Radio wave reflection device

Abstract

To improve the reflection gain of a radio wave reflection device.SOLUTION: A radio wave reflection device includes a plurality of first patch electrodes, a plurality of second patch electrodes with a size different from that of the first patch electrodes, a ground electrode that is provided facing the first patch electrodes and the second patch electrodes and apart from the first patch electrodes and the second patch electrodes, and a liquid crystal layer provided between the first patch electrodes and the second patch electrodes and the ground electrode. In a plan view, the first patch electrodes and the second patch electrodes are disposed in a first direction and a second direction. When a distance between centers of the two adjacent first patch electrodes is a distance W1, the second patch electrode is disposed at a position W1 / 2 apart from the first patch electrode in the first direction in parallel and a position W1 / 2 apart from the first patch electrode in the second direction in parallel.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] One embodiment of the present invention relates to a radio wave reflection device capable of controlling the traveling direction of reflected radio waves.

Background Art

[0002] A phased array antenna device includes a plurality of antenna elements arranged in a plane. In the phased array antenna device, the amplitude and phase of a high-frequency signal applied to each of the plurality of antenna elements are adjusted. As a result, the phased array antenna device can control the directivity of the antenna while each of the plurality of antenna elements is fixed.

[0003] In order to adjust the amplitude and phase of the high-frequency signal applied to each of the plurality of antenna elements, the phased array antenna device requires a phase shifter. For example, Patent Document 1 discloses a phased array antenna device using a phase shifter that utilizes a change in dielectric constant due to the alignment state of liquid crystal.

[0004] The antenna element of the phased array antenna device shown in Patent Document 1 includes a plurality of strip wirings, a planar electrode facing the plurality of strip wirings, and a liquid crystal layer provided between the plurality of strip wirings and the planar electrode. For example, different voltages are applied to the plurality of strip wirings. As a result, since the reflected waves generated based on the alignment of the liquid crystal in the liquid crystal layer being adjusted for each antenna element can be superimposed, the phase of the radio wave can be changed. Thereby, the reflection direction of the radio wave can be set in an arbitrary direction.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] In the telecommunications sector, the introduction of the fifth-generation communication standard, known as 5G, is progressing. This standard employs frequencies in the millimeter-wave band, such as 26GHz to 28GHz. 5G communication achieves extremely high throughput and enables transmission over wide bandwidths due to the use of millimeter-wave frequencies. However, radio waves in the millimeter-wave band have high directivity and are difficult to propagate around obstacles. Therefore, a problem arises in urban areas where the coverage area of ​​5G is limited.

[0007] To address these problems, one might consider using reflectors to change the direction of radio wave transmission in order to avoid obstacles and expand the communication area. However, in the phased array antenna device described in Patent Document 1, the amount of phase change of radio waves is insufficient, and it is not possible to reflect radio waves in the target direction.

[0008] In view of these problems, one of the objectives of one embodiment of the present invention is to improve the reflection gain of a radio wave reflector. [Means for solving the problem]

[0009] A radio wave reflector according to one embodiment of the present invention includes a plurality of first patch electrodes, a plurality of second patch electrodes having a different size from the plurality of first patch electrodes, a ground electrode provided opposite to the plurality of first patch electrodes and the plurality of second patch electrodes and spaced apart from the plurality of first patch electrodes and the plurality of second patch electrodes, and a liquid crystal layer provided between the plurality of first patch electrodes and the plurality of second patch electrodes and the ground electrode, wherein in a plan view, the plurality of first patch electrodes and the plurality of second patch electrodes are arranged in a matrix in a first direction and a second direction intersecting the first direction, and when the distance between the centers of two adjacent first patch electrodes is distance W1, the second patch electrodes are positioned at a distance W1 / 2 parallel to the first direction and a distance W1 / 2 parallel to the second direction from the first patch electrodes, with reference to the position of the first patch electrodes. [Brief explanation of the drawing]

[0010] [Figure 1] This is a plan view showing a reflector unit cell used in a radio wave reflector according to the first embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the cross-section of the line A1-A2 shown in Figure 1. [Figure 3] This is a cross-sectional view showing the cross-section of the line B1-B2 as shown in Figure 1. [Figure 4] Figure 1 shows a cross-sectional view of the cross-section of the line C1-C2 or the line C3-C4. [Figure 5] This is a diagram illustrating a first subunit cell included in a reflector unit cell according to a first embodiment of the present invention. [Figure 6] This is a diagram illustrating a second subunit cell included in a reflector unit cell according to the first embodiment of the present invention. [Figure 7] This figure shows a state in which no voltage is applied between the patch electrode and the ground electrode in a reflector unit cell used in a radio wave reflector according to the first embodiment of the present invention. [Figure 8]This figure shows a state in which a voltage is applied between the patch electrode and the ground electrode in a reflector unit cell used in a radio wave reflector according to the first embodiment of the present invention. [Figure 9] This diagram schematically illustrates how the propagation direction of reflected waves changes due to the radio wave reflector according to the first embodiment of the present invention. [Figure 10] This is a plan view showing the configuration of a radio wave reflector according to the first embodiment of the present invention. [Figure 11] Figure 10 is a plan view showing the configuration of the reflector unit cell. [Figure 12] This is a cross-sectional view showing a cross-section of a reflector unit cell in a radio wave reflector according to the first embodiment of the present invention. [Figure 13] The configuration of a radio wave reflector according to a second embodiment of the present invention is shown. [Figure 14] This is a plan view showing a reflector unit cell used in a radio wave reflector according to a second embodiment of the present invention. [Figure 15] This is a cross-sectional view showing the cross-section along the line D1-D2, as shown in Figure 14. [Figure 16] This is a cross-sectional view showing the cross-section of the line E1-E2 shown in Figure 14. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described below. In order to make the explanation clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In addition, in this specification and each drawing, elements similar to those described above with respect to previously shown drawings are denoted by the same reference numerals (or numerals followed by a, b, etc.), and detailed explanations may be omitted as appropriate. Furthermore, the letters "1st," "2nd," etc., attached to each element are convenient indicators used to distinguish each element and have no further meaning unless specifically explained.

[0012] In this specification, when a certain member or region is said to be "above (or below)" another member or region, unless otherwise specified, this includes not only the case where it is directly above (or directly below) the other member or region, but also the case where it is above (or below) the other member or region, that is, it also includes the case where another component is included between them above (or below) the other member or region.

[0013] In the specification of this application, the X direction intersects the Y direction. The X direction is called the first direction, and the Y direction is called the second direction.

[0014] In the specification of this application, when the notations "identical" and "coincident" are used, they may include errors within the scope of the design.

