Radio wave reflecting device

Abstract

The radio wave reflecting device 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 that faces the plurality of first patch electrodes and the plurality of second patch electrodes and is provided separately 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, the plurality of first patch electrodes and the plurality of second patch electrodes being alternately arranged in a first direction or a second direction intersecting the first direction, and each of the first patch electrodes and each of the second patch electrodes being adjacent to each other in the first direction or the second direction.

Description

Technical Field

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

[0002] A phased array antenna device adjusts the amplitude and phase of a high-frequency signal applied to each of a plurality of antenna units arranged in a planar shape, thereby controlling the directivity with the antenna fixed. A phased array antenna device needs to be provided with a phase shifter. In the past, a phased array antenna device using a phase shifter has been disclosed, wherein the phase shifter utilizes a change in the dielectric constant based on the orientation state of the liquid crystal (for example, refer to Patent Document 1).

[0003] The antenna unit of the phased array antenna device in Patent Document 1 includes: a plurality of strip-shaped wirings; a planar electrode facing the plurality of strip-shaped wirings; and a liquid crystal layer provided between the plurality of strip-shaped wirings and the planar electrode. In the plurality of antenna units, different voltages are applied to the plurality of strip-shaped wirings. Furthermore, by adjusting the dielectric constant of the liquid crystal layer of each antenna unit so that the reflected waves overlap, the phase can be changed. Thus, the reflection direction of the radio wave can be set to an arbitrary direction.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: JP Patent Publication No. 11-103201 Summary of the invention

[0007] In the field of communications, the introduction of the fifth generation of communication standards, known as 5G, has been promoted. This communication standard uses the millimeter wave band frequency of 26GHz to 28GHz. Communications based on the 5G standard can achieve very high throughput by using the millimeter wave band frequency, and can be transmitted with a wide bandwidth. However, radio waves based on the millimeter wave band frequency have the characteristics of high linearity and difficulty in propagating around obstacles. Therefore, there is a problem of narrowing the communication area that can be covered by the 5G standard in urban areas.

[0008] In order to avoid obstacles and expand the communication area, it is considered to use a reflector to change the transmission direction of radio waves. However, in the phased array antenna device described in Patent Document 1, the phase change amount is insufficient and the radio waves cannot be reflected in the target direction.

[0009] In view of such a problem, one object of one embodiment of the present invention is to improve the reflection gain of a radio wave reflection device.

[0010] An electric wave reflecting device according to one embodiment of the present invention includes: a plurality of first patch electrodes; a plurality of second patch electrodes having a size different from that of the plurality of first patch electrodes; a ground electrode, which is opposite to the plurality of first patch electrodes and the plurality of second patch electrodes and is separated from the plurality of first patch electrodes and the plurality of second patch electrodes; and a liquid crystal layer, which is arranged between the plurality of first patch electrodes and the plurality of second patch electrodes and the ground electrode, the plurality of first patch electrodes and the plurality of second patch electrodes are alternately arranged in a first direction or in a second direction intersecting the first direction, and each first patch electrode is adjacent to each second patch electrode in the first direction or the second direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1A It is a top view of a reflector unit cell used in the radio wave reflection device according to one embodiment of the present invention.

[0012] Figure 1B It is shown Figure 1A A diagram showing the cross-sectional structure between A1 and A2 in the top view.

[0013] Figure 2A This is a diagram showing a state in which no voltage is applied between the patch electrode and the ground electrode in the reflector unit body used in the radio wave reflection device according to one embodiment of the present invention.

[0014] Figure 2B This is a diagram showing a state where a voltage is applied between a patch electrode and a ground electrode in a reflector unit body used in a radio wave reflection device according to an embodiment of the present invention.

[0015] Figure 3 This is a diagram schematically showing how the traveling direction of a reflected wave is changed by the radio wave reflecting device according to one embodiment of the present invention.

[0016] Figure 4 This is a diagram showing the results of simulation of the relationship between frequency and amplitude when patch electrodes of two sizes are used in the radio wave reflection device according to one embodiment of the present invention.

[0017] Figure 5 This is a diagram showing the results of simulation of the relationship between frequency and phase when patch electrodes of two sizes are used in the radio wave reflection device according to one embodiment of the present invention.

[0018] Figure 6 It is a diagram showing the configuration of a radio wave reflection device according to one embodiment of the present invention.

[0019] Figure 7 It is a diagram showing the configuration of a radio wave reflection device according to one embodiment of the present invention.

[0020] Figure 8 It is a diagram showing a cross-sectional structure of a reflecting plate unit body in the radio wave reflecting device according to one embodiment of the present invention.

[0021] Fig. 9 It is a diagram showing the structure of a radio wave reflection device according to Modification 1.

[0022] Fig.10 It is a diagram showing the structure of a radio wave reflection device according to Modification 2.

[0023] Fig.11 This is a diagram showing the results of simulation of the relationship between frequency and amplitude when patch electrodes of one size are used in the radio wave reflection device according to one embodiment of the present invention.

[0024] Fig.12 This is a diagram showing the results of simulation of the relationship between frequency and phase when patch electrodes of one size are used in the radio wave reflection device according to one embodiment of the present invention.

[0025] Fig.13 This is a diagram showing the results of simulation of the relationship between frequency and amplitude when two types of patch electrodes having greatly different sizes are used in the radio wave reflection device according to one embodiment of the present invention.

[0026] Fig.14 This is a diagram showing the results of a simulation of the relationship between frequency and phase when two types of patch electrodes having greatly different sizes are used in the radio wave reflection device according to one embodiment of the present invention. DETAILED DESCRIPTION

[0027] Hereinafter, the embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms, and is not limited to the description of the embodiments illustrated below. In order to make the description clearer, the width, thickness, shape, etc. of each part of the accompanying drawings are sometimes schematically shown compared to the actual form, but this is only an example and does not limit the interpretation of the present invention. In addition, in this specification and each figure, the same figure mark (or a, b, etc. are marked after the number) is sometimes used for the same elements as the elements in the accompanying drawings that have appeared, and detailed descriptions are appropriately omitted. Moreover, the text marked as "1st" and "2nd" for each element is to facilitate the identification used to distinguish each element, and does not have more meaning unless otherwise specified.

