Mechanically adjustable wide-angle gradient metasurface integrated device and design method

Abstract

The present invention discloses a mechanically adjustable wide-angle gradient metasurface integrated device and its design method. The mechanically adjustable metasurface device is composed of a periodic extension of M*M metasurface units. The metasurface units are stacked from top to bottom in a five-layer structure: metal structure-dielectric plate-resin plate-dielectric plate-metal floor. The first layer is a cross-shaped metal patch, and the first and fifth layers of metal are etched on the F4B dielectric plate. The third layer of resin plate is a mechanically adjustable device used to mechanically flip the unit to achieve phase and amplitude control. A flip support frame is designed using 3D printing technology, and then M dielectric plates with etched metal structures are bonded to the resin plate to form flip strips. Finally, the M flip strips are assembled side by side along the x-direction to form a mechanically adjustable metasurface device. The present invention provides a wide-angle gradient metasurface with a flipped internal structure, which realizes linearly polarized electromagnetic wave control and dynamic electromagnetic reflection-backtracking-stealth integrated devices, with the advantages of reconfigurability, assemblability, and high integration.

Description

Technical Field

[0001] The present invention belongs to the interdisciplinary field of novel artificial electromagnetic materials and wireless communication technology, and relates to a mechanically adjustable wide-angle gradient metasurface integrated device and a design method. Background Art

[0002] Metasurfaces, artificial composite two-dimensional materials composed of subwavelength units, possess unique electromagnetic properties not found in natural materials. Different amplitude and phase responses can be achieved by designing different structural units. Furthermore, tunable metasurfaces, constructed by loading active components or deforming them, have further expanded the methods for controlling electromagnetic waves and have attracted widespread attention. Active metasurfaces are planes composed of subwavelength arrays that can be reconfigured using active components to manipulate their optical properties (such as amplitude, phase, and polarization) for electromagnetic wave manipulation. As a novel dynamic beamforming device, tunable metasurfaces achieve highly flexible, real-time control of the incident wave by dynamically presetting the phase distribution of the reflection / transmission array, thereby achieving high-speed scanning and switching of far-field beams. Although the manufacturing cost of tunable metasurfaces is significantly lower than that of phased array antennas, the high cost of designing large arrays of tunable metasurfaces, due to the need for independent switching diodes for each metasurface unit, makes them difficult to deploy commercially on a large scale. Therefore, the search for more cost-effective tunable metasurfaces is becoming increasingly important. In recent years, the introduction of folding and kirigami techniques into metasurface structures has significantly expanded electromagnetic functionality, necessitating the exploration and development of design theories and methods. By enabling manipulation through folding, flipping, and shearing, metasurfaces possess more degrees of freedom, allowing them to combine their inherent properties to design efficient electromagnetic functions, broadening their application and prospects. However, most mechanically tunable metasurfaces operate on a single function, making it difficult to integrate multiple functions. Summary of the Invention

[0003] This paper, based on mechanically controlling electromagnetic waves and incorporating 3D printing technology, has published a mechanically adjustable wide-angle gradient metasurface integrated device. The disclosed metasurface device utilizes a flip unit to establish 1-bit phase control at frequency f, creating different phase distributions and thus achieving dynamic beam deflection. When the metasurface unit is incident at wide angles, the 1-bit phase control is maintained, enabling dynamic backscatter and beam deflection. When the incident wave is parallel to the surface of the flip unit, the device can achieve invisibility in certain circumstances.

[0004] The present invention discloses a mechanically adjustable wide-angle gradient metasurface integrated device, comprising M*M metasurface units with identical structural parameters and periodically extended at equal intervals in a plane; the metasurface units sequentially comprise a first metal structure layer, a second dielectric plate layer, a third resin plate layer, a fourth dielectric plate layer, and a fifth metal floor layer;

[0005] The first layer of metal structure is a cross metal patch. The length of the horizontal bar of the cross metal patch along the x direction is the same as the width of the vertical bar along the y direction. The width of the horizontal bar of the cross metal patch along the x direction is the same as the length of the vertical bar along the y direction.

[0006] Connect a row of metasurface units along the y-direction into a strip structure with flipping function; finally, assemble M strip structures side by side along the x-direction to form a mechanically adjustable metasurface device;

[0007] By flipping the metasurface unit 0° and 180° along the y direction, the two states constitute a 180° phase difference, achieving 1-bit phase control.

[0008] Furthermore, when the transverse electric wave TE and the transverse magnetic wave TM are incident perpendicularly, siinθ i =0°, the phase distribution of the metasurface integrated device for:

[0009]

[0010] x is the coordinate position, θ r is the reflection angle, k0 is the wave vector, and k0=2πf0Ic, c is the speed of light, f0 is the operating frequency;

[0011] The phase distribution is discretized into 1-bit by the discrete criterion:

[0012]

[0013] Phase “90°” and “270°” correspond to unit flip angles β of 180° and 0°, respectively.

[0014] Furthermore, when the transverse electric wave TE and the transverse magnetic wave TM are incident obliquely, the phase distribution of the metasurface integrated device is for:

[0015]

[0016] x is the coordinate position, θ r is the reflection angle, θ i is the angle of incidence, k0 is the wave vector, and k0=2πf0Ic, c is the speed of light, f0 is the operating frequency;

[0017] The phase distribution is discretized into 1-bit by the discrete criterion:

[0018]

[0019] Phase “90°” and “270°” correspond to unit flip angles β of 180° and 0°, respectively.

