Programmable metasurface unit chip and programmable metasurface

Abstract

The invention discloses a programmable metasurface unit chip and a programmable metasurface, and the unit chip sequentially comprises a first dielectric layer, a first bonding dielectric layer, a controllable metal layer, a second bonding dielectric layer, a third dielectric layer, a third metal layer, a third bonding dielectric layer, a fourth dielectric layer and a fourth metal layer from top to bottom. The controllable metal layer comprises a metal structure and a controllable element and is used for forming two isolation electromagnetic wave regulation and control channels so as to independently control orthogonal polarization electromagnetic waves and provide independent and controllable electromagnetic response for the incident orthogonal polarization electromagnetic waves; the third metal layer is used as a radio frequency ground for improving the electromagnetic wave reflection performance; the fourth metal layer is used for inputting bias voltage; and bias voltage is loaded to the controllable element through the metal holes of each layer. The plurality of unit chips are arranged on the substrate in an array mode to form the metasurface. The unit chip provided by the invention can greatly reduce the design and implementation complexity of the metasurface, reduce the production and maintenance cost, and promote the application of the metasurface in a wireless information system.

Description

Technical Field

[0001] The present invention belongs to the technical field of novel artificial electromagnetic materials, and in particular relates to a programmable metasurface unit chip and a programmable metasurface. Background Art

[0002] Programmable metasurfaces are flat array structures composed of many artificially designed adjustable electromagnetic units. They have powerful capabilities in real-time control of electromagnetic waves and have important application potential in information fields such as wireless communications, radar remote sensing, and intelligent computing. Among them, adjustable electromagnetic units mainly include artificially designed metal structures and controllable elements. By applying control signals to the controllable elements in the electromagnetic units, the response characteristics of the electromagnetic units can be accurately controlled. Therefore, by setting the response state of each electromagnetic unit in the metasurface, a specific electromagnetic response distribution can be achieved on the metasurface, so that the metasurface can realize various important electromagnetic functions, such as beamforming, electromagnetic stealth, waveform generation, etc. With the rapid development of information technology, higher requirements are placed on the functions and performance of programmable metasurfaces, resulting in increasingly complex design and control systems for metasurfaces.

[0003] However, existing programmable metasurfaces often couple all electromagnetic units and control signal transmission structures together, so after processing, the array size and shape are fixed, which cannot meet the actual needs of adjusting the array size and shape, replacing failed units, etc., increasing the generation and maintenance costs of the metasurface. In addition, the current metasurface design cycle is long and the experimental verification is complex, which hinders the rapid development and iteration of complex systems based on metasurfaces, and is not conducive to the further development and engineering application of metasurfaces. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a programmable metasurface unit chip that can achieve independent control of two orthogonally polarized electromagnetic waves.

[0005] Another object of the present invention is to provide a programmable metasurface based on the programmable metasurface unit chip, which helps to realize the rapid design, modification and reuse of information systems based on the programmable metasurface.

[0006] Technical solution: The programmable metasurface unit chip described in the present invention includes at least one electromagnetic unit, and the at least one electromagnetic unit includes at least three metal layers, at least three dielectric layers and at least three bonding dielectric layers, which are, from top to bottom: a first dielectric layer, a first bonding dielectric layer, a controllable metal layer, a second bonding dielectric layer, a third dielectric layer, a third metal layer, a third bonding dielectric layer, a fourth dielectric layer and a fourth metal layer, wherein the controllable metal layer includes a metal structure and a controllable element, which is used to form two isolated electromagnetic wave control channels to independently control orthogonally polarized electromagnetic waves and provide independently controllable electromagnetic responses for incident orthogonally polarized electromagnetic waves; the third metal layer is used as a radio frequency ground to improve the electromagnetic wave reflection performance of the unit chip; the fourth metal layer is used for bias voltage input; the second bonding layer, the third dielectric layer, the third metal layer, the third bonding layer and the fourth dielectric layer are all provided with metal holes, which are used to load the bias voltage input on the fourth metal layer onto the controllable element.

[0007] Optionally, the metal structure of the controllable metal layer includes two orthogonally arranged first metal layers and second metal layers, a second dielectric layer is further arranged between the first metal layer and the second metal layer, the second dielectric layer isolates the first metal layer and the second metal layer on its upper and lower surfaces, and controllable elements are respectively arranged on the first metal layer and the second metal layer, the first metal layer and the controllable elements arranged thereon form a first control channel, the second metal layer and the controllable elements arranged thereon form a second control channel, and the first control channel and the second control channel are isolated from each other.

[0008] Optionally, the first metal layer and the second metal layer are both butterfly-shaped metal patches, and two wings of the butterfly-shaped metal patches are electrically connected through a controllable element.

[0009] Optionally, the unit chip also includes a metal wall structure, wherein the metal wall is arranged on four sides of the at least one electromagnetic unit and is connected to the third metal layer and the fourth metal layer; or is arranged on four sides of the structure between the first dielectric layer and the third dielectric layer and is connected to the third metal layer; the metal wall is a whole metal patch or a structure of metal strips arranged at intervals.

[0010] Optionally, the controllable element is a semiconductor device or a non-semiconductor device.

[0011] Optionally, the shapes of the layers of the at least one electromagnetic unit are the same or different.