[0015] <First Embodiment> In the first embodiment, a radio wave reflection device 100a (FIG. 10) capable of biaxial reflection control will be described with reference to FIGS. 1 to 12.

[0016] <1. Reflector Unit Cell> First, the reflector unit cell 102 used in the radio wave reflection device 100a according to the first embodiment of the present invention will be described. The radio wave reflection device 100a includes a plurality of reflector unit cells 102.

[0017] FIG. 1 is a plan view of the reflector unit cell 102 as viewed from above (the side where radio waves are incident). FIG. 2 is a cross-sectional view showing the cross-section along line A1 - A2 shown in FIG. 1, FIG. 3 is a cross-sectional view showing the cross-section along line B1 - B2 shown in FIG. 1, and FIG. 4 is a cross-sectional view showing the cross-section along line C1 - C2 or C3 - C4 shown in FIG. 1. FIG. 5 is a diagram for explaining the first sub-unit cell 103a included in the reflector unit cell 102, and FIG. 6 is a diagram for explaining the second sub-unit cell 103b included in the reflector unit cell 102.

[0018] As shown in Figures 1, 2, 3, 4, 5, or 6, the reflector unit cell 102 includes a first subunit cell 103a and a second subunit cell 103b. A portion of the first subunit cell 103a overlaps with the second subunit cell 103b, and a portion of the second subunit cell 103b overlaps with the first subunit cell 103a. The first subunit cell 103a includes a counter substrate 106, a ground electrode 110, a second alignment film 112b, a liquid crystal layer 114, a first alignment film 112a, a patch electrode 108a, an array layer 180, and a dielectric substrate 104. Furthermore, the second subunit cell 103b includes a dielectric substrate 104, a counter substrate 106, a ground electrode 110, a second alignment film 112b, a liquid crystal layer 114, a first alignment film 112a, a patch electrode 108b, an array layer 180, and the dielectric substrate 104. In both the first subunit cell 103a and the second subunit cell 103b, the dielectric substrate 104 can be considered as a single dielectric layer. Therefore, the dielectric substrate 104 is sometimes referred to as a dielectric layer. As will be described in detail later, the array layer 180 includes switching elements 134 (Figure 11) electrically connected to the patch electrodes 108a and 108b, respectively. The patch electrode 108a is sometimes referred to as the first patch electrode, and the patch electrode 108b is sometimes referred to as the second patch electrode.

[0019] As shown in Figures 2 to 4, an array layer 180 is provided on a dielectric substrate 104. Patch electrodes 108a and 108b are provided on the array layer 180. A first alignment film 112a is provided so as to cover the patch electrodes 108a and 108b. A ground electrode 110 is provided on a counter substrate 106. A second alignment film 112b is provided so as to cover the ground electrode 110. The patch electrodes 108a and 108b are positioned opposite the ground electrode 110. A liquid crystal layer 114 is provided between the patch electrodes 108a and 108b and the ground electrode 110. The first alignment film 112a is interposed between the patch electrodes 108a and 108b and the liquid crystal layer 114. The second alignment film 112b is interposed between the ground electrode 110 and the liquid crystal layer 114. The thickness T of the dielectric substrate 104 is, for example, the length from the surface of the patch electrode 108 on the liquid crystal layer 114 side to the surface of the dielectric substrate 104 opposite to the surface on which the patch electrode 108 is provided.

[0020] In the radio wave reflector 100a, the difference between the first subunit cell 103a and the second subunit cell 103b is, for example, the size of the patch electrodes 108a and 108b. In the example shown in Figure 1, the size of patch electrode 108a is larger than the size of patch electrode 108b. However, the size of patch electrode 108a may be smaller than the size of patch electrode 108b. In this specification, when the first subunit cell 103a and the second subunit cell 103b are not particularly distinguished, they are simply referred to as reflector unit cell 102. Also, when there is no need to particularly distinguish between patch electrodes 108a and 108b, they are simply referred to as patch electrode 108.

[0021] As shown in Figure 5, in a plan view of the multiple first subunit cells 103a, the multiple patch electrodes 108a are arranged in a matrix in the X direction (first direction) and the Y direction (second direction) intersecting the X direction. The distance between the center O1 of a patch electrode 108a parallel to the X direction and the center O1 of an adjacent patch electrode 108a is distance W1. Similarly, the distance between the center O1 of a patch electrode 108a parallel to the Y direction and the center O1 of an adjacent patch electrode 108a is also distance W1. In other words, the multiple patch electrodes 108a are arranged at the same pitch (distance W1) in the X and Y directions. To put it another way, the multiple first subunit cells 103a are arranged at the same pitch (distance W1) in the X and Y directions.

[0022] The shape of the patch electrode 108a is, for example, a cross shape. The length of the pattern parallel to the X direction of the cross shape is the same as the length of the pattern parallel to the Y direction of the cross shape, and this length is W3. The width of the pattern parallel to the X direction of the cross shape is the same as the width of the pattern parallel to the Y direction of the cross shape, and this width is W4. The distance between one patch electrode 108a and an adjacent patch electrode 108a is W2.

[0023] As shown in Figure 6, in a plan view of the multiple second subunit cells 103b, the multiple patch electrodes 108b are arranged in a matrix in the X and Y directions, similar to the multiple patch electrodes 108a. The distance between the center O2 of one patch electrode 108b and the center O2 of an adjacent patch electrode 108b, parallel to the X direction, and the distance between the center O2 of one patch electrode 108b and the center O2 of an adjacent patch electrode 108a, parallel to the Y direction, is distance W5. That is, the multiple patch electrodes 108b are arranged at the same pitch (distance W5) in the X and Y directions. In other words, the multiple second subunit cells 103b are arranged at the same pitch (distance W5) in the X and Y directions. In this specification, distance W5 is the same as distance W1. That is, the second subunit cells 103b are arranged at the same pitch as the first subunit cells 103a.

[0024] The shape of patch electrode 108b is similar to that of patch electrode 108a, for example, a cross shape. In patch electrode 108b, the length of the pattern parallel to the X direction of the cross shape is the same as the length of the pattern parallel to the Y direction of the cross shape, and this length is W7. The width of the pattern parallel to the X direction of the cross shape is the same as the width of the pattern parallel to the Y direction of the cross shape, and this width is W8. The distance between patch electrode 108b and an adjacent patch electrode 108b is W6.

[0025] For example, distance W1 is the same as distance W5, distance W2 is shorter than distance W6, width W3 is longer than length W7, and width W4 is longer than width W8.