[0020] Taking a step further, for the traceback matrix, its characteristics satisfy that the reflection direction is along the incident direction, sinθ r = -sinθ i , the phase distribution of the metasurface integrated device for:

[0021]

[0022] x is the coordinate position, θ i is the angle of incidence, k0 is the wave vector, and k0=2πf0Ic, c is the speed of light, f0 is the operating frequency;

[0023] The phase distribution is discretized into 1-bit using the discrete criterion:

[0024]

[0025] Phase “90°” and “270°” correspond to unit flip angles β of 180° and 0°, respectively.

[0026] Furthermore, under TE wave excitation, high transmittance can be achieved at the resonant frequency f = 11.3 GHz and under TM wave excitation, except for the resonant frequency f = 11.6 GHz.

[0027] The plane where any metasurface unit is located is parallel to the incident direction to achieve the stealth function:

[0028] θ i +β=90°

[0029] θ i is the incident angle, and β is the unit flip angle.

[0030] Furthermore, the mechanically adjustable wide-angle gradient metasurface integrated device optimizes and determines the final structural parameters of the metasurface unit;

[0031] The number of metasurface units is 27*27; the unit period is p=10mm, the length of the horizontal bar of the cross metal patch in the x-direction and the width of the vertical bar in the u-direction of the first layer of metal structure are l1=7.3mm, the width of the horizontal bar of the cross metal patch in the x-direction and the length of the vertical bar in the y-direction are l2=4.8mm, the thickness of the first layer of metal structure and the fifth layer of metal floor is 0.018mm, the thickness of the second layer of dielectric plate and the fourth layer of dielectric plate are both t1=0.1mm, the length of the third layer of resin plate in the x-direction is p1=9.9mm, the width in the y-direction is p2=10mm, and the thickness is t2=1mm.

[0032] A method for designing a mechanically adjustable wide-angle gradient metasurface integrated device is also provided, the design method comprising the following steps:

[0033] Step 1: Design a reversible metasurface unit and metasurface integrated device;

[0034] Step 2: By studying the vertical and oblique incidence conditions of the metasurface unit, 1-bit phase control is constructed to achieve one-dimensional dynamic beam deflection when the linear polarization wave is incident on the metasurface; further, the incident angle θ is constructed when the electromagnetic wave is incident on the metasurface. i and reflection angle θ r Equal, to achieve backtracking function;

[0035] Step 3: By studying the incident direction parallel to the surface where the flip unit is located, an efficient transmission mode is constructed to achieve the stealth function;

[0036] Step 4: By combining 3D printing technology with printed circuit board technology, an adjustable structure that can be flipped at will is constructed;

[0037] Step 5: Construct a wide-angle gradient metasurface integrated device through a mechanically adjustable method.

[0038] Furthermore, in step 1, the mechanically adjustable wide-angle gradient metasurface integrated device includes M*M metasurface units with the same structural parameters and equidistant periodic extension in a plane; the metasurface units sequentially include a first metal structure layer, a second dielectric plate layer, a third resin plate layer, a fourth dielectric plate layer, and a fifth metal floor layer;

[0039] The first layer of metal structure is a cross metal patch. The length of the horizontal bar of the cross metal patch along the x direction is the same as the width of the vertical bar along the y direction. The width of the horizontal bar of the cross metal patch along the x direction is the same as the length of the vertical bar along the y direction.

[0040] Bonding M dielectric plates with etched metal structures to strip dielectric plates to form rotating strips; finally, assembling the M rotating strips side by side along the x-direction to form a mechanically tunable metasurface device;

[0041] By flipping the metasurface unit 0° and 180° along the y direction, the two states constitute a 180° phase difference, achieving 1-bit phase control.

[0042] Next, in step 2, when the transverse electric wave TE and the transverse magnetic wave TM are incident perpendicularly, sinθ i =0°, the phase distribution of the metasurface integrated device for:

[0043]

[0044] x is the coordinate position, θ r is the reflection angle, k0 is the wave vector, and k0=2πf0 / c, c is the speed of light, f0 is the operating frequency;

[0045] Phase distribution of the metasurface integrated device when transverse electric wave TE and transverse magnetic wave TM are incident obliquely for:

[0046]

[0047] θ i is the angle of incidence;

[0048] For the retrospective matrix, its characteristics satisfy that the reflection direction is along the incident direction, sinθ r = -sinθ i , the phase distribution of the metasurface integrated device for:

[0049]

[0050] The phase distribution is discretized into 1-bit using the discrete criterion:

[0051]

[0052] Phase “90°” and “270°” correspond to unit flip angles β of 180° and 0°, respectively.

[0053] Furthermore, in step 3, in the case of TE waves, high transmittance can be achieved at the resonant frequency f = 11.3 GHz and in the case of TM waves, except for the resonant frequency f = 11.6 GHz, and the surface where the metasurface unit is located is parallel to the incident direction to achieve the stealth function:

[0054] θ i +β=90°

[0055] θ i is the incident angle, and β is the unit flip angle.