[0012] The programmable metasurface based on the unit chip includes a plurality of the programmable metasurface unit chips and a metasurface substrate, wherein the plurality of programmable metasurface unit chips are arrayed on the metasurface substrate.

[0013] Optionally, the metasurface substrate includes a metal structure and a signal transmission structure, and the plurality of programmable metasurface unit chips are detachably mounted on the metal structure. The signal transmission structure is used to provide a control signal for each electromagnetic wave control channel of the plurality of metasurface unit chips, thereby setting their electromagnetic response state.

[0014] Optionally, the metal structure includes a top metal layer, a metal layer II, a metal layer III and a bottom metal layer, and the signal transmission structure includes a DC bias network arranged on the metal layer III and the bottom metal layer, the top metal layer is used to install the several programmable metasurface unit chips and provide a DC control voltage for the controllable elements of the several programmable metasurface unit chips; the metal layer II serves as the ground plane of the DC signal, and the positive electrodes of all controllable elements are connected to the metal layer II; the multi-channel control voltage is transmitted to the negative electrodes of the controllable elements inside the several programmable metasurface unit chips through the DC bias network and the metal holes arranged on each metal layer.

[0015] Optionally, the multi-channel control voltage is generated by a multi-channel programmable driver, which is connected to the metasurface substrate and includes a single-chip microcomputer, an analog multiplexing chip, a bus switching chip and an input / output expansion chip. The single-chip microcomputer is used to receive external control instructions and parse the metasurface reflection phase distribution information therein, thereby converting them into internal instructions to independently drive each electromagnetic wave control channel of each unit chip through the analog multiplexing chip, the bus switching chip and the input / output expansion chip.

[0016] Beneficial effects: Compared with the prior art, the significant technical effects of the present invention are as follows: (1) The controllable elements are buried inside the metasurface unit chip, which realizes the protection of the controllable elements and prevents the influence of adverse environmental factors such as external moisture, dust and static electricity. (2) By embedding the controllable elements into different layers inside the unit chip, two independent electromagnetic wave response channels are realized in the same caliber. Because the response structures of the two electromagnetic wave control channels are designed in different layers and have no physical connection, the control isolation of the two channels is improved, and the independent control of two orthogonal polarized electromagnetic waves can be realized; (3) By setting up a metal wall structure, the angular stability of its electromagnetic response can be effectively enhanced, and at the same time, the mutual interference between the unit chip and its adjacent unit chip after the unit chip forms an array can be effectively suppressed, helping the metasurface to achieve large-angle beam scanning; (4) The programmable metasurface unit chip can be conveniently connected and fixed on the substrate to form a programmable metasurface, realizing the decoupling design of the metasurface and the control system, which can greatly reduce the design complexity and implementation difficulty of the metasurface system, and can reduce the production and Maintenance cost; (5) The use of programmable metasurface unit chips can overcome the problem that the programmable metasurface cannot be expanded after processing. The metasurface unit chips can also be removed from the old substrate and installed on the new substrate to achieve the reuse of the metasurface unit chips; and the failed metasurface unit chips can be quickly repaired by replacing them; (6) Programmable metasurface unit chips with different functions can be integrated on the same substrate to form a programmable metasurface with complex functions, and new functions can also be realized by replacing different metasurface unit chips; (7) The programmable metasurface adopts a modular design, and the metasurface unit chips, metasurface substrates and multi-channel programmable drivers are designed separately and combined into a whole through interfaces, which can improve the scalability and reusability of the metasurface system; and the two channels in all unit chips can be independently controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A three-dimensional schematic diagram of a programmable metasurface unit chip provided according to an embodiment of the present invention;

[0018] Figure 2 A schematic diagram of a stacked structure of a programmable metasurface unit chip provided according to an embodiment of the present invention;

[0019] Figure 3 A schematic diagram of the detailed structure of each layer of a programmable metasurface unit chip provided according to an embodiment of the present invention;

[0020] Figure 4The following is a graph showing the change of reflection response obtained by simulation with frequency under the condition of vertical incidence of electromagnetic waves of the programmable metasurface unit chip provided by an embodiment of the present invention, wherein (a) is the simulation result of the x-polarization reflection amplitude and phase under different equivalent capacitance states of the varactor Dx, and (b) is the simulation result of the y-polarization reflection amplitude and phase under different equivalent capacitance states of the varactor Dy;

[0021] Figure 5 Graphs showing how the reflection response of a programmable metasurface unit chip according to an embodiment of the present invention varies with the incident angle, wherein (a) is a graph showing how the TM polarization reflection phase of four equivalent capacitance states of the varactor Dx varies with the incident angle, (b) is a graph showing how the TM polarization reflection amplitude of four equivalent capacitance states of the varactor Dx varies with the incident angle, (c) is a graph showing how the TE polarization reflection phase of four equivalent capacitance states of the varactor Dy varies with the incident angle, and (d) is a graph showing how the TE polarization reflection amplitude of four equivalent capacitance states of the varactor Dy varies with the incident angle;

