the counter substrate 106 are bonded together with a sealant 128, and the liquid crystal layer is provided in a region inside the sealant 128.

[0015] The dielectric substrate (dielectric layer) 104 has a region facing the counter substrate 106, as well as a peripheral region 122 extending outward from the counter substrate 106. A first drive circuit 124 and a terminal section 126 are provided in the peripheral region 122. The first drive circuit 124 outputs a control signal to the patch electrode 108. The terminal section 126 is a region for forming a connection with an external circuit, and is connected to, for example, a flexible printed circuit board (not shown). A signal for controlling the first drive circuit 124 is input to the terminal section 126.

[0016] As described above, a plurality of patch electrodes 108 are arranged in a first direction (column direction) and a second direction (row direction) on the dielectric substrate (dielectric layer) 104. A plurality of first signal lines 118 extending in the first direction and a plurality of second signal lines 132 extending in the second direction are disposed on the dielectric substrate (dielectric layer) 104. The plurality of first signal lines 118 and the plurality of second signal lines 132 are arranged to intersect with each other across an insulating layer (not shown). The plurality of first signal lines 118 are connected to a first drive circuit 124, and the plurality of second signal lines 132 are connected to a second drive circuit 130. The first drive circuit 124 outputs control signals, and the second drive circuit 130 outputs scanning signals. The first signal lines 118 are electrically connected to a plurality of reflective elements 102 arranged in the first direction (column direction). In other words, the plurality of reflective elements 102 arranged in the first direction (column direction) are connected by the first signal lines 118. The radio wave reflector 120 has a configuration in which a plurality of reflecting element arrays connected by first signal lines 118 are arranged in a row in the second direction (row direction).

[0017] 3 includes an inset view showing an enlarged arrangement of four reflective elements 102 and two first and second signal lines 118 and 132. Each of the four reflective elements 102 is provided with a switching element 134. The switching of the switching element 134, i.e., the on / off state, is controlled by a scanning signal applied to the second signal line 132. When the switching element 134 is turned on, the reflective element 102 is electrically connected to the first signal line 118 and a control signal is applied to the reflective element 102. The switching element 134 is formed of, for example, a thin film transistor. With this configuration, it is possible to select a plurality of patch electrodes 108 arranged in the second direction (row direction) for each row, and apply control signals of different voltage levels to each row.

[0018] 3 can control the propagation direction of the reflected wave in the left-right direction of the drawing, centered on a reflection axis VR parallel to the first direction (column direction), of the radio wave irradiated onto the reflector 120, and can also control the propagation direction of the reflected wave in the up-down direction of the drawing, centered on a reflection axis HR parallel to the second direction (row direction). In other words, since the radio wave reflector 120 has a reflection axis VR parallel to the first direction (column direction) and a reflection axis HR parallel to the second direction (row direction), it can control the reflection angle in the direction about the reflection axis VR as the rotation axis and in the direction about the reflection axis HR as the rotation axis.

[0019] FIG. 4 is a plan view showing the configuration of the reflective element 102 corresponding to the inset in FIG. 3 . FIG. 5 is a cross-sectional view taken along line A1-A2 in FIG. 4 . Referring to FIGS. 4 and 5 , the reflective element 102 includes a dielectric substrate 104, a counter substrate 106, a patch electrode 108, a conductive layer 110, a liquid crystal layer 114, a first alignment film 112a, and a second alignment film 112b. The dielectric substrate 104 of the reflective element 102 can also be considered as a single layer, i.e., a dielectric layer. The patch electrode 108 is provided on the dielectric substrate (dielectric layer) 104, and the conductive layer 110 is provided on the counter substrate 106. A first alignment film 112a is provided on the dielectric substrate (dielectric layer) 104 to cover the patch electrode 108, and a second alignment film 112b is provided on the counter substrate 106 to cover the conductive layer 110. The patch electrode 108 and the conductive layer 110 are disposed opposite each other, with a liquid crystal layer 114 interposed therebetween. A first alignment film 112 a is interposed between the patch electrode 108 and the liquid crystal layer 114 , and a second alignment film 112 b is interposed between the conductive layer 110 and the liquid crystal layer 114 .

