VARIABLE REFLECTORY AND METHOD FOR DESIGNING VARIABLE REFLECTORY

Abstract

To provide a variable reflect array and a variable reflect array design method that flexibly adjusts the incident directivity in a vertical plane or a horizontal plane by making the incident directivity reconfigurable.SOLUTION: A variable reflect array includes a variable mechanism that makes the spacing between a plurality of supercells variable. When the spacing between the plurality of supercells is changed in the variable mechanism, one of the incident angle and the reflected angle is changed while the other of the incident angle and the reflection angle is kept constant for an electromagnetic wave having a predetermined wavelength.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a variable reflector using a variable reflectarray and a metasurface, which have a variable structure of reflection directivity. [Background technology]

[0002] In communications, reflectors are sometimes placed in the propagation path to achieve high linearity in the millimeter wave band and to compensate for propagation loss. It is desirable for the reflector placed in the propagation path to have a large aperture size and a gain of 75 dBi or more when converted into antenna gain. The gain of a metamaterial reflector changes depending on the aperture area. In order to compensate for the gain, it is necessary to increase the size of the reflector. However, when the gain is increased, the directivity becomes sharper, so the installation accuracy at the time of installation has a significant impact on the installation effect and performance. As the directivity becomes sharper, it becomes difficult to adjust it to the incident direction from the base station. For this reason, with the sharp directivity at high gain, it is difficult to directly face the incident wave from the base station.

[0003] Therefore, a mechanism that can adjust the angle of incidence is required. A mechanical adjustment mechanism for adjusting the orientation of the entire reflector is also possible. Also, a configuration in which the reflection angle is variable using a two-layer structure is known (Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] "Construction of a Two-Layer Patch-Type Variable Reflection Angle Metasurface" IEICE technical report, IEICE Technical Report, Vol. 114(522), pp. 13-16, March 19, 2015, Ryuji Kuze et al. Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the adjustment to the incident direction is performed mechanically, such as by changing the orientation of the entire reflector, a mechanism for mechanical adjustment is required, which makes the entire device larger and negates the advantage of the reflector, that is, the reflector itself is thin and does not require a large space for installation. Furthermore, if a two-layer structure is used to make the reflection angle variable, the structure becomes large. Therefore, an object of the present invention is to make it possible to flexibly adjust the incident directivity in the vertical or horizontal plane by making the incident directivity reconfigurable. Another object of the present invention is to achieve the above adjustment by a single layer, not by a laminate. [Means for solving the problem]

