Beam conversion system and beam conversion method

Abstract

One aspect of the present invention is a beam conversion system comprising: an active metasurface on which electromagnetic waves that have been transmitted by an antenna are incident; an AMS distribution control device which changes the in-plane distribution of the active metasurface in a change in the amplitude or phase of the electromagnetic waves due to the active metasurface; an AMS rotation system which rotates the active metasurface; and an AMS rotation control device which controls the operation of the AMS rotation system, wherein the change in the amplitude or phase of the electromagnetic waves due to the active metasurface is uniform in both the amplitude and the phase in the direction of a first axis along the plane and is not uniform in at least one of the amplitude and the phase in the direction of a second axis that is not parallel to the direction of the first axis along the plane, and the AMS rotation system rotates the active metasurface about a rotation axis that is an axis which is non-parallel to the phase.

Description

Beam transformation system and beam transformation method

[0001] The present invention relates to a beam transformation system and a beam transformation method.

[0002] In wireless communication, the received power can be improved by performing amplitude and phase control on the aperture plane. Note that amplitude and phase control refers to control of the amplitude or phase.

[0003] Amplitude and phase control is achieved by an array antenna, but further improvement of received power requires an increase in the array size (aperture area), which, however, poses challenges in terms of cost and power consumption.

[0004] Therefore, attention has been focused on beamforming using active metasurfaces, such as RIS (Reconfigurable Intelligent Surface), which are metasurfaces that can actively control at least one of the reflection amplitude characteristic, reflection phase characteristic, transmission amplitude characteristic, or transmission phase characteristic (see Non-Patent Document 1). It is expected that the use of active metasurfaces will enable the expansion of the aperture area at low cost and with low power consumption.

[0005] S. Abdollahramezani et al., “Electrically driven reprogrammable phase-change metasurface reaching 80% efficiency”, Nature Communications, 13, Article number: 1696 (2022). J. Durnin, “Exact solutions for nondiffracting beams. I. The scalar theory”, J. Opt. Soc. Am. A, Vol. 4, No. 4, pp. 651-654 (1987).

[0006] However, there is a problem in that it is difficult to perform planar amplitude and phase control of an active metasurface on an area similar to that of an array antenna. Planar amplitude and phase control using an active metasurface is generally achieved by controlling the electrical length of each metaelement. To control the electrical length of each metaelement, it is necessary to be able to control the voltage, current, or power individually for each metaelement. To do this, metal wires must be arranged to transmit control signals so that individual control signals can be sent to each metaelement. As a result, the active metasurface surface is arranged with a complex arrangement of metal wires.

[0007] The more complex the layout, the more intertwined the metal wires become, resulting in an increased amount of metal wires being used. Furthermore, the metal wires themselves absorb electromagnetic waves or scatter them in unintended directions. As the aperture area increases, the amount of metal wires used increases according to the size, and the complexity of the metal wire layout also increases. As a result, the received power may decrease due to absorption or scattering by the metal wires themselves.

[0008] In this way, beamforming using active metasurfaces can sometimes result in a decrease in received power.

[0009] In view of the above circumstances, the present invention aims to provide a technology that suppresses the reduction in received power due to the use of an active metasurface.

[0010] One aspect of the present invention is a beam transformation system comprising an active metasurface on which electromagnetic waves transmitted by an antenna are incident, an AMS distribution control device that changes the distribution within the surface of the active metasurface of the change in amplitude or phase of the electromagnetic wave caused by the active metasurface, an AMS rotation system that rotates the active metasurface, and an AMS rotation control device that controls the operation of the AMS rotation system, wherein the change in amplitude or phase of the electromagnetic wave caused by the active metasurface is uniform in both amplitude and phase in the direction of a first axis along the surface, and is not uniform in at least one of amplitude and phase in the direction of a second axis along the surface that is non-parallel to the direction of the first axis, and the AMS rotation system rotates the active metasurface around an axis that is non-parallel to the surface as a rotation axis.