[0028] In this specification, when a certain component or region is located "on (or below)" other components or regions, unless otherwise specified, it includes not only the case where it is located directly above (or directly below) other components or regions, but also the case where it is located above (or below) other components or regions, that is, it also includes the case where other components are included between the above (or below) other components or regions.

[0029] (First embodiment)

[0030] In this embodiment, refer to Figure 1A to Figure 10 A radio wave reflection device according to one embodiment of the present invention will be described.

[0031] 1. Reflector unit

[0032] First, the reflection plate units 102a and 102b used in the radio wave reflection device will be described.

[0033] Figure 1A This is a top view of the reflector unit bodies 102a and 102b used in the radio wave reflection device according to one embodiment of the present invention as viewed from above (radio wave incident side). Figure 1B yes Figure 1A A cross-sectional view between A1-A2 is shown.

[0034] like Figure 1A as well as Figure 1BAs shown, the reflector unit body 102a includes a dielectric substrate 104, an opposing substrate 106, a patch electrode 108a, a ground electrode 110, a liquid crystal layer 114, a first orientation film 112a, and a second orientation film 112b. In addition, the reflector unit body 102b includes a dielectric substrate 104, an opposing substrate 106, a patch electrode 108b, a ground electrode 110, a liquid crystal layer 114, a first orientation film 112a, and a second orientation film 112b. In the reflector unit bodies 102a and 102b, the dielectric substrate 104 can also be regarded as a dielectric layer forming one layer. Therefore, the dielectric substrate 104 is sometimes referred to as a dielectric layer. The patch electrodes 108a and 108b are provided on the dielectric substrate 104, and the ground electrode 110 is provided on the opposing substrate 106. A first orientation film 112a is provided on the dielectric substrate 104 so as to cover the patch electrodes 108a and 108b. A second orientation film 112b is provided on the counter substrate 106 so as to cover the ground electrode 110. The patch electrode 108a and the ground electrode 110 are arranged opposite to each other, and a liquid crystal layer 114 is provided between them. Similarly, the patch electrode 108b and the ground electrode 110 are arranged opposite to each other, and a liquid crystal layer 114 is provided between them. The first orientation film 112a is interposed between the patch electrodes 108a and 108b and the liquid crystal layer 114. The second orientation film 112b is interposed between the ground electrode 110 and the liquid crystal layer 114.

[0035] In one embodiment of the present invention, the difference between the reflector unit body 102a and the reflector unit body 102b lies in the size (or area) of the patch electrode 108a and the patch electrode 108b. Figure 1A In the description, the size of the patch electrode 108a is larger than the size of the patch electrode 108b. In the following description, when the reflector unit body 102a and the reflector unit body 102b are not particularly distinguished, they are simply described as the reflector unit body 102. In addition, when there is no need to particularly distinguish the patch electrode 108a and the patch electrode 108b, they are simply described as the patch electrode 108.

[0036] In the present embodiment, when looking down at the reflector unit bodies 102a and 102b, the plurality of patch electrodes 108a and the plurality of patch electrodes 108b are arranged in a staggered pattern (Checked pattern). Specifically, the plurality of patch electrodes 108a and the plurality of patch electrodes 108b are arranged alternately in the first direction (X-axis direction) or the second direction (Y-axis direction) intersecting the first direction. In addition, each patch electrode 108a is adjacent to each patch electrode 108b in the first direction or the second direction. In addition, in the patch electrodes 108a and the patch electrodes 108b arranged in the first direction, the center O1 of the patch electrode 108a and the center O2 of the patch electrode 108b are arranged in the first direction. In the patch electrodes 108a and the patch electrodes 108b arranged in the second direction, the center O1 of the patch electrode 108a and the center O2 of the patch electrode 108b are arranged in the second direction.

[0037] The shape of the patch electrode 108 is preferably a shape having rotational symmetry with respect to the center O of the patch electrode 108. For example, the shape of the patch electrode 108 may be a four-fold rotationally symmetrical shape, having a square or rhombus shape in a plan view. In addition, as a four-fold rotationally symmetrical shape, it may be a quadrilateral with chamfered vertices or a quadrilateral with rounded vertices. In addition, the shape of the patch electrode 108 may be circular. Figure 1A The patch electrode 108 is shown to be square in a plan view. By making the shape of the patch electrode 108 rotationally symmetric with respect to the center of the patch electrode 108, anisotropy related to the reflection of the vertical polarization and horizontal polarization of the incident radio wave can be reduced. That is, it is possible to suppress Figure 1A The vertical polarization and horizontal polarization in the XY plane are biased, and the vertical polarization and horizontal polarization can be reflected uniformly. The shape of the ground electrode 110 is not particularly limited, and has a shape that extends to substantially the entire surface of the counter substrate 106 in a manner that has a wider area than the patch electrode 108 .

[0038] The materials forming the patch electrode 108 and the ground electrode 110 are not limited, and they are formed using conductive metals or metal oxides. The first wiring 118 may also be provided on the dielectric substrate 104. The first wiring 118 connects the patch electrode 108a and the patch electrode 108b. The first wiring 118 can be used when a control signal is applied to the patch electrode 108a and the patch electrode 108b. In addition, when a plurality of reflector unit bodies 102a and 102b are arranged, the first wiring 118 can be used when, for example, the patch electrode 108a and the patch electrode 108b are connected.