[0056] The beneficial effects achieved by the present invention are:

[0057] The present invention innovatively combines mechanical adjustability with metasurface design to realize a flippable wide-angle gradient metasurface, achieving linearly polarized electromagnetic wave control and dynamic electromagnetic reflection-backtracking-stealth integrated devices and their design methods, further expanding the control freedom and electromagnetic space control range, and has important potential applications in the fields of national defense and information communications.

[0058] Compared with active antenna arrays such as programmable metamaterials and massive MIMO antennas that use active devices (such as switching diodes and varactor diodes), the present invention eliminates active devices and peripheral circuits and can efficiently control the beam simply by flipping, greatly reducing costs.

[0059] The present invention has the unique advantage of zero static power consumption compared to active antenna arrays such as programmable metamaterials and massive MIMO antennas that use active devices, which have certain static power consumption due to the inclusion of a large number of switching diodes or varactor diodes and peripheral circuits.

[0060] Since the present invention does not include active devices such as switching diodes or varactor diodes, it can work in high-power microwave scenarios such as radar detection and electronic countermeasures;

[0061] Compared with existing metasurface devices, the present invention is easy to transport due to its detachable device structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 Schematic diagram of a mechanically adjustable wide-angle gradient metasurface integrated device designed based on 3D printing technology;

[0063] Figure 2 This is a diagram of the unit structure of the mechanically adjustable wide-angle gradient metasurface;

[0064] Figure 3 Electromagnetic characteristics of the mechanically tunable wide-angle gradient metasurface unit at normal incidence. (a) Amplitude and phase responses of TE waves and (b) TM waves at flip angles β of 0° and 180°.

[0065] Figure 4 The phase distribution of the metasurface unit under oblique incidence. When the flip angle (a) β = 0° and (b) β = 180°, the different incident angles θ i The phase change below.

[0066] Figure 5 When the incident light is incident on the metasurface unit at 11.3 GHz, the phase difference changes with the incident angle θ under the two states of flip angle β being 0° and 180°. i changes.

[0067] Figure 6 is the amplitude distribution when the incident beam is parallel to the surface where the metasurface unit is located. The co-polarized (a) transmission amplitude t when the TE wave is incident yy and (b) reflection amplitude r yy TM wave incident co-polarization (c) transmission amplitude t xx and (d) reflection amplitude r xx .

[0068] Figure 7 is the amplitude distribution when the incident beam is parallel to the surface of the all-metal unit. (a) The co-polarized reflection amplitude r when the TE wave is incident yy (b) Co-polarized transmission amplitude t when TM wave is incident xx .

[0069] Figure 8 is the incident angle θ i =0°, surface current distribution of the metasurface unit at a flip angle β = 90°. (a) TE wave; (b) TM wave.

[0070] Figure 9 This is the 3D printed flip bracket model.

[0071] Figure 10 Flowchart for sample fabrication of mechanically tunable wide-angle gradient metasurface integrated devices.

[0072] Figure 11 Schematic diagram of the far-field test platform.

[0073] Figure 12 Phase distribution and metal structure distribution in the sample when the beam is deflected for a mechanically adjustable wide-angle gradient metasurface integrated device. Reflection angle θ r are (a) 10°, (b) 20°, (c) 30°, (d) 40°, (e) 50°, and (f) 60°.

[0074] Figure 13 Simulated and experimental far-field radiation patterns of the mechanically tunable wide-angle gradient metasurface at normal incidence at 11.3 GHz. (a) TE polarization and (b) TM polarization.

[0075] Figure 14 Simulated and experimental far-field radiation patterns of the mechanically tunable wide-angle gradient metasurface at oblique incidence at 11.3 GHz. (a) TE polarization and (b) TM polarization.

[0076] Figure 15 Phase distribution when realizing a retrospective array for mechanically adjustable wide-angle gradient metasurface integrated devices.

[0077] Figure 16 Simulated and experimental far-field radiation patterns of a mechanically tunable wide-angle gradient metasurface for a traceback array at 11.3 GHz. (a) TE polarization and (b) TM polarization.

[0078] Figure 17 Achieving high transmission function for the mechanically adjustable wide-angle gradient metasurface. (a) At a frequency of 11.3 GHz, the incident angle θ i = 0° TE wave. At a frequency of 10.8 GHz, the incident angle (b) θ i =0°, (c)θ i = 20° and (d)θ i TM wave when =40°. DETAILED DESCRIPTION

[0079] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, these embodiments are merely exemplary and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solutions of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, and such modifications and replacements fall within the scope of protection of the present invention.

[0080] Example 1

[0081] As attached Figure 1 As shown, the present invention provides a mechanically adjustable wide-angle gradient metasurface integrated device, which is composed of M*M metasurface unit periodic extensions.

[0082] 1. Introduce a reversible metasurface unit to construct a mechanically adjustable wide-angle gradient metasurface.