[0022] Figure 6 The present invention provides a programmable metasurface unit chip according to an embodiment of the present invention, wherein the reflection response of the programmable metasurface unit chip under 60° incident wave illumination varies with the varactor state in the orthogonal direction, wherein (a) is a graph showing the TM polarization reflection phase of the four equivalent capacitance states of the varactor Dx varies with the equivalent capacitance state of the varactor Dy, (b) is a graph showing the TM polarization reflection amplitude of the four equivalent capacitance states of the varactor Dx varies with the equivalent capacitance state of the varactor Dy, (c) is a graph showing the TE polarization reflection phase of the four equivalent capacitance states of the varactor Dy varies with the equivalent capacitance state of the varactor Dx, and (d) is a graph showing the TE polarization reflection amplitude of the four equivalent capacitance states of the varactor Dy varies with the equivalent capacitance state of the varactor Dx;

[0023] Figure 7 A physical picture of a programmable metasurface unit chip provided according to an embodiment of the present invention;

[0024] Figure 8 A scene diagram of an experimental measurement of the reflection characteristics of a programmable metasurface unit chip provided according to an embodiment of the present invention;

[0025] Fig. 9 The following is a graph showing the reflection response of the programmable metasurface unit chip according to an embodiment of the present invention measured under the condition of vertical incidence of electromagnetic waves of different frequencies and the reverse bias voltage of the varactor, wherein (a) is the measurement result of the x-polarization reflection amplitude and phase of the varactor Dx under different reverse bias voltages, and (b) is the measurement result of the y-polarization reflection amplitude and phase of the varactor Dy under different reverse bias voltages;

[0026] Fig.10The following is a graph showing the change of the reflection phase measured by the programmable metasurface unit chip provided by the embodiment of the present invention with the voltage state of the varactor in the orthogonal direction under the irradiation of the incident wave at 60°, wherein (a) is the measurement result of the change of the TM polarization reflection phase of the four voltage states of the varactor Dx with the voltage state of the varactor Dy, and (b) is the measurement result of the change of the TE polarization reflection phase of the four voltage states of the varactor Dy with the voltage state of the varactor Dx;

[0027] Fig.11 A physical picture of a programmable metasurface based on a metasurface unit chip provided according to an embodiment of the present invention;

[0028] Fig.12 A schematic diagram of a supersurface substrate principle of a programmable supersurface based on a supersurface unit chip provided according to an embodiment of the present invention, wherein (a) is a top metal layer, (b) is a metal layer II, (c) is a metal layer III, and (d) is a bottom metal layer;

[0029] Fig.13 A multi-channel programmable driver for a programmable metasurface based on a metasurface unit chip according to an embodiment of the present invention;

[0030] Fig.14 A far-field pattern test scene diagram of a programmable metasurface based on a metasurface unit chip provided according to an embodiment of the present invention;

[0031] Fig.15 The test results of beam scanning far-field pattern of a programmable metasurface based on a metasurface unit chip provided according to an embodiment of the present invention under normal incident and oblique incident electromagnetic wave irradiation are shown, wherein (a) is the far-field result of TM polarized beam scanning of the metasurface under normal incident wave irradiation, (b) is the far-field result of TE polarized beam scanning of the metasurface under normal incident wave irradiation, (c) is the far-field result of TM polarized beam scanning of the metasurface under 30° incident wave irradiation, (d) is the far-field result of TE polarized beam scanning of the metasurface under 30° incident wave irradiation, (e) is the far-field result of TM polarized beam scanning of the metasurface under 60° incident wave irradiation, and (f) is the far-field result of TE polarized beam scanning of the metasurface under 60° incident wave irradiation;

[0032] In the figure: 1-Detailed diagram of each layer of the programmable metasurface unit chip, 101-first dielectric layer, 102-second dielectric layer, 103-third dielectric layer, 104-fourth dielectric layer, 105-first bonding dielectric layer, 106-second bonding dielectric layer, 107-third bonding dielectric layer, 108-first metal layer, 109-second metal layer, 110-third metal layer, 111-fourth metal layer, 112-metal wall, 113-metal through hole. DETAILED DESCRIPTION

[0033] Some embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0034] There are different design methods for the RF part and the baseband control part in the programmable metasurface. Decoupling the RF part and the baseband control part can effectively reduce the design complexity of the programmable metasurface system. Therefore, a new form of programmable metasurface with stable functions, verified and easy integration can be developed to improve the adaptability of programmable metasurfaces and promote the widespread use of metasurfaces.

[0035] The following describes a programmable metasurface unit chip of an embodiment of the present invention with reference to the accompanying drawings. The present invention provides a programmable metasurface unit chip, each of which includes an electromagnetic unit structure, which has a customizable electromagnetic response and can be combined into a programmable metasurface by arraying on a substrate, providing a stable and independent electromagnetic response for orthogonally polarized incident electromagnetic waves incident within a wide angle range, which helps to realize the rapid design, modification and reuse of programmable metasurface information systems.

[0036] The programmable metasurface unit chip described in the present invention includes at least one electromagnetic unit, and the at least one electromagnetic unit includes at least three metal layers, at least three dielectric layers and at least three bonding dielectric layers, which are, from top to bottom: a first dielectric layer, a first bonding dielectric layer, a controllable metal layer, a second bonding dielectric layer, a third dielectric layer, a third metal layer, a third bonding dielectric layer, a fourth dielectric layer and a fourth metal layer, wherein the controllable metal layer includes a metal structure and a controllable element, which is used to form two isolated electromagnetic wave control channels to independently control orthogonally polarized electromagnetic waves and provide independently controllable electromagnetic responses for incident orthogonally polarized electromagnetic waves; the third metal layer is used as a radio frequency to improve the reflection performance of the metasurface unit chip; the fourth metal layer is used for bias voltage input; the second bonding layer, the third dielectric layer, the third metal layer, the third bonding layer and the fourth dielectric layer are all provided with metal holes, which are used to load the bias voltage input on the fourth metal layer onto the controllable element. The programmable metasurface unit chip has a controllable electromagnetic response and can control electromagnetic wave reflection parameters, transmission parameters, radiation parameters or any combination thereof, where the electromagnetic wave parameters include amplitude, phase, polarization, frequency, etc.