[0020] Although not shown, the dielectric substrate (dielectric layer) 104 and the counter substrate 106 are bonded together with a sealant. The dielectric substrate (dielectric layer) 104 and the counter substrate 106 are disposed opposite each other with a gap therebetween, and the liquid crystal layer 114 is provided within the area surrounded by the sealant. The liquid crystal layer 114 is provided to fill the gap between the dielectric substrate (dielectric layer) 104 and the counter substrate 106. The gap between the dielectric substrate (dielectric layer) 104 and the counter substrate 106 may be 20 to 100 μm, and is, for example, 50 μm. Because the patch electrode 108, the conductive layer 110, the first alignment film 112 a, and the second alignment film 112 b are provided between the dielectric substrate (dielectric layer) 104 and the counter substrate 106, the thickness of the liquid crystal layer 114 is precisely the gap between the first alignment film 112 a and the second alignment film 112 b provided on the dielectric substrate 104 and the counter substrate 106, respectively. Although not shown, a spacer may be provided between the dielectric substrate (dielectric layer) 104 and the opposing substrate 106 to maintain a constant gap therebetween.

[0021] A control signal that controls the orientation of the liquid crystal molecules in the liquid crystal layer 114 is applied to the patch electrode 108 via a first signal line 118. The control signal is a DC voltage signal or a polarity inversion signal in which positive and negative DC voltages alternate. Ground or a voltage at an intermediate level of the polarity inversion signal is applied to the conductive layer 110. Application of the control signal to the patch electrode 108 changes the orientation state of the liquid crystal molecules in the liquid crystal layer 114. A liquid crystal material having dielectric anisotropy is used for the liquid crystal layer 114. For example, nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, or discotic liquid crystal can be used for the liquid crystal layer 114. The dielectric constant of the liquid crystal layer 114 changes depending on the orientation state of the liquid crystal molecules. The control signal applied to the patch electrode 108 can change the dielectric constant of the liquid crystal layer 114, thereby allowing the reflective element 102 to delay the phase of the reflected wave when reflecting radio waves.

[0022] The frequency bands of radio waves reflected by the reflective element 102 are the very high frequency (VHF) band, the ultra high frequency (UHF) band, the super high frequency (SHF) band, the submillimeter wave (THF) band, and the extra high frequency (EHF) band. The liquid crystal molecules in the liquid crystal layer 114 change their orientation in response to a control signal applied to the patch electrode 108, but the orientation hardly changes with the frequency of the radio waves irradiated onto the patch electrode 108. Therefore, the reflective element 102 can control the phase of the reflected radio waves without being affected by the radio waves themselves.

[0023] 6 shows a state (referred to as the "first state") in which no voltage is applied between the patch electrode 108 and the conductive layer 110. Fig. 6 shows a case in which the first alignment film 112a and the second alignment film 112b are horizontal alignment films. In the first state, the long axes of the liquid crystal molecules 116 are aligned horizontally with respect to the surfaces of the patch electrode 108 and the conductive layer 110 by the first alignment film 112a and the second alignment film 112b.

[0024] 7 shows a state (referred to as the "second state") in which a control signal (voltage signal) is applied to the patch electrode 108. In the second state, the liquid crystal molecules 116 are subjected to the action of an electric field, and their long axes are oriented perpendicular to the surfaces of the patch electrode 108 and the conductive layer 110. The angle at which the long axes of the liquid crystal molecules 116 are oriented can also be adjusted to a direction intermediate between the horizontal and vertical directions by adjusting the magnitude of the control signal applied to the patch electrode 108 (the magnitude of the electric field between the counter electrode and the patch electrode).

[0025] When the liquid crystal molecules 116 have positive dielectric anisotropy, the dielectric constant is greater in the second state than in the first state. When the liquid crystal molecules 116 have negative dielectric anisotropy, the apparent dielectric constant is smaller in the second state than in the first state. The liquid crystal layer 114 having dielectric anisotropy can also be considered as a variable dielectric layer. The reflective element 102 can control the phase of the reflected wave to delay or not delay by utilizing the dielectric anisotropy of the liquid crystal layer 114.