[0026] The cross shape has four-fold rotational symmetry with respect to the center O1 of patch electrode 108a and the center O2 of patch electrode 108b. Because patch electrode 108a has rotational symmetry with respect to its center O1, the anisotropy of radio wave reflection with respect to the vertical and horizontal polarization of the incident radio wave can be reduced. Similarly, because patch electrode 108b has rotational symmetry with respect to its center O2, the anisotropy of radio wave reflection with respect to the vertical and horizontal polarization of the incident radio wave can be reduced. In other words, the bias of vertical and horizontal polarization within the XY plane in Figures 1, 5, and 6 can be suppressed, allowing for uniform reflection of vertical and horizontal polarization.

[0027] As shown in Figures 1, 5, and 6, in a plan view of the radio wave reflector 100a, the multiple patch electrodes 108a and 108b are arranged in a houndstooth pattern or checkered pattern. Specifically, the patch electrodes 108b are positioned at a distance of W1 / 2 (W5 / 2) parallel to the X direction and W1 / 2 (W5 / 2) parallel to the Y direction from the patch electrodes 108a. Furthermore, in a square formed by connecting the centers O2 of the four patch electrodes 108b surrounding one patch electrode 108a with lines, the intersection of the diagonals of this square coincides with the center O1 of the patch electrode 108a. Similarly, in a square formed by connecting the centers O1 of the four patch electrodes 108a surrounding one patch electrode 108b with lines, the intersection of the diagonals of this square coincides with the center O2 of the patch electrode 108b.

[0028] In the radio wave reflector 100a, for example, the shapes of the multiple patch electrodes 108a and the multiple patch electrodes 108b are cross-shaped, but the shapes of the multiple patch electrodes 108a and the multiple patch electrodes 108b are not limited to a cross shape. For example, the shapes of the patch electrodes 108a and the patch electrodes 108b may be polygons obtained by rotating a square of the same length in the X and Y directions by 45 degrees, or they may be rhombuses with 4-fold rotational symmetry with respect to the patch electrode 108a and rhombuses with 4-fold rotational symmetry with respect to the center O2 of the patch electrode 108b.

[0029] The shape of the grounding electrode 110 is not limited. For example, the shape of the grounding electrode 110 can be any shape that has a larger area than the patch electrode 108a. In the radio wave reflector 100a, the grounding electrode 110 is arranged over the entire surface or substantially over the entire surface on the side of the opposing substrate 106 where the liquid crystal layer 114 is provided.

[0030] Furthermore, there are no restrictions on the materials used to form the patch electrode 108 and the ground electrode 110. For example, the patch electrode 108 and the ground electrode 110 can be formed using conductive metals or metal oxides.

[0031] Furthermore, as will be described in detail later, the dielectric substrate 104 may be provided with first wirings 118a and 118b. For example, the first wiring 118a connects to patch electrodes 108a arranged in the same row, and the first wiring 118b connects to patch electrodes 108b arranged in the same row. The first wirings 118a and 118b can be used when applying control signals to patch electrodes 108a and 108b. In addition, the first wirings 118a and 118b can be used when connecting patch electrodes 108a and 108b.

[0032] The reflector unit cell 102 is used as a reflector 120 that reflects radio waves in a predetermined direction. Therefore, it is preferable that the amplitude of the reflected radio waves is not attenuated as much as possible in the reflector unit cell 102. As is clear from the structure shown in Figures 2 to 4, when radio waves propagating in the air are reflected by the reflector unit cell 102, the radio waves pass through the dielectric substrate 104 twice. The dielectric substrate 104 is preferably made of a dielectric material such as glass or resin.

[0033] The dielectric substrate 104 is bonded to the opposing substrate 106 using a sealing material 128 (Figure 10). The dielectric substrate 104 is positioned opposite the opposing substrate 106 such that a gap exists between the dielectric substrate 104 and the opposing substrate 106. The liquid crystal layer 114 is provided within the region surrounded by the sealing material 128. In a side view, the gap between the dielectric substrate 104 and the opposing substrate 106 is 20 μm or more and 100 μm or less. In the radio wave reflector 100a, the gap between the dielectric substrate 104 and the opposing substrate 106 is, for example, 75 μm. A patch electrode 108, a ground electrode 110, a first alignment film 112a, and a second alignment film 112b are provided between the dielectric substrate 104 and the opposing substrate 106. More precisely, the gap between the first alignment film 112a and the second alignment film 112b, provided on the dielectric substrate 104 and the opposing substrate 106, respectively, is the thickness of the liquid crystal layer 114. Although not shown in the figures, a spacer may be provided between the dielectric substrate 104 and the opposing substrate 106 to maintain a constant distance.

[0034] A control signal is applied to the patch electrode 108 to control the orientation of the liquid crystal molecules in the liquid crystal layer 114. The control signal is either a DC voltage signal or a polarity reversal signal in which positive DC voltage and negative DC voltage alternate. An intermediate voltage between the ground or polarity reversal signal is applied to the ground electrode 110. The application of the control signal to the patch electrode 108 changes the orientation state of the liquid crystal molecules contained in the liquid crystal layer 114. A liquid crystal material with dielectric anisotropy is used for the liquid crystal layer 114. For example, nematic liquid crystal, smectic liquid crystal, cholestic liquid crystal, or discotic liquid crystal can be used as the liquid crystal layer 114. In a liquid crystal layer 114 with dielectric anisotropy, the dielectric constant changes with the change in the orientation state of the liquid crystal molecules. The reflector unit cell 102 can change the dielectric constant of the liquid crystal layer 114 by the control signal applied to the patch electrode 108. This allows for a delay in the phase of the reflected wave when reflecting radio waves.

[0035] The frequency bands of radio waves reflected by the reflector unit cell 102 are the very high frequency (VHF), ultra-high frequency (UHF), super high frequency (SHF), submillimeter wave (THF), and extra high frequency (EHF) bands. Millimeter waves refer to, for example, the frequency band from 30 GHz to 300 GHz. Note that the frequency band of the fifth-generation communication standard called 5G includes the 26 GHz to 29 GHz band, and frequencies above 26 GHz are sometimes collectively referred to as millimeter waves. The orientation of the liquid crystal molecules in the liquid crystal layer 114 changes in response to the control signal applied to the patch electrode 108, but it hardly follows the frequency of the radio waves incident on the patch electrode 108. Therefore, the reflector unit cell 102 can control the phase of the reflected radio waves without being affected by the radio waves.

[0036] The multiple patch electrodes 108a and 108b are electrodes capable of reflecting radio wave frequencies corresponding to the 5G communication standard. As mentioned above, these frequencies are, for example, millimeter-wave frequencies, and may be 26 GHz or higher, or in the range of 26 GHz to 36 GHz.