[0011] One aspect of the present invention is a beam conversion method performed by a beam conversion system, comprising: an active metasurface onto which electromagnetic waves transmitted from an antenna are incident; an AMS distribution control device that changes the distribution within the surface of the active metasurface of the change in amplitude or phase of the electromagnetic wave caused by the active metasurface; an AMS rotation system that rotates the active metasurface; and an AMS rotation control device that controls the operation of the AMS rotation system, wherein the change in amplitude or phase of the electromagnetic wave caused by the active metasurface is uniform in both amplitude and phase in the direction of a first axis along the surface, and is not uniform in at least one of amplitude and phase in the direction of a second axis along the surface that is non-parallel to the direction of the first axis, and the AMS rotation system rotates the active metasurface around an axis that is non-parallel to the surface as a rotation axis, the beam conversion method comprising: an AMS distribution control step in which the AMS distribution control device changes the distribution within the surface of the active metasurface; and an AMS rotation control step in which the AMS rotation control device controls the AMS rotation system.

[0012] The present invention makes it possible to suppress the reduction in received power caused by using an active metasurface.

[0013] An explanatory diagram for explaining a beam generation system of an embodiment. An explanatory diagram for explaining a first example of the in-plane amplitude or phase distribution of an active metasurface in an embodiment. An explanatory diagram for explaining a second example of the in-plane amplitude or phase distribution of an active metasurface in an embodiment. An explanatory diagram for an example of an AMS rotation system in an embodiment. A diagram showing an example of the hardware configuration of an AMS distribution control device 2 in an embodiment. A diagram showing an example of the hardware configuration of an AMS rotation control device in an embodiment. A flowchart showing an example of the processing flow performed by a beam conversion system of an embodiment. An explanatory diagram for explaining a beam generation system 100a in a modified example.

[0014] 1 is an explanatory diagram illustrating a beam generation system 100 according to an embodiment. The beam generation system 100 includes an antenna 9 and a beam conversion system 10. The antenna 9 is an antenna that radiates electromagnetic waves. The beam conversion system 10 converts the electromagnetic waves radiated by the antenna 9 into a desired beam.

[0015] The beam transformation system 10 includes an active metasurface (AMS) 1, an AMS distribution control device 2, an AMS rotation system 3, and an AMS rotation control device 4.

[0016] The active metasurface 1 is an active metasurface onto which electromagnetic waves transmitted by the antenna 9 are incident and which satisfies the metaconditions. Note that the active metasurface is a metasurface that can actively control at least one of the reflection amplitude characteristic, reflection phase characteristic, transmission amplitude characteristic, and / or transmission phase characteristic. Therefore, the active metasurface 1 may be, for example, a RIS (Reconfigurable Intelligent Surface) that satisfies the metaconditions.

[0017] The Meta condition is a condition regarding the magnitude of the amplitude or phase that the active metasurface imparts to the incident electromagnetic wave. More specifically, the Meta condition is a condition that the change in the amplitude or phase of the electromagnetic wave caused by the active metasurface 1 is uniform in both amplitude and phase in the direction of the first axis, and is not uniform in at least one of amplitude and phase in the direction of the second axis. The first axis is an axis along the surface of the active metasurface 1. The second axis is an axis along the surface of the active metasurface 1 that is non-parallel to the direction of the first axis.

[0018] Figure 2 is an explanatory diagram illustrating a first example of the in-plane amplitude or phase distribution of the active metasurface 1 in an embodiment. Note that in the example of Figure 2, for at least one of the first to fourth regions, the electric field applied to the metaelement belonging to that region is different from the electric field applied to the metaelement belonging to at least one of the other regions, as will be described later, but this is merely an example. The electric field applied to the metaelement may be the same regardless of which of the first to fourth regions it belongs to.

[0019] Figure 2 is an example of a view of the surface of the active metasurface 1 viewed from a direction perpendicular to the surface. In the example of Figure 2, the active metasurface 1 has a total of 16 metaelements within its surface, including metaelements C101 to C104, metaelements 201 to 204, metaelements C301 to C304, and metaelements 401 to 404.

[0020] An active metasurface is a two-dimensionally periodic arrangement of metaelements of a given shape made of a given material. When an electric field is applied to a metaelement, its physical properties, such as its effective permittivity, change compared to when no electric field is applied.