[0039] The reflector unit 102 is used as a reflector 120 that reflects radio waves in a predetermined direction. Therefore, it is preferable that the reflector unit 102 minimizes attenuation of the amplitude of the reflected radio waves. Figure 1B As is clear from the structure shown, when radio waves propagating in the air are reflected by the reflector unit 102, the radio waves pass through the dielectric substrate 104 twice. The dielectric substrate 104 is preferably formed of a dielectric material such as glass or resin.

[0040] Although Figure 1A as well as Figure 1B 1, but the dielectric substrate 104 and the counter substrate 106 are sealed with a sealing material 128 (see Figure 6 ) are bonded together. The dielectric substrate 104 and the opposing substrate 106 are arranged relative to each other with a gap therebetween. The liquid crystal layer 114 is considered to be filled in the area surrounded by the sealing material 128. The gap between the dielectric substrate 104 and the opposing substrate 106 is 20μm to 100μm, for example, a gap of 75μm. A patch electrode 108, a ground electrode 110, a first orientation film 112a, and a second orientation film 112b are provided between the dielectric substrate 104 and the opposing substrate 106. To be precise, the gap between the first orientation film 112a and the second orientation film 112b provided on the dielectric substrate 104 and the opposing substrate 106, respectively, is the thickness of the liquid crystal layer 114. In addition, although in Figure 1B Although not shown, a spacer for maintaining a certain distance may be provided between the dielectric substrate 104 and the counter substrate 106 .

[0041] A control signal for controlling the orientation of the liquid crystal molecules of the liquid crystal layer 114 is applied to the patch electrode 108. The control signal is a DC voltage signal, or a polarity reversal signal in which a positive DC voltage and a negative DC voltage are alternately reversed. A voltage of an intermediate level of the ground or polarity reversal signal is applied to the ground electrode 110. By applying a control signal to the patch electrode 108, the orientation state of the liquid crystal molecules contained in the liquid crystal layer 114 is changed. The liquid crystal layer 114 uses a liquid crystal material having dielectric anisotropy. For example, nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal, or discotic liquid crystal. The dielectric constant of the liquid crystal layer 114 having dielectric anisotropy changes according to the change in the orientation state of the liquid crystal molecules. The reflector unit 102 can change the dielectric constant of the liquid crystal layer 114 according to the control signal applied to the patch electrode 108. As a result, when the radio wave is reflected, the phase of the reflected wave is delayed.

[0042] The frequency bands of the radio waves reflected by the reflector unit 102 are the very short wave (VHF: Very High Frequency) band, the ultra-short wave (UHF: UItra-High Frequency) band, the microwave (SHF: Super High Frequency) band, the submillimeter wave (THF: Tremendously high frequency), and the millimeter wave (EHF: Extra High Frequency) band. In addition, millimeter waves refer to the frequency band of 30GHz to 300GHz. In addition, the fifth generation communication standard called 5G also includes the 26GHz band to the 29GHz band, and the frequencies above the 26GHz band are sometimes collectively referred to as millimeter waves. The liquid crystal molecules of the liquid crystal layer 114 respond to the control signal applied to the patch electrode 108 to change the orientation of the liquid crystal molecules, but basically do not follow the frequency of the radio wave incident on the patch electrode 108. Therefore, the reflector unit 102 can control the phase of the reflected radio wave without being affected by the radio wave.

[0043] Figure 2A The state in which no voltage is applied between the patch electrode 108 and the ground electrode 110 (the “first state”) is shown. Figure 2A The first and second alignment films 112a and 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 ground electrode 110 by the first and second alignment films 112a and 112b. Figure 2B The state (the "second state") in which a control signal (voltage signal) is applied to the patch electrode 108 is shown. In the second state, the liquid crystal molecules 116 are affected by the electric field, and their long axes are oriented perpendicularly to the surfaces of the patch electrode 108 and the ground electrode 110. The angle of the long axis orientation of the liquid crystal molecules 116 can also be oriented in a direction intermediate between the horizontal direction and the vertical direction according to 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).

[0044] When the liquid crystal molecules 116 have positive dielectric anisotropy, the dielectric constant of the second state becomes larger than that of the first state. In addition, when the liquid crystal molecules 116 have negative dielectric anisotropy, the dielectric constant of the second state becomes smaller than that of the first state. The liquid crystal layer 114 having dielectric anisotropy can also be regarded as a variable dielectric layer. The reflector unit 102 can utilize the dielectric anisotropy of the liquid crystal layer 114 to control the phase of the reflected wave in a manner that is delayed (or not delayed).

[0045] Figure 3The schematic diagram shows that the traveling direction of the reflected wave is changed by using the reflector unit 102a and the reflector unit 102b. The reflector unit 102a and the reflector unit 102b are adjacent to each other in the first direction (X-axis direction). That is, the patch electrode 108a and the patch electrode 108b are connected to different first wirings 118. When the radio wave is incident on the reflector unit 102a and the reflector unit 102b with the same potential, since different control signals (V1≠V2) are applied to the reflector unit 102a and the reflector unit 102b, the phase change of the reflected wave based on the reflector unit 102b is greater than that of the reflector unit 102a. As a result, the phase of the reflected wave R1 reflected by the reflector unit 102a is different from the phase of the reflected wave R2 reflected by the reflector unit 102b (in Figure 3 In the figure, the phase of the reflected wave R2 is ahead of the phase of the reflected wave R1), indicating that the traveling direction of the reflected wave changes toward the inclined direction.