[0006] The variable reflectarray according to claim 1 of the present invention comprises: A plurality of supercells having different angles of incidence and reflection for electromagnetic waves of a given wavelength; and A variable mechanism for varying the intervals between the plurality of supercells is provided, The supercell is composed of a plurality of unit cells, each of the unit cells having an antenna; The variable mechanism is a supercell interval adjustment unit that arranges the plurality of supercells at an interval selected from two or more intervals; This is a variable reflectarray in which, when the spacing between the multiple supercells is changed in the variable mechanism, the angle of incidence or the angle of reflection is changed while keeping one of the angle of incidence or the angle of reflection constant for the electromagnetic wave of the specified wavelength. This configuration makes it possible to flexibly adjust the incident directivity or reflection directivity in a vertical or horizontal plane by making the incident directivity or reflection directivity reconfigurable. This configuration also makes it possible to realize this adjustment in a single layer, not in a multilayer structure, and while taking advantage of the reflector's advantages of being thin and not requiring a large space for installation, it is possible to realize a mechanism that makes it easy to face the incident wave from the base station even with sharp directivity at high gain, and allows adjustment according to the incident angle. The variable reflectarray according to claim 2 of the present invention comprises: 2. The tunable reflectarray according to claim 1, wherein the angle of incidence or the angle of reflection is changed by 10° or more by changing the spacing between the supercells in the variable mechanism. The variable reflectarray according to claim 3 of the present invention comprises: The spacing between the supercells is Expanding from the predetermined spacing increases the angle of incidence or reflection, and shrinking from the predetermined spacing decreases the angle of incidence or reflection, or 3. The variable reflectarray according to claim 1, wherein the angle of incidence or the angle of reflection decreases when the distance is enlarged from the predetermined distance, and the angle of incidence or the angle of reflection increases when the distance is reduced from the predetermined distance. The variable reflectarray according to claim 4 of the present invention comprises: the electromagnetic wave of the predetermined wavelength is other than horizontally polarized and other than vertically polarized, and has a polarization inclined at a predetermined angle from the horizontal direction, 4. The tunable reflectarray according to claim 1, wherein the unit cells are arranged in a direction tilted at a predetermined angle from a horizontal direction to a direction the same as the polarization of a predetermined electromagnetic wave. The variable reflectarray according to claim 5 of the present invention comprises: the electromagnetic wave of the predetermined wavelength is 45° polarized, 5. The tunable reflectarray according to claim 4, wherein the unit cells are arranged at an angle of 45 degrees from the horizontal direction. The variable reflectarray according to claim 6 of the present invention comprises: The supercells are arranged in a direction perpendicular to a longitudinal direction of the supercells, and 6. The tunable reflectarray according to claim 1, wherein the first and second electrodes are arranged at predetermined intervals in the longitudinal direction of the supercell. The variable reflectarray according to claim 7 of the present invention comprises: the supercells include a first plurality of supercells and a second plurality of supercells; The first plurality of supercells are arranged in a direction perpendicular to a longitudinal direction of the supercells and shifted by a predetermined amount in a first direction which is one direction of the longitudinal direction of the supercells, and 6. The variable reflectarray according to claim 1, wherein the second plurality of supercells are arranged in a direction perpendicular to a longitudinal direction of the supercells and shifted by a predetermined amount in a second direction opposite to the first direction. The variable reflectarray according to claim 8 of the present invention comprises: 8. The variable reflectarray according to claim 1, wherein the unit cell has a substantially linear metal plate extending radially from a center portion. The variable reflectarray according to claim 9 of the present invention comprises: 8. The tunable reflectarray according to claim 1, wherein the unit cell is a cross dipole having a metal plate having a substantially cross shape. This configuration makes it possible to accommodate two orthogonal polarized waves. The tunable reflectarray according to claim 10 of the present invention comprises: 10. The variable reflectarray according to claim 1, wherein changing the spacing between the supercells changes both the angle of incidence and the angle of reflection. A method for designing a variable reflectarray according to claim 11 of the present invention comprises the steps of: A method for designing a variable reflectarray according to any one of claims 1 to 10, comprising the steps of: A method for designing a variable reflectarray, comprising a step of changing the intervals between the plurality of supercells, thereby changing the angle of incidence or the angle of reflection for an electromagnetic wave of the specified wavelength while keeping one of the angle of incidence or the angle of reflection constant. A method for designing a variable reflectarray according to claim 12 of the present invention comprises the steps of: A method for designing a tunable reflectarray, comprising a plurality of supercells each having different angles of incidence and reflection for an electromagnetic wave of a predetermined wavelength, each of the supercells being composed of a plurality of unit cells, each of the unit cells having an antenna, the method comprising the steps of: designing the supercell having the plurality of unit cells; and a step of changing an interval between the plurality of supercells after designing the supercell, thereby changing an angle of incidence or an angle of reflection for an electromagnetic wave of the specified wavelength while keeping one of the angle of incidence or the angle of reflection constant. [Brief description of the drawings]