[0037] Figure 7 shows the state in which no voltage is applied between the patch electrode 108 and the ground electrode 110 (referred to as the "first state"). Figure 7 shows the case where the first alignment film 112a and the second alignment film 112b are horizontal alignment films. In the first state, the long axis of the liquid crystal molecules 116 is oriented horizontally with respect to the surfaces of the patch electrode 108 and the ground electrode 110 by the first alignment film 112a and the second alignment film 112b. Figure 8 shows the state in which a control signal (voltage signal) is applied to the patch electrode 108 (referred to as the "second state"). In the second state, the liquid crystal molecules 116 are affected by the electric field and their long axes are oriented perpendicular to the surfaces of the patch electrode 108 and the ground electrode 110. The angle at which the long axis of the liquid crystal molecules 116 is oriented can also be adjusted to an intermediate direction between the horizontal and vertical directions, depending on the magnitude of the control signal applied to the patch electrode 108 (the magnitude of the voltage between the ground electrode and the patch electrode).

[0038] When the liquid crystal molecules 116 have positive dielectric anisotropy, the dielectric constant is higher in the second state than in the first state. Conversely, when the liquid crystal molecules 116 have negative dielectric anisotropy, the apparent dielectric constant is lower in the second state than in the first state. The liquid crystal layer 114 with dielectric anisotropy can also be considered a variable dielectric layer. The reflector unit cell 102 can control the phase of the reflected wave by delaying (or not delaying) it by utilizing the dielectric anisotropy of the liquid crystal layer 114.

[0039] Figure 9 schematically illustrates how the direction of reflected wave propagation changes with respect to any first subunit cell 103a and any first subunit cell 103a adjacent to any first subunit cell 103a. Any first subunit cell 103a and any first subunit cell 103a adjacent to any first subunit cell 103a are adjacent in the X direction. In other words, any patch electrode 108a and any patch electrode 108a adjacent to any patch electrode 108a are connected to different first wirings 118 (first wiring 118a, first wiring 118b). When radio waves are incident on any first subunit cell 103a and an adjacent first subunit cell 103a with the same phase, different control signals (V1 ≠ V2) are applied to the arbitrary first subunit cell 103a and the adjacent first subunit cell 103a. As a result, the phase change of the reflected wave by the arbitrary first subunit cell 103a is greater than the phase change of the reflected wave by the adjacent first subunit cell 103a. Consequently, the phase of the reflected wave R1 reflected by the arbitrary first subunit cell 103a is different from the phase of the reflected wave R2 reflected by the adjacent first subunit cell 103a (in Figure 9, the phase of the reflected wave R2 is ahead of the phase of the reflected wave R1), and the apparent direction of propagation of the reflected wave changes diagonally. In the radio wave reflector 100a, when the first wiring is to be distinguished, it is to be represented as first wiring 118a, first wiring 118b, etc., and when the first wiring is not to be distinguished, it is to be represented as first wiring 118, etc.

[0040] Next, we will describe the results of a simulation of the phase change amount (deg) in the radio wave reflector 100a, where the thickness of the liquid crystal layer was set to 75 μm, and patch electrodes 108a and 108b of the above sizes were used. In the simulation, a reflector with patch electrodes 108a and 108b arranged as shown in Figure 1 was assumed, and the simulation was performed using CST Studio Suite (manufactured by Dassault Systèmes K.K.).

[0041] Although not shown in the diagram, in the radio wave reflector 100a, as an example, it was shown that, when the radio wave frequency is 31 GHz, the phase change when voltage is applied to the liquid crystal layer is -416 degrees, using the phase when no voltage is applied to the liquid crystal layer as the reference. On the other hand, as a comparative example, when a simulation similar to that of the radio wave reflector 100a was performed using a radio wave reflector that includes only one type of patch electrode with a square shape, it was shown that the phase change was -270 degrees. In other words, using cross-shaped patch electrodes 108a and 108b of different sizes, as in the radio wave reflector 100a, is effective in increasing the amount of phase change. Also, although not shown in the diagram, for example, by using cross-shaped patch electrodes 108a and 108b of different sizes, it is possible to create two peaks in the resonant frequency in the millimeter wave band (points where reflectivity is minimum) due to the resonance occurring at patch electrode 108a and the resonance occurring at patch electrode 108b, thereby suppressing the attenuation of the amplitude of the reflected wave and increasing the amount of phase change.

[0042] Furthermore, as shown in Figures 1, 5, and 6, the radio wave reflector 100a uses cross-shaped patch electrodes 108a and 108b of different sizes, allowing a smaller patch electrode 108b to be placed at a distance W1 / 2 away from patch electrode 108a in the X and Y directions. As a result, as shown in Figure 1, the cross-shaped protrusions 109a of patch electrode 108a and 109b of patch electrode 108b can be alternately arranged along the C1-C2 line parallel to the X direction, and the cross-shaped protrusions 109a of patch electrode 108a and 109b of patch electrode 108b can be alternately arranged along the C3-C4 line parallel to the Y direction. Therefore, the radio wave reflector 100a can achieve a higher density of patch electrodes within the reflector 120 (the occupancy rate of patch electrodes within the reflector 120, and the ratio of the area within the reflector 120 where patch electrodes are placed to the area where patch electrodes are not placed) compared to the case where only one type of patch electrode with a square shape is arranged, as in the comparative example. By using cross-shaped patch electrodes 108a and 108b of different sizes, the area of ​​electrodes that can reflect radio waves is increased, and thus the reflection intensity of radio waves can be increased.

[0043] Furthermore, as shown in Figures 1, 5, and 6, the multiple patch electrodes 108a and multiple patch electrodes 108b are arranged adjacent to each other. It is preferable that the multiple patch electrodes 108a and multiple patch electrodes 108b are arranged to be 2-fold or 4-fold rotationally symmetric with respect to the center of the reflector unit cell 102 (in Figures 1, 5, and 6, the center O2 of the patch electrode 108b located in the middle). By arranging the multiple patch electrodes 108a and multiple patch electrodes 108b to be 2-fold or 4-fold rotationally symmetric, symmetry with respect to vertical polarization and horizontal polarization can be achieved.

[0044] In the radio wave reflector 100a, as an example, a reflector unit cell 102 is shown that includes two types of patch electrodes, patch electrode 108a and patch electrode 108b, but the number of patch electrodes is not limited to two types. The reflector unit cell 102 may also include a third patch electrode (not shown) that is different from patch electrodes 108a and 108b. Here, the size of the third patch electrode is different from the size of patch electrodes 108a and 108b. For example, the size of the third patch electrode may be smaller than the size of patch electrode 108a, larger than the size of patch electrode 108b, and smaller than the size of patch electrode 108a. Also, the third patch electrode may be positioned between the shape of patch electrode 108a and patch electrode 108b. If the radio wave reflector 100a includes a third patch electrode, the radio wave reflector according to one embodiment of the present invention is configured by appropriately adjusting the size and arrangement of the third patch electrode in accordance with the size and arrangement of patch electrodes 108a and 108b.

