Composite resonator and radio wave control plate

Abstract

This composite resonator comprises: a first electrode that constitutes a first resonator and is disposed on a first surface; and a second electrode that constitutes a second resonator and is disposed on a second surface which is separated from the first surface in a first direction. In a plan view along a direction orthogonal to the first surface and the second surface, the second electrode has a rotationally-symmetrical opening located in a portion that faces a portion of the first electrode where the magnetic field is relatively small. In a plan view along the direction orthogonal to the first surface and the second surface, the first electrode and the second electrode overlap with each other in a rotationally symmetrical manner.

Description

Composite resonator and radio wave control board

[0001] The present disclosure relates to a composite resonator and a radio wave control plate.

[0002] There are known techniques for controlling electromagnetic waves without using a dielectric lens. For example, Patent Document 1 describes a technique for refracting radio waves by changing the parameters of each element in a structure in which resonator elements are arranged.

[0003] JP 2015-231182 A

[0004] The composite resonator of the present disclosure comprises a first electrode constituting a first resonator and arranged on a first surface, and a second electrode constituting a second resonator and arranged on a second surface spaced apart from the first surface in a first direction, wherein, when viewed in a plan view from a direction perpendicular to the first and second surfaces, the second electrode has a rotationally symmetric opening in a portion facing a portion of the first electrode where a magnetic field is relatively small, and when viewed in a plan view from a direction perpendicular to the first and second surfaces, the first electrode and the second electrode overlap in a rotationally symmetric manner.

[0005] The radio wave control board of the present disclosure includes a plurality of composite resonators of the present disclosure.

[0006] FIG. 1 is a diagram for explaining an overview of a radio wave control plate. FIG. 2 is a diagram showing an example of the configuration of a radio wave control plate according to a comparative example. FIG. 3 is a diagram showing an example of the configuration of a unit structure according to a comparative example. FIG. 4 is a diagram showing analysis conditions for the Q value according to the first embodiment. FIG. 5 is a diagram showing an example of the configuration of a unit structure according to a comparative example. FIG. 6 is a diagram showing an example of the configuration of a unit structure according to the first embodiment. FIG. 7 is a diagram showing an example of the configuration of a unit structure according to the second embodiment. FIG. 8 is a diagram for explaining a problem solved by the third embodiment. FIG. 9 is a diagram showing an example of the configuration of a unit structure according to the third embodiment. FIG. 10 is a diagram showing an example of the configuration of a unit structure according to a modified example of the third embodiment.

[0007] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to this embodiment, and in the following embodiments, the same components are designated by the same reference numerals, and redundant explanations will be omitted.

[0008] In the following description, an XYZ Cartesian coordinate system is set, and the positional relationship of each part will be described with reference to this XYZ Cartesian coordinate system. The direction parallel to the X axis in a horizontal plane is defined as the X-axis direction, the direction parallel to the Y axis in the horizontal plane perpendicular to the X axis is defined as the Y-axis direction, and the direction parallel to the Z axis perpendicular to the horizontal plane is defined as the Z-axis direction. Furthermore, the plane including the X axis and Y axis will be referred to as the XY plane as appropriate, the plane including the X axis and Z axis will be referred to as the XZ plane as appropriate, and the plane including the Y axis and Z axis will be referred to as the YZ plane as appropriate. The XY plane is parallel to the horizontal plane. The XY plane, XZ plane, and YZ plane are perpendicular to each other.

[0009] [Outline] (Radio wave control board) An outline of the radio wave control board will be described with reference to Fig. 1. Fig. 1 is a diagram for explaining the outline of the radio wave control board.

[0010] The radio wave control board 1 is a plate-shaped member configured to be able to reflect or transmit (refract) radio waves transmitted from a base station. For example, when receiving radio waves transmitted from a base station, the radio wave control board 1 is configured to reflect or refract the radio waves at a predetermined angle. The radio wave control board 1 can be configured, for example, from a metamaterial that changes the phase of the incident wave.

[0011] 1, the radio wave control plate 1 may include, for example, a substrate 2 and unit structures 10a, 10b, 10c, and 10d. When there is no need to distinguish between the unit structures 10a to 10d, they will be collectively referred to as unit structures 10. The unit structures 10 are also called composite resonators.