[0007] [Figure 1] 1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Diagram 2] 1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Diagram 3] 1 shows an example of a metasurface in accordance with one embodiment of the present invention. [Figure 4] 1 shows an example of a configuration of a supercell in an embodiment of the present invention. [Diagram 5] 1 shows an example of the configuration of a unit cell in one embodiment of the present invention. [Figure 6] 1 shows an example of the configuration of a unit cell in one embodiment of the present invention. [Figure 7] 1 shows an example of the configuration of a unit cell in one embodiment of the present invention. [Figure 8] 1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Figure 9] 1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Figure 10] 1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Figure 11] 1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Figure 12]1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Figure 13] 1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Figure 14] 1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Figure 15] 1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Figure 16] 1 shows an example of a configuration of a supercell in an embodiment of the present invention. [Figure 17] 1 shows an example of a configuration of a supercell in an embodiment of the present invention. [Figure 18] 1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Figure 19] 1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Figure 20] 1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Figure 21] 1 shows an example of the configuration of a variable reflectarray in one embodiment of the present invention. [Figure 22] 1 shows an example of a method for designing a tunable reflectarray in an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] 1 shows an example of the configuration of a variable reflectarray 10 according to an embodiment of the present invention. The variable reflectarray 10 includes a variable reflector. The tunable reflectarray 10 includes a plurality of supercells 20 and a tuning mechanism 30. When the supercells 20 are substantially rectangular, the spacing between the supercells 20 may be adjusted in the short side direction of the supercells 20 as shown in Fig. 1, or may be adjusted in the long side direction of the supercells 20 as shown in Fig. 2. As shown in Fig. 3, the supercell 20 is a metasurface that has different angles of incidence and reflection for electromagnetic waves of a given wavelength. In Fig. 3, the cases where the reflection direction is negative and positive are overlapped. As shown in FIG. 4, the supercell 20 is composed of a plurality of unit cells 21.

[0009] As shown in FIG. 5, in this embodiment, the unit cell 21 has an antenna having a substantially linear metal plate extending radially from the center. In this embodiment, the unit cell 21 has a cross-shaped resonator 22 as an antenna arranged on the surface of a dielectric substrate 23, and a ground layer 24 is provided on the back surface of the dielectric substrate 23. Here, the cross shape may include an approximately square shape in one form. Also, the antenna may be an approximately linear antenna instead of the cross-shaped dipole in this embodiment. Although it is stated that "the incident angle and the reflection angle are different for electromagnetic waves of a predetermined wavelength," this may include the case where the incident angle and the reflection angle become the same when the interval of the supercell 20 is adjusted. In other words, the supercell 20 constitutes a metasurface, which means that the incident angle and the reflection angle are not fundamentally limited to being the same, but can be changed by adjustment.

[0010] FIG. 6 shows a lateral or horizontal view of a unit cell 21 in one embodiment. In this embodiment, the unit cell 21 has a cross-shaped resonator 22, and the resonator 22 is of a so-called mushroom type supported on a substrate 25 via a support portion.

[0011] FIG. 7 shows the structure of a unit cell 21 in one embodiment as viewed from above. In this embodiment, the unit cell 21 has an L-shaped resonator 22 that extends vertically and horizontally within the horizontal direction. The resonator 22 is a so-called mushroom type supported on a substrate 25 via a support, but it may also be configured such that the resonator 22 is placed on the front surface of a dielectric substrate 23 and has a ground layer 24 on the rear surface of the dielectric substrate 23.

[0012] Next, the design of the supercell 20 will be described. Depending on the desired angle of incidence and angle of reflection, the cell size D is determined by the angle of incidence θ i , reflection angle θr The supercell 20 is designed by deriving the relation between the wavelength λ0 and the mode m.

number

[0013] When the reflection angle is constant, if the incidence angle is variable, the length of the supercell 20 changes but the phase gradient does not change. For example, it can be designed as follows. -5° incidence to 60° reflection: 11.2 mm 12.3mm for 0° incidence and 60° reflection 13.7mm for 5° incidence and 60° reflection

[0014] Figures 8 and 9 show the reflectarray 10 with variable cell spacing for an incident angle of 0°. In contrast, expanding the spacing between the unit cells 21 by 1.2 mm as shown in Figures 10 and 11 corresponds to an incident angle of +5°, and contracting the spacing between the unit cells 21 by 1.2 mm as shown in Figures 12 and 13 corresponds to an incident angle of -5°. In this way, by adjusting the spacing between the unit cells 21 within 1.2 mm, it is possible to accommodate an incident angle of -5° to +5°. In this way, by adjusting the horizontal spacing of the supercells 20 while keeping the phase gradient (supercells 20) unchanged, the angle of incidence can be varied while keeping the angle of reflection constant.