[0045] As described above, the radio wave reflector 100a has at least two different sizes of patch electrodes for the reflector unit cell 102. Using the radio wave reflector 100a according to the first embodiment of the present invention is effective in suppressing attenuation of the amplitude of reflected waves, improving the amount of phase change, and strengthening the reflection intensity of radio waves. By using the radio wave reflector 100a, even when multiple radio wave reflectors 100a are combined to form a transmission path in the air, attenuation of radio waves can be suppressed, so that communication equipment can communicate well.

[0046] Furthermore, in the radio wave reflector 100a, the patch electrode 108 and the ground electrode 110 are formed using a transparent conductive film, and the liquid crystal layer 114 is light-transmitting, so radio waves can be reflected without impairing light collection. Therefore, the radio wave reflector 100a can be installed in the windows of high-rise buildings such as skyscrapers. As a result, it becomes possible to reflect highly directional radio waves in a predetermined direction at high altitudes where there are relatively few obstacles. Therefore, the radio wave reflector 100a can be used to eliminate radio wave dead zones (places where radio waves cannot reach) in urban areas.

[0047] <2.Radio wave reflection device> Next, the configuration of the radio wave reflector 100a, in which the reflector unit cells 102 are integrated, will be described. The radio wave reflector 100a is a radio wave reflector capable of two-axis reflection control. Figure 10 is a plan view showing the configuration of the radio wave reflector 100a. Figure 11 is an enlarged plan view of the reflector unit cell 102 shown in Figure 10, showing the configuration of the reflector unit cell 102. Figure 12 is a cross-sectional view showing a cross-section of the reflector unit cell 102. Configurations that are the same as or similar to those in Figures 1 to 9 will not be explained here.

[0048] As described in "1. Reflector Unit Cell," the reflector 120 is provided between the dielectric substrate 104 and the opposing substrate 106. As shown in Figure 10, the reflector 120 has a structure in which a plurality of reflector unit cells 102 are integrated. The reflector unit cell 102 includes a first subunit cell 103a and a second subunit cell 103b. For example, the plurality of reflector unit cells 102 (a plurality of first subunit cells 103a and a plurality of second subunit cells 103b) are arranged in the X and Y directions. The first subunit cell 103a includes a ground electrode 110, a second alignment film 112b placed on the ground electrode 110, a patch electrode 108a, a first alignment film 112a placed on the patch electrode 108a, an array layer 180, and a liquid crystal layer (not shown) provided between the first alignment film 112a and the second alignment film 112b. The second subunit cell 103b includes a ground electrode 110, a second alignment film 112b placed on the ground electrode 110, a patch electrode 108b, a first alignment film 112a placed on the patch electrode 108b, an array layer 180, and a liquid crystal layer (not shown) provided between the first alignment film 112a and the second alignment film 112b. The patch electrodes 108a and 108b are provided on the array layer 180, which is placed on the dielectric substrate 104, and the ground electrode 110 is provided on the opposing substrate 106. The dielectric substrate 104 is bonded to the opposing substrate 106 using a sealing material 128. The liquid crystal layer is provided in the region inside the sealing material 128.

[0049] In the reflector unit cell 102, patch electrodes 108a and 108b are arranged to face the incident surface of the radio waves. The ground electrode 110 is flat. Multiple patch electrodes 108a and 108b are arranged in a matrix within the plane of the flat ground electrode 110 and inside the sealing material 128.

[0050] As explained in "1. Reflector Unit Cell," in a plan view of the radio wave reflector 100a, the multiple patch electrodes 108a and multiple patch electrodes 108b are arranged in a staggered or checkerboard pattern. Specifically, the patch electrodes 108b are positioned at a distance of W1 / 2 (W5 / 2) parallel to the X direction and a distance of W1 / 2 (W5 / 2) parallel to the Y direction from the patch electrodes 108a. In addition, each patch electrode 108a is adjacent to each patch electrode 108b in the X or Y direction.

[0051] Multiple first wirings 118a and 118b extending in the Y direction are arranged on the dielectric substrate 104. The first wirings 118a and 118b are arranged alternately in the X direction. Each of the multiple first wirings 118a is electrically connected to a plurality of patch electrodes 108a arranged in the second direction, and each of the multiple first wirings 118b is electrically connected to a plurality of patch electrodes 108b arranged in the second direction. The reflector 120 has a configuration in which a plurality of patch electrode arrays connected by the first wirings 118a and 118b are arranged in the Y direction.

[0052] Furthermore, the dielectric substrate 104 is provided with a plurality of second wirings 132a and a plurality of second wirings 132b extending in the X direction. The second wirings 132a and 132b are arranged alternately in the Y direction. Each of the plurality of second wirings 132a is electrically connected to a plurality of patch electrodes 108a arranged in the second direction, and each of the plurality of second wirings 132b is electrically connected to a plurality of patch electrodes 108b arranged in the second direction. The reflector 120 has a configuration in which a plurality of patch electrode arrays connected by the second wirings 132a and 132b are arranged in the X direction.

[0053] In the dielectric substrate 104, the area other than where the reflector 120 is provided is called the peripheral region 122. The peripheral region 122 is provided with the first drive circuit 124 and the terminal section 126. The terminal section 126 is an area that forms a connection with an external circuit, and for example, a flexible printed circuit is connected to the terminal section 126 (not shown). A signal to control the first drive circuit 124 is input to the terminal section 126 from the flexible printed circuit.

[0054] Multiple first wirings 118a and 118b arranged on the reflector 120 extend in the Y-axis direction and into the peripheral region 122, and are connected to the first drive circuit 124. The first drive circuit 124 outputs control signals to patch electrodes 108a and 108b via the first wirings 118a and 118b. The first drive circuit 124 can output control signals of different voltage levels to each of the multiple first wirings 118a and 118b. These control signals of different voltage levels are, for example, a control signal of a first voltage level and a control signal of a second voltage level duration.

[0055] Multiple second wirings 132a and 132b, which are arranged on the reflector 120 and extend in the X direction, extend in the X direction and are connected to the second drive circuit 130. The second drive circuit 130 outputs scanning signals to the multiple second wirings 132a and 132b.