[0046] Next, the simulation results of the phase change (deg) and amplitude (dB) in a radio wave reflection device using patch electrodes of two sizes are described. Figure 1A The figure shows a reflector of a radio wave reflection device in which patch electrodes of two sizes are arranged in the first direction and the second direction. The size of the patch electrode 108a is 2.8 mm×2.8 mm (7.84 mm 2 ), the size of the patch electrode 108b is 2.5mm×2.5mm(6.25mm 2 ). The interval between the patch electrode 108a and the patch electrode 108b is 3.7 mm. In addition, the thickness of the liquid crystal layer 114 of the reflector unit bodies 102a and 102b is 75 μm. In addition, the dielectric constants of the liquid crystal layer 114 are calculated as ε=a, b, c (a>b>c) with respect to the respective dielectric constants. In addition, the dielectric constant ε=a is a state in which a voltage V1 is applied to the liquid crystal layer 114, and the dielectric constant ε=c is a state in which no voltage is applied to the liquid crystal layer 114. In addition, the dielectric constant ε=b is a state in which an intermediate voltage V2 is applied to the liquid crystal layer 114 (V1>V2>0).

[0047] Figure 4 This is a diagram showing the relationship between frequency and reflection amplitude in a radio wave reflection device using patch electrodes of two sizes. Figure 5 : is a graph showing the relationship between the frequency and the phase change amount in the radio wave reflection device using patch electrodes of two sizes. Note that this simulation was performed using CST Studio Suite (manufactured by Dassault Systèmes Co., Ltd.).

[0048] according to Figure 4, showing that at 28 GHz, the reflection amplitude is -1.8 dB when ε=c (no voltage applied), and -5.4 dB when ε=a (voltage applied). Figure 5 , showing that at 28 GHz, the phase change in the case of ε=a is -335.2, taking the phase in the case of ε=c as the reference.

[0049] The size (area) of the patch electrode 108a used in the simulation is 25% larger than the size (area) of the patch electrode 108b. Figure 5 As shown, there are two peak values ​​of the resonance frequency (the point with the smallest reflection amplitude) in the dielectric constant ε=a, b, c within the range of 25 GHz to 35 GHz. Figure 5 , for each of dielectric constants ε=a, b, and c, the peak value of the resonance frequency due to the patch electrode 108a and the peak value of the resonance frequency due to the patch electrode 108b are shown.

[0050] Next, the results of simulating the phase change (deg) and amplitude (dB) in a radio wave reflection device using patch electrodes of one size are described. The simulation assumes a reflector of a radio wave reflection device in which patch electrodes of one size are arranged in the first direction and the second direction. The size of the patch electrodes is 2.8 mm × 2.8 mm (7.84 mm 2 ). The interval between the patch electrodes is 3.7 mm. In addition, the thickness of the liquid crystal layer 114 of the reflector unit bodies 102a and 102b is 40 μm. In addition, as ε=a, b, c (a>b>c), the dielectric constant of the liquid crystal layer 114 is calculated for each dielectric constant. In addition, the dielectric constant ε=a is a state where a voltage V1 is applied to the liquid crystal layer 114, and the dielectric constant ε=c is a state where no voltage is applied to the liquid crystal layer 114. In addition, the dielectric constant ε=b is a state where an intermediate voltage V2 is applied to the liquid crystal layer 114 (V1>V2>0).

[0051] Fig.11 This is a diagram showing the relationship between frequency and reflection amplitude in a radio wave reflection device using patch electrodes of one size. Fig.12 This is a diagram showing the relationship between the frequency and the phase change amount in a radio wave reflection device using patch electrodes of one size. Note that this simulation was performed using CST Studio Suite (manufactured by Dassault Systèmes Co., Ltd.).

[0052] exist Fig.11In any dielectric constant ε = a, b, c, the peak value of the resonance frequency is one. When using a patch electrode of one size (when the patch electrodes are all the same size), the reflection amplitude is insufficient due to material loss (dielectric tangent tanδ of the liquid crystal material and conductor loss of the patch electrode material), and the variable range of the dielectric constant is insufficient due to the limitation of the dielectric anisotropy of the liquid crystal material. Therefore, if Fig.12 As shown, the phase change amount in the frequency band near the target frequency becomes lower than the desired phase change amount. Both are limited by material properties. Therefore, one embodiment of the present invention using patch electrodes of different sizes in the radio wave reflection device is effective.

[0053] Next, the results of simulating the phase change (deg) and amplitude (dB) in a radio wave reflection device using patch electrodes of two sizes are described in the case where the size of the patch electrode 108a is too large relative to the size of the patch electrode 108b. The simulation assumes a reflector of a radio wave reflection device in which patch electrodes of one size are arranged in the first direction and the second direction. The size of the patch electrode 108a is 3.1 mm × 3.1 mm (9.61 mm 2 The size of the patch electrode 108b is 2.5mm×2.5mm(6.25mm 2 ). The interval between the patch electrode 108a and the patch electrode 108b is 3.7 mm. In addition, the thickness of the liquid crystal layer 114 of the reflector unit bodies 102a and 102b is 50 μm. In addition, the dielectric constant of the liquid crystal layer 114 is calculated relative to the respective dielectric constants as ε=a, b, c (a>b>c). In addition, the dielectric constant ε=a is a state in which a voltage V1 is applied to the liquid crystal layer 114, and the dielectric constant ε=c is a state in which no voltage is applied to the liquid crystal layer 114. In addition, the dielectric constant ε=b is a state in which an intermediate voltage V2 is applied to the liquid crystal layer 114 (V2>V1>0).

[0054] Fig.13 This is a diagram showing the relationship between frequency and reflection amplitude in a radio wave reflection device using patch electrodes of two sizes. Fig.14 : is a graph showing the relationship between the frequency and the phase change amount in the radio wave reflection device using patch electrodes of two sizes. Note that this simulation was performed using CST Studio Suite (manufactured by Dassault Systèmes Co., Ltd.).

[0055] The size of the patch electrode 108a used in the simulation is 54% larger than the size of the patch electrode 108b. Fig.13 As shown in the figure, the resonant frequency will deviate greatly from the target frequency band (28GHz band). Resonance occurs in the two greatly deviated frequency bands. Fig.14As shown, there occurs a problem that the phase change amount in the section near the target frequency becomes lower than the desired phase change amount.