[0012] The unit structures 10a, 10b, 10c, and 10d may be formed on a substrate 2. The substrate 2 may be, for example, a dielectric substrate made of a dielectric material. The substrate 2 may have, for example, but is not limited to, a rectangular shape. The unit structures 10a, 10b, 10c, and 10d may be arranged two-dimensionally.

[0013] In the radio wave control board 1, a plurality of unit structures 10a are arranged along the X-axis direction on one tier. A plurality of unit structures 10b are arranged along the X-axis direction on the tier above the tier on which unit structures 10a are arranged. A plurality of unit structures 10c are arranged along the X-axis direction on the tier above the tier on which unit structures 10b are arranged. A plurality of unit structures 10d are arranged along the X-axis direction on the tier above the tier on which unit structures 10c are installed. In the example shown in FIG. 1 , unit structures 10a, unit structures 10b, unit structures 10c, and unit structures 10d are arranged periodically along the Y-axis direction.

[0014] In this embodiment, unit structure 10a, unit structure 10b, unit structure 10c, and unit structure 10d are all different in size. In the example shown in FIG. 1 , unit structure 10a is the largest, followed by unit structure 10b, unit structure 10c, and unit structure 10d in order of size. That is, in this embodiment, radio wave control plate 1 has a structure in which a plurality of unit structures 10 of different sizes are periodically arranged. Here, radio wave control plate 1 is not limited to a structure in which a plurality of unit structures 10 of different sizes are periodically arranged, as long as a plurality of unit structures of different phase change amounts are periodically arranged.

[0015] The unit structures 10a to 10d may each have a different phase shift amount of the received radio waves. That is, the unit structures 10a to 10d are periodically arranged so as to have a gradient in the phase shift amount. The unit structures 10a to 10d each have a rectangular shape, but are not limited to this. For example, the frequency band and phase shift amount of the reflected or refracted radio waves can be adjusted by changing only one or a combination of two or more of the size, shape, and dielectric constant of the unit structures 10a to 10d. When a material with a controllable dielectric constant, such as liquid crystal, is used for the unit structures, the frequency band and phase shift amount of the reflected or refracted radio waves can be adjusted simply by periodically arranging unit structures of the same size and shape.

[0016] [Comparative Example] A radio wave control plate and a configuration example of a unit structure according to a comparative example will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a diagram showing a configuration example of a radio wave control plate according to a comparative example. Fig. 3 is a diagram showing a configuration example of a unit structure according to a comparative example.

[0017] 2, the radio wave control plate 1 has a plurality of unit structures 10. The unit structures 10 are periodically arranged on the XY plane.

[0018] As shown in FIGS. 2 and 3, the unit structure 10 includes a first electrode 12, a second electrode 14, and a liquid crystal layer 16.

[0019] The first electrode 12 is disposed on the top surface of the unit feature 10. The top surface of the unit feature 10 is also referred to as the first surface. The first electrode 12 is formed of a conductor. The first electrode 12 is a λ / 2 resonator. λ is the effective wavelength of the radio waves transmitted or reflected by the radio wave control plate 1.

[0020] The second electrode 14 is disposed on the bottom surface of the unit feature 10, away from the first electrode 12 in the Z-axis direction. The Z-axis direction is also referred to as the first direction. The bottom surface of the unit feature 10 is also referred to as the second surface. The second electrode 14 is formed of a conductor. The second electrode 14 is a ground conductor.

[0021] The liquid crystal layer 16 is disposed between the first electrode 12 and the second electrode 14. The liquid crystal layer 16 extends in the XY plane. When a voltage is applied between the first electrode 12 and the second electrode 14, the orientation state of the liquid crystal molecules 18 contained in the liquid crystal layer 16 changes. The change in the orientation state of the liquid crystal molecules 18 changes the capacitance value of the unit feature 10. By adjusting the capacitance value of the unit feature 10, the refraction direction or reflection direction of the radio wave can be changed.