[0083] In order to design a mechanically adjustable wide-angle gradient metasurface integrated device, it is first necessary to design a metasurface unit that can be flipped. Figure 2 As shown, the metasurface unit consists of a five-layer stacked structure: metal structure - dielectric plate - 3D-printed resin plate - dielectric plate - metal floor. The first metal structure layer is a cross-shaped metal patch; the first metal structure layer is etched above the second dielectric plate, and the fifth metal floor is etched below the fourth dielectric plate. Both the second and fourth dielectric plates are F4B dielectric plates (dielectric constant 2.65, tangent loss 0.001). The third resin plate is a 3D-printed resin plate (ABS-M30 material, dielectric constant 2.7, tangent loss 0.005) and is primarily a mechanically adjustable device used to mechanically flip the unit to achieve amplitude and phase control. The unit period is p. The length of the cross metal patch's horizontal bar in the x-direction is the same as its width in the y-direction, both l1. The width of the cross metal patch's horizontal bar in the x-direction is the same as its width in the y-direction, both l2. The thickness of the second and fourth dielectric plates is t1. The 3D-printed third resin plate has a length in the x-direction of p1, a width in the y-direction of p2, and a thickness of t2. The flip angle of the unit center in the y-direction is β. The geometric dimensions are optimized to: p = 10 mm, l1 = 7.3 mm, l2 = 4.8 mm, t1 = 0.1 mm, t2 = 1 mm, p1 = 9.9 mm, p2 = 10 mm. The copper thickness is 0.018 mm.

[0084] Then, the CST electromagnetic simulation software was used to simulate the metasurface unit. When calculating the reflection / transmission phase and amplitude under frequency domain conditions, the boundary conditions in the x and y directions were set to unit cell. The designed metasurface unit changes in spatial height with the change of flip angle in the whole space. In order to ensure that the electric field detection reference surface remains at the same height, an air surface is set at ±10mm respectively. Then, the boundary conditions in the Zmax and Zmin directions are set to open. Finally, all simulations are excited by linearly polarized plane waves. Under the excitation of transverse electric wave TE and transverse magnetic wave TM at a frequency of 11.3GHz, Figure 3 (a) and (b) show that when the unit is flipped along the y-direction by β = 180°, the phase response differs by 180° from that at β = 0° (no flip), achieving 1-bit phase modulation and a reflection amplitude close to 1. Therefore, under TE and TM wave excitation, the phase is altered by changing the flip angle β.

[0085] Furthermore, the oblique incidence of TE and TM waves is discussed. Figure 4 As shown in the figure, when the unit flip angle β = 0° and β = 180°, it can be seen that as the incident angle θ of the TE wave i Increase, phase The TM wave also has the same physical characteristics. However, at 11.3 GHz, the phase difference between the flip angles β = 0° and β = 180° is about 180°, as shown in Figure 5 Therefore, at wide angles of incidence (θ i When the phase angle is 0° to 45°, 1-bit phase control can also be achieved.

[0086] In addition, when β≠0°, the reflection and transmission amplitudes of the unit cell under TE wave and TM wave incidence change as follows: Figure 6 As shown, here we only consider the case where the incident beam is parallel to the surface where the flip unit is located (θ i +β=90°). Figure 6 As shown in (a) and (b), when the TE wave is incident vertically, the incident electric field is parallel to the surface of the flip unit, while the magnetic field is perpendicular to the surface of the unit. At this time, the transmission amplitude of the unit at the resonant frequency of 11.3 GHz increases with the increase of β. When the incident angle θ i = 0° and β = 90°, the co-polarization transmission amplitude is close to 1. When TM wave is incident, θ i In the case of 0°~40°, the co-polarization reflection amplitude at the resonant frequency of 11.6GHz is close to 0.85, while the transmittance near the non-resonant point is extremely high, such as Figure 6 (c) and (d). To further explain this phenomenon, Figure 7(a) and (b) respectively show the total reflection and total transmission of equal-sized metal plates (both dielectric plates and 3D-printed resin plates are replaced with metal) under full-band TE and TM wave excitation. Figure 8 The current distribution diagram of the flip unit at the resonant frequency of 11.3GHz and 11.6GHz under vertical incidence of TE wave and TM wave is given. Figure 8 As shown in Figure (a), when a TE wave is incident, the current is primarily concentrated in the metal patch along the y-direction. This indicates that the introduction of the metal cross-patch unit generates electrical resonance at 11.3 GHz, disrupting the total reflection state created by the equal-sized metal plates, thereby achieving transmission. Similarly, when a TM wave is incident, the current in the z-direction generates electrical resonance, disrupting the total transmission state of the metal plates and causing reflection at the resonance point of 11.6 GHz.

[0087] 2. Combine 3D printing technology to build mechanically adjustable metasurface integrated devices and testing platforms.

[0088] Based on the above-designed flip unit, the present invention designs a mechanically adjustable wide-angle gradient metasurface integrated device based on 3D printing. Figure 9 The flip frame designed for modeling in the full-wave simulation software CST. Figure 10 The sample processing flow chart of the mechanically adjustable wide-angle gradient metasurface integrated device is given. First, ABS-M30 material is added to the 3D printer to manufacture the corresponding components, which include a resin plate, a flip support frame and a fixed flip head. Then, the 0.1mm thick dielectric plate containing a metal structure printed by the PCB processing technology is cut into strips. Next, the strip dielectric plate is pasted onto the resin plate to form a rotating flip strip, and finally assembled into a mechanically adjustable device. Each column of units in the flippable metasurface can only be flipped along the y direction, and the phase distribution in each column of units is The same. Therefore, a one-dimensional dynamically adjustable gradient metasurface is formed. The number of units of the mechanically adjustable wide-angle gradient metasurface set here is 27*27, and the size is 270*270mm. 2 .