[0021] The amplitude or phase of an electromagnetic wave changes depending on the interaction with the meta-element that it is incident on, and if the physical properties change, the interaction between the meta-element and the electromagnetic wave that is incident on that meta-element changes. Therefore, the amplitude or phase of an electromagnetic wave changes depending on the change in the electric field applied to the meta-element that it is incident on.

[0022] Since an active metasurface is a surface in which metaelements are arranged periodically in two dimensions, it is a planar material. Of course, since an active metasurface is not a mathematical object but a material that exists in real space, it is a three-dimensional material that has a surface and a length perpendicular to the surface.

[0023] In the example of Figure 2, meta-elements C101 to C104 are located within a first region R1 within the plane of the active metasurface 1. That is, meta-elements C101 to C104 belong to the first region R1 within the plane of the active metasurface 1. The same electric field is applied to meta-elements C101 to C104. The same electric field is applied to meta-elements within the first region R1. Therefore, meta-elements C101 to C104 impart the same amplitude or phase change to electromagnetic waves passing through them.

[0024] In the example of Figure 2, metaelements C201 to C204 are located within a second region R2 within the plane of the active metasurface 1. That is, metaelements C201 to C204 belong to the second region R2 within the plane of the active metasurface 1. The second region R2 is a region that does not overlap with the first region R1. The same electric field is applied to the metaelements within the second region R2. Therefore, metaelements C201 to C204 impart the same amplitude or phase change to the electromagnetic waves passing through them.

[0025] In the example of Figure 2, metaelements C301 to C304 are located within a third region R3 within the plane of active metasurface 1. That is, metaelements C301 to C304 belong to the third region R3 within the plane of active metasurface 1. The third region R3 is a region that does not overlap with either the first region R1 or the second region R2. The same electric field is applied to metaelements within the third region R3. Therefore, metaelements C301 to C304 impart the same amplitude or phase change to electromagnetic waves passing through them.

[0026] In the example of Figure 2, metaelements C401 to C404 are located within a fourth region R4 within the plane of active metasurface 1. That is, metaelements C401 to C404 belong to the fourth region R4 within the plane of active metasurface 1. The fourth region R4 is a region that does not overlap with any of the first region R1, second region R2, and third region R3. The same electric field is applied to metaelements within the fourth region R4. Therefore, metaelements C401 to C404 impart the same amplitude or phase change to electromagnetic waves passing through them.

[0027] In this way, the same electric field is applied to the meta-elements in each region. However, the electric fields applied to the meta-elements in different regions are not necessarily the same. For example, as shown in the example of Figure 2, the electric field applied to the meta-elements in at least one of the first to fourth regions may be different from the electric field applied to the meta-elements in at least one of the other regions.

[0028] For example, the electric field applied to metaelements 101 to 104 is different from the electric field applied to metaelements 201 to 204, but the electric field applied to metaelement 101, the electric field applied to metaelement 102, the electric field applied to metaelement 103, and the electric field applied to metaelement 104 are the same.

[0029] 2, the X axis is the first axis and the Y axis is the second axis, and the electromagnetic wave is incident along, for example, the Z axis.

[0030] Figure 3 is an explanatory diagram illustrating a second example of the in-plane amplitude or phase distribution of the active metasurface 1 in an embodiment. Figure 3 is an example of a view of the surface of the active metasurface 1 viewed from a direction perpendicular to the surface. In the example of Figure 3, the directions of the X-axis, Y-axis, and Z-axis correspond to the directions of the X-axis, Y-axis, and Z-axis in Figure 2, respectively. The example of Figure 3 is the result of rotating the active metasurface 1 of the example of Figure 2 by 90 degrees.

[0031] The examples in Figures 2 and 3 are visually easy to understand, and show that when the meta-conditions are met, the direction of propagation of the electromagnetic wave incident on the active metasurface 1 can be changed simply by rotating the active metasurface 1 without changing the distribution of meta-changes within the plane of the active metasurface 1. Specifically, the change in the direction of propagation of the electromagnetic wave is rotation. Note that the meta-change is a change in amplitude or phase that the active metasurface 1 imparts to the incident electromagnetic wave. The incident electromagnetic wave is the electromagnetic wave that has been incident on the active metasurface 1. Note that if the electric field applied to the meta-element is not changed, the distribution of meta-changes within the plane of the active metasurface 1 does not change.