[0026] When the reflecting element 102 reflects radio waves in a predetermined direction, it is preferable that the amplitude of the reflected radio waves be attenuated as little as possible. As is clear from the structure shown in Figure 5, when radio waves propagating through the air are reflected by the reflecting element 102, the radio waves pass through the dielectric substrate (dielectric layer) 104 twice. The dielectric substrate (dielectric layer) 104 is formed of a dielectric material such as glass or resin. Since the phase velocity of radio waves changes when passing through a dielectric, the thickness of the dielectric substrate (dielectric layer) 104 is adjusted to prevent attenuation of the amplitude of the reflected wave. Note that the thickness of the dielectric substrate (dielectric layer) 104 can be defined as the length from the surface of the patch electrode 108 facing the liquid crystal layer 114 to the surface of the dielectric substrate (dielectric layer) 104 opposite the surface on which the patch electrode 108 is provided.

[0027] The shape of the patch electrode 108 is preferably rotationally symmetric with respect to the center of the patch electrode 108. For example, the shape of the patch electrode 108 may be four-fold rotationally symmetric, and may be a square or rhombic shape in a planar view. Furthermore, the four-fold rotationally symmetric shape may be a quadrangle with chamfered vertices or a quadrangle with rounded vertices. The patch electrode 108 may also be circular. In this embodiment, the patch electrode 108 is square in a planar view. By having the shape of the patch electrode 108 rotationally symmetric with respect to the center of the patch electrode 108, the anisotropy of the reflection of incident vertically polarized and horizontally polarized radio waves can be reduced. In other words, the polarization of the vertically polarized and horizontally polarized waves can be suppressed, and the vertically polarized and horizontally polarized waves can be uniformly reflected. When reflecting radio waves in the millimeter wave band of 24 GHz to 29 GHz, if the patch electrode 108 has a square shape, the size of the patch electrode 108 may be approximately 3.0 mm x approximately 3.0 mm to approximately 4.5 mm x approximately 4.5 mm.

[0028] 8 is a diagram illustrating the phase shift amount δ of the reflecting element 102 based on the control signal (voltage signal) applied to the patch electrode 108. FIG. 8 shows two reflecting elements 102-1 and 102-2 adjacent to each other in the second direction. As shown in FIG. 8, when reflecting radio waves incident on the radio wave reflector 120 from the front in the θ direction, in other words, when aligning the phases of the radio waves reflected from the two adjacent reflecting elements 102-1 and 102-2 in the θ direction, it is sufficient that the phases at points P and Q in the figure are aligned. Therefore, the phase shift amount δ of each reflecting element 102 is determined based on the following equation 1: δ=(2π / λ)*d sin θ (Equation 1)

[0029] In the above formula 1, λ represents the wavelength of the radio wave, d represents the spacing (pitch) between adjacent patch electrodes 108 in one direction, and θ represents the reflection angle. In other words, the voltage of the control signal applied to the patch electrode 108 of the reflecting element 102-2 is set so that the reflected wave from the reflecting element 102-2 is delayed in phase by (2π / λ)*d sin θ compared to the reflected wave from the adjacent reflecting element 102-1. For example, if the wavelength λ of the incident radio wave is 10.7 mm, the pitch d is 3.7 mm, and the reflection angle θ is 30°, the voltage of the control signal applied to the patch electrode 108 of the reflecting element 102-2 is set so that the reflected wave from the reflecting element 102-2 is delayed in phase by 62.2° compared to the reflected wave from the reflecting element 102-1.

[0030] In the radio wave reflector 120, the voltage of the control signal applied to the patch electrode 108 of each reflecting element 102 is controlled based on the phase of the radio wave reflected by each reflecting element 102, which is determined according to the phase shift δ calculated using the above-mentioned equation 1. Hereinafter, the phase of the reflected wave set for each reflecting element 102 according to the phase shift δ will be referred to as the "set phase." Hereinafter, if the phase change amount of each reflecting element 102 can be adjusted by 360°, desired phase control can be achieved for all reflecting elements 102 by adjusting the voltage of the applied control signal. However, there is a trade-off between the amplitude (reflectivity) of the radio wave reflector 120 and the phase change amount of the reflecting element 102, and the phase change amount of the reflecting element 102 becomes smaller when attempting to obtain an amplitude sufficient for communication.

