Mechanical adjustable wide angle gradient metasurface integrated device and design method

Abstract

The invention discloses a mechanically adjustable wide-angle gradient metasurface integrated device and a design method thereof. The mechanical adjustable metasurface device is formed by periodically extending M * M metasurface units; the metasurface unit is formed by stacking a metal structure, a dielectric plate, a resin plate, a dielectric plate and a metal floor from top to bottom, the first layer of structure is a cross-shaped metal patch, and the first layer of metal and the fifth layer of metal are both etched on the F4B dielectric plate; the third layer of resin plate is a mechanical adjustable device and is used for mechanically overturning the unit to form phase and amplitude regulation and control; a turnover supporting frame is designed through a 3D printing technology, then M dielectric plates with etched metal structures are bonded with a resin plate to form turnover strips, and finally M turnover strips are assembled side by side in the x direction to form the mechanical adjustable metasurface device. The invention provides a wide-angle gradient metasurface with an overturning internal structure, realizes linear polarization electromagnetic wave regulation and control and a dynamic electromagnetic reflection-backtracking-stealth integrated device, and has the advantages of reconfigurability, assemblability, high integration level and the like.

Description

Technical Field

[0001] The present invention belongs to the intersecting 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, as an artificial composite two-dimensional material composed of subwavelength units, have unique electromagnetic properties that natural materials do not have. Different amplitude and phase responses can be obtained by designing different structural units. On this basis, adjustable metasurfaces constructed by loading active components or deformation have further expanded the control methods of electromagnetic waves and have attracted widespread attention from researchers. Active metasurfaces are planes composed of subwavelength arrays, which can be reconfigured by active components to design their optical properties (such as amplitude, phase and polarization) for manipulating electromagnetic waves. As a new type of dynamic beamforming device, adjustable metasurfaces can achieve highly flexible real-time control of incident waves by dynamically presetting the phase distribution of the reflection / transmission array, thereby achieving the goal of high-speed scanning and switching of far-field beams. Although the manufacturing cost of adjustable metasurfaces is greatly reduced compared to phased array antennas, since each metasurface unit needs to be equipped with an independent switching diode, the design cost of large array adjustable metasurfaces is high and difficult to use for large-scale commercial deployment. Therefore, the importance of seeking lower-cost adjustable metasurfaces has gradually become prominent. In recent years, with the introduction of folding / paper cutting technology into metasurface structures, the electromagnetic functions have been greatly expanded, and its design theory and methods are in urgent need of exploration and development. Through folding, flipping and shearing and other control methods, metasurfaces have more degrees of freedom and can be combined with some of their own characteristics to design efficient electromagnetic functions, broadening the scope of application and prospects of metasurfaces. However, most mechanically adjustable metasurfaces have a single function and it is difficult to integrate multiple functions. Summary of the invention

[0003] The present invention is based on mechanically regulating electromagnetic waves and combines 3D printing technology to publish a mechanically adjustable wide-angle gradient metasurface integrated device. The published metasurface device constructs 1-bit phase regulation through a flip unit at the frequency point f, so that it forms different phase distributions, thereby realizing dynamic beam deflection; when the metasurface unit is incident at a wide angle, it still maintains 1-bit phase regulation to realize dynamic backtracking array and beam deflection; when the incident wave is parallel to the surface where the flip unit is located, it can achieve stealth under certain circumstances.

[0004] The present invention discloses a mechanically adjustable wide-angle gradient metasurface integrated device, the mechanically adjustable wide-angle gradient metasurface integrated device comprises M*M metasurface units with the same structural parameters and equidistant periodic extension in a plane; the metasurface units sequentially comprise a first metal structure, a second dielectric plate, a third resin plate, a fourth dielectric plate and a fifth metal floor;

[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, and 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 a flipping function; finally, assemble M strip structures side by side along the x direction into a mechanically adjustable metasurface device;

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

[0008] Next, when the transverse electric wave TE and the transverse magnetic wave TM are incident vertically, 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 using 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 incident angle, 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 using the discrete criterion:

[0018]