[0056] Figure 11 shows an enlarged view of the arrangement of two patch electrodes 108a and two patch electrodes 108b, first wirings 118a and 118b, and second wirings 132a and 132b. A switching element 134 is provided on each of the two patch electrodes 108a and two patch electrodes 108b. The switching (on and off) of the switching element 134 is controlled by a scanning signal applied to the second wirings 132a and 132b. When the switching element 134 is turned on in response to the scanning signal applied to the second wiring 132a, the patch electrode 108a conducts with the first wiring 118a and a control signal is applied. Similarly, when the switching element 134 is turned on in response to the scanning signal applied to the second wiring 132b, the patch electrode 108b conducts with the first wiring 118b and a control signal is applied. The switching element 134 is formed, for example, from a thin-film transistor. With this configuration, multiple patch electrodes 108a and 108b arranged in the X direction can be selected row by row, and control signals with different voltage levels can be applied to each row.

[0057] The radio wave reflector 100a can control the propagation direction of reflected waves in the left-right direction of the drawing, centered on a reflection axis VR parallel to the Y direction, and can also control the propagation direction of reflected waves in the up-down direction of the drawing, centered on a reflection axis HR parallel to the X direction. In other words, the radio wave reflector 100a includes a reflection axis VR parallel to the Y direction and a reflection axis VH parallel to the X direction, and can control the reflection angle in the direction around the reflection axis VR as the axis of rotation and in the direction around the reflection axis HR as the axis of rotation.

[0058] In the example of the radio wave reflector 100a shown in Figure 10, in the Y direction, patch electrode 108a is positioned parallel to the X direction on the side farther from the first drive circuit 124, and patch electrode 108b is positioned parallel to the X direction on the side closer to the first drive circuit 124. Also, in the example of the radio wave reflector 100a shown in Figure 10, in the X direction, patch electrode 108a is positioned parallel to the Y direction on the side farther from the second drive circuit 130, and patch electrode 108a is positioned parallel to the Y direction on the side closer to the second drive circuit 130. The arrangement of patch electrodes 108a and 108b is not limited to the arrangement shown in Figure 10. For example, patch electrode 108b may be positioned parallel to the X direction on the side farther from the first drive circuit 124, and patch electrode 108a may be positioned parallel to the X direction on the side closer to the first drive circuit 124. Furthermore, the patch electrode 108b may be arranged parallel to the Y direction on the side farther from the second drive circuit 130, or it may be arranged parallel to the Y direction on the side closer to the second drive circuit 130. The radio wave reflector 100a is not limited in its configuration as long as it includes a configuration that controls the reflection angle in the direction with respect to the reflection axis VR as the axis of rotation and in the direction with respect to the reflection axis HR as the axis of rotation.

[0059] Figure 12 shows an example of the cross-sectional structure of a reflector unit cell 102 in which a switching element 134 is connected to a patch electrode 108. The reflector unit cell 102 includes a first subunit cell 103a and a second subunit cell 103b, and the cross-section of the first subunit cell 103a is the same as the cross-section of the second subunit cell 103b. Here, the cross-section of the first subunit cell 103a will be mainly described. The switching element 134 is provided on the dielectric substrate 104. The switching element 134 is a transistor. The switching element 134 includes a structure in which a first gate electrode 138, a second gate insulating layer 146, a semiconductor layer 142, a second gate insulating layer 146, and a second gate electrode 148 are stacked. An undercoat layer 136 may be provided between the first gate electrode 138 and the dielectric substrate 104. A first wiring 118a is provided between the first gate insulating layer 140 and the second gate insulating layer 146. The first wiring 118a is provided so as to be in contact with the semiconductor layer 142. Furthermore, the first connecting wiring 144 is provided on the same conductive layer as the first wiring 118a. The first connecting wiring 144 is also provided so as to be in contact with the semiconductor layer 142. The connection structure of the first wiring 118a and the first connecting wiring 144 to the semiconductor layer 142 is such that one wiring is connected to the source of the transistor and the other wiring is connected to the drain.

[0060] A first interlayer insulating layer 150 is provided so as to cover the switching element 134. A second wiring 132a is provided on the first interlayer insulating layer 150. The second wiring 132a is connected to the second gate electrode 148 via a contact hole formed in the first interlayer insulating layer 150. Although not shown, the first gate electrode 138 and the second gate electrode 148 are electrically connected to each other in a region that does not overlap with the semiconductor layer 142. A second connecting wiring 152 is provided on the first interlayer insulating layer 150, using the same conductive layer as the second wiring 132a. The second connecting wiring 152 is connected to the first connecting wiring 144 via a contact hole formed in the first interlayer insulating layer 150.

[0061] A second interlayer insulating layer 154 is provided so as to cover the second wiring 132a and the second connecting wiring 152. Furthermore, a flattening layer 156 is provided to fill the step created by the formation of the switching element 134. By providing the flattening layer 156, the step created by the switching element 134 can be filled, so the surface of the flattening layer 156 becomes flat. Therefore, a patch electrode 108a can be formed on the flat surface of the flattening layer 156 without being affected by the step created by the switching element 134. A passivation layer 158 is provided on the flat surface of the flattening layer 156. In the radio wave reflector 100a, the array layer 180 includes, for example, an undercoat layer 136, a conductive layer including a first gate electrode 138, a first gate insulating layer 140, a semiconductor layer 142, a conductive layer including a first connection wiring 144, a second gate insulating layer 146, a conductive layer including a second gate electrode 148, a first interlayer insulating layer 150, a conductive layer including a second connection wiring 152, a second interlayer insulating layer 154, a planarization layer 156, and a passivation layer 158. The array layer 180 may also include a conductive layer that forms a patch electrode 108 provided in a contact hole penetrating the passivation layer 158, the planarization layer 156, and the second interlayer insulating layer 154.

[0062] The patch electrode 108 is provided on the passivation layer 158. The patch electrode 108 is connected to the second connection wiring 152 via contact holes that penetrate the passivation layer 158, the planarization layer 156, and the second interlayer insulating layer 154. The first orientation film 112a is provided on the patch electrode 108.

[0063] On the opposing substrate 106, a ground electrode 110 and a second alignment film 112b are provided, similar to the structure of the cross-sections shown in Figures 2 to 4. The side of the dielectric substrate 104 on which the switching element 134 and patch electrode 108a are provided is positioned opposite the side of the opposing substrate on which the ground electrode 110 is provided, and a liquid crystal layer 114 is provided between the side on which the switching element 134 and patch electrode 108a are provided and the side on which the ground electrode 110 is provided. The thickness T of the dielectric substrate 104 can be the length from the surface of the patch electrode 108a on the liquid crystal layer 114 side to the side of the dielectric substrate 104 opposite to the side on which the patch electrode 108 is provided. In this case, the thickness of at least one insulating layer (undercoat layer 136, first gate insulating layer 140, second gate insulating layer 146, first interlayer insulating layer 150, second interlayer insulating layer 154, planarization layer 156, passivation layer 158) between the patch electrode 108 and the dielectric substrate 104 can be taken into consideration.