[0032] <Effects of the active metasurface 1 that satisfies the meta conditions> When the meta conditions are satisfied, there is no need to change the electric field applied to the metaelements along the first axis. Therefore, compared to controlling each metaelement individually, it is possible to simplify the placement of metal wires. Therefore, using the active metasurface 1 that satisfies the meta conditions reduces the reduction in received power due to the use of the active metasurface.

[0033] However, simplifying the metal wire arrangement can lead to a situation where the reduction in received power by receivers located in a specific direction is suppressed but the reduction in received power by receivers located in other directions is not suppressed. However, an active metasurface 1 that satisfies the metaconditions can change the direction of propagation of electromagnetic waves simply by rotating the active metasurface 1 without changing the distribution of meta-changes within the active metasurface 1. Therefore, rotating an active metasurface that satisfies the metaconditions 1 can suppress this situation. Therefore, rotating an active metasurface 1 that satisfies the metaconditions can suppress the reduction in received power not only for receivers located in a specific position, but also for receivers located in other directions.

[0034] Returning to the explanation of Figure 1, the AMS distribution control device 2 executes AMS distribution control processing. The AMS distribution control processing is a processing for changing the distribution of the amplitude or phase change of the incident electromagnetic wave by the active metasurface 1 within the plane of the active metasurface. In other words, the AMS distribution control processing is a processing for changing the distribution of meta-change within the plane of the active metasurface. In the AMS distribution control processing, the distribution of meta-change within the plane of the active metasurface 1 is changed by changing the electric field applied to the meta-element.

[0035] More specifically, in the AMS distribution control process, the application of an electric field to each meta-element provided in the active metasurface 1 is controlled based on information indicating the distribution of meta-changes (hereinafter referred to as "meta-change distribution information") so as to change the distribution of meta-changes to the distribution indicated by the meta-change distribution information.

[0036] The AMS rotation system 3 rotates the active metasurface 1. More specifically, the AMS rotation system 3 rotates the active metasurface 1 around an axis that is non-parallel to the plane of the active metasurface 1.

[0037] Figure 4 is an explanatory diagram of an example of an AMS rotation system 3 in an embodiment. The AMS rotation system 3 includes, for example, a prime mover 31 and a power transmission device 32. The prime mover 31 is a prime mover that generates power. The prime mover is, for example, a motor or an engine. The power transmission device 32 is a power transmission device that transmits the power generated by the prime mover 31 to the active metasurface 1 to rotate the active metasurface 1. The power transmission device may be any device that rotates the active metasurface 1 by transmitting the power generated by the prime mover to the active metasurface 1, and may be configured, for example, by combining a transmission shaft, gears, etc.

[0038] Returning to the explanation of Figure 1, the AMS rotation control device 4 controls the operation of the AMS rotation system 3. Since the AMS rotation system 3 is a device that rotates the active metasurface 1, the rotation of the active metasurface 1 is controlled by controlling the AMS rotation system 3 with the AMS rotation control device 4.

[0039] More specifically, the AMS rotation control device 4 controls the operation of the AMS rotation system 3 based on information indicating the rotation angle (hereinafter referred to as "rotation angle information") so as to rotate the active metasurface 1 by the rotation angle indicated by the rotation angle information. As a result, the rotation of the AMS rotation system 3 rotates the active metasurface 1 by the rotation angle indicated by the rotation angle information.

[0040] <Example of Hardware Configuration of AMS Distribution Control Device 2> FIG. 5 is a diagram illustrating an example of a hardware configuration of the AMS distribution control device 2 in the embodiment.

[0041] The AMS distribution control device 2 has a control unit 21 including a processor 91 such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit) or NPU (Neural Network Processing Unit) and a memory 92 connected by a bus, and executes a program. The AMS distribution control device 2 functions as a device including the control unit 21, interface unit 22 and storage unit 23 by executing the program.

[0042] More specifically, the processor 91 reads out a program stored in the storage unit 23 and stores the read program in the memory 92. When the processor 91 executes the program stored in the memory 92, the AMS distribution control device 2 functions as a device including the control unit 21, the interface unit 22, the storage unit 23, and the AMS control circuit 24.