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

[0020] Next, for the traceback matrix, its characteristics satisfy the reflection direction 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 incident angle, 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 by 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 of the metasurface units 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 first layer of metal structure along the x direction and the width of the vertical bar along the u direction are l1=7.3mm, the width of the horizontal bar of the cross metal patch along the x direction and the length of the vertical bar along 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 along the x direction is p1=9.9mm, the width along 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, designing a reversible metasurface unit and a 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 With the reflection angle θ r Equal, to achieve the 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, a second dielectric plate, a third resin plate, a fourth dielectric plate and a fifth metal floor;

[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, and 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 adjustable metasurface device;

[0041] By flipping the metasurface unit by 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 the transverse electric wave TE and the transverse magnetic wave TM are incident obliquely for:

[0046]

[0047] θ i is the angle of incidence;

[0048] For the traceback array, 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 by 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 adjustable methods with metasurface design to realize a flippable wide-angle gradient metasurface, achieves linear polarization electromagnetic wave control and dynamic electromagnetic reflection-backtracking-stealth integrated devices and their design methods, further expands 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 omits active devices and peripheral circuits, and can efficiently control beams by simply flipping, greatly reducing costs.

[0059] The present invention and active antenna arrays such as programmable metamaterials and massive MIMO antennas using active devices have certain static power consumption because they contain a large number of switching diodes or varactor diodes and peripheral circuits, while the present invention has the unique advantage of zero static power consumption;

[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 a mechanically adjustable wide-angle gradient metasurface;

[0064] Figure 3 Electromagnetic properties of the mechanically tunable wide-angle gradient metasurface unit at normal incidence. (a) Amplitude and phase responses of TE waves and (b) TM waves when the flip angle β is 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°, 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 when the flip angle β is 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 ; Co-polarization (c) transmission amplitude t when TM wave is incident xx and (d) reflection amplitude r xx .

[0068] Figure 7 is the amplitude distribution when the incident beam is parallel to the plane where the all-metal unit is located. (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 diagram of the metasurface unit under the flip angle β=90°. (a) TE wave; (b) TM wave.

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

[0071] Fig.10 Flow chart for sample fabrication of mechanically tunable wide-angle gradient metasurface integrated devices.

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

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

[0074] Fig.13 Simulation 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] Fig.14 Simulation 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] Fig.15 Phase distribution when realizing a retrospective array for a mechanically adjustable wide-angle gradient metasurface integrated device.

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

[0078] Fig.17 Achieving high transmission function for mechanically adjustable wide-angle gradient metasurface. (a) At a frequency of 11.3 GHz, the incident angle θ i = 0° TE wave. At the 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 in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, these embodiments are exemplary only 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 solution of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the scope of protection of the present invention.

[0080] Embodiment 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 flippable 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 in the figure, the metasurface unit is composed of a five-layer structure stack of "metal structure-dielectric plate-3D printed resin plate-dielectric plate-metal floor". Among them, the first metal structure is a cross metal patch; the first metal structure is etched above the second dielectric plate, and the fifth metal floor is etched below the fourth dielectric plate. The second and fourth dielectric plates are both F4B dielectric plates (dielectric constant is 2.65, tangent loss is 0.001); the third resin plate uses a 3D printed resin plate (ABS-M30 material, dielectric constant is 2.7, tangent loss is 0.005) and is mainly a mechanically adjustable device, which is used to mechanically flip the unit to form amplitude and phase control. The unit period is p, 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, both are l1, 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, both are l2, the thickness of the second and fourth dielectric plates is t1, the length of the third layer of the 3D printed resin plate along the x direction is p1, the width along the y direction is p2, the thickness is t2, and the flip angle of the unit center along the y direction is β. The geometric dimensions are optimized as follows: p = 10mm, l1 = 7.3mm, l2 = 4.8mm, t1 = 0.1mm, t2 = 1mm, p1 = 9.9mm, p2 = 10mm, and the thickness of the metal copper is 0.018mm.

[0084] Then, the CST electromagnetic simulation software was used to simulate the metasurface unit. When calculating the reflection / transmission phase and amplitude in the frequency domain, the boundary conditions in the x and y directions were set to unit cell. The spatial height of the designed metasurface unit changes with the change of the 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 waves TE and transverse magnetic waves 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 is 180° different from that of β = 0° (no flip), 1-bit phase modulation can be achieved, and the reflection amplitude is also close to 1. Therefore, under the excitation of TE waves and TM waves, the phase is changed 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°. Figure 5 Therefore, at wide angles of incidence (θ i When the phase angle is 0°~45°), 1-bit phase control can also be achieved.