[0056] from Figure 4 as well as Figure 5 The results show that the size of the patch electrode 108a is preferably 107% or more and 140% or less relative to the size of the patch electrode 108b. In addition, when the radio wave reflection device 100a is used in the 28 GHz band, for example, the size of each patch electrode 108a is 7.0 mm 2 Above 9.3mm 2 Below, the size of each patch electrode 108b is 5.5mm 2 Above 7.0mm 2 the following.

[0057] exist Figure 1A In the embodiment, the plurality of patch electrodes 108a and the plurality of patch electrodes 108b are arranged adjacent to each other. At this time, the plurality of patch electrodes 108a and the plurality of patch electrodes 108b are preferably arranged in a manner that is two-fold rotationally symmetrical or four-fold rotationally symmetrical with respect to the center of the region where the plurality of patch electrodes 108a and the plurality of patch electrodes 108b are arranged in the first direction and the second direction. By configuring the arrangement of the plurality of patch electrodes 108a and the plurality of patch electrodes 108b in this manner, it is possible to achieve symmetry with respect to vertical polarization and horizontal polarization.

[0058] As described above, in the radio wave reflection device of one embodiment of the present invention, the sizes of the patch electrodes of the reflector unit body are set to at least two. Thus, the peak values ​​of the resonance frequency in the millimeter wave band (the points with the minimum reflectivity) can be set to two by the resonance generated in the patch electrode 108a and the resonance generated in the patch electrode 108b. Thus, the attenuation of the amplitude of the reflected wave can be suppressed, and the phase change amount can be increased. According to this characteristic, even when a plurality of radio wave reflection devices are combined to form a transmission path in the air, the attenuation of the radio wave can be suppressed, and the communication device can perform good communication.

[0059] The radio wave reflection device of one embodiment of the present invention can be formed using a transparent conductive film as the patch electrode 108 and the ground electrode 110. In addition, the liquid crystal layer 114 also has light transmittance. Therefore, by installing the radio wave reflection device in the window of a high-rise building such as a building to reflect the radio wave in a predetermined direction, it can be used to eliminate the blind spot of the radio wave (the place where the radio wave does not reach) in the urban area.

[0060] In this embodiment, the size of the patch electrode 108a is larger than the size of the patch electrode 108b, but one embodiment of the present invention is not limited to this. The size of the patch electrode 108a can be smaller than the size of the patch electrode 108b. In this case, the size of the patch electrode 108a only needs to be 70% or more and 93% or less relative to the size of the patch electrode 108b. For example, the size of each patch electrode 108a is 5.5mm 2 Above 7.0mm 2 Below, the size of each patch electrode 108b is 7.0 mm 2 Above 9.3mm 2 the following.

[0061] 2. Radio wave reflection device

[0062] Next, the configuration of the radio wave reflecting device in which the radio wave reflecting unit is integrated will be described.

[0063] 2-1. Radio wave reflection device (one-axis reflection control)

[0064] Figure 6 This is the structure of a radio wave reflection device 100a according to one embodiment of the present invention.

[0065] The radio wave reflection device 100 a includes a reflection plate 120 , a first drive circuit 124 , and a terminal portion 126 .

[0066] The reflector 120 is provided between the dielectric substrate 104 and the counter substrate 106. The reflector 120 has a structure in which a plurality of reflector unit bodies 102a and 102b are integrated. The plurality of reflector unit bodies 102a and 102b are, for example, arranged in a first direction ( Figure 6 The X-axis direction shown) and the second direction intersecting the first direction ( Figure 6 The reflector unit 102a includes a ground electrode 110, a patch electrode 108a, and a liquid crystal layer (not shown) disposed between the ground electrode 110 and the patch electrode 108a. In addition, the reflector unit 102b includes a ground electrode 110, a patch electrode 108b, and a liquid crystal layer (not shown) disposed between the ground electrode 110 and the patch electrode 108b. The patch electrode 108a and the patch electrode 108b are disposed on the dielectric substrate 104, and the ground electrode 110 is disposed on the opposing substrate 106. In addition, the dielectric substrate 104 and the opposing substrate 106 are bonded together by a sealing material 128, and the liquid crystal layer is disposed in a region inside the sealing material 128.

[0067] In the reflector unit bodies 102a and 102b, the patch electrodes 108a and 108b are arranged to face the incident surface of the radio wave. The ground electrode 110 is in the form of a plate. A plurality of patch electrodes 108a and 108b are arranged in a matrix on the surface of the flat ground electrode 110.

[0068] In this embodiment, when looking down at the reflector 120, the plurality of patch electrodes 108a and the plurality of patch electrodes 108b are arranged in a staggered pattern. Specifically, the plurality of patch electrodes 108a and the plurality of patch electrodes 108b are alternately arranged in the first direction (X-axis direction) or in the second direction (Y-axis direction) intersecting the first direction. In addition, each patch electrode 108a is adjacent to each patch electrode 108b in the first direction or the second direction.

[0069] A plurality of first wirings 118 extending in the second direction are provided on the dielectric substrate 104. Each of the plurality of first wirings 118 is electrically connected to a plurality of patch electrodes 108a and patch electrodes 108b arranged in the second direction. In other words, the patch electrodes 108a and patch electrodes 108b arranged in the second direction are connected by the first wirings 118. The reflector 120 has a configuration in which a plurality of patch electrode arrays connected by the first wirings 118 are arranged in the second direction.

[0070] In the dielectric substrate 104, the area other than the reflector 120 is defined as a peripheral area 122. The peripheral area 122 is provided with a first drive circuit 124 and a terminal portion 126. The terminal portion 126 is a region for forming a connection with an external circuit, and for example, a flexible printed circuit is connected to the terminal portion 126 (not shown). A signal for controlling the first drive circuit 124 is input from the flexible printed circuit to the terminal portion 126.