[0015] The variable mechanism 30 varies the interval between the multiple supercells 20, and has a substrate portion and a supercell-side fixing portion, the supercells 20 are fixed to the substrate portion via the supercell-side fixing portions, and the distance between the supercells 20 can be selected from two or more intervals. In particular, in this embodiment, the interval can be selected from continuous values. The variable mechanism 30 has a supercell interval adjustment section 31 that arranges the multiple supercells 20 at an interval selected from two or more intervals. The variable mechanism 30 may have a structure that allows the supercells 20 to be fixed at a desired interval and then the interval can be changed. If the interval can be changed, the adjustment can be made easier. Alternatively, the variable mechanism 30 may have a structure that does not allow the interval to be changed after the supercells 20 are fixed at a desired interval. If the interval cannot be changed, the structure can be made strong. The variable mechanism 30 and the supercell interval adjustment section 31 include any structure as long as the interval of the supercells 20 can be manually or automatically adjusted during manufacturing or the like, or the position of the supercell side fixing section can be manually or automatically adjusted.

[0016] Of course, as in the above case, the angle of reflection can be adjusted while keeping the angle of incidence constant. In this way, when the spacing between the multiple supercells 20 is changed in the variable mechanism 30, the angle of incidence or the angle of reflection is changed while keeping one of the angles constant for an electromagnetic wave of a specified wavelength.

[0017] When the spacing of the supercells 20 is increased from a predetermined spacing, the angle of incidence or the angle of reflection increases, and when the spacing is reduced from the predetermined spacing, the angle of incidence or the angle of reflection decreases, or when the spacing is increased from the predetermined spacing, the angle of incidence or the angle of reflection decreases, and when the spacing is reduced from the predetermined spacing, the angle of incidence or the angle of reflection increases. This configuration makes it possible to flexibly adjust the incident directivity or reflection directivity in a vertical or horizontal plane by making the incident directivity or reflection directivity reconfigurable. This configuration also makes it possible to realize this adjustment in a single layer, not in a multilayer structure, and while taking advantage of the reflector's advantages of being thin and not requiring a large space for installation, it is possible to realize a mechanism that makes it easy to face the incident wave from the base station even with sharp directivity at high gain, and allows adjustment according to the incident angle.

[0018] In one embodiment, the variable reflectarray 10 changes the angle of incidence or the angle of reflection by 10° or more by changing the spacing between the supercells 20 in the variable mechanism 30 . Figure 14 shows a reflectarray in which the incident angle is changed by 10 degrees or more. Figure 15 shows a reflectarray in which the reflection angle is changed by 10 degrees or more. When installing the variable reflectarray 10, it is difficult to fine-tune the direction of the reflectarray to face the base station, but it is often easy to install the reflectarray in the direction of the base station with approximate accuracy. Therefore, if the reflectarray can be adjusted within a range of about 10°, both installation and adjustment will be easy.

[0019] In this way, the supercell 20, which is an assembly of unit cells 21 that make up the metasurface reflectarray, is further assembled into an assembly in which the horizontal spacing between the supercells or the horizontal positional relationship between the upper and lower assemblies is variable, making it possible to flexibly adjust the incident directivity while keeping the reflection direction constant. In addition, it is possible to adjust both the horizontal and vertical in-plane directivity. Furthermore, when the relationship between the incident direction and the reflection direction is reversed, it is possible to adjust the reflection directivity while keeping the incident direction fixed.