[0064] Each layer formed on the dielectric substrate 104 is formed using the following materials. The undercoat layer 136 is formed, for example, from a silicon oxide film. The first gate insulating layer 140 and the second gate insulating layer 146 are formed, for example, from a silicon oxide film or from a laminated structure of a silicon oxide film and a silicon nitride film. The semiconductor layer is formed from an oxide semiconductor containing silicon semiconductors such as amorphous silicon and polycrystalline silicon, or metal oxides such as indium oxide, zinc oxide, and gallium oxide. The first gate electrode 138 and the second gate electrode 148 may be composed of, for example, molybdenum (Mo), tungsten (W), or alloys thereof. The first wiring 118, the second wiring 132, the first connecting wiring 144, and the second connecting wiring 152 are formed using metallic materials such as titanium (Ti), aluminum (Al), and molybdenum (Mo). For example, they may be composed of a titanium (Ti) / aluminum (Al) / titanium (Ti) laminated structure or a molybdenum (Mo) / aluminum (Al) / molybdenum (Mo) laminated structure. The planarization layer 156 is formed from a resin material such as acrylic or polyimide. The passivation layer 158 is formed from, for example, a silicon nitride film. The patch electrode 108a and the ground electrode 110 are formed from a metal film such as aluminum (Al) or copper (Cu), or a transparent conductive film such as indium tin oxide (ITO).

[0065] As shown in Figure 12, by connecting the second wiring 132a to the gate of a transistor used as a switching element 134, connecting the first wiring 118a to one of the source and drain of the transistor, and connecting the patch electrode 108a to the other of the source and drain, a control signal can be applied to a predetermined patch electrode from among a plurality of patch electrodes 108a arranged in a matrix. Furthermore, by providing a switching element 134 to each patch electrode 108a in the reflector 120, a control voltage can be applied to each patch electrode 108a arranged in a horizontal row parallel to the X direction, or to each patch electrode 108a arranged in a vertical row parallel to the Y direction. For example, when the reflector 120 is upright, the reflection direction of the reflected wave can be controlled in the left-right and up-down directions.

[0066] Furthermore, the second subunit cell 103b includes a configuration in which the patch electrode 108a, first wiring 118a, and second wiring 132a are replaced with the patch electrode 108b, first wiring 118b, and second wiring 132b.

[0067] <Second Embodiment> In the second embodiment, a radio wave reflector 100b capable of uniaxial reflection control will be described as an example. The reflection axis RY of the radio wave reflector 100b is uniaxial. In the radio wave reflector 100b, the reflection angle can be controlled in the direction with respect to the reflection axis RY as the axis of rotation. The radio wave reflector 100b according to the second embodiment does not include, at least, an array layer 180, a plurality of second wirings 132a and a plurality of second wirings 132b, and a second drive circuit 130 compared to the radio wave reflector 100a according to the first embodiment. In the second embodiment, the differences from the first embodiment will be mainly described.

[0068] Figure 13 is a plan view showing the configuration of the radio wave reflector 100b according to the second embodiment. Figure 14 is a plan view showing the reflector unit cell 102b used in the radio wave reflector 100b. Figure 15 is a cross-sectional view showing the cross-section of line D1-D2 shown in Figure 14, and Figure 16 is a cross-sectional view showing the cross-section of line E1-E2 shown in Figure 14. Configurations that are the same as or similar to those in Figures 1 to 12 are omitted from this description.

[0069] As shown in Figure 13, the reflector 120 according to the second embodiment includes a plurality of reflector unit cells 102b. The reflector 120 according to the second embodiment includes a configuration in which the plurality of reflector unit cells 102 of the reflector 120 according to the first embodiment are replaced with a plurality of reflector unit cells 102b.

[0070] As shown in Figures 13 and 14, a plurality of patch electrodes 108a arranged in the Y direction are electrically connected to the first wiring 118a, and a plurality of patch electrodes 108b arranged in the Y direction are electrically connected to the first wiring 118b. In the reflector 120 according to the second embodiment, a plurality of patch electrodes 108a electrically connected to the first wiring 118a and a plurality of patch electrodes 108b electrically connected to the first wiring 118b form a set of voltage application units 190a, and a plurality of voltage application units 190a are arranged in the X direction. The first wiring 118a is electrically connected to the first wiring 118b in the peripheral region 122. In the reflector 120 according to the second embodiment, the voltage application units 190b include the same configuration as the voltage application units 190a, and the voltage application units 190a and 190b are arranged alternately in the X direction. The first wiring 118a included in the voltage application unit 190a is sometimes called the 1-1 wiring, the first wiring 118b included in the voltage application unit 190a is sometimes called the 1-2 wiring, the first wiring 118a included in the voltage application unit 190b is sometimes called the 1-3 wiring, and the first wiring 118b included in the voltage application unit 190b is sometimes called the 1-4 wiring.

[0071] Similar to the reflector 120 described in "1. Reflector Unit Cell," the reflector 120 according to the second embodiment is provided between the dielectric substrate 104 and the opposing substrate 106. As shown in Figures 13 and 14, the reflector 120 according to the second embodiment has a structure in which a plurality of reflector unit cells 102b are integrated. Similar to the reflector unit cell 102, the reflector unit cell 102b includes a first subunit cell 103a and a second subunit cell 103b.

[0072] As shown in Figures 15 and 16, the first subunit cell 103a includes a ground electrode 110, a second alignment film 112b placed on the ground electrode 110, a patch electrode 108a, a first alignment film 112a placed on the patch electrode 108a, and a liquid crystal layer 114 provided between the first alignment film 112a and the second alignment film 112b. The second subunit cell 103b also includes a ground electrode 110, a second alignment film 112b placed on the ground electrode 110, a patch electrode 108b, a first alignment film 112a placed on the patch electrode 108b, and a liquid crystal layer (not shown) provided between the first alignment film 112a and the second alignment film 112b. The patch electrodes 108a and 108b are provided on a dielectric substrate 104, and the ground electrode 110 is provided on a counter substrate 106. The dielectric substrate 104 is bonded to the counter substrate 106 using a sealing material 128. The liquid crystal layer is provided in the area inside the sealing material 128.

[0073] In the reflector unit cell 102b, patch electrodes 108a and 108b are arranged to face the incident surface of the radio waves. The ground electrode 110 is flat. Multiple patch electrodes 108a and 108b are arranged in a matrix within the plane of the flat ground electrode 110 and inside the sealing material 128.