[0043] The control unit 21 controls the operation of each functional unit included in the AMS distribution control device 2. The control unit 21 executes, for example, AMS distribution control processing. By executing the AMS distribution control processing, the control unit 21 controls the electric field applied to each metaelement of the active metasurface 1 via control of the operation of the AMS control circuit 24. Controlling the electric field applied to each metaelement changes the in-plane distribution of metachanges on the active metasurface.

[0044] The control unit 21 acquires, for example, information stored in the storage unit 23. The process of acquiring information stored in the storage unit 23 is specifically a read process.

[0045] The interface unit 22 includes a communication interface for connecting the AMS distribution control device 2 to an external device. The interface unit 22 communicates with the external device via wired or wireless communication. The external device is, for example, a device that has transmitted the meta change distribution information. In such a case, the interface unit 22 acquires the meta change distribution information by communicating with the device that has transmitted the meta change distribution information. The meta change distribution information acquired by the interface unit 22 is output to the control unit 21.

[0046] The storage unit 23 is configured using a computer-readable storage medium device (non-transitory computer-readable recording medium) such as a magnetic hard disk device or a semiconductor storage device. The storage unit 23 stores various information related to the AMS distribution control device 2. The storage unit 23 stores, for example, meta change distribution information. The storage unit 23 may also store, for example, a history of meta change distribution information. The storage unit 23 stores, for example, various information generated by the operation of the control unit 21. The storage unit 23 may exist on a cloud, for example.

[0047] The AMS control circuit 24 is a circuit that operates under the control of the control unit 21, is connected to each metaelement of the active metasurface 1, and is capable of applying an electric field to the connected metaelement. The AMS control circuit 24 may be, for example, a circuit including a power supply circuit and a transistor. In such a case, the transistor is turned on and off under the control of the control unit 21, thereby controlling the power supplied from the power supply circuit to each metaelement.

[0048] <Example of Hardware Configuration of AMS Rotation Control Device 4> FIG. 6 is a diagram showing an example of the hardware configuration of the AMS rotation control device 4 in the embodiment.

[0049] AMS rotation control device 4 has a control unit 41 including a processor 93 such as a CPU, GPU, or NPU, and a memory 94, which are connected by a bus, and executes a program. AMS rotation control device 4 functions as a device including control unit 41, interface unit 42, and memory unit 43 by executing the program.

[0050] More specifically, the processor 93 reads the program stored in the storage unit 43 and stores the read program in the memory 94. The processor 93 executes the program stored in the memory 94, whereby the AMS rotation control device 4 functions as a device including the control unit 41, the interface unit 42, and the storage unit 43.

[0051] The control unit 41 controls the operation of each functional unit included in the AMS rotation control device 4. The control unit 41 controls, for example, the operation of the AMS rotation system 3. Based on the rotation angle information, the control unit 41 controls the operation of the AMS rotation system 3 so as to rotate the active metasurface 1 by the rotation angle indicated by the rotation angle information.

[0052] For example, if the AMS rotation system 3 is composed of a prime mover 31 and a power transmission device 32, and the prime mover 31 is a motor, the control unit 41 controls the rotation speed and rotation time of the motor so that the active metasurface 1 rotates by the rotation angle indicated by the rotation angle information. This causes the active metasurface 1 to rotate by the rotation angle indicated by the rotation angle information.

[0053] For example, if the AMS rotation system 3 is composed of a prime mover 31 and a power transmission device 32, and the prime mover 31 is an engine, the control unit 41 controls the horsepower of the engine and the time for which the engine is operated so as to rotate the active metasurface 1 by the rotation angle indicated by the rotation angle information. As a result, the active metasurface 1 rotates by the rotation angle indicated by the rotation angle information.

[0054] The control unit 41 acquires, for example, information stored in the storage unit 43. The process of acquiring information stored in the storage unit 43 is specifically a read process.

[0055] The interface unit 42 includes a communication interface for connecting the AMS rotation control device 4 to an external device. The interface unit 42 communicates with the external device via wired or wireless communication. The external device is, for example, a device that has transmitted rotation angle information. In such a case, the interface unit 42 acquires the rotation angle information by communicating with the device that has transmitted the rotation angle information. The rotation angle information acquired by the interface unit 42 is output to the control unit 41.