[0071] The plurality of first wirings 118 disposed on the reflector 120 extend to the peripheral region 122 and are connected to the first drive circuit 124. The first drive circuit 124 outputs a control signal to the patch electrodes 108a and 108b via the first wirings 118. The first drive circuit 124 can output control signals of different voltage levels to the plurality of first wirings 118. Thus, in the reflector 120, the control signal is applied to the patch electrodes 108a and 108b arranged in the second direction, with respect to the patch electrodes 108a and 108b arranged in the first direction and the second direction.

[0072] The radio wave reflection device 100a applies a control signal to each group of the plurality of patch electrodes 108 arranged in the second direction, thereby being able to control the reflection direction of the reflected wave of the radio wave incident on the reflection plate 120. That is, the radio wave reflection device 100a can control the traveling direction of the reflected wave of the radio wave incident on the reflection plate 120 to be the left-right direction of the drawing centered on the reflection axis RY parallel to the second direction (Y-axis direction).

[0073] In addition, Figure 6 In the embodiment, a plurality of patch electrodes 108a and 108b arranged in the second direction are electrically connected by the first wiring 118 and are electrically at the same potential. Therefore, instead of considering dividing into a plurality of shapes, it is possible to consider replacing them with strip-shaped electrodes connected to the second direction (Y-axis direction). However, the sizes of the patch electrodes 108a and 108b have an appropriate range due to the different wavelengths of the reflected radio waves. Therefore, if the electrode shape is set to a strip shape, the sensitivity to the wavelength of the target decreases, and the actions with respect to vertical polarization and horizontal polarization will be different. Therefore, if Figure 6 As shown, the patch electrodes 108a and 108b are symmetrical with respect to the vertical polarization and the horizontal polarization (in Figure 6 The plurality of patch electrodes 108a and the plurality of patch electrodes 108b arranged parallel to the reflection axis RY are preferably connected by the first wiring 118.

[0074] 2-2. Radio wave reflection device (two-axis reflection control)

[0075] The reflection axis RY of the radio wave reflection device 100a shown in the first embodiment is an axis, so the reflection angle can be controlled to be the direction in which the reflection axis RY is set as the rotation axis. In contrast, this embodiment shows an example of a radio wave reflection device 100b that can perform two-axis reflection control. In the following description, the part different from the second embodiment is described as the center.

[0076] Figure 7 The structure of the radio wave reflection device 100b of this embodiment is shown. Figure 6 The description will focus on the different parts of the radio wave reflection device 100a shown.

[0077] The radio wave reflection device 100b has a plurality of first wirings 118 extending in the second direction (Y-axis direction) on the reflection plate 120, and also has a plurality of second wirings 132 extending in the first direction (X-axis direction). The plurality of first wirings 118 and the plurality of second wirings 132 are arranged to cross each other via an insulating layer not shown. The plurality of first wirings 118 are connected to the first drive circuit 124, and the plurality of second wirings 132 are connected to the second drive circuit 130. The first drive circuit 124 outputs a control signal, and the second drive circuit 130 outputs a scanning signal.

[0078] Figure 7 An inset diagram showing the arrangement of two patch electrodes 108a and two patch electrodes 108b, two first wirings 118, and second wirings 132 is enlarged. A switch element 134 is provided on each of the two patch electrodes 108a and the two patch electrodes 108b. The switching (on and off) of the switch element 134 is controlled by a scanning signal applied to the second wiring 132. The patch electrode 108 to which the switch element 134 is turned on is conducted with the first wiring 118, and a control signal is applied. The switch element 134 is formed, for example, by a thin film transistor. According to this configuration, a plurality of patch electrodes 108a and 108b arranged in the first direction (X-axis direction) are selected for each row, and control signals of different voltage levels can be applied to each row.

[0079] Figure 7 The radio wave reflection device 100b shown can control the traveling direction of the reflected wave to the left and right direction of the drawing with the reflection axis VR parallel to the second direction (Y-axis direction) as the center, and can also control the traveling direction of the reflected wave to the up and down direction of the drawing with the reflection axis HR parallel to the first direction (X-axis direction) as the center, based on the radio wave incident on the reflector 120. That is, the radio wave reflection device 100b has the reflection axis VR parallel to the second direction (Y-axis direction) and the reflection axis HR parallel to the first direction (X-axis direction), so the reflection angle can be controlled to the direction with the reflection axis VR as the rotation axis and the direction with the reflection axis HR as the rotation axis.

[0080] Figure 8An example of a cross-sectional structure of a reflector unit body 102 in which a switch element 134 is connected to a patch electrode 108 is shown. The switch element 134 is provided on a dielectric substrate 104. The switch element 134 is a transistor, and has 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. A primer layer 136 may be provided between the first gate electrode 138 and the dielectric substrate 104. A first wiring 118 is provided between the first gate insulating layer 140 and the second gate insulating layer 146. The first wiring 118 is provided in contact with the semiconductor layer 142. In addition, a first connecting wiring 144 is provided in the same layer as the conductive layer forming the first wiring 118. The first connecting wiring 144 is provided in contact with the semiconductor layer 142. The connection structure of the semiconductor layer 142 with respect to the first wiring 118 and the first connection wiring 144 shows a structure in which one wiring is connected to the source of the transistor and the other wiring is connected to the drain.

[0081] A first interlayer insulating layer 150 is provided so as to cover the switching element 134. A second wiring 132 is provided on the first interlayer insulating layer 150. The second wiring 132 is connected to the second gate electrode 148 via a contact hole formed in the first interlayer insulating layer 150. In addition, 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 connection wiring 152 is provided on the first interlayer insulating layer 150 in the same conductive layer as the second wiring 132. The second connection wiring 152 is connected to the first connection wiring 144 via a contact hole formed in the first interlayer insulating layer 150.