[0086] In addition, when β≠0°, the reflection and transmission amplitudes of the unit under TE 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 where the flip unit is located, while the magnetic field is perpendicular to the surface where the unit is located. 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° to 40°, the co-polarized reflection amplitude at the resonant frequency of 11.6 GHz 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 11.3 GHz and 11.6 GHz under vertical incidence of TE wave and TM wave is given. Figure 8 (a) shows that when the TE wave is incident, its current is mainly concentrated on the metal patch along the y direction, indicating that the introduction of the metal cross patch unit generates electrical resonance at 11.3GHz, breaking the total reflection state formed by the equal-sized metal plates, thereby achieving transmission. Similarly, when the TM wave is incident, the current in the z direction generates electrical resonance, thus breaking the total transmission state of the metal plate and forming a reflection at the resonance point of 11.6GHz.

[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. Fig. 9 A flip frame designed for modeling in the full-wave simulation software CST. Fig.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 PCB processing technology is cut into strips. Next, the strip dielectric plate is pasted to 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] Fig.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 Fig.12(b) The measurement method is that 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 similar to 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 according to 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 traceback array functions of the mechanically adjustable metasurface of the present invention need to design 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 With 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] According to the above calculation, the phase distribution of different situations is obtained, 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 unit flip angles β of "90°" and "270°" correspond to 180° and 0°, respectively. Through the above description, the phase distribution forms a one-to-one correspondence with the internal flip structure of the mechanically adjustable wide-angle gradient metasurface integrated device, which can realize the one-dimensional dynamic beam deflection and traceback array functions. The metasurface unit is flipped and discussed in combination with experiments.

[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 Fig.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 Fig.12 Second row. Then, the far-field scattering results were measured using CST software simulation and the far-field test bench experiment. Fig.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 All of them can appear near the preset angles of 10°, 20°, 30°, 40°, 50° and 60°. The reflection angles of the simulation calculation and the experimental test are basically consistent, with a slight angle deviation of about 2°. The error mainly comes from the misalignment between the flip units during the manufacturing process. In addition, due to the problem of feed source shielding, the θ with large scattering appears. 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 satisfy different one-dimensional unit structure distributions by flipping β in the unit, thereby achieving any preset reflection angle. Therefore, the device can satisfy the dynamic beam deflection range of 0° to 60°. The feasibility of the mechanically adjustable gradient metasurface designed by the present invention is proved.

[0109] Function 2: When TE waves and TM waves are incident at an angle, one-dimensional dynamic beam deflection and tracing 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. Fig.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°. i =30°, the beam is reflected along -58° and 8°, and the reflection angle θ can be calculated. r is -57° and 9°. 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 the surface wave. The above proves that the reflection angles of theoretical calculation, simulation and experimental test are basically consistent, with a slight angle deviation of about 2°. The error mainly comes from the 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 the incident light is incident on the designed metasurface at 0° to 45°, the wide-angle gradient metasurface function can be realized. Combined with different phase distributions, the dynamic wavefront control of the wide-angle gradient metasurface can be realized, thereby realizing one-dimensional dynamic beam deflection at different incident angles.

[0112] Next, we discuss the case 3 of the back-tracking array. The phase is discretized by 1 bit. 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, so two beams will appear. In this case, in addition to realizing the back-tracking 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°. By calculation, we can get Fig.15 Next, the flip structure is designed according to the phase distribution and the device is experimentally tested. Fig.16 The simulation and experimental far-field radiation results of the designed gradient metasurface at a frequency of 11.3 GHz to achieve the traceback array. Fig.16 As shown in (a), at an incident angle θ i In the case of TE waves of 20° and 40°, the angles of the reflected beam are 19° and 42°. However, on the mirror symmetry plane of the reflected beam (angles of -19° and -42°), a mirror sidelobe of about -5dB appears. This phenomenon was 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 satisfy the phase distribution of different incident angles by flipping β in the unit, thereby realizing the tracing array function. Therefore, the device can satisfy 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 greater than the tracing angle. The feasibility of the mechanically adjustable wide-angle gradient metasurface designed in the present invention is proved.