[0056] The storage unit 43 is configured using a computer-readable storage medium device (non-transitory computer-readable recording medium) such as a magnetic hard disk device or a semiconductor storage device. The storage unit 43 stores various information related to the AMS rotation control device 4. The storage unit 43 stores, for example, rotation angle information. The storage unit 43 may also store, for example, a history of rotation angle information. The storage unit 43 stores, for example, various information generated by the operation of the control unit 41. The storage unit 43 may exist on the cloud, for example.

[0057] 7 is a flowchart showing an example of the processing flow executed by the beam conversion system 10 of the embodiment. The control unit 21 of the AMS distribution control device 2 acquires meta-change distribution information (step S101). Next, the control unit 21 changes the distribution of meta-changes within the surface of the active metasurface 1 (step S102). Specifically, based on the acquired meta-change distribution information, the control unit 21 controls the operation of the AMS control circuit 24 so as to change the distribution of meta-changes to the distribution indicated by the meta-change distribution information. As a result, an electric field is applied to each meta-element included in the active metasurface 1 so that the distribution of meta-changes changes to the distribution indicated by the meta-change distribution information. In this way, the distribution of meta-changes within the surface of the active metasurface 1 changes to the distribution indicated by the meta-change distribution information.

[0058] Next, the control unit 41 of the AMS rotation control device 4 acquires the rotation angle information (step S103). Next, the control unit 41 controls the AMS rotation system 3 (step S104). Specifically, based on the acquired rotation angle information, the control unit 41 controls the operation of the AMS rotation system 3 so as to rotate the active metasurface 1 by the rotation angle indicated by the rotation angle information. Due to the operation of the AMS rotation system 3, the active metasurface 1 rotates by the rotation angle indicated by the rotation angle information.

[0059] The process of step S102 may be executed at any timing as long as it is executed after the process of step S101. The process of step S104 may be executed at any timing as long as it is executed after the process of step S103. The process of step S103 does not necessarily have to be executed after the process of step S101. The process of step S103 may be executed before the process of step S101, or may be executed in parallel with the process of step S101.

[0060] The beam conversion system 10 configured in this manner includes the active metasurface 1. Therefore, the beam conversion system 10 can suppress the reduction in received power caused by using the active metasurface, as described in <Effects of the active metasurface 1 that satisfies the metaconditions>.

[0061] The beam conversion system 10 also includes an AMS rotation system 3, which allows the active metasurface 1 to rotate. Therefore, as described in <Effects of the active metasurface 1 that satisfies the metaconditions>, the beam conversion system 10 can prevent a situation in which a decrease in the received power by a receiver located in a specific direction is suppressed but a decrease in the received power by a receiver located in another direction is not suppressed.

[0062] The beam generating system 100 includes the beam conversion system 10. This makes it possible to suppress the reduction in received power due to the use of an active metasurface. It also makes it possible to prevent a situation in which the reduction in received power by a receiver located in a specific direction is suppressed but the reduction in received power by a receiver located in another direction is not suppressed.

[0063] (Modification) Figure 8 is an explanatory diagram illustrating a beam generation system 100a in a modification. Hereinafter, components having the same functions as those in Figure 1 are denoted by the same reference numerals as in Figure 1, and description thereof will be omitted. The beam generation system 100a differs from the beam generation system 100a in that it includes a beam conversion system 10a instead of the beam conversion system 10. The beam conversion system 10a differs from the beam conversion system 10 in that it further includes a Bessel beam generating element 5.

[0064] The Bessel beam generating element 5 converts the electromagnetic wave transmitted by the antenna 9 into a Bessel beam. In the beam generating system 100a, the Bessel beam generated by the Bessel beam generating element 5 is incident on the active metasurface 1.

[0065] The second axis may be perpendicular to the first axis. Furthermore, the rotation axis along which the AMS rotation system 3 rotates the active metasurface 1 may be perpendicular to the first and second axes. Furthermore, the rotation of the active metasurface 1 may be a rotation around the above rotation axis. The rotation of the active metasurface 1 may also be a revolution around the above rotation axis.