[0020] Incidentally, for vertically polarized and horizontally polarized waves, when the incident direction changes to the reflection direction, the gain tends to decrease. Also, when an incident angle is applied, the side lobes in the front direction tend to increase. In one embodiment, the variable reflectarray 10 shown in Fig. 16 reflects electromagnetic waves that are neither horizontally nor vertically polarized and have a polarization tilted at a predetermined angle from the horizontal direction. The unit cells 21 are arranged in a direction tilted at a predetermined angle from the horizontal direction in the same direction as the polarization, with respect to the polarization tilted at a predetermined angle from the horizontal direction. Here, "arranged tilted in the same direction as the polarization direction" means arranged tilted by approximately the same amount as the rotation angle of the polarization.

[0021] In one embodiment, the electromagnetic wave having polarization inclined at a predetermined angle from the horizontal direction is a 45° polarization, and in the tunable reflectarray 10 shown in FIG. 17, the unit cells 21 are arranged at an angle of 45° from the horizontal direction. Even with 45° polarization, if it is rotated 45° around the Z axis, i.e., the vertical direction on the paper in Figure 14, it is possible to adjust the angle of incidence while maintaining a constant reflection angle. In addition, the side lobes, such as the amount of reflection in the front direction, have been improved by more than -10 dB compared to the VH polarization such as the horizontal and vertical polarizations mentioned above.

[0022] Instead of adjusting the horizontal spacing, a tilt can be applied by arranging horizontal supercells 20 vertically and shifting them horizontally at regular intervals as shown in Figure 18. In other words, in reflection in the vertical direction (up and down in the drawing), the reflected wave or incident wave can be tilted with respect to the vertical direction. In this embodiment, the supercells include a first plurality of supercells and a second plurality of supercells. The supercells 20 are arranged in a direction perpendicular to the longitudinal direction of the supercells 20, and are arranged so as to be shifted by a predetermined amount in the longitudinal direction of the supercells 20.

[0023] Also, in an arrangement in which supercells 20 are arranged vertically in the horizontal direction as in FIG. 19, and shifted horizontally a predetermined number to the right and a predetermined number to the left at regular intervals, the beam can be widened. In this embodiment, the first plurality of supercells 20 are arranged perpendicular to the longitudinal direction of the supercell 20 and shifted by a predetermined amount in a first direction which is one of the longitudinal directions of the supercell 20, and the second plurality of supercells 20 are arranged perpendicular to the longitudinal direction of the supercell 20 and shifted by a predetermined amount in a second direction which is the opposite direction to the first direction.

[0024] In one embodiment, as shown in FIG. 20, the spacing of the supercells 20 is such that varying the spacing changes both the angle of incidence and the angle of reflection. This configuration makes it possible to flexibly accommodate both the angle of incidence and the angle of reflection.

[0025] 21 shows an embodiment of the variable reflectarray 10. In this embodiment, the variable reflectarray 10 has flexibility, can be installed on a curved surface, and is installed on a cover 40. In many cases, the radius of curvature of the curved surface on which the reflector is to be installed is already determined, and therefore, it is often easy to design the variable reflectarray 10 in advance to match the curved surface.

[0026] In one embodiment, the design method of the variable reflectarray 10 includes a step of changing the angle of incidence or the angle of reflection for an electromagnetic wave of a predetermined wavelength while keeping one of the angle of incidence or the angle of reflection constant by changing the intervals between the multiple supercells 20. By this design method of the variable reflectarray 10, any of the variable reflectarrays 10 described above can be designed.

[0027] In one embodiment, the tunable reflectarray 10 designed by the design method for the tunable reflectarray 10 includes a plurality of supercells 20 having different angles of incidence and reflection for electromagnetic waves of a predetermined wavelength, and the supercells 20 are composed of a plurality of unit cells 21, and each unit cell 21 has an antenna. As shown in Figure 22, the method includes a supercell design step S10 for designing a supercell 20 having a plurality of unit cells 21, and a spacing adjustment step S20 for changing the spacing between the plurality of supercells 20 after designing the supercell 20, thereby changing the angle of incidence or the angle of reflection for an electromagnetic wave of a specified wavelength while keeping one of the angles constant.