[0031] FIG. 9 is a graph showing an example of the phase change amount of an existing reflective element. In the graph shown in FIG. 9, the horizontal axis represents the voltage applied between the electrodes of the reflective element (between the patch electrode 108 and the conductive layer 110 in this embodiment), and the vertical axis represents the phase change amount [deg.]. The applied voltage shown on the horizontal axis represents the voltage obtained by dividing the maximum power supply voltage of a drive circuit (e.g., the first drive circuit 124 in this embodiment) that applies voltage to the electrodes (e.g., the patch electrode 108 in this embodiment) by 24. As shown in FIG. 9, the phase change amount of the existing reflective element is approximately 300°, which is less than 360°. In this case, if the set phase for the reflective element exceeds 300°, the desired phase cannot be set with that reflective element.

[0032] 9 , if the amount of phase change of each reflecting element 102 in the radio wave reflecting plate 120 is less than 360°, it may not be possible to set a desired phase for each reflecting element 102 depending on the set phase. If the number of reflecting elements 102 for which the phase cannot be set increases, the amplitude of the radio wave reflecting plate 120 decreases. In order to reduce the number of reflecting elements 102 for which the phase cannot be set in the radio wave reflecting plate 120, in this embodiment, a rotation mechanism 200 is used to adjust the angle of incidence of the radio waves incident on the reflecting elements 102.

[0033] [Rotation Mechanism] Returning to FIG. 2 , the rotation mechanism 200 will be described. As described above, the rotation mechanism 200 is attached to the rear surface 120b of the radio wave reflecting plate 120. The rotation mechanism 200 supports the radio wave reflecting unit 100 relative to the installation surface on which the radio wave reflecting device 10 is installed. Although not shown, if a support member is disposed on the installation surface of the radio wave reflecting device 10, the rotation mechanism 200 is attached to the support member and supports the radio wave reflecting unit 100 relative to the support member. The rotation mechanism 200 rotates the radio wave reflecting plate 120 about at least one axis. The configuration of the rotation mechanism 200 is not particularly limited as long as it can rotate the radio wave reflecting plate 120 about at least one axis. In this specification, "single-axis rotation" means rotation about one axis extending in a predetermined direction. In this embodiment, as an example, a case will be described in which the rotation mechanism 200 has a structure in which a cylindrical rotating body rotates the radio wave reflecting plate 120 in the left-right direction in the figure with the second direction as an axis.

[0034] 10, the radio wave reflector 120 is rotated by θ in the left and right directions in the drawing with the second direction as the axis. ０ In this case, the incident angle of the radio wave incident on the radio wave reflector 120 from the front is θ ０ In this way, the angle of incidence of the radio wave incident on the radio wave reflecting plate 120 of the radio wave reflecting unit 100 can be set arbitrarily by rotating the radio wave reflecting plate 120 using the rotation mechanism 200. When the angle of incidence of the radio wave incident on the radio wave reflecting plate 120 changes, the amount of phase shift δ of each reflecting element 102 also changes.

[0035] FIG. 11 shows the rotation of the radio wave reflector 120 by the rotation mechanism 200. ０ 11 is a diagram for explaining the phase shift amount δ of the reflecting element 102 based on the control signal (voltage signal) applied to the patch electrode 108 when the reflecting element 102 is rotated by θ . FIG. 11 shows two reflecting elements 102-1 and 102-2 that are adjacent in the second direction. When the radio wave reflecting plate 120 is not rotated and radio waves are incident on the radio wave reflecting plate 120 from the front (i.e., the incident angle of the radio wave is 0°), the radio wave reflecting plate 120 is rotated by the rotation mechanism by θ . ０ When the reflector 120 rotates by ±θ, the incident angle of the radio wave incident on the radio wave reflector 120 changes depending on the direction of rotation. ０ In this case, when the phases of the radio waves reflected from two adjacent reflecting elements 102-1 and 102-2 are aligned in the θ direction, it is sufficient that the phases at points P and Q in the figure are aligned. Therefore, the phase shift amount δ of each reflecting element 102 is determined based on the following equation 2: δ = (2π / λ) * d(sin θ) ０ −sinθ) (Equation 2)