[0066] In general, active metasurfaces are lighter than antennas, so the energy consumed in rotating the active metasurface 1 is less than the energy consumed in rotating the antenna.

[0067] The AMS distribution control device 2 may be implemented using a plurality of information processing devices connected to each other via a network so that they can communicate with each other. In this case, the processes executed by the control unit 21 may be distributed and executed by the plurality of information processing devices.

[0068] The AMS rotation control device 4 may be implemented using a plurality of information processing devices connected to each other via a network so that they can communicate with each other. In this case, the processes executed by the control unit 41 may be distributed among the plurality of information processing devices.

[0069] The AMS distribution control device 2 and the AMS rotation control device 4 do not necessarily have to be mounted in different housings. The AMS distribution control device 2 and the AMS rotation control device 4 may be mounted in a single housing. In such a case, the control unit 21 and the control unit 41 do not necessarily have to be different units, and a single control unit may execute the processing executed by the control unit 21 and the processing executed by the control unit 41.

[0070] Note that all or part of the functions of the beam generation system 100 and the beam generation system 100a may be realized using hardware such as an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array). The program may be recorded on a computer-readable recording medium. Examples of computer-readable recording media include portable media such as flexible disks, magneto-optical disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into computer systems. The program may be transmitted via a telecommunications line.

[0071] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0072] 100, 100a...Beam generating system, 10, 10a...Beam conversion system, 1...Active metasurface, 2...AMS distribution control device, 3...AMS rotation system, 4...AMS rotation control device, 5...Bessel beam generating element, 31...Prime mover, 32...Power transmission device, 21...Control unit, 22...Interface unit, 23...Memory unit, AMS control circuit, 41...Control unit, 42...Interface unit, 43...Memory unit, 91...Processor, 92...Memory, 93...Processor, 94...Memory

Claims

1. A beam transformation system comprising: an active metasurface onto which electromagnetic waves transmitted by an antenna are incident; an AMS distribution control device that changes the distribution within the surface of the active metasurface of the change in amplitude or phase of the electromagnetic wave caused by the active metasurface; an AMS rotation system that rotates the active metasurface; and an AMS rotation control device that controls the operation of the AMS rotation system, wherein the change in amplitude or phase of the electromagnetic wave caused by the active metasurface is uniform in both amplitude and phase in the direction of a first axis along the surface, and is not uniform in at least one of amplitude and phase in the direction of a second axis along the surface that is non-parallel to the direction of the first axis, and the AMS rotation system rotates the active metasurface around an axis that is non-parallel to the surface as a rotation axis.

2. The beam transformation system of claim 1, wherein the second axis is perpendicular to the first axis.

3. The beam transformation system of claim 1, wherein the rotation axis is perpendicular to the first axis and the second axis.

4. The beam conversion system of claim 1, wherein the rotation of the active metasurface is a rotation around the rotation axis.

5. The beam conversion system according to claim 1, further comprising: a Bessel beam generating element that converts the electromagnetic wave transmitted by the antenna into a Bessel beam, and the electromagnetic wave incident on the active metasurface is a Bessel beam obtained by the Bessel beam generating element.

6. A beam conversion method performed by a beam conversion system comprising: an active metasurface onto which electromagnetic waves transmitted from an antenna are incident; an AMS distribution control device that changes the distribution within the surface of the active metasurface of the change in amplitude or phase of the electromagnetic wave caused by the active metasurface; an AMS rotation system that rotates the active metasurface; and an AMS rotation control device that controls the operation of the AMS rotation system, wherein the change in amplitude or phase of the electromagnetic wave caused by the active metasurface is uniform in both amplitude and phase in the direction of a first axis along the surface, and is not uniform in at least one of amplitude and phase in the direction of a second axis along the surface that is non-parallel to the direction of the first axis, and the AMS rotation system rotates the active metasurface around an axis that is non-parallel to the surface as a rotation axis, the beam conversion method comprising: an AMS distribution control step in which the AMS distribution control device changes the distribution within the surface of the active metasurface; and an AMS rotation control step in which the AMS rotation control device controls the AMS rotation system.

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