[0022] Here, because the thickness of the liquid crystal layer 16 is several μm (micrometers), the distance between the first electrode 12 and the second electrode 14 is short. If the distance between the first electrode 12 and the second electrode 14 becomes short, there is a problem that loss in the unit structure 10 increases. In the present disclosure, even when the distance between the first electrode 12 and the second electrode 14 is short, an increase in loss is suppressed by providing an opening in the second electrode 14 and adjusting the degree of overlap between the first electrode 12 and the second electrode 14.

[0023] [First embodiment] (Analysis conditions for Q value) Analysis conditions for the Q value of the unit structure according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram showing the analysis conditions for the Q value according to the first embodiment.

[0024] As shown in Figure 4, the Q value was calculated under the condition that a glass substrate 20 was placed on the first electrode 12 of the unit structure 10 and a glass substrate 22 was placed on the second electrode 14 of the unit structure 10. The electrical conductivity of the first electrode 12 and the second electrode 14 was 5.7 x 10 ６ The liquid crystal layer 16 has a dielectric constant of 5.07, a dielectric loss tangent of 0, and a thickness of 30 μm. The glass substrates 20 and 22 have a dielectric constant of 5.6, a dielectric loss tangent of 0, and a thickness of 0.3 mm.

[0025] (Configuration Example of Comparative Example) A configuration example of a unit structure according to a comparative example will be described with reference to Fig. 5. Fig. 5 is a diagram showing a configuration example of a unit structure according to a comparative example.

[0026] FIG. 5 shows the positional relationship between a first electrode 12A disposed on the upper surface and a second electrode 14A disposed on the lower surface of a unit structure 10A according to a comparative example.

[0027] The first electrode 12A is formed in a rectangular shape.

[0028] The second electrode 14A is formed in a rectangular shape. The second electrode 14A has an opening 30, an opening 32, an opening 34, and an opening 36. The openings 30, 32, 34, and 36 are formed in a triangular shape. The second electrode 14A includes a linear portion 40 and a linear portion 42.

[0029] The straight line portion 40 is formed on one diagonal of the second electrode 14. The straight line portion 42 is formed on the other diagonal of the second electrode 14.

[0030] When viewed from the Z-axis direction, the first electrode 12A and the linear portion 40 overlap one diagonal of the first electrode 12A. When viewed from the Z-axis direction, the first electrode 12A and the linear portion 42 overlap the other diagonal of the first electrode 12A.

[0031] A simulation was performed on the operating frequency and the Q value of the unit structure 10A shown in Fig. 5. As a result, the operating frequency of the unit structure 10A was 21.0146 [GHz] and the Q value was 18.

[0032] (Configuration Example of First Embodiment) A configuration example of a unit structure according to the first embodiment will be described with reference to Fig. 6. Fig. 6 is a diagram showing a configuration example of a unit structure according to the first embodiment.

[0033] As shown in Fig. 6, the unit structure 10B according to the first embodiment includes a first electrode 12B and a second electrode 14B. Fig. 6 shows the positional relationship between the first electrode 12B disposed on the upper surface of the unit structure 10B and the second electrode 14B disposed on the lower surface.

[0034] The first electrode 12B is an electrode that constitutes the first λ / 2 resonator. The first electrode 12B is formed in a rectangular shape. The first electrode 12B is not limited to a rectangular shape, and may be formed in any shape that is rotationally symmetric in the XY plane. Because the first electrode 12B has a rotationally symmetric shape, two resonances occur at the same frequency as orthogonal modes. The first electrode 12B has an end 50a, an end 50b, an end 50c, and an end 50d. The arrow V11 indicates the direction of the current vector of the resonance mode. Note that the above description and drawings describe one of the resonances in the orthogonal modes; in reality, a resonance that is rotationally symmetric to this resonance also exists. Similarly, hereinafter, only one of the resonances may be described.

[0035] The second electrode 14B faces the first electrode 12B. The second electrode 14B is formed in a rectangular shape. The second electrode 14B has an opening 60. The opening 60 is formed in a portion facing a portion of the first electrode 12B where the magnetic field generated therein is relatively strong. The opening 60 is formed in a rotationally symmetric shape on the XY plane. The opening 60 is formed in, for example, a cross shape, but is not limited to this. The second electrode 14B is an electrode that constitutes a second λ / 2 resonator and is also a ground conductor.