[0036] In the above formula 2, λ represents the wavelength of the radio wave, d represents the interval (pitch) between adjacent patch electrodes 108 in one direction, θ represents the reflection angle, and θ ０ indicates the rotation angle of the rotation mechanism 200. In other words, when the radio wave reflector 120 rotates at an angle θ ０ When the reflecting element 102-2 is rotated by 1, the voltage of the control signal applied to the patch electrode 108 of the reflecting element 102-2 is (2π / λ)*d(sinθ) so that the reflected wave from the reflecting element 102-2 is larger than the reflected wave from the adjacent reflecting element 102-1. ０ The phase is set to lag by −sin θ.

[0037] In this way, by rotating the radio wave reflector 120 using the rotation mechanism 200, the phase shift amount δ of each reflecting element 102 provided on the radio wave reflector 120 changes. ０ By adjusting the phase shift amount δ, the phase shift amount δ can be adjusted, and by adjusting the phase shift amount δ, the set phase for each reflecting element 102 can also be adjusted. By adjusting the set phase so that it falls within the range of the phase change amount for each reflecting element 102, the number of reflecting elements 102 for which the desired phase cannot be set can be reduced. As a result, the amplitude of the radio wave reflecting plate 120 can be improved.

[0038] 1 , the control device 300 will be described. The control device 300 controls the driving of the radio wave reflecting unit 100 and the rotation mechanism 200. Although not shown, the control device 300 includes an operation unit that accepts user operations, an arithmetic processing circuit such as a CPU, and storage devices such as a RAM and a ROM. The control device 300 executes a control program stored in the storage device by the CPU, and realizes various functions in the radio wave reflecting device 10, including the drive control function of the radio wave reflecting unit 100 and the rotation mechanism 200.

[0039] 12 is a block diagram showing an example of the configuration of a drive control function 30 for the radio wave reflecting unit 100 and the rotation mechanism 200, which is executed by the CPU of the control device 300. The drive control function 30 includes an input unit 301, a calculation unit 303, a phase setting unit 305, a voltage setting unit 307, and a rotation drive unit 309.

[0040] The input unit 301 receives as input the incident angle of the radio wave incident on the radio wave reflector 120 of the radio wave reflecting unit 100, the reflection angle of the radio wave reflected by the radio wave reflector 120, and the wavelength of the radio wave, which are set by the user via the operation unit of the control device 300. The input unit 301 outputs the acquired incident angle, reflection angle, and wavelength of the radio wave to the calculation unit 303.

[0041] The calculation unit 303 calculates the optimum rotation angle θ of the radio wave reflector 120 by the rotation mechanism 200 using the incident angle, reflection angle, and wavelength of the radio wave that has been acquired based on a predetermined algorithm.０ and the corresponding optimum phase shift amount δ is determined. Here, the predetermined algorithm determines the rotation angle θ of the radio wave reflector 120 by the rotation mechanism 200. ０ and the set phase of each reflecting element 102.

[0042] 13 to 16 show the optimum rotation angle θ of the radio wave reflector 120 calculated by the calculation unit 303. ０ 13 to 16 are diagrams showing examples of calculation of the optimum rotation angle θ for twelve reflecting elements 102 arranged in one direction. ０ 13 to 16, the optimum rotation angle θ of the radio wave reflector 120 is shown. ０ and the corresponding optimal phase shift amount δ, the rotation angle θ of the rotation mechanism 200 ０ The maximum angle of rotation of the reflecting element 102 was set to 15°, and the rotation mechanism 200 rotated in increments of 1°. The pitch (the distance between adjacent reflecting elements 102 in one direction) of the reflecting elements 102 provided on the radio wave reflecting plate 120 was set to 3.7 mm, and the amount of phase change of each reflecting element 102 was set to be equal to or greater than 0° and less than 180°.