[0089] Figure 11 (a) is a schematic diagram of the remote test environment. The metasurface sample is placed on the booth on the left. Two linearly polarized horn antennas with frequencies of 2 to 18 GHz are used to receive and transmit electromagnetic waves, respectively. They are placed on a two-dimensional rotating platform bracket at the same level as the sample. In order to make the electromagnetic waves emitted by the horn close to plane waves, it is placed on a bracket about two meters away from the sample. The two horn antennas are connected to the AV3672B vector network analyzer via cables to receive and transmit electromagnetic wave signals. During the test, the two-dimensional rotating platform collects spatial electromagnetic signals at intervals of 1°. Due to the problem of feed source shielding, the Figure 12(b) Measurement method, that is, the transmitting horn is slightly lower than the center of the metasurface, while the receiving horn is slightly higher than the center of the metasurface to ensure that the reflection angle of the retrospective array can be measured. However, since the transmitting horn is close to the sample, the spherical wave it radiates is approximately a plane wave.

[0090] 3. Combined with the generalized Snell's law, design the one-dimensional dynamic beam deflection and retracement array functions of mechanically adjustable metasurface integrated devices.

[0091] A one-dimensional phase gradient metasurface is constructed based on the phase distribution of different predetermined reflection angles to achieve dynamically adjustable wavefront control. When a plane electromagnetic wave is incident obliquely, based on the anomalous reflection of the generalized Snell's law, the reflection angle satisfies the following formula:

[0092]

[0093] Where, wave vector k0 = 2πf0 / c, c is the speed of light. r is the reflection angle, is the phase gradient along the x direction.

[0094] The dynamic beam deflection and retracement array functions of the mechanically tunable metasurface of the present invention require designing the unit reflection angle β to be 0° or 180° according to different phase distributions. Therefore, integrating formula (1), the phase distribution can be written as:

[0095]

[0096] The following three situations are analyzed:

[0097] Case 1: For normal incidence (sinθ i =0°), according to formula (2), the reflection angle θ r and phase distribution Satisfy the following formula:

[0098]

[0099] Case 2: For oblique incidence, the incident angle θ i , reflection angle θ r and phase The relationship between the designed metasurface phase distribution and the incident angle θ is shown in formula (2). i , reflection angle θ r The relationship between the reflection angle and the incident angle is discussed by taking a certain phase distribution as an example.

[0100] Assume that the phase distribution has been determined as (Compared to the reflection angle θ under vertical incidence r =20°). Therefore, when the electromagnetic wave is incident on the device obliquely, the reflection angle satisfies

[0101] sinθ r = sinθ i ±sin20° (4)

[0102] Case 3: In addition, for the traceback matrix, its characteristics satisfy the reflection direction along the incident direction, that is, sinθ r = -sinθ i Therefore, the phase satisfies the following equation

[0103]

[0104] The phase distribution of different situations is calculated based on the above, and then 1-bit discretization is performed using the following discretization criterion:

[0105]

[0106] By comparing with the simulation results of the unit, the phase The phase distribution of "90°" and "270°" corresponds to a unit flip angle β of 180° and 0°, respectively. The above description establishes a one-to-one correspondence between the phase distribution and the internal flipping structure of the mechanically adjustable wide-angle gradient metasurface integrated device, enabling the realization of one-dimensional dynamic beam deflection and backtracking array functions. The following section discusses the flipping of the metasurface unit and experimentally demonstrates this.

[0107] Function 1: When TE waves and TM waves are incident vertically, one-dimensional dynamic beam deflection is achieved.

[0108] First, based on the theoretical analysis of Case 1, a metasurface device is designed to achieve one-dimensional dynamic beam deflection under vertical incidence. The reflection angle θ is given by the above formula (3): r For phase distributions of 10°, 20°, 30°, 40°, 50° and 60°, see Figure 12 First row. Combining the one-to-one correspondence between the wide-angle gradient metasurface structure and the phase, the metal structure distribution map in the sample is flipped out, see Figure 12 Second row. Then, the far-field scattering results were measured using CST software simulation and a far-field test bench experiment. Figure 13 (a) and (b) show the reflection angle θ of the simulation and test results when the 11.3 GHz TE wave and TM wave are incident vertically. r The reflection angles can appear at preset angles of 10°, 20°, 30°, 40°, 50°, and 60°. The simulation results are basically consistent with the experimental results, with a slight deviation of about 2°. The error mainly comes from the misalignment between the flip units during the manufacturing process. In addition, due to the obstruction of the feed source, the θ r=10°, and the intermediate angle data is not accurate enough. The above description shows that the designed mechanically adjustable wide-angle gradient metasurface can meet different one-dimensional unit structure distributions by flipping the β in the unit, thereby achieving any preset reflection angle. Therefore, the device can meet the dynamic beam deflection range of 0° to 60°. This proves the feasibility of the mechanically adjustable gradient metasurface designed by the present invention.

[0109] Function 2: When TE waves and TM waves are incident at an angle, one-dimensional dynamic beam deflection and retracement array are realized.