[0082] The second interlayer insulating layer 154 is provided so as to cover the second wiring 132 and the second connection wiring 152. Furthermore, the planarizing layer 156 is provided so as to bury the height difference of the switch element 134. By providing the planarizing layer 156, the patch electrode 108 can be formed without being affected by the configuration of the switch element 134. A passivation layer 158 is provided on the flat surface of the planarizing layer 156. The patch electrode 108 is provided on the passivation layer 158. The patch electrode 108 is connected to the second connection wiring 152 via a contact hole penetrating the passivation layer 158, the planarizing layer 156, and the second interlayer insulating layer 154. The first orientation film 112a is provided on the patch electrode 108.

[0083] and Figure 1BSimilarly, the ground electrode 110 and the second orientation film 112b are provided on the counter substrate 106. The surface on which the switch element 134 and the patch electrode 108 of the dielectric substrate 104 are provided is arranged to be opposite to the surface on which the ground electrode 110 of the counter substrate is provided, and the liquid crystal layer 114 is provided therebetween. The thickness T of the dielectric substrate 104 can be set to be the length from the surface on the liquid crystal layer 114 side of the patch electrode 108 to the surface on the opposite side of the surface on which the patch electrode 108 of the dielectric substrate 104 is provided. In this case, the thickness of at least one insulating layer (primer layer 136, first gate insulating layer 108, second gate insulating layer 146, first interlayer insulating layer 150, second interlayer insulating layer 4, planarizing layer 156, passivation layer 158) located between the patch electrode 108 and the dielectric substrate 104 can be taken into consideration.

[0084] Each layer formed on the dielectric substrate 104 is formed using the following materials. The base coat 136 is formed, for example, of a silicon oxide film. The first gate insulating layer 140 and the second gate insulating layer 146 are formed, for example, of a silicon oxide film, or a stacked structure of a silicon oxide film and a silicon nitride film. The semiconductor layer is formed of a silicon semiconductor such as amorphous silicon and polycrystalline silicon, and an oxide semiconductor including metal oxides such as indium oxide, zinc oxide, gallium oxide, and IGZO. The first gate electrode 138 and the second gate electrode 148 may also be formed, for example, of molybdenum (Mo), tungsten (W), or an alloy thereof. The first wiring 118, the second wiring 132, the first connecting wiring 144, and the second connecting wiring 152 are formed using metal materials such as titanium (Ti), aluminum (Al), and molybdenum (Mo). For example, it may also be formed of a stacked structure of titanium (Ti) / aluminum (Al) / titanium (Ti), or a stacked structure of molybdenum (Mo) / aluminum (Al) / molybdenum (Mo). The planarization layer 156 is formed of a resin material such as acrylic or polyimide. The passivation layer 158 is formed of, for example, a silicon nitride film. The patch electrode 108 and the ground electrode 110 are formed of a metal film such as aluminum (Al) or copper (Cu) or a transparent conductive film such as indium tin oxide (ITO).

[0085] like Figure 8As shown, by connecting the second wiring 132 to the gate of the transistor used as the switching element 134, connecting the first wiring 118 to one of the source and the drain of the transistor, and connecting the patch electrode 108 to the other of the source and the drain, it is possible to apply a control signal by selecting a predetermined patch electrode from a plurality of patch electrodes 108 arranged in a matrix. Furthermore, by providing the switching element 134 for each patch electrode 108 in the reflector 120, it is possible to apply a control voltage to each of the patch electrodes 108 arranged in a horizontal row along the first direction (X-axis direction) or the patch electrodes 108 arranged in a vertical row along the second direction (Y-axis direction). For example, when the reflector 120 is upright, the reflection direction of the reflected wave can be controlled to be the left-right direction and the up-down direction.

[0086] (Variant 1)

[0087] In the first and second embodiments, an example is described in which one patch electrode 108a and one patch electrode 108b are alternately arranged in the first direction and the second direction, but one embodiment of the present invention is not limited to this. For example, three arranged patch electrodes 108a and three arranged patch electrodes 108b may be alternately arranged in the first direction and the second direction.

[0088] Fig. 9 This is the structure of the radio wave reflection device 100c of Modification Example 1. Fig. 9 As shown, in the radio wave reflection device 100c, three arrayed patch electrodes 108a and three arrayed patch electrodes 108b are alternately arranged in the first direction and the second direction. By arranging the plurality of patch electrodes 108a and the plurality of patch electrodes 108b in this way, it is possible to achieve symmetry with respect to vertical polarization and horizontal polarization.

[0089] In addition, the number of patch electrodes 108a and patch electrodes 108b arranged in connection is not limited to three. The number of patch electrodes 108a and patch electrodes 108b arranged in connection is not limited to two, and may be four or more. The number of patch electrodes 108a and patch electrodes 108b arranged in connection is not particularly limited. However, it is preferred that the plurality of patch electrodes 108a and the plurality of patch electrodes 108b are arranged in a two-fold rotational symmetry or four-fold rotational symmetry with respect to the center of the region where the plurality of patch electrodes 108a and the plurality of patch electrodes 108b are arranged in the first direction and the second direction. By arranging the plurality of patch electrodes 108a and the plurality of patch electrodes 108b in this way, it is possible to achieve symmetry with respect to vertical polarization and horizontal polarization.

[0090] (Variant 2)

[0091] In the first and second embodiments, the radio wave reflection devices 100a, 100b, and 100c using two types of patch electrodes 108a and patch electrodes 108b of different sizes are described, but one embodiment of the present invention is not limited thereto. In the radio wave reflection devices 100a, 100b, and 100c, patch electrodes of different sizes from the patch electrodes 108a and the patch electrodes 108b may also be used.