[0043] FIG. 13 shows the optimum rotation angle θ of the radio wave reflector 120 when the incident angle of the radio wave is set to 0°, the desired reflection angle θ is set to 15°, and the wavelength λ of the radio wave is set to 10.7 mm. ０ 14 shows an example of calculating the optimum rotation angle θ of the radio wave reflector 120 when the incident angle of the radio wave is set to 0°, the desired reflection angle θ is set to 30°, and the wavelength λ of the radio wave is set to 10.7 mm. ０ 15 shows an example of calculating the optimum rotation angle θ of the radio wave reflector 120 when the incident angle of the radio wave is set to 0°, the desired reflection angle θ is set to 45°, and the wavelength λ of the radio wave is set to 10.7 mm. ０ 16 shows an example of calculating the optimum rotation angle θ of the radio wave reflector 120 when the incident angle of the radio wave is set to 0°, the desired reflection angle θ is set to 60°, and the wavelength λ of the radio wave is set to 10.7 mm. ０and an example of calculating the corresponding optimal phase shift amount δ. The phase shift amount δ of the reflecting element 102 corresponding to the rotation angle of the rotation mechanism 200 is calculated based on Equation 2. The set phase for each reflecting element 102 is calculated based on a predetermined algorithm, as described above. In the set phases shown in FIGS. 13 to 16, angles shown in gray indicate that the phase change amount of each reflecting element 102 is 180° or more, and the corresponding reflecting element 102 cannot be set to the desired phase. Hereinafter, a reflecting element 102 that cannot be set to the desired phase will be referred to as an "unsettable element," and a reflecting element 102 that can be set to the desired phase will be referred to as a "settable element."

[0044] As shown in FIG. 13, when the desired reflection angle is set to 15°, the rotation angle θ of the rotation mechanism 200 ０ is 8° or more, all 12 reflecting elements 102 are settable elements. In this case, calculation unit 303 selects the rotation angle of rotation mechanism 200 from 8° to 15°, and outputs the selected rotation angle to rotation driver 309. Calculation unit 303 also outputs the phase shift amount δ corresponding to the selected rotation angle to phase setting unit 305. Here, rotation angle θ ０ If there are multiple options, the calculation unit 303 selects the rotation angle that results in the least amount of change from the angle of the rotation mechanism 200 at that time.

[0045] As shown in FIG. 14, when the desired reflection angle is set to 30°, the rotation angle θ of the rotation mechanism 200 ０ When the rotation angle is 4°, 7°, 9°, or 10°, the number of settable elements is at its maximum (8). In this case, the calculation unit 303 selects one of 4°, 7°, 9°, or 10° as the rotation angle of the rotation mechanism 200, and outputs the selected rotation angle to the rotation driver 309. The calculation unit 303 also outputs the phase shift amount δ corresponding to the selected rotation angle to the phase setting unit 305.

[0046] As shown in FIG. 15, when the desired reflection angle is set to 45°, the rotation angle θ of the rotation mechanism 200 ０When the rotation angle δ is 3°, 6°, or 7°, the number of settable elements is at its maximum (8). In this case, the calculation unit 303 selects one of 3°, 6°, or 7° as the rotation angle of the rotation mechanism 200, and outputs the selected rotation angle to the rotation driver 309. The calculation unit 303 also outputs the phase shift amount δ corresponding to the selected rotation angle to the phase setting unit 305.

[0047] As shown in FIG. 16, when the desired reflection angle is set to 60°, the rotation angle θ of the rotation mechanism 200 ０ When the rotation angle δ is 15°, the number of settable elements reaches the maximum (8). In this case, the calculation unit 303 determines the rotation angle of the rotation mechanism 200 to be 15° and outputs the determined rotation angle to the rotation driver 309. The calculation unit 303 also outputs the phase shift amount δ corresponding to the rotation angle of 15° to the phase setting unit 305.