[0110] According to Case 2, taking the metasurface device with known phase distribution as an example, the incident angle θ is discussed. i and the reflection angle θ r to verify the function of the wide-angle gradient metasurface. Figure 14 The simulation and experimental measurement of far-field scattering results for oblique incident TE and TM waves at 11.3 GHz. i =15°, the beam is reflected along -38° and 6°. The reflection angle θ can be calculated by the above formula (4): r is -37° and 5°. When the incident angle θ i =30°, the beam is reflected along -58° and 8°, and the reflection angle θ can be calculated. r is -57° and 9°. When the incident angle θ i = 45°, the simulation and test results show that there is only one beam, which is reflected along -20°. The calculation shows that the reflection angle is -21°. The other part of the electromagnetic wave energy is due to sinθ r ≥1, so the space wave is completely converted into a surface wave. This demonstrates that the reflection angles from theoretical calculations, simulations, and experimental tests are essentially consistent, with a slight deviation of approximately 2°. This error primarily stems from misalignment between the flip units during the manufacturing process.

[0111] Combined with other phase distributions of function 1, when the linearly polarized wave is incident at an angle θ i When incident on the designed metasurface at an angle of 0° to 45°, it can realize the wide-angle gradient metasurface function. Combined with different phase distributions, it can realize dynamic wavefront control of the wide-angle gradient metasurface, thereby achieving one-dimensional dynamic beam deflection at different incident angles.

[0112] Next, we discuss the case 3 of the retrospective array. The phase is discretized into 1 bits. According to the generalized Snell's law, this discretization method will result in energy distribution along the left and right sides of the incident plane, resulting in two beams. In this case, in addition to realizing the retrospective array function, the reflection angle of the other beam satisfies sinθ r =3sinθ iTherefore, only when the space wave is transformed into a surface wave can the condition be met. So, sinθ i ≥1 / 3, the incident angle θ is calculated i ≥19.5°. Through calculation, we can get Figure 15 Then, the flip structure is designed according to the phase distribution and the device is experimentally tested. Figure 16 The simulation and experimental far-field radiation results of the designed gradient metasurface at a frequency of 11.3 GHz are shown. Figure 16 As shown in (a), at the incident angle θ i In the case of TE waves with an angle of 20° and 40°, the angle of the reflected beam is 19° and 42°. However, a mirror sidelobe of about -5dB appears on the mirror symmetry plane of the reflected beam (angles of -19° and -42°). This phenomenon is not observed under TM wave incidence. This phenomenon is mainly caused by the greater scattering of surface waves when TE polarization is incident. In addition, the reflection angles of the simulation calculation and the experimental test are basically consistent, with a slight angle deviation of about 3°. In addition, the above description shows that the designed mechanically adjustable wide-angle gradient metasurface can meet the phase distribution of different incident angles by flipping β in the unit, thereby realizing the tracing array function. Therefore, the device can meet the tracing array function when the incident angle of the linear polarization wave is 20° to 45°. When the incident angle is 10° to 20°, in addition to the tracing function, there is another deflected beam that is larger than the tracing angle. This proves the feasibility of the mechanically adjustable wide-angle gradient metasurface designed by the present invention.

[0113] 4. Based on the high transmittance of the designed metasurface, the stealth function is achieved in TE waves / TM waves.

[0114] Function three: When the incident direction is parallel to the surface where the metasurface unit is located, the function of hiding its own structure is realized.

[0115] Further considering the case of oblique incidence, when the incident direction is parallel to the surface where the metasurface unit is located, there is a high transmittance in some specific cases, achieving the stealth function. According to the change of reflection and transmission amplitude with frequency in the above Figure (6), some simulation results of the metasurface when the strip is flipped at a certain angle are given. Figure 17 As shown in (a), in the case of TE waves, high transmittance can only be achieved when the incident wave is perpendicular to the resonant frequency f = 11.3 GHz. In the case of TM waves, high transmittance can be achieved in all frequency bands except the resonant frequency f = 11.6 GHz, and when the incident angle θ i When the flip angle β is 0° to 60°, the incident direction is parallel to the surface of the metasurface unit (θ i +β=90°), can satisfy the device hiding itself. Figure 17As shown in (b)-(e), 10.8 GHz is selected as an example to verify the high transmittance of the metasurface device, demonstrating the feasibility and effectiveness of the method of the present invention in realizing mechanically tunable integrated devices.

[0116] Example 2

[0117] According to the requirements of the mechanically adjustable wide-angle gradient metasurface integrated device and its design method, the specific steps are as follows:

[0118] Step 1: Design a metasurface unit that can be flipped along the y direction;

[0119] Inspired by spatially ordered metasurfaces, a reversible metasurface unit was designed. This unit comprises a five-layer metal structure, composed from top to bottom of a "metal structure-dielectric plate-3D-printed resin plate-dielectric plate-metal backplane." The unit, made of resin (ABS-M30), was constructed using the full-wave simulation software CST (2018). The first and fifth layers of the metasurface unit were designed as cross-shaped metal patches and a metal backplane. The metal backplane not only achieves high reflectivity but also provides a corresponding phase response when the unit is flipped 180°.