[0036] When viewed from the Z-axis direction, the end portions 50a, 50b, 50c, and 50d overlap the second electrode 14B. By applying a voltage between the end portions 50a, 52a, 54a, and 56a and the second electrode 14B, the orientation state of the liquid crystal molecules 18 in the liquid crystal layer 16 can be changed, thereby changing the capacitance value of the unit structure 10B. In other words, by applying a voltage between the end portions 50a, 52a, 54a, and 56a and the second electrode 14B, the refraction direction or transmission direction of the radio wave can be adjusted.

[0037] When viewed from the Z-axis direction, the first electrode 12B overlaps with the opening 60 except for the ends 50a, 50b, 50c, and 50d. The magnetic field generated in the center of the first electrode 12B is relatively small. Therefore, by forming the opening 60 in the second electrode 14B in the portion where the magnetic field is relatively small, the current loss induced by the magnetic field can be reduced and the Q value can be improved. Here, the center of the first electrode 12B includes, for example, the center point of the first electrode 12B.

[0038] Second Embodiment A second embodiment will be described. In the first λ / 2 resonator, current is concentrated in one location as indicated by the arrow V11 in Fig. 6, which reduces the size of the unit structure. Therefore, in the second embodiment, the electrodes constituting the first λ / 2 resonator are divided to disperse the current, thereby increasing the size of the unit structure 10 and further improving the Q value.

[0039] (Configuration Example of Second Embodiment) A configuration example of a unit structure according to the second embodiment will be described with reference to Fig. 7. Fig. 7 is a diagram showing a configuration example of a unit structure according to the second embodiment.

[0040] As shown in Fig. 7, a unit structure 10C according to the second embodiment includes a first electrode 12Ca, a first electrode 12Cb, a first electrode 12Cc, a first electrode 12Cd, and a second electrode 14C. Fig. 6 shows the positional relationship between the first electrode 12C arranged on the upper surface of the unit structure 10C and the second electrode 14C arranged on the lower surface.

[0041] The second electrode 14C is formed in a rectangular shape. The first electrodes 12Ca and 12Cc are electrodes that constitute a third λ / 2 resonator, and the first electrodes 12Cb and 12Cd are electrodes that constitute a fourth λ / 2 resonator. The first electrodes 12Ca, 12Cb, 12Cc, and 12Cd are all the same size. The first electrodes 12Ca and 12Cc, and the first electrodes 12Cb and 12Cd, all have rotationally symmetric shapes, so two resonances occur at the same frequency as orthogonal modes.

[0042] The second electrode 14C faces the first electrodes 12Ca, 12Cb, and 12Cc. The second electrode 14C is formed in a rectangular shape. The second electrode 14C has an opening 80. The second electrode 14C and the opening 80 are the same as the second electrode 14B and the opening 60 shown in FIG. 6 , and therefore a description thereof will be omitted.

[0043] The first electrode 12Ca has an end 70a and an end 70b. When viewed from the Z-axis direction, the end 70a and the end 70b overlap with the second electrode 14C. When viewed from the Z-axis direction, the center of the first electrode 12Ca faces the opening 80 and does not overlap with the second electrode 14C. In other words, when viewed from the Z-axis direction, only both end portions of the first electrode 12Ca overlap with the second electrode 14C.

[0044] The first electrode 12Cb has an end 72a and an end 72b. When viewed from the Z-axis direction, the end 72a and the end 72b overlap with the second electrode 14C. The degree of overlap between the end 72a and the end 72b and the second electrode 14C is the same as the degree of overlap between the end 70a and the end 70b of the first electrode 12Ca and the second electrode 14C. When viewed from the Z-axis direction, the center of the first electrode 12Cb faces the opening 80 and does not overlap with the second electrode 14C. In other words, when viewed from the Z-axis direction, only both end portions of the first electrode 12Cb overlap with the second electrode 14C.

[0045] The first electrode 12Cc has an end 74a and an end 74b. When viewed from the Z-axis direction, the end 74a and the end 74b overlap with the second electrode 14C. The degree of overlap between the end 74a and the end 74b and the second electrode 14C is the same as the degree of overlap between the end 74a and the end 74b of the first electrode 12Cc and the second electrode 14C. When viewed from the Z-axis direction, the center of the first electrode 12Cc faces the opening 80 and therefore does not overlap with the second electrode 14C. In other words, when viewed from the Z-axis direction, only both end portions of the first electrode 12Cc overlap with the second electrode 14C.