[0048] In this way, the calculation unit 303 calculates the rotation angle θ of the rotation mechanism 200 based on a predetermined algorithm. ０ At this time, the rotation angle θ at which the number of configurable elements is maximized, in other words, the number of unconfigurable elements is minimized, is calculated. ０ and the determined rotation angle θ ０ The calculation unit 303 determines the optimum rotation angle θ ０ is output to the rotation drive unit 309, and the rotation angle θ ０ The phase setting unit 305 outputs the phase shift amount δ corresponding to

[0049] The phase setting unit 305 determines the set phase of each reflecting element 102 based on the phase shift amount δ acquired from the calculation unit 303. The phase setting unit 305 outputs the determined set phase of each reflecting element 102 to the voltage setting unit 307.

[0050] The voltage setting unit 307 determines a voltage value to be applied to the patch electrode 108 of each reflecting element 102 based on the set phase of each reflecting element 102, and outputs the determined voltage value to the first driving circuit 124. The first driving circuit 124 supplies a control signal to the patch electrode 108 of each reflecting element 102 based on the voltage value acquired from the voltage setting unit 307.

[0051] The rotation driving unit 309 calculates the rotation angle θ０ The rotation mechanism 200 is driven based on the rotation control signal 309, and the rotation of the rotation mechanism 200 is controlled. The rotation drive unit 309 may be realized by the rotation mechanism 200, instead of the control device 300.

[0052] As described above, in this embodiment, the rotation mechanism 200 rotates the radio wave reflector 120 at a rotation angle θ ０ By adjusting the phase shift amount δ, it is possible to adjust the set phase for each reflecting element 102. By adjusting the set phase so that the number of non-settable elements is minimized, it is possible to reduce the number of reflecting elements 102 in which a desired phase cannot be set in the radio wave reflecting plate 120, i.e., the number of non-settable elements, and improve the amplitude of the radio wave reflecting plate 120.

[0053] The radio wave reflecting device 10 according to this embodiment can be used to reflect radio waves in the 24 GHz to 53 GHz (millimeter wave band), such as the 28 GHz, 39 GHz, and 47 GHz wave bands, in a desired direction.

[0054] [Modifications] Although one embodiment of the present disclosure has been described above, the present invention can be implemented in various aspects as follows.

[0055] (Variation 1) In the above-described embodiment, the radio wave reflecting plate 120 is provided with a plurality of first signal lines 118 extending in the first direction and a plurality of second signal lines 132 extending in the second direction. However, the configuration of the radio wave reflecting plate 120 is not limited to this. For example, the second signal lines 132 may be omitted. In this case, the second drive circuit 130 and the switching elements 134 provided in each reflecting element 102 may also be omitted.

[0056] (Variation 2) In the above-described embodiment, the rotation mechanism 200 has a structure in which a cylindrical rotating body rotates the radio wave reflector 120 in the left-right direction in the figure around the second direction as an axis. However, the configuration of the rotation mechanism 200 is not limited to this. For example, the rotation mechanism 200 may rotate the radio wave reflector 120 around two axes or three axes. "Two-axis rotation" means rotation around two axes extending in two different directions, and "three-axis rotation" means rotation around three axes extending in three different directions. For example, if the rotation mechanism 200 has a spherical rotating body, the rotation mechanism 200 can rotate the radio wave reflector 120 around two axes. Furthermore, the rotation mechanism 200 may be, for example, a device that generates power in a linear direction, such as a linear actuator. In this case, linear actuators are attached to both ends of the radio wave reflector 120 in the desired rotation direction, and the radio wave reflector 120 can be rotated around one axis, two axes, or three axes by driving each linear actuator so that the radio wave reflector 120 rotates at the desired angle. The rotation mechanism 200 may also have a configuration similar to an air cushion that is compressed and expanded by supplied air. In this case, by inflating the side opposite to the desired direction of rotation, the radio wave reflector 120 can be rotated around one or two axes in the desired direction. Furthermore, by adjusting the amount of intake air supplied, it is also possible to rotate around three axes.