[0120] Step 2, by studying the incident (θ i ≥0°), construct 1-bit phase control;

[0121] First, the geometric structure of the cross metal patch is optimized so that when the TE wave and TM wave with a frequency of 11.3 GHz are incident vertically, the phase difference between the two states of the metasurface unit along the y direction, β = 0° (no flip) and β = 180°, is 180°, and the amplitudes of both states are close to 1, thus forming a 1-bit phase control, laying the foundation for the realization of gradient metasurface. i When the angle θ is 0°~45°) to the metasurface unit, it is found that i The reflection phase under the TE / TM wave incident condition increases Both gradually increase, but the unit phase difference between flip angles β = 0° and β = 180° is about 180°, so wide-angle 1-bit phase control can also be designed.

[0122] Step 3, constructing an efficient transmission mode by studying the incident direction parallel to the surface where the flip unit is located;

[0123] Further research, with the incident direction parallel to the surface where the flip unit resides, revealed that TE waves have high transmittance at a frequency of f = 11.3 GHz, while TM waves have high reflectance near the resonance point of 11.6 GHz. Transmittance is also high at other frequencies. When the transmittance approaches 1, the mechanically adjustable wide-angle gradient metasurface integrated device can be prevented from detection, achieving stealth.

[0124] Step 4: By combining 3D printing technology with metasurfaces, an adjustable structure that can be flipped arbitrarily is constructed;

[0125] The purpose of integrating the third layer of resin plate into the designed metasurface unit is to use 3D printing technology to manufacture the unit's third layer of resin plate and the frame of the mechanically adjustable metasurface, and then assemble them to design a spatial structure that can be flipped along the y-direction. Therefore, each column of structure in the designed mechanically adjustable wide-angle gradient metasurface can be flipped along the y-direction. The design of the mechanically adjustable wide-angle gradient metasurface sample is as follows: First, the dielectric plate of etched metal is designed into a strip shape. Secondly, the third layer of resin plate and the supporting frame are manufactured using a 3D printer. Next, the strip-shaped dielectric plate is pasted to the resin plate to form a strip structure. Finally, the strip structure and the frame are assembled into a mechanically adjustable wide-angle gradient metasurface.

[0126] Step 5: Construct a wide-angle gradient metasurface integrated device through a mechanically adjustable method.

[0127] The present invention forms different phase distributions by mechanically flipping the unit, which can achieve 1-bit phase wavefront control. Its phase control mechanism satisfies the generalized Snell reflection law. When linear polarization is vertically incident, different phase gradients are formed by flipping the unit structure at the frequency point f = 11.3GHz, thereby achieving a dynamic beam deflection range of 0° to 60°; at wide angles (θ i When the linearly polarized wave is incident on the metasurface unit at a parallel angle of 0° to 45°, the inversion unit still maintains 1-bit phase control, which can realize dynamic backtracking array and beam deflection. When the linearly polarized wave is incident on the metasurface unit in a parallel inversion direction, the TE wave at the frequency f = 11.3 GHz and the TM wave near the non-resonant frequency (11.6 GHz) can be efficiently transmitted, realizing the stealth function.

[0128] The above are only specific steps of the present invention and do not constitute any limitation to the scope of protection of the present invention; any technical solutions formed by equivalent transformation or equivalent replacement fall within the scope of protection of the present invention; the parts not elaborated in detail in the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A mechanically adjustable wide-angle gradient metasurface integrated device, characterized in that: The mechanically adjustable wide-angle gradient metasurface integrated device comprises M*M metasurface units with identical structural parameters and periodically extended at equal intervals in a plane; the metasurface units sequentially comprise a first metal structure layer, a second dielectric plate layer, a third resin plate layer, a fourth dielectric plate layer, and a fifth metal floor layer; The first layer of metal structure is a cross metal patch. The length of the horizontal bar of the cross metal patch along the x direction is the same as the width of the vertical bar along the y direction. The width of the horizontal bar of the cross metal patch along the x direction is the same as the length of the vertical bar along the y direction. Connect a row of metasurface units along the y-direction into a strip structure with flipping function; finally, assemble M strip structures side by side along the x-direction to form a mechanically adjustable metasurface device; By flipping the metasurface unit 0° and 180° along the y direction, the two states constitute a 180° phase difference, achieving 1-bit phase control.

2. The mechanically adjustable wide-angle gradient metasurface integrated device according to claim 1, characterized in that: When the transverse electric wave TE and the transverse magnetic wave TM are incident vertically, sinθ i =0°, the phase distribution of the metasurface integrated device for: x is the coordinate position, θ r is the reflection angle, k0 is the wave vector, and k0=2πf0 / c, c is the speed of light, f0 is the operating frequency; The phase distribution is discretized into 1-bit by the discrete criterion: Phase "90°" and "270°" correspond to unit flip angles β of 180° and 0°, respectively.

3. The mechanically adjustable wide-angle gradient metasurface integrated device according to claim 1, characterized in that: Phase distribution of the metasurface integrated device when transverse electric wave TE and transverse magnetic wave TM are incident obliquely for: x is the coordinate position, θ r is the reflection angle, θ i is the angle of incidence, k0 is the wave vector, and k0=2πf0 / c, c is the speed of light, f0 is the operating frequency; The phase distribution is discretized into 1-bit by the discrete criterion: Phase "90°" and "270°" correspond to unit flip angles β of 180° and 0°, respectively.