[0113] 4. Based on the high transmittance of the designed metasurface, the stealth function is realized 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. Fig.17 As shown in (a), in the case of TE waves, high transmittance can only be achieved when the incident frequency is vertically incident at the resonant frequency f = 11.3 GHz. In the case of TM waves, except for the resonant frequency f = 11.6 GHz, high transmittance can be achieved in other frequency bands, and when the incident angle θ i When the flip angle β is 0° to 60°, the incident direction is parallel to the surface where the metasurface unit is located (θ i +β=90°), both can satisfy the requirement of device hiding itself. Fig.17As shown in (b)-(e), 10.8 GHz is selected as an example for illustration to verify the high transmittance of the metasurface device, which proves the feasibility and effectiveness of the method of the present invention in realizing mechanically adjustable integrated devices.

[0116] Embodiment 2

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

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

[0119] Inspired by the spatially ordered metasurface, a reversible metasurface unit is designed, which includes a five-layer metal structure, which is composed of "metal structure-dielectric plate-3D printed resin plate-dielectric plate-metal backplane" from top to bottom. The present invention constructs a unit containing resin (ABS-M30 material) in the full-wave simulation software CST (2018). The first and fifth layers of the metasurface unit are designed as cross metal patches and metal backplanes. In addition to achieving high reflectivity, the metal backplane also provides 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 with a flip angle of β = 0° (no flip) and β = 180° is 180°, and both amplitudes are close to 1, thus forming a 1-bit phase control, laying the foundation for the realization of the gradient metasurface. i When the angle θ is 0°~45°, it is found that i The reflection phase under the condition of TE wave / TM wave incidence 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 found that the incident direction is parallel to the surface where the flip unit is located, and found that the transmittance of TE waves at the frequency point f = 11.3GHz is high, while the reflectivity of TM waves near the resonance point of 11.6GHz is high, and the transmittance at other frequencies is high. When the transmittance is close to 1, the mechanically adjustable wide-angle gradient metasurface integrated device can be prevented from being detected, achieving stealth.

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

[0125] The third layer of resin plate is integrated into the designed metasurface unit in order to use 3D printing technology to manufacture the third layer of resin plate of the unit 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 the 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 the etched metal is designed into a strip shape. Secondly, the third layer of resin plate and the supporting frame are manufactured with a 3D printer. Next, the strip-shaped dielectric plate is pasted to the resin plate to form a strip structure, and 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 means of mechanical flipping units, and can realize 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 realizing 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 flip 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 flip angle, 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 protection scope of the present invention; any technical solutions formed by equivalent transformation or equivalent replacement shall fall within the protection scope of the present invention; some parts not elaborated in detail in the present invention belong to the known technologies 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 the same structural parameters and equidistantly periodically extended in a plane; the metasurface units sequentially comprise a first metal structure, a second dielectric plate, a third resin plate, a fourth dielectric plate and a fifth metal floor; 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, and 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 a flipping function; finally, assemble M strip structures side by side along the x direction into a mechanically adjustable metasurface device; By flipping the metasurface unit by 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 using 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 the transverse electric wave TE and the transverse magnetic wave TM are incident obliquely for: x is the coordinate position, θ r is the reflection angle, θ i is the incident 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 using 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 traceback array, 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 incident 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 using 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 along the x-direction and the width of the vertical bar along the y-direction of the cross metal patch of the first layer of metal structure is l1=7.3mm, the width of the horizontal bar along the x-direction and the length of the vertical bar along the y-direction of the cross metal patch is 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 along the x-direction is p1=9.9mm, the width along 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, characterized in that: The design method comprises the following steps: Step 1, designing a reversible metasurface unit and a 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 With the reflection angle θ r Equal, to achieve the 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 arbitrarily 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, a second dielectric plate, a third resin plate, a fourth dielectric plate and a fifth metal floor; 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, and 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 adjustable metasurface device; By flipping the metasurface unit by 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, characterized in that: 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 the transverse electric wave TE and the transverse magnetic wave TM are incident obliquely for: θ i is the angle of incidence; For the traceback array, 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 using 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, in the case of TE waves, high transmittance is achieved at the resonance frequency f = 11.3 GHz and in the case of TM waves, except for the resonance frequency f = 11.6 GHz. 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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