[0046] The first electrode 12Cd has an end 76a and an end 76b. When viewed from the Z-axis direction, the end 76a and the end 76b overlap with the second electrode 14C. The degree of overlap between the end 76a and the end 76b and the second electrode 14C is the same as the degree of overlap between the end 76a and the end 76b of the first electrode 12Cd and the second electrode 14C. When viewed from the Z-axis direction, the center of the first electrode 12Cd faces the opening 80 and does not overlap with the second electrode 14C. In other words, when viewed from the Z-axis direction, only both end portions of the first electrode 12Cd overlap with the second electrode 14C.

[0047] Arrows V21 and V22 indicate the direction of the current vector of unit structure 10C. As indicated by arrows V21 and V22, the current vector is dispersed compared to unit structure 10B shown in Fig. 6. This allows the size of unit structure 10C to be increased, thereby improving the Q value.

[0048] Third Embodiment A problem to be solved by the third embodiment will be described with reference to Fig. 8. Fig. 8 is a diagram for explaining a problem to be solved by the third embodiment.

[0049] 8, the size of the unit structure 10C can be increased, but an electric field is generated in the second electrode 14C. Arrows V31, V32, V41, and V42 indicate electric field vectors. Increasing the size of the unit structure 10C increases the electric field, which creates a problem in that the size cannot be increased.

[0050] (Configuration Example According to Third Embodiment) A configuration example of a unit structure according to the third embodiment will be described with reference to Fig. 9. Fig. 9 is a diagram showing a configuration example of a unit structure according to the third embodiment.

[0051] As shown in FIG. 9, the unit structure 10D includes a first electrode 12Da, a first electrode 12Db, a first electrode 12Dc, a first electrode 12Dd, and a second electrode 14D.

[0052] The first electrode 12Da has an end 90a and an end 90b. The first electrode 12Db has an end 92a and an end 92b. The first electrode 12Dc has an end 94a and an end 94b. The first electrode 12Dd has an end 96a and an end 96b. The first electrodes 12Da, 12Db, 12Dc, and 12Dd are the same as the first electrodes 12Ca, 12Cb, 12Cc, and 12Cd shown in FIG. 8 , respectively, and therefore will not be described further.

[0053] The second electrode 14D is formed in a rectangular shape and has an opening 100. The opening 100 of the second electrode 14D has a different shape from the opening 80 of the second electrode 14C shown in FIG.

[0054] The opening 100 is formed in a square shape in the center of the second electrode 14D. The opening 100 may be formed in a circular shape in the center of the second electrode 14D. Here, the center of the second electrode 14D includes, for example, the center point of the second electrode 14D. The opening 100 may be formed in a rotationally symmetric shape in the center of the second electrode 14D. The opening 100 is formed by removing a portion of the second electrode 14C shown in FIG. 8 where a relatively large electric field is generated.

[0055] An electric field is generated in the second electrode 14D as indicated by arrows V32 and V42. The electric field generated in the second electrode 14D is weaker than the electric field generated in the second electrode 14C shown in Fig. 8. By increasing the opening at the same frequency, the unit structure 10D can be made larger, thereby further improving the Q value.

[0056] [Modification of Third Embodiment] (Configuration Example of Modification of Third Embodiment) A configuration example of a unit structure according to a modification of the third embodiment will be described with reference to Fig. 10. Fig. 10 is a diagram showing a configuration example of a unit structure according to a modification of the third embodiment.

[0057] As shown in FIG. 10, a unit structure 10E includes a first electrode 12Ea, a first electrode 12Eb, a first electrode 12Ec, a first electrode 12Ed, and a second electrode 14E.

[0058] The first electrode 12Ea has an end 110a and an end 110b. The first electrode 12Eb has an end 112a and an end 112b. The first electrode 12Ec has an end 114a and an end 114b. The first electrode 12Ed has an end 116a and an end 116b. The first electrodes 12Ea, 12Eb, 12Ec, and 12Ed are the same as the first electrodes 12Ca, 12Cb, 12Cc, and 12Cd shown in FIG. 8 , respectively, and therefore will not be described further.