[0037] The unit chip also includes a metal wall structure, which is arranged on the four sides of the at least one electromagnetic unit and connected to the third metal layer and the fourth metal layer; or is arranged on the four sides of the structure between the first dielectric layer and the third dielectric layer and connected to the third metal layer; the metal wall is a whole metal patch or a metal strip structure arranged at intervals.

[0038] The programmable metasurface unit chip is a multi-layer structure based on a printed circuit board process, and can be produced by a printed circuit board process. The outer contour can be any shape, and all dielectric layers, bonding dielectric layers and metal layers can be the same or different geometric shapes, and the geometric shapes can be circular, triangular, rectangular, square, hexagonal and other geometric shapes.

[0039] Materials of all metal layers include tin, copper, silver or gold, and combinations of tin, copper, silver or gold.

[0040] The controllable element may be a semiconductor device such as a diode, a varactor, a triode, an analog switch, a filter, an amplifier, or a non-semiconductor device such as a liquid crystal, graphene, or vanadium dioxide.

[0041] The metal structure of the controllable metal layer includes two orthogonally arranged first metal layers and second metal layers, a second dielectric layer is further arranged between the first metal layer and the second metal layer, the second dielectric layer isolates the first metal layer and the second metal layer on its upper and lower surfaces, and controllable elements are respectively arranged on the first metal layer and the second metal layer, the first metal layer and the controllable elements arranged thereon form a first control channel, the second metal layer and the controllable elements arranged thereon form a second control channel, and the first control channel and the second control channel are isolated from each other. Further preferably, the first metal layer and the second metal layer are both butterfly-shaped metal patches, and the two wings of the butterfly-shaped metal patches are electrically connected through a controllable element. Specifically, as Figure 1-3As shown, the programmable metasurface unit chip is a multi-layer printed circuit board structure, which is composed of a dielectric layer, an adhesive dielectric layer, a metal structure and a controllable element, and includes 4 metal layers, 4 dielectric layers and 3 adhesive dielectric layers, which are respectively a first dielectric layer 101, a second dielectric layer 102, a third dielectric layer 103, a fourth dielectric layer 104, a first adhesive dielectric layer 105, a second adhesive dielectric layer 106, a third adhesive dielectric layer 107, a first metal layer 108, a second metal layer 109, a third metal layer 110 and a fourth metal layer 111; the dielectric layer and the bonding dielectric layer of the programmable metasurface unit chip are square, and the dielectric layer size of the upper part of the unit chip is slightly smaller than that of the lower part, leaving space for physical processing; the first metal layer 108 and the second metal layer 109 are respectively arranged on the upper surface and the lower surface of the second dielectric layer 102. In this embodiment, the first metal layer 108 and the second metal layer 109 are both butterfly-shaped metal patches, and the first metal layer 108 and the second metal layer 109 are orthogonally arranged. A varactor is selected as a controllable element, and two varactor tubes are installed Inside the metasurface unit chip, the varactor Dx is installed at the center of the butterfly-shaped metal patch 109 in the x direction, and the varactor Dy is installed at the center of the butterfly-shaped metal patch 108 in the y direction; the third metal layer 110 is a square metal patch, which is used as a radio frequency ground to improve the electromagnetic wave reflection performance of the metasurface unit chip; the fourth metal layer 111 includes a pad structure, wherein the four pads in the middle are used for DC bias voltage input, and the peripheral pads are used to fix the metasurface unit chip on the substrate; the four sides of all dielectric layers and bonding dielectric layers of the metasurface unit chip are designed with metal wall structures 112, which are connected to the third metal layer to form a reflection cavity, which can effectively enhance the angular stability of its electromagnetic response, and are connected to the peripheral pads in the fourth metal layer 111; four metal holes 113 are set on the second dielectric layer, the second bonding dielectric layer, the third dielectric layer, the third metal layer, the third bonding layer and the fourth dielectric layer, which are used to connect the middle pad of the fourth metal layer 111 and the two butterfly-shaped metal patches in the controllable metal layer, so as to load the input bias voltage onto the varactor.

[0042] In one embodiment of the present invention, the side length of the programmable metasurface unit chip is set to p=15.8 mm, and the side length of its upper part (including the first dielectric layer 101, the first bonding dielectric layer 105, the second dielectric layer 102, the second bonding dielectric layer 106 and the third dielectric layer 103) is designed to be e=15.4 mm; the materials of the first dielectric layer 101, the second dielectric layer 102, the third dielectric layer 103 and the fourth dielectric layer 104 are selected from Rogers 4350 type plates, with thicknesses of 0.1 mm, 0.1 mm, 1.5 mm and 0.5 mm respectively, and the relative dielectric constant is 3.66, and the loss tangent is 0.0037; the first bonding dielectric layer 105, the second bonding dielectric layer 106 and the third bonding dielectric layer 107 use Rogers 4450F type plates, which are used to bond the dielectric layer and the metal layer into a whole, and the dielectric constant is 3.52, and the loss tangent is 0.004; because the varactor MACOM used The thickness of MAVR-000120-14110P is 0.2mm, so the thickness of the selected bonding dielectric layer is 0.3mm, leaving enough thickness space for burying the varactor; in order to obtain similar x and y polarization reflection responses, the butterfly-shaped metal patches 108 and 109 have the same geometric dimensions, and the geometric parameters are b=14mm, c=6.1mm, d=1.3mm, g=2.2mm and w=0.5mm respectively; in addition, all metal structures use copper as the conductive material, and its thickness is 35μm.

[0043] By controlling the voltages at both ends of the varactor Dx and Dy respectively, the capacitance state of the corresponding varactor can be adjusted, thereby regulating the x and y polarization electromagnetic responses of the programmable metasurface unit chip respectively; in the full-wave simulation, the varactor is modeled as a resistor-inductor-capacitor series circuit with adjustable capacitance, where the resistor is set to Rs = 1.1Ω, the inductor is set to Ls = 0.4nH, and the adjustable equivalent capacitance C T The range is 0.15pF to 0.75pF; Figure 4 (a) shows the reflection amplitude and phase simulation results of the metasurface unit chip under the condition of vertical incidence of x-polarized electromagnetic waves, with different equivalent capacitance values ​​of the varactor Dx; Figure 4 (b) shows the reflection amplitude and phase simulation results of the metasurface unit chip under the condition of vertical incidence of y-polarized electromagnetic waves, and the different equivalent capacitance values ​​of the varactor Dy. By comparing the two simulation results, it can be found that the metasurface unit chip has similar reflection responses to orthogonal polarization incident waves. For x-polarization, when the equivalent capacitance value C of the varactor Dx is TxWhen it is reduced to 0.15pF, the amplitude resonance point will move to 5.5GHz, and within the frequency range of 4.5GHz to 5.2GHz, the adjustable reflection phase range exceeds 270°, meeting the minimum phase shift range requirement of 2-bit phase encoding, while the maximum phase shift range is 334°. For y-polarization, the amplitude resonance point of the metasurface unit chip will change with the equivalent capacitance value C of the varactor Dy. Ty It shows similar changes, and its adjustable reflection phase shift range also exceeds 270° in the frequency range of 4.5GHz to 5.2GHz, while the maximum value is 332°; therefore, four reflection phase coding states with an interval of 90° can be determined for the metasurface unit chip to form a 2-bit phase coding, thereby digitally manipulating the x and y polarized electromagnetic waves respectively.

[0044] In the embodiment of the present invention, the metal wall 112 around the programmable metasurface unit chip can effectively suppress the mutual interference between the adjacent electromagnetic units after forming an array, and can form a reflection cavity with the radio frequency in the third metal layer 110 to enhance the angular stability of its electromagnetic response; here, the electromagnetic wave obliquely incident from the xoz plane is selected to evaluate the angular stability of the metasurface unit chip, and the geometric symmetry of the structure ensures that the electromagnetic wave obliquely incident from the yoz plane has similar characteristics; Figure 5 (a) to (d) show the reflection phase and amplitude responses of the four coding states of the metasurface unit chip under TM (x polarization in the xoz plane) and TE (y polarization in the xoz plane) polarization when the electromagnetic wave is incident at different zenith angles θ; Figure 5 From (a) and (c), we can see that for electromagnetic waves incident from the xoz plane at a zenith angle of 0° to 60°, the reflection phase errors of TM and TE polarizations are approximately 20° and 30°, respectively, which are significantly smaller than the 90° phase interval of 2-bit phase encoding, indicating that the reflection phase of the metasurface unit chip can remain stable at different incident angles. Figure 5 From (b) and (d), it can be seen that the reflection amplitude of the metasurface unit chip can remain stable under different incident angles; therefore, the metasurface unit chip can maintain the stability of the preset reflection response, especially under large angle incidence.

[0045] By designing electromagnetic structures that respond to different polarizations in different metal layers, the physical connection between the two electromagnetic structures is avoided, which can effectively improve the control isolation of the programmable metasurface unit chip to orthogonal polarization electromagnetic waves. Figure 6 (a) to (d) show the curves of the reflection amplitude and phase response of the metasurface unit chip changing with the state of the varactor in the orthogonal direction under the irradiation of oblique incident electromagnetic waves; Figure 6From the variation of the TM polarization phase response of the varactor Dx in the four states with the equivalent capacitance value of the varactor Dy in (a), it can be seen that the TM polarization phase response of the metasurface unit chip is mainly controlled by the varactor Dx. Therefore, when the equivalent capacitance value of the varactor Dy changes, its reflection phase remains stable, and the phase change does not exceed 7°. Similarly, from Figure 6 From the results in (c), we can see that the TE polarization reflection phase of the four states of the varactor Dy can remain stable when the equivalent capacitance of the varactor Dx changes, and the phase change is also less than 7°; according to Figure 6 As shown in (b) and (d), the reflection amplitude can also remain stable when changing the state of the orthogonal varactor; as an example, the frequency of the TM and TE polarized oblique incident electromagnetic waves used in the above simulation is 4.9 GHz, and the incident plane is the xoz plane, and the incident zenith angle is θ i =60°; under other frequencies and incident angles, the metasurface unit chip also has similar and almost independent orthogonal polarization control performance.

[0046] In the embodiment of the present invention, the programmable metasurface unit chip can be produced using an advanced printed circuit board process, which includes a process of embedding electronic components into a circuit board. Figure 7 As shown; a direction mark is added to the upper left corner of the surface of the metasurface unit chip to clearly identify the orientation of the metasurface unit chip and facilitate its integration into the substrate; the unit chip contains two varactors, denoted as varactors Dx and Dy, which are welded in the middle of the butterfly-shaped metal patches in the x and y directions respectively; the outlines of the two butterfly-shaped metal patches are also printed on the upper surface of the metasurface unit chip to add more appearance features to it; in addition, the part of the metal through hole located above the butterfly-shaped metal patch may affect the RF performance, so it is removed and the remaining holes are filled with epoxy resin to form four brown dots in the center; pin pads are designed on the bottom surface of the metasurface unit chip, which are divided into a central pad and a peripheral pad, among which the central pad is mainly used to input the control voltage of the two varactors, and the peripheral pad is not only used to fix the unit chip, but also as an RF ground lead-out interface connected to the RF ground structure in the unit chip; in addition to the central pad and the peripheral pad, a layer of green solder resist ink is covered to prevent possible short circuits during welding.

[0047] The electromagnetic response characteristics of the programmable metasurface unit chip were measured experimentally. Figure 8 As shown in Figure 1, after multiple metasurface unit chips are formed into a small array, their reflection response can be measured using the free space method. First, the relationship between the x and y polarization reflection response of the metasurface unit chip and the bias voltage on the varactor Dx and Dy is measured experimentally when the electromagnetic wave is vertically incident. The results are shown in Figure 1. Fig. 9As shown in (a) and (b); according to the measurement results, in the range of 4.7 GHz to 5.0 GHz, the controllable phase shift range of the two polarizations exceeds 270°, among which the maximum values ​​of the x and y polarization phase shift ranges are 330° and 328° respectively at 4.7 GHz, while the results at 5.0 GHz are 297° and 287° respectively; therefore, the phase encoding state of the metasurface unit chip can be determined based on the above measurement results; in addition, the measured reflection amplitude loss is basically less than 5.0 dB, and better reflection amplitude performance can be obtained at higher frequency bands; there is a slight difference between the measured value and the simulated value of the reflection amplitude, and the error is mainly concentrated at the resonant position, because the measurement result at the resonance is easily affected by the non-ideal factors of the metasurface unit chip sample; therefore, the measured reflection coefficient of the metasurface unit chip is basically consistent with the simulation result, which proves its effectiveness in controlling the orthogonal polarization reflection phase.

[0048] In order to verify the performance of the programmable metasurface unit chip in decoupling and regulating orthogonally polarized oblique incident electromagnetic waves, the electromagnetic waves at 4.9 GHz were measured from the xoz plane at a zenith angle θ. i =Reflection phase at 60°incident, the result is as follows Fig.10 As shown in (a) and (b); Fig.10 From (a), we can see that the TM polarization reflection phase of the varactor Dx in the four states can remain stable when the voltage across the varactor Dy is changed; Fig.10 It can also be seen in (b) that the TE polarization reflection phase in the four states of the varactor Dy can also remain stable when the voltage across the varactor Dx is changed; the variation range of the two polarization reflection phase measurement values ​​is less than 8°, which is consistent with the simulation results; moreover, similar results can be obtained at other incident angles; therefore, the metasurface unit chip can approximately independently manipulate orthogonally polarized electromagnetic waves, especially under large-angle incidence conditions.

[0049] According to the programmable metasurface unit chip proposed in an embodiment of the present invention, two high-isolation electromagnetic wave control channels are integrated inside the same electromagnetic unit to control orthogonally polarized electromagnetic waves, and can provide stable and independent electromagnetic responses for orthogonally polarized electromagnetic waves incident within a large angle range; by arranging the metasurface unit chips in an array on a substrate, metasurfaces of different sizes and shapes can be formed, which can be used for large-scale real-time control of electromagnetic waves in space, and will promote the application of metasurface-based information systems in wireless communications, the Internet of Things, and intelligent sensing.

[0050] Based on the programmable metasurface unit chip, the present invention also designs a programmable metasurface, including a plurality of programmable metasurface unit chips and a metasurface substrate, wherein the plurality of programmable metasurface unit chips are arrayed on the metasurface substrate. The metasurface substrate can be of any size and shape.

[0051] The metasurface substrate has a structure for connecting the metasurface unit chip, and the metasurface unit chip can be installed and removed, wherein the connection structure can be a fixing hole, a pad, a buckle, a socket, magnetic attraction, glue bonding, etc.

[0052] In this embodiment, the connection structure between the metasurface unit chip and the metasurface substrate is a pad, and the metasurface unit chip can be welded on the metasurface substrate.

[0053] The metasurface substrate is a multilayer structure based on a printed circuit board process and can be produced by a printed circuit board process. The programmable metasurface can independently provide a control signal for each electromagnetic wave control channel in each metasurface unit chip.

[0054] The metasurface substrate includes a metal structure and a signal transmission structure, the plurality of programmable metasurface unit chips are detachably mounted on the metal structure, and the signal transmission structure is used to provide a control signal for each electromagnetic wave control channel of the plurality of metasurface unit chips, thereby setting their electromagnetic response state. The metal structure includes a top metal layer, a metal layer II, a metal layer III and a bottom metal layer, and the signal transmission structure includes a DC bias network arranged on the metal layer III and the bottom metal layer, the top metal layer is used to install the plurality of programmable metasurface unit chips, and provide a DC control voltage for the controllable elements of the plurality of programmable metasurface unit chips; the metal layer II is used as a ground plane for the DC signal, and the positive electrodes of all the controllable elements are connected to the metal layer II; the multi-channel control voltage is transmitted to the negative electrodes of the controllable elements inside the plurality of programmable metasurface unit chips through the DC bias network and the metal holes arranged on each metal layer.

[0055] The multi-channel control voltage is generated by a multi-channel programmable driver, which is connected to the metasurface substrate through a flexible cable connector, and includes a single-chip microcomputer, an analog multiplexing chip, a bus switching chip, and an input / output expansion chip. The single-chip microcomputer is used to receive external control instructions and parse the metasurface reflection phase distribution information therein, thereby converting them into internal instructions to independently drive each electromagnetic wave control channel of each unit chip through the analog multiplexing chip, the bus switching chip, and the input / output expansion chip.

[0056] The following describes a programmable metasurface based on a metasurface unit chip according to an embodiment of the present invention with reference to the accompanying drawings. The programmable metasurface based on a metasurface unit chip described in the present invention constructs a programmable metasurface by installing the metasurface unit chip on a metasurface substrate, thereby realizing a decoupling design of the radio frequency and baseband parts of the programmable metasurface, reducing the design complexity of the programmable metasurface system, and promoting the widespread use of programmable metasurfaces.

[0057] like Fig.11 As shown in the figure, the programmable metasurface based on metasurface unit chips is composed of 441 metasurface unit chips welded on the metasurface substrate, with an overall size of 366mm×366mm, and space is reserved on the four sides for installing fixed brackets. Among all the installed unit chips, nearly half of the unit chips are used for the first time, while the remaining unit chips are reused, showing the reusable characteristics of the unit chips; it can be observed that the surface color of the reused unit chips is different from that of the first use, which is mainly caused by the high temperature when the unit chips are disassembled. A layer of high temperature resistant material, such as solder resist ink, can be applied on its surface to prevent the change of surface color.

[0058] The unit chip integrates two orthogonally polarized electromagnetic wave control channels in the same aperture plane, and the control interference between the two channels is very small; at the same time, the unit chip has large-angle stability and can provide stable electromagnetic response to electromagnetic waves incident within a large angle range; therefore, by integrating this unit chip, the programmable metasurface has two orthogonally polarized electromagnetic wave control channels, and has large-angle stability and polarization decoupling characteristics.

[0059] In the embodiment of the present invention, the metasurface substrate is mainly used to support the metasurface unit chip and provide control signals for it. As a demonstration, the metasurface substrate designed here can accommodate 21×21 unit chips, such as Fig.12 As shown in (a) to (d); the metasurface substrate includes 4 metal layers; the top metal layer includes a welding interface for installing all unit chips, wherein the pads XP, XN, YP and YN are respectively connected to the positive and negative electrodes of the varactors Dx and Dy, providing a DC control voltage for the two varactors; all the pads on the metasurface substrate for connecting the RF ground of the unit chips are connected together, so that the RF ground inside all installed unit chips can be connected together to form a complete RF ground plane, which can enhance the reflection performance of the metasurface; metal layer II is a complete metal patch, which serves as the ground plane for DC signals, and the positive electrodes of all varactors are connected to this layer; metal layer III and the bottom metal layer include a DC bias network, which transmits the multi-channel control voltage input from the back connector to the negative electrode of the varactors inside all unit chips; the back connector is divided into two groups, which are connected to the voltage output connector of the multi-channel programmable driver through a flexible cable, and receive the control signals of the varactors Dx and Dy respectively; the metasurface substrate can be produced using conventional printed circuit board processes and materials, and has little effect on the electromagnetic properties of the metasurface.

[0060] In order to control the varactor Dx and Dy in each unit chip, a multi-channel programmable driver is designed to provide control voltages for them respectively, such as Fig.13As shown; a single-chip microcomputer is used as the main control module of the driver to receive external control instructions and parse the metasurface reflection phase distribution information therein, thereby generating internal instructions to drive all digital chips; four voltages are used here to set the reflection phase encoding state of the metasurface. In order to simplify the driver design, an analog multiplexing chip is used to output the target voltage; each multiplexing chip can select one of four preset voltages as an output by controlling its logic input pin; in order to independently set the control voltages of the varactor Dx and Dy, the multiplexing chips used are divided into two groups, so that the preset voltages of different groups can be set independently; in order to control all the multiplexing chips, an input / output (I / O) expansion chip and a bus switching chip are used to achieve the desired effect through internal integration (inter-integrated The IC (Inter-Integrated Circuit) bus protocol expands the I / O pins of the microcontroller. In order to match the scalable array size of the metasurface, the driver also uses a modular design, with the bus switching module and I / O expansion module designed on different printed circuit boards. Finally, three high-precision regulated power supplies are used to power all the chips and provide eight control voltages for the varactors Dx and Dy.

[0061] Real-time beam scanning is an important function of programmable metasurfaces. Benefiting from the electromagnetic wave manipulation capability of polarization decoupling and the enhanced angular stability of reflection response, the metasurface can simultaneously and independently realize large-angle beam scanning of orthogonally polarized oblique incident waves; the reflection phase distribution on the programmable metasurface can be calculated by generalized Snell's law, and then the calculated continuous phase result can be quantized to four selected coding states; Fig.14 As shown, the experimental measurement of the far-field radiation pattern of the metasurface is carried out in a microwave darkroom, which can reduce the influence of environmental electromagnetic scattering, and a vector network analyzer is used to measure the reflection coefficient of the metasurface at different zenith angles θ in the xoz plane; the dual-channel programmable metasurface and the transmitting antenna are placed at both ends of the turntable bracket with a spacing of 2m to meet the far-field conditions for plane wave generation, and the receiving antenna is located in the far-field region.

[0062] The far-field pattern test results of the programmable metasurface TM and TE polarization large-angle beam scanning are shown in Fig.15 As shown in (a) to (f), the electromagnetic wave is incident from the xoz plane at different zenith angles, and its operating frequency is 4.9 GHz; Fig.15 (a) and (b) show the incident zenith angle θ i = 0°, where the reflected beam of the programmable metasurface points to ±10°, ±30°, and ±60° respectively; Fig.15 (c) and (d) show the incident zenith angle θ i=30°, where the reflected beam of the programmable metasurface points to 0°, ±20°, and ±60° respectively; Fig.15 (e) and (f) show the incident zenith angle θ i =60°, where the reflected beams point to 0°, ±30°, and ±50°, respectively; overall, all reflection pattern measurement results are consistent with theoretical calculation results, verifying that the metasurface can achieve dual-polarization reflected beam scanning in a large angle range; it can be observed that there is a slight deterioration in the measurement results of the metasurface reflected beam pattern, which is mainly attributed to inevitable non-ideal factors, including quantization errors caused by finite coding states, changes in reflection phase with angle, and limited array size; using optimization algorithms and larger array sizes can help reduce distortion and enhance the performance of the metasurface.

[0063] According to the programmable metasurface based on the metasurface unit chip proposed in the embodiment of the present invention, the rapid construction of the programmable metasurface is realized using the verified programmable metasurface unit chip. The modular design effectively reduces the complexity of the programmable metasurface system design, and can quickly realize programmable metasurfaces of different sizes and shapes, thereby improving the scalability and reusability of the metasurface. Therefore, the programmable metasurface based on the metasurface unit chip can be used for real-time control of large-scale distributed space electromagnetic waves, and has important application prospects in electromagnetic information fields such as wireless communications, the Internet of Things, and intelligent sensing.

[0064] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0065] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "N" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

Claims

1. A programmable metasurface unit chip, characterized in that: The invention comprises at least one electromagnetic unit, wherein the at least one electromagnetic unit comprises at least three metal layers, at least three dielectric layers and at least three bonding dielectric layers, which are, from top to bottom, a first dielectric layer, a first bonding dielectric layer, a controllable metal layer, a second bonding dielectric layer, a third dielectric layer, a third metal layer, a third bonding dielectric layer, a fourth dielectric layer and a fourth metal layer, wherein the controllable metal layer comprises a metal structure and a controllable element, which is used to form two isolated electromagnetic wave control channels to independently control orthogonally polarized electromagnetic waves and provide independently controllable electromagnetic responses for incident orthogonally polarized electromagnetic waves; the third metal layer is used as a radio frequency ground to improve the electromagnetic wave reflection performance of the unit chip; the fourth metal layer is used for bias voltage input; the second bonding layer, the third dielectric layer, the third metal layer, the third bonding layer and the fourth dielectric layer are all provided with metal holes, which are used to load the bias voltage input on the fourth metal layer onto the controllable element.

2. The programmable metasurface unit chip according to claim 1, characterized in that: The metal structure of the controllable metal layer includes two orthogonally arranged first metal layers and second metal layers, a second dielectric layer is further arranged between the first metal layer and the second metal layer, the second dielectric layer isolates the first metal layer and the second metal layer on its upper and lower surfaces, and controllable elements are respectively arranged on the first metal layer and the second metal layer, the first metal layer and the controllable elements arranged thereon form a first control channel, the second metal layer and the controllable elements arranged thereon form a second control channel, and the first control channel and the second control channel are isolated from each other.

3. The programmable metasurface unit chip according to claim 2, characterized in that: The first metal layer and the second metal layer are both butterfly-shaped metal patches, and two wings of the butterfly-shaped metal patches are electrically connected through a controllable element.

4. The programmable metasurface unit chip according to claim 1, characterized in that: The unit chip also includes a metal wall structure, which is arranged on the four sides of the at least one electromagnetic unit and connected to the third metal layer and the fourth metal layer; or is arranged on the four sides of the structure between the first dielectric layer and the third dielectric layer and connected to the third metal layer; the metal wall is a whole metal patch or a metal strip structure arranged at intervals.

5. The programmable metasurface unit chip according to claim 1, characterized in that: The controllable element is a semiconductor device or a non-semiconductor device.

6. The programmable metasurface unit chip according to claim 1, characterized in that: The shapes of the layers of the at