[0074] In the second embodiment, the multiple first wirings 118a and 118b arranged on the reflector 120 extend into the peripheral region 122 and are connected to the first drive circuit 124. The first drive circuit 124 outputs control signals to the patch electrodes 108a and 108b via the first wirings 118a and 118b. As a result, in the reflector 120, control signals are applied to the patch electrodes 108a and 108b arranged in the Y direction, as well as to the patch electrodes 108a and 108b arranged in the Y direction.

[0075] In the radio wave reflector 100b, the first drive circuit 124 can apply a control signal to each voltage application unit 190a (voltage application unit 190b) arranged in the second direction. For each voltage application unit 190a (voltage application unit 190b) arranged in the second direction, the reflection direction of the reflected wave of the radio wave incident on the reflector 120 can be controlled. That is, in the radio wave reflector 100a, the first drive circuit 124 can apply (supply) different voltages (first voltage and second voltage) to the voltage application unit 190a and the voltage application unit 190b, so that the propagation direction of the reflected wave of the radio wave incident on the reflector 120 can be controlled in the left-right direction of the drawing, centered on the reflection axis VR parallel to the Y direction.

[0076] Multiple patch electrodes 108a and 108b, arranged in a second direction and included in a single voltage application unit 190a (voltage application unit 190b), are electrically connected in the peripheral region 122 using first wirings 118a and 118b, and are electrically at the same potential. In the radio wave reflector 100b, as shown in Figure 13, the patch electrodes 108a and 108b are arranged in an array shape symmetrical with respect to vertical and horizontal polarization, and the multiple patch electrodes 108a and 108b, arranged parallel to the reflection axis RY, are connected by first wirings 118a and 118b. This allows the propagation direction of the reflected waves of radio waves incident on the reflector 120 to be controlled in the left-right direction of the drawing, centered on a reflection axis VR parallel to the Y direction.

[0077] The various configurations of the radio wave reflector and reflector unit exemplified as one embodiment of the present invention can be combined as appropriate, as long as they do not contradict each other. Furthermore, any radio wave reflector and reflector unit disclosed in this specification and drawings, to which a person skilled in the art has added, deleted, or modified components, or to which processes have been added, omitted, or conditions changed, are also included within the scope of the present invention, as long as they retain the essence of the present invention.

[0078] Any effects or benefits other than those brought about by the embodiments disclosed herein are to be understood to be brought about by the present invention if they are clear from the description herein or can be easily predicted by a person skilled in the art. [Explanation of symbols]

[0079] 100a: Radio wave reflector, 100b: Radio wave reflector, 102: Reflector unit cell, 102b: Reflector unit cell, 103a: First subunit cell, 103b: Second subunit cell, 104: Dielectric substrate, 106: Opposing substrate, 108: Patch electrode, 108a: Patch electrode, 108b: Patch electrode, 109a: Protrusion, 109b: Protrusion, 110: Ground electrode, 112a: First alignment film, 112b: Second alignment film, 114: Liquid crystal layer, 116: Liquid crystal molecule, 118: First wiring, 118a: First wiring, 118b: First wiring, 120: Reflector, 122: Peripheral region, 124: 1. Drive circuit, 126: Terminal section, 128: Sealing material, 130: Second drive circuit, 132: Second wiring, 132a: Second wiring, 132b: Second wiring, 134: Switching element, 136: Undercoat layer, 138: First gate electrode, 140: First gate insulating layer, 142: Semiconductor layer, 144: First connection wiring, 146: Second gate insulating layer, 148: Second gate electrode, 150: First interlayer insulating layer, 152: Second connection wiring, 154: Second interlayer insulating layer, 156: Planarization layer, 158: Passivation layer, 180: Array layer, 190a: Voltage application unit, 190b: Voltage application unit

Claims

1. Multiple first patch electrodes, A plurality of second patch electrodes having different sizes from the plurality of first patch electrodes, A ground electrode is provided facing the plurality of first patch electrodes and the plurality of second patch electrodes, and spaced apart from the plurality of first patch electrodes and the plurality of second patch electrodes, The system includes the plurality of first patch electrodes and the plurality of second patch electrodes, and a liquid crystal layer provided between them and the ground electrode, In a plan view, the plurality of first patch electrodes and the plurality of second patch electrodes are arranged in a matrix in a first direction and a second direction intersecting the first direction. A radio wave reflector, wherein, when the distance between the centers of two adjacent first patch electrodes is defined as distance W1, the second patch electrode is positioned at a distance W1 / 2 parallel to the first direction and a distance W1 / 2 parallel to the second direction from the first patch electrode, with respect to the position of the first patch electrode.

2. In a square formed by connecting the centers of four second patch electrodes adjacent to one of the multiple first patch electrodes with lines, The intersection of the diagonals of the square coincides with the center of one of the first patch electrodes. The radio wave reflector according to claim 1.

3. In a square formed by connecting the centers of four of the first patch electrodes adjacent to one of the multiple second patch electrodes with lines, The intersection of the diagonals of the square coincides with the center of one of the second patch electrodes. The radio wave reflector according to claim 1.

4. The radio wave reflector according to claim 1, wherein the size of the plurality of first patch electrodes is larger than the size of the plurality of second patch electrodes.

5. The radio wave reflector according to claim 1, wherein, in a plan view, the shapes of the plurality of first patch electrodes and the plurality of second patch electrodes are cross-shaped.

6. The plurality of first patch electrodes and the plurality of second patch electrodes are arranged in a checkerboard pattern. The radio wave reflector according to claim 1.

7. A first-first wiring is electrically connected to at least two of the plurality of first patch electrodes, Of the plurality of second patch electrodes, at least two second patch electrodes are electrically connected to the first-second wiring, which is arranged parallel to the first-first wiring, A drive circuit electrically connected to the wiring 1-1 and the wiring 1-2, It further includes, The drive circuit supplies a first voltage to the wiring 1-1 and the wiring 1-2. The radio wave reflector according to claim 6.

8. Among the plurality of first patch electrodes, at least two first patch electrodes different from the at least two first patch electrodes are electrically connected to the first to third wirings which are arranged parallel to the first to second wirings, Among the plurality of second patch electrodes, at least two second patch electrodes different from the at least two second patch electrodes are electrically connected to the first to fourth wirings which are arranged parallel to the first to third wirings, It further includes, The wiring described in 1-3 and the wiring described in 1-4 are electrically connected to the drive circuit. The drive circuit supplies a second voltage, different from the first voltage, to the wirings 1-3 and 1-4. The radio wave reflector according to claim 7.

9. The radio wave reflector according to claim 1, wherein each of the plurality of first patch electrodes and the plurality of second patch electrodes is electrically connected to a switching element.

10. The radio wave reflector according to claim 1, wherein the plurality of first patch electrodes and the plurality of second patch electrodes are capable of reflecting radio wave frequencies corresponding to the 5G communication standard.

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