[0059] The second electrode 14E is formed in a rectangular shape and has an opening 120. The opening 120 of the second electrode 14E has a different shape from the opening 100 of the second electrode 14E shown in FIG.

[0060] The opening 120 is formed in a square shape in the center of the second electrode 14E. The opening 120 has a shape obtained by further trimming the conductor portions on the top, bottom, left, and right sides of the square-shaped portion of the opening 100 shown in Fig. 9 into a triangular shape. In other words, the opening 120 of this modification is larger than the shape of the opening 100 shown in Fig. 9. As a result, the Q value can be improved more in the case of Fig. 10 than in the case of Fig. 9.

[0061] In the second electrode 14E, electric field vectors as indicated by arrows V32 and V42 are generated, similar to the second electrode 14D shown in Fig. 9. That is, the unit structure 10E can also be made larger, similar to the unit structure 10D shown in Fig. 9, and therefore the Q value can be further improved.

[0062] The present disclosure may also be configured as follows. (1) A composite resonator comprising: a first electrode constituting a first resonator and arranged on a first surface; and a second electrode constituting a second resonator and arranged on a second surface spaced apart from the first surface in a first direction, wherein, when viewed in a plan view from a direction orthogonal to the first and second surfaces, the second electrode has a rotationally symmetric opening at a portion facing a portion of the first electrode where the magnetic field is relatively weak, and when viewed in a plan view from a direction orthogonal to the first and second surfaces, the first electrode and the second electrode overlap in a rotationally symmetric manner. (2) The composite resonator according to (1), wherein the first electrode is divided into a plurality of parts, and when viewed in a plan view from a direction orthogonal to the first and second surfaces, the portions of the first electrode where the magnetic field is relatively weak face the openings and are arranged in a rotationally symmetric manner. (3) The composite resonator according to (1) or (2), wherein the opening is provided so as to remove a portion of the second electrode where a relatively strong electric field is generated. (4) The composite resonator according to (3), wherein the second electrode has the opening at a center when viewed in a plan view from a direction perpendicular to the first surface and the second surface. (5) The composite resonator according to any one of (1) to (4), wherein a liquid crystal layer is disposed between the first electrode and the second electrode. (6) A radio wave control board including a plurality of composite resonators according to any one of (1) to (5).

[0063] REFERENCE SIGNS LIST 1 Radio wave control plate 10 Unit structure 12, 12A, 12B, 12Ca, 12Cb, 12Cc, 12Cd, 12Da, 12Db, 12Dc, 12Dd, 12Ea, 12Eb, 12Ec, 12Ed First electrode 14, 14A, 14B, 14C, 14D, 14E Second electrode 16 Liquid crystal layer 18 Liquid crystal molecules 20, 22 Glass substrate 30, 32, 34, 36, 60, 80, 100, 120 Opening 40, 42 Straight portion

Claims

1. A composite resonator comprising: a first electrode constituting a first resonator and arranged on a first surface; and a second electrode constituting a second resonator and arranged on a second surface separated from the first surface in a first direction, wherein when viewed in a plane from a direction perpendicular to the first and second surfaces, the second electrode has a rotationally symmetric opening in a portion facing a portion of the first electrode where a magnetic field is relatively small, and when viewed in a plane from a direction perpendicular to the first and second surfaces, the first electrode and the second electrode overlap in a rotationally symmetric manner.

2. The composite resonator according to claim 1, wherein the first electrode is divided into multiple parts, and when viewed in a plane from a direction perpendicular to the first surface and the second surface, a portion of the first electrode in which the magnetic field is relatively small faces the opening and is arranged in rotational symmetry.

3. The composite resonator according to claim 1 or 2, wherein the opening is provided so as to remove a portion of the second electrode where a relatively large electric field is generated.

4. The composite resonator according to claim 3, wherein the second electrode has the opening at a central portion when viewed in a plan view from a direction perpendicular to the first surface and the second surface.

5. The composite resonator according to claim 1 or 2, wherein a liquid crystal layer is disposed between the first electrode and the second electrode.

6. A radio wave control board comprising a plurality of composite resonators according to claim 1.

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