[0057] (Variation 3) In the above embodiment, when the radio wave reflection angle of the radio wave reflecting unit 100 is switched, the rotation angle of the radio wave reflecting plate 120 is changed by the rotation mechanism 200, thereby enabling the reflection angle in the radio wave reflecting unit 100 to be switched quickly. In the radio wave reflecting plate 120, depending on the distance between the patch electrode 108 and the conductive layer 110, it may take some time for the liquid crystal in the liquid crystal layer 114 to respond. In such a case, when the radio wave reflection angle in the radio wave reflecting plate 120 is changed, if the difference in the set phase of the reflecting element 102 before and after changing the reflection angle is large, it takes some time to switch the reflection angle. On the other hand, by rotating the radio wave reflecting plate 120 by the rotation mechanism 200 and setting the rotation angle by the rotation mechanism 200 so that the difference in the set phase of the reflecting element 102 before and after changing the reflection angle is small, the reflection angle can be switched more quickly without significantly changing the voltage applied between the patch electrode 108 and the conductive layer 110.

[0058] The various configurations of the radio wave reflecting device and reflecting element exemplified as one embodiment of the present invention can be combined as appropriate as long as they are not mutually contradictory. Furthermore, those in which a person skilled in the art appropriately adds or deletes components or modifies the design, or adds or omits processes or modifies conditions based on the radio wave reflecting device and reflecting element disclosed in this specification and drawings, are also included in the scope of the present invention as long as they include the gist of the present invention.

[0059] Even if there are other effects and advantages different from those brought about by the aspects of the embodiments disclosed in this specification, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention.

[0060] 10: radio wave reflecting device, 100: radio wave reflecting unit, 102: reflecting element, 104: dielectric substrate, 106: opposing substrate, 108: patch electrode, 110: conductive layer, 112a: first alignment film, 112b: second alignment film, 114: liquid crystal layer, 116: liquid crystal molecules, 118: first signal line, 120: radio wave reflecting plate, 122: peripheral area, 124: first driving circuit, 126: terminal section, 128: sealing material, 130: second driving circuit, 132: second signal line, 134: switching element, 200: rotation mechanism, 300: control device, 301: input section, 303: calculation section, 305: phase setting section, 307: voltage setting section, 309: rotation control section

Claims

1. A radio wave reflection device comprising: a radio wave reflector having a plurality of reflection elements arranged thereon; a rotation mechanism attached to the radio wave reflector for rotating the radio wave reflector about at least one axis; and a control device for controlling the rotation of the radio wave reflector by the rotation mechanism.

2. The radio wave reflection device according to claim 1, wherein the radio wave reflector has a first surface on which radio waves are incident and a second surface opposite to the first surface, and the rotation mechanism is attached to the second surface.

3. The radio wave reflection device according to claim 1, wherein the control device determines the rotation angle of the radio wave reflector based on a predetermined algorithm.

4. The radio wave reflection device according to claim 3, wherein the predetermined algorithm is based on the relationship between the phase shift amount of each of the plurality of reflection elements based on the rotation angle of the radio wave reflector and the phase of the reflected wave set for each of the plurality of reflection elements.

5. The radio wave reflection device according to claim 4, wherein the control device determines, as the rotation angle of the radio wave reflector, a rotation angle at which the number of reflection elements for which a desired phase cannot be set in the plurality of reflection elements is minimized based on the phase change amount of the plurality of reflection elements.

6. The radio wave reflection device according to claim 3, wherein the control device further determines the phase of the reflected wave set for each of the plurality of reflection elements.

7. The radio wave reflection device according to claim 6, wherein the control device sets the voltage value of the control signal supplied to each of the plurality of reflection elements based on the determined phase of the reflected wave.

8. The radio wave reflector extends in a predetermined direction and has a first signal line for supplying the control signal. Each of the plurality of reflection elements has a patch electrode, a conductive layer disposed spaced apart from the patch electrode and facing the patch electrode, and a liquid crystal layer disposed between the patch electrode and the conductive layer. The control signal is applied to the patch electrode.

Images