4. The mechanically adjustable wide-angle gradient metasurface integrated device according to claim 1, characterized in that: For the retrospective matrix, its characteristics satisfy that the reflection direction is along the incident direction, sinθ r = -sinθ i , the phase distribution of the metasurface integrated device for: x is the coordinate position, θ i is the angle of incidence, k0 is the wave vector, and k0=2πf0 / c, c is the speed of light, f0 is the operating frequency; The phase distribution is discretized into 1-bit by the discrete criterion: Phase "90°" and "270°" correspond to unit flip angles β of 180° and 0°, respectively.

5. The mechanically adjustable wide-angle gradient metasurface integrated device according to claim 1, characterized in that: Under TE wave excitation, high transmittance can be achieved at the resonance frequency f = 11.3 GHz and under TM wave excitation, except for the resonance frequency f = 11.6 GHz. The plane where any of the metasurface units is located is parallel to the incident direction to achieve the stealth function: i i +β=90° θ i is the incident angle, and β is the unit flip angle.

6. The mechanically adjustable wide-angle gradient metasurface integrated device according to claim 1, characterized in that: The mechanically adjustable wide-angle gradient metasurface integrated device optimizes and determines the final structural parameters of the metasurface unit; The number of metasurface units is 27*27; the unit period is p=10mm, the length of the horizontal bar of the cross metal patch in the x-direction and the width of the vertical bar in the y-direction of the first layer of metal structure are l1=7.3mm, the width of the horizontal bar of the cross metal patch in the x-direction and the length of the vertical bar in the y-direction are l2=4.8mm, the thickness of the first layer of metal structure and the fifth layer of metal floor is 0.018mm, the thickness of the second layer of dielectric plate and the fourth layer of dielectric plate are both t1=0.1mm, the length of the third layer of resin plate in the x-direction is p1=9.9mm, the width in the y-direction is p2=10mm, and the thickness is t2=1mm.

7. A method for designing a mechanically adjustable wide-angle gradient metasurface integrated device based on the mechanically adjustable wide-angle gradient metasurface integrated device according to claim 1, characterized in that: The design method comprises the following steps: Step 1: Design a reversible metasurface unit and metasurface integrated device; Step 2: By studying the vertical and oblique incidence conditions of the metasurface unit, 1-bit phase control is constructed to achieve one-dimensional dynamic beam deflection when the linear polarization wave is incident on the metasurface; further, the incident angle θ is constructed when the electromagnetic wave is incident on the metasurface. i and reflection angle θ r Equal, to achieve backtracking function; Step 3: By studying the incident direction parallel to the surface where the flip unit is located, an efficient transmission mode is constructed to achieve the stealth function; Step 4: By combining 3D printing technology with printed circuit board technology, an adjustable structure that can be flipped at will is constructed; Step 5: Construct a wide-angle gradient metasurface integrated device through a mechanically adjustable method.

8. The method for designing a mechanically adjustable wide-angle gradient metasurface integrated device according to claim 7, characterized in that: In step 1, the mechanically adjustable wide-angle gradient metasurface integrated device includes M*M metasurface units with the same structural parameters and equidistant periodic extension in a plane; the metasurface units sequentially include a first metal structure layer, a second dielectric plate layer, a third resin plate layer, a fourth dielectric plate layer, and a fifth metal floor layer; The first layer of metal structure is a cross metal patch. The length of the horizontal bar of the cross metal patch along the x direction is the same as the width of the vertical bar along the y direction. The width of the horizontal bar of the cross metal patch along the x direction is the same as the length of the vertical bar along the y direction. Bonding M dielectric plates with etched metal structures to strip dielectric plates to form rotating strips; finally, assembling the M rotating strips side by side along the x-direction to form a mechanically tunable metasurface device; By flipping the metasurface unit 0° and 180° along the y direction, the two states constitute a 180° phase difference, achieving 1-bit phase control.

9. The method for designing a mechanically adjustable wide-angle gradient metasurface integrated device according to claim 7, wherein: In step 2, when the transverse electric wave TE and the transverse magnetic wave TM are incident perpendicularly, sinθ i =0°, the phase distribution of the metasurface integrated device for: x is the coordinate position, θ r is the reflection angle, k0 is the wave vector, and k0=2πf0 / c, c is the speed of light, f0 is the operating frequency; Phase distribution of the metasurface integrated device when transverse electric wave TE and transverse magnetic wave TM are incident obliquely for: θ i is the angle of incidence; For the retrospective matrix, its characteristics satisfy that the reflection direction is along the incident direction, sinθ r = -sinθ i , the phase distribution of the metasurface integrated device for: The phase distribution is discretized into 1-bit by the discrete criterion: Phase "90°" and "270°" correspond to unit flip angles β of 180° and 0°, respectively.

10. The method for designing a mechanically adjustable wide-angle gradient metasurface integrated device according to claim 7, characterized in that: In step 3, high transmittance is achieved at the resonance frequency f = 11.3 GHz in the case of TE waves and at the resonance frequency f = 11.6 GHz in the case of TM waves. The surface where the metasurface unit is located is parallel to the incident direction to achieve the stealth function: i i +β=90° θ i is the incident angle, and β is the unit flip angle.

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