[0092] Fig.10 This is the structure of the radio wave reflection device 100d of Modification Example 2. Fig.10 As shown, the size of the patch electrode 108c may be smaller than the patch electrodes 108a and 108b. Alternatively, the size of the patch electrode 108c may be larger than the patch electrodes 108a and 108b. Alternatively, the size of the patch electrode 108c may be between the size of the patch electrode 108a and the size of the patch electrode 108b. In this way, it is preferred that the size of the patch electrode is set to three or more types, so that the phase change amount can be increased. With respect to the center of the region where the plurality of patch electrodes 108a, the plurality of patch electrodes 108b, and the plurality of patch electrodes 108c are arranged in the first direction and the second direction, the plurality of patch electrodes 108a, the plurality of patch electrodes 108b, and the plurality of patch electrodes 108c are arranged in a two-fold rotational symmetry or a four-fold rotational symmetry. By configuring the arrangement of the plurality of patch electrodes 108a, the plurality of patch electrodes 108b, and the plurality of patch electrodes 108c in this way, it is possible to be symmetrical with respect to the vertical polarization and the horizontal polarization.

[0093] In the radio wave reflection devices 100a, 100b, 100c, and 100d of one embodiment of the present invention, the phase change amount is sufficient as long as it is 360°. Therefore, the size of the patch electrode 108c can be appropriately determined to ensure 360°. In this case, the size of the patch electrode 108c is 6.5 mm. 2 Above 8.5mm 2 the following.

[0094] In addition, although the modification examples 1 and 2 describe a radio wave reflection device with one-axis reflection control, the modification examples 1 and 2 can also be applied to a radio wave reflection device with two-axis reflection control.

[0095] The various configurations of the radio wave reflection device and the reflector unit illustrated as one embodiment of the present invention can be appropriately combined as long as they do not contradict each other. In addition, based on the radio wave reflection device and the reflector unit disclosed in this specification and the accompanying drawings, those skilled in the art can add, delete or change the design of appropriate components, or add, omit or change the conditions of the process as long as they have the gist of the present invention, which is included in the scope of the present invention.

[0096] Other effects that are clearly obtained from the description of this specification or that are easily predicted by those skilled in the art and are different from the effects brought about by the forms of the embodiments disclosed in this specification are of course also understood as the effects proposed by the present invention.

[0097] Description of Reference Numerals

[0098] 100a, 100b, 100c: radio wave reflection device, 102: reflection plate unit body, 102a, 102b, reflection plate unit body, 104: dielectric substrate, 106: opposing substrate, 108: patch electrode, 108a, 108b: patch electrode, 110: ground electrode, 112a: first orientation film, 112b: second orientation film, 114: liquid crystal layer, 116: liquid crystal molecules, 118: first wiring, 120: reflection plate, 122: peripheral area, 124: first drive Circuit, 126: terminal portion, 128: sealing material, 130: second driving circuit, 132: second wiring, 134: switching element, 136: base layer, 138: first gate electrode, 140: first gate insulating layer, 142: semiconductor layer, 144: first connecting wiring, 146: second gate insulating layer, 148: second gate electrode, 150: first interlayer insulating layer, 152: second connecting wiring, 154: second interlayer insulating layer, 156: planarization layer, 158: passivation layer.

Claims

1. A radio wave reflection device, characterized in that: include: A plurality of first patch electrodes; a plurality of second patch electrodes having a size different from that of the plurality of first patch electrodes; a ground electrode, which is opposite to the plurality of first patch electrodes and the plurality of second patch electrodes and is disposed separately from the plurality of first patch electrodes and the plurality of second patch electrodes; as well as a liquid crystal layer provided between the plurality of first patch electrodes, the plurality of second patch electrodes and the ground electrode, The plurality of first patch electrodes and the plurality of second patch electrodes are alternately arranged in a first direction or a second direction intersecting the first direction. Each of the first patch electrodes and each of the second patch electrodes are adjacent to each other in the first direction or the second direction.

2. The radio wave reflection device according to claim 1, characterized in that: The shape of each of the first patch electrodes and the shape of each of the second patch electrodes are four-fold rotationally symmetrical shapes.

3. The radio wave reflection device according to claim 1, characterized in that: The shape of each of the first patch electrodes and the shape of each of the second patch electrodes is a square, a rhombus, a quadrilateral with chamfered vertices, a quadrilateral with rounded vertices, or a circle.

4. The radio wave reflection device according to claim 1, characterized in that: The size of each first patch electrode is not less than 107% and not more than 140% of the size of each second patch electrode.

5. The radio wave reflection device according to claim 1, characterized in that: The size of each first patch electrode is 7.0 mm 2 Above 9.3mm 2 The size of each second patch electrode is 5.5 mm. 2 Above 7.0mm 2 the following.

6. The radio wave reflection device according to claim 1, characterized in that: The size of each first patch electrode is not less than 70% and not more than 93% of the size of each second patch electrode.

7. The radio wave reflection device according to claim 1, characterized in that: The size of each first patch electrode is 5.5 mm 2 Above 7.0mm 2 Below, the size of each second patch electrode is 7.0 mm 2 Above 9.3mm 2 the following.

8. The radio wave reflection device according to claim 1, characterized in that: The first patch electrodes and the second patch electrodes are arranged to have two-fold rotational symmetry or four-fold rotational symmetry with respect to the center of the region where the first patch electrodes and the second patch electrodes are arranged in the first direction and the second direction.

9. The radio wave reflection device according to claim 1, characterized in that: The frequency of the radio waves incident on the plurality of first patch electrodes and the plurality of second patch electrodes is 28 GHz.

10. The radio wave reflection device according to claim 1, characterized in that: The plurality of first patch electrodes and the plurality of second patch electrodes are respectively connected to switching elements.

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