[0028] It goes without saying that the present invention is not limited to the above-described embodiments, but includes various embodiments within the scope of the present invention. [Explanation of symbols]

[0029] 10 Variable Reflect Array 20. Supercell 21 Unit Cell 22 resonator 23 Dielectrics 24 Ground Layer 25 Substrate 30 Variable Mechanism 31 Supercell spacing adjustment section 40 Cover

Claims

1. A plurality of supercells and a variable mechanism for varying the intervals between the plurality of supercells, The supercell is A metasurface that has different angles of incidence and reflection for electromagnetic waves of a given wavelength, The antenna is made up of a plurality of unit cells, each unit cell having an antenna; The variable mechanism is a supercell interval adjustment unit that arranges the plurality of supercells at an interval selected from two or more intervals; A variable reflectarray in which, when the spacing between the multiple supercells is changed in the variable mechanism, the angle of incidence or the angle of reflection is changed while keeping one of the angle of incidence or the angle of reflection constant for an electromagnetic wave of the specified wavelength.

2. The tunable reflectarray according to claim 1 , wherein the angle of incidence or the angle of reflection is changed by 10° or more by changing the spacing between the supercells in the variable mechanism.

3. The spacing between the supercells is Expanding from the predetermined spacing increases the angle of incidence or reflection, and shrinking from the predetermined spacing decreases the angle of incidence or reflection, or 3. The variable reflectarray according to claim 1, wherein the angle of incidence or the angle of reflection decreases when the distance is increased from the predetermined distance, and the angle of incidence or the angle of reflection increases when the distance is decreased from the predetermined distance.

4. the electromagnetic wave of the predetermined wavelength is other than horizontally polarized and other than vertically polarized, and has a polarization inclined at a predetermined angle from the horizontal direction, 4. The variable reflectarray according to claim 1, wherein the unit cells are arranged in a direction inclined at a predetermined angle from the horizontal direction to the same direction as the polarization of a predetermined electromagnetic wave.

5. the electromagnetic wave of the predetermined wavelength is 45° polarized, The tunable reflectarray according to claim 4 , wherein the unit cells are arranged at an angle of 45° from the horizontal direction.

6. The supercells are arranged in a direction perpendicular to a longitudinal direction of the supercells, and 6. The variable reflectarray according to claim 1, wherein the supercells are arranged so as to be shifted by a predetermined amount in the longitudinal direction thereof.

7. the supercells include a first plurality of supercells and a second plurality of supercells; The first plurality of supercells are arranged in a direction perpendicular to a longitudinal direction of the supercells and shifted by a predetermined amount in a first direction which is one direction of the longitudinal direction of the supercells, and 6. The tunable reflectarray according to claim 1, wherein the second plurality of supercells are arranged in a direction perpendicular to a longitudinal direction of the supercells and shifted by a predetermined amount in a second direction opposite to the first direction.

8. 8. The variable reflectarray according to claim 1, wherein the unit cell has substantially linear metal plates extending radially from a central portion.

9. 8. The tunable reflectarray according to claim 1, wherein the unit cell is a cross dipole having a metal plate having a substantially cross shape.

10. 10. The variable reflectarray according to claim 1, wherein changing the spacing between the supercells changes both the angle of incidence and the angle of reflection.

11. A method for designing a variable reflectarray according to any one of claims 1 to 10, comprising the steps of: A method for designing a tunable reflectarray, comprising a step of changing an angle of incidence or an angle of reflection for an electromagnetic wave of the specified wavelength while keeping one of the angle of incidence or the angle of reflection constant by changing an interval between the plurality of supercells.

12. A method for designing a tunable reflectarray having multiple supercells, comprising the steps of: The supercell is A metasurface that has different angles of incidence and reflection for electromagnetic waves of a given wavelength, The antenna is made up of a plurality of unit cells, each unit cell having an antenna; designing the supercell having the plurality of unit cells; and and after designing the supercell, changing the spacing between the plurality of supercells to change the angle of incidence or the angle of reflection for an electromagnetic wave of the specified wavelength while keeping the other angle of incidence or the angle of reflection constant.

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