Mechanically actuated smart electromagnetic metasurface

Abstract

The application discloses a kind of reflection type mechanical drive intelligent electromagnetic super surface.The intelligent surface combines electromagnetic super surface and mechanical drive structure, breaks the limitation that traditional passive super surface is not reconfigurable and cannot be real-time regulated, compared with active super surface, no loss is introduced, with higher reflection efficiency.Based on the above advantages, the intelligent surface can realize beamforming and coverage enhancement of two orthogonal linearly polarized electromagnetic waves when electromagnetic wave is incident in free space.The intelligent surface responds to electromagnetic wave of specified frequency band through optimized square patch structure, and its dynamic adjustable property is realized by real-time control of three step motors driven adjustable metal backboard bidirectional movement through computer and control board output pulse signal.This polarization multiplexing reflection type mechanical drive intelligent surface has the characteristics of high efficiency, easy to process, real-time dynamic continuous adjustment, etc., and has application prospect in widening channel capacity and improving communication efficiency.

Description

Technical fields:

[0001] This invention designs a mechanically driven reflective intelligent electromagnetic metasurface, belonging to the field of artificial electromagnetic materials. It features high efficiency, speed, and real-time dynamic adjustability, and can also achieve electromagnetic wave coverage enhancement and beam control within the designed communication frequency band. Background technology:

[0002] Smart surfaces, a concept first proposed by electromagnetists, have been gradually introduced into practical applications in mobile communication systems in recent years. Early smart surfaces were primarily used in military radar and anti-radar equipment. Recently, with the rise of artificial electromagnetic materials, the freedom to manipulate electromagnetic waves across various frequency bands has greatly increased, leading to the application of smart surfaces in wireless communication. Electromagnetic metasurfaces, as two-dimensional forms of artificial electromagnetic materials, offer both electromagnetic wave manipulation capabilities and low profile characteristics. Most current smart electromagnetic surfaces are composed of active metasurfaces, using PIN diodes or varactors in each device unit to switch and control different operating states, resulting in different electromagnetic responses from the smart surface. While this method allows for rapid manipulation of electromagnetic waves, the introduction of active devices introduces insertion loss into the metasurface units, limiting the overall efficiency of the smart surface. Passive metasurfaces, unlike active metasurfaces, are not affected by insertion loss and can solve the efficiency limitation problem. However, passive metasurfaces often cannot reconstruct and rapidly manipulate electromagnetic waves in real time. To address this issue, the intelligent electromagnetic metasurface described in this invention utilizes a square metal patch structure to generate electromagnetic resonance. By mechanically driving a stepper motor to change the air layer thickness of the unit, phase modulation of the reflected electromagnetic wave is achieved. This mechanically driven electromagnetic metasurface can achieve full phase modulation of electromagnetic waves at 2.6 GHz while maintaining high reflection efficiency. It features a simple structure, ease of fabrication, and fast modulation speed, making it a promising candidate for application in wireless communication systems. Summary of the Invention:

[0003] Objective of the Invention: The present invention proposes a reflective, mechanically driven intelligent electromagnetic metasurface. By introducing a mechanical drive device into a passive metasurface, the intelligent metasurface enables efficient real-time phase modulation of electromagnetic waves at designed microwave communication frequencies. Compared with active metasurfaces, this intelligent surface has higher reflection efficiency and has many potential applications in coverage enhancement and beamforming in 5G and 6G wireless communication technologies.

[0004] Technical Solution: The mechanically driven intelligent electromagnetic metasurface of this invention consists of two parts: an electromagnetic metasurface and a mechanical drive device. Each unit's electromagnetic metasurface includes an upper metal patch layer, a dielectric layer, a metal cavity, and a metal backplate. The dielectric layer is made of F4B substrate with a dielectric constant of 2.2. The metal pattern of each unit of the intelligent metasurface consists of 16 identical metal patches, which induce electromagnetic resonance, thereby enabling full-phase phase modulation of the reflected bipolar electromagnetic waves. Optimized parameters such as the size of the square metal patches and the thickness of the dielectric layer ensure a wide phase adjustment range for the intelligent surface unit. The metal cavity is made of aluminum, serving two purposes: firstly, to isolate electromagnetic leakage crosstalk between units caused by differences in air layer thickness; and secondly, to support the vertically placed intelligent surface array. The metal backplate of the metasurface is connected to a screw in the mechanical drive structure. By continuously adjusting the air layer thickness between the metal backplate and the dielectric plate, the reflection phase can be continuously adjusted. The mechanical drive device includes a stepper motor and a control system. Each intelligent surface unit's adjustable backplane is driven by three stepper motors combined with three screws, with a displacement range of 0-15mm along the normal direction of the metasurface. The three motors are synchronously controlled by the control system. In the assembled 16×16 intelligent metasurface array, each unit can independently and quickly control the air layer thickness of the electromagnetic metasurface, enabling the array to quickly switch between different phase distributions.

[0005] Beneficial effects: 1. At the 2.6GHz wireless communication frequency, the mechanically driven intelligent electromagnetic metasurface designed in this invention can achieve 360° phase modulation of reflected dual-polarized electromagnetic waves, with reflection amplitudes mostly above 0.97. 2. The intelligent surface designed in this invention can quickly switch the phase distribution of the array, achieving enhanced coverage and beamforming of electromagnetic waves. 3. The intelligent surface designed in this invention has high reflection efficiency, a simple and easy-to-design structure, is suitable for dual-polarized electromagnetic waves, is field-programmable, and can switch quickly, showing potential application prospects in the field of wireless communication. Attached image description:

[0006] Figure 1 This is an overall schematic diagram of the real-time dynamic mechanically adjustable electromagnetic beam control system involved in the embodiment;

[0007] Figure 2 This is a schematic diagram of the intelligent surface unit structure. (a) Internal structure of the unit, (b) Schematic diagram of the mechanical structure on the back of the unit.

[0008] Figure 3These are physical images of the intelligent surface's mechanical drive component and a schematic diagram of its working principle. (a) Physical mechanical structure (side view), (b) Physical mechanical structure (back view), (c) Schematic diagram when the air layer between the adjustable reflector and the dielectric layer is small, (d) Schematic diagram when the air layer between the adjustable reflector and the dielectric layer is large. The switching between different air layer thicknesses in (c) and (d) is achieved by driving the adjustable reflector to move using a stepper motor and a screw.

[0009] Figure 4 These are curves showing the phase and reflection coefficient of the smart surface unit at 2.6 GHz as a function of air layer thickness. (a) shows the phase modulation effect of x-polarized electromagnetic waves incident on the smart surface unit, and (b) shows the amplitude modulation effect of x-polarized electromagnetic waves incident on the smart surface unit. Because this unit is equivalent in the x and y directions, it has the same modulation effect on y-polarized electromagnetic waves, which is not shown.

[0010] Figure 5 These are, respectively, the full-wave simulation far-field energy distribution diagrams of the smart surface achieving dual-beam scanning by changing the proportional arrangement period of 0° / 180° units; (a) is the far-field simulation result diagram with a period of 2 rows; (b) is the far-field simulation result diagram with a period of 8 rows.

[0011] Figure 2 In the middle, 1-square metal patch; 2-dielectric layer; 3-adjustable reflector; 4-metal cavity; 5-screw; 6-metal back plate; 7-stepper motor; 8-control board. Detailed implementation method:

[0012] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. However, it should be understood that the present invention can be implemented in various forms. The exemplary and non-limiting embodiments shown in the drawings and described below are not intended to limit the invention to the specific embodiments illustrated.

[0013] It should be understood that, where technically feasible, the technical features listed above for different embodiments can be combined with each other to form other embodiments within the scope of this invention. Furthermore, the specific examples and embodiments described in this invention are non-limiting, and corresponding modifications can be made to the structures, steps, and order described above without departing from the protection scope of this invention.

[0014] Example 1:

[0015] Figure 1A schematic diagram illustrating the working principle of a mechanically driven intelligent electromagnetic metasurface operating at a 2.6 GHz communication frequency is shown, including the electromagnetic metasurface and the mechanical drive structure. In the diagram, an electromagnetic wave is incident along the negative z-axis onto an array of intelligent surfaces in the xy-plane. The array contains 16*16 uniformly arranged intelligent surface units, each of which can independently control its reflection phase response. Real-time pulse signals output by a computer and control board drive a stepper motor to change the structural parameters of the electromagnetic metasurface, thereby rapidly switching the phase distribution of the intelligent surface to achieve real-time beamforming and coverage enhancement.

[0016] like Figure 2 As shown, Figure 2 (a) The internal structure of the mechanically driven smart surface unit is shown, including 16 square metal patches 1 on the front of the dielectric layer, an F4B dielectric layer 2 (dielectric constant 2.2, loss tangent 0.001), an adjustable reflector 3 behind the dielectric layer, a metal aluminum plate cavity 4 to isolate crosstalk between units, three screws 5 connecting the adjustable reflector, and a metal backplate 6 fixing three stepper motors 7 and a control board 8. In this embodiment, the 16 square metal patch structures with a side length p0 of 2mm are made of copper with a thickness of 0.018mm. The thickness h0 of the F4B dielectric layer 2 is 2.5mm. The metal patches are processed onto the dielectric layer surface using PCB manufacturing processes. The interval d between every two square metal patches is 10mm, and the distance between the patch on the outer side of each unit and the edge is 5mm. The 16 metal patches are evenly distributed on the dielectric layer of each unit. Figure 2 (b) A schematic diagram of the back of the intelligent surface unit is shown. Three stepper motors 7 and a gear transmission mechanism (not shown) drive three screws 5 to move along the Z-axis. Based on the principle that three points determine one surface, the simultaneous advancement of the three screws ensures that the adjustable reflector moves back and forth while remaining on the xy-plane, thereby changing the thickness of the air layer inside the electromagnetic metasurface and achieving continuous adjustment of the reflection phase. The radius r0 of the three screws 5 is 1mm, passing through a hole in the fixed aluminum plate 6. The three stepper motors are model 28BYJ-48, with a voltage of DC 5V-12V. A series of continuous pulses are synchronously applied to the three stepper motors via a computer and control board 8, causing them to rotate through a certain angle, thereby driving the adjustable reflector to move forward / backward a specified distance. The three stepper motors 7 and the control board 8 are fixed to the aluminum plate 6 with screws. The control board is then connected to the computer to receive instructions from the computer.

[0017] exist Figure 3 The document presents the process of a stepper motor driving an adjustable reflector and actual machining diagrams of the mechanical structure of the intelligent surface unit. (For example...) Figure 3 (a) and Figure 3As shown in (b), when the stepper motor is running, it can drive the reflector in the vertical plane to move back and forth. This movement can change the thickness of the air layer between the dielectric layer 2 and the adjustable reflector 3. Since the three screws are fixed to the adjustable reflector 3, the stepper motor can drive the reflector 3 to move forward and backward in both directions. Figure 3 (c) shows the actual stepper motor 7, screw 5 and control board 8. The USB interface on the right side of the control board is connected to the computer, and the entire smart surface unit can receive control signals from the computer.

[0018] The air layer thickness varies from 1 to 15 mm. Under different thicknesses, the electromagnetic response of each element differs. The design objective of this element is to achieve 360° phase modulation of the reflected dual-polarized electromagnetic wave while maintaining a high reflection amplitude. Based on this design objective, we used the commercial simulation software CST to simulate the element structure. The simulation boundary conditions for this element are set as periodic boundary conditions in the x and y axes, and as open boundary conditions in the z-axis direction. The square metal patch material in the element is copper, with a conductivity of 5.8 × 10⁻⁶. 7 S / m. The dielectric layer 2 is made of F4B material (dielectric constant 2.2, loss tangent 0.001), the adjustable reflector 3 is a copper-plated F4B (polytetrafluoroethylene) dielectric plate, and the metal cavity 4 for transmitting crosstalk between isolation units and the metal backplate 6 for fixing the stepper motor are made of aluminum with a conductivity of 3.56 × 10⁻⁶. 7 S / m. The structural period p of the unit is set to 128mm, the total thickness h2 is 20.5mm, the side length p0 of each small square metal patch 1 is 22mm, the distance d between every two small metal patches is 10mm, the thickness h0 of the dielectric layer 2 is 2.5mm, and the thickness of the metal cavity is 3mm. Figure 2 In (a), the internal structure of each unit is shown as d0 = 1.5mm. The thickness h1 of the adjustable reflector 3 is 1mm, and the gap d0 between it and the metal cavity 4 is 0.5mm, which is to prevent the adjustable backplate from jamming with the metal cavity 4. The thickness h2 of the metal backplate 6 is set to 2mm. Figure 4 The paper presents the reflection amplitude and phase curves of a smart surface unit at 2.6 GHz as a function of air layer thickness. From... Figure 4 (a) It can be seen that as the air layer thickness increases, the smart surface unit can achieve 360° phase coverage within the range of 1-15 mm, while Figure 4 (b) also shows that under linearly polarized electromagnetic wave incidence, the same polarization reflection amplitude is mostly above 0.97, which can maintain high reflection efficiency. Since the electromagnetic metasurface structure of this unit is equivalent in the x and y directions, the reflection amplitude phase curve is equally effective for x-polarized and y-polarized electromagnetic wave incidence.

[0019] In the concept of metasurfaces, beamforming and other functions can be achieved by setting the phase distribution of a metasurface array, thus providing more degrees of freedom for controlling electromagnetic waves. Based on this principle, this invention realizes a dual-beam angle scanning function. When the phase distribution of the array is in a state of uniform periodic switching between 0° and 180° (period T), it will excite a symmetrical dual beam with a certain angle (deflection angle θ), where the deflection angle can be calculated using the formula θ = arcsin(λ / T).

[0020] This invention is verified here using phase distributions of "0°, 180°, 0°, 180°" and "0°, 0°, 0°, 0°, 180°, 180°, 180°, 180°, 180°, as shown below. Figure 5 As shown, the abnormal deflection angles of the dual beams obtained from the full-wave simulation in the two cases are ±6° and ±27°, respectively, which are in good agreement with the theoretical values, proving the reliability of the invention in practical application.

[0021] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0022] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A mechanically driven smart electromagnetic metasurface, characterized by, The electromagnetic metasurface structure and mechanical driving structure are included; the electromagnetic metasurface unit structure comprises 16 square metal patches (1), a dielectric layer (2), an adjustable reflecting plate (3) and a metal cavity (4) for isolating the crosstalk between units; the mechanical driving structure part comprises three screw rods (5) for driving the adjustable metal back plate, a metal back plate (6) for fixing, three stepping motors (7) and a control board (8); the uppermost metal patch (1) structure is attached to the upper surface of the dielectric layer (2), and the dielectric layer (2) is attached to the metal cavity (4); the adjustable reflecting plate (3) is connected with the three screw rods (5) to ensure that it can move back and forth along the screw rods; the three stepping motors (7) and the control board (8) are fixed on the metal back plate (6), and the computer is connected with the control board through a USB interface; the computer and the control board can output different pulse signals in real time to control the adjustable reflecting plate (3) to move back and forth along the Z-axis direction, change the thickness of the air layer between the adjustable reflecting plate (3) and the dielectric layer (2), and thus dynamically control the phase of the reflected electromagnetic wave by 360 degrees.

2. The mechanically-driven, smart electromagnetic metasurface of claim 1, wherein, The 16 square metal patches (1) are made of copper and uniformly distributed on the outer surface of the dielectric layer (2), and the distance between the outermost metal patch and the unit edge is half of the distance between the metal patches.

3. The mechanically-driven, smart electromagnetic metasurface of claim 1, wherein, The dielectric layer (2) is made of F4B and attached to the metal cavity (4).

4. The mechanically-driven, smart electromagnetic metasurface of claim 1, wherein, The adjustable reflecting plate (3) is composed of a double-sided copper-coated F4B dielectric plate; in order to ensure that the adjustable reflecting plate can move in the metal cavity (4), a certain amount of space is left between the edge and the metal cavity (4).

5. The mechanically-driven, smart electromagnetic metasurface of claim 1, wherein, The three screw rods (5) are distributed in a regular triangle shape at the three fixed positions of the adjustable reflecting plate, ensuring that the adjustable reflecting plate always remains in the xy plane during movement along the Z-axis.

6. The mechanically-driven, smart electromagnetic metasurface of claim 1, wherein, The stepping motor (7) is connected with the non-coaxial screw rod through a gear structure.

7. The mechanically-driven, smart electromagnetic metasurface of claim 1, wherein, Each intelligent surface unit is connected to the computer through a separate lead from the control board, so that the phase distribution of the entire intelligent surface array can be quickly and dynamically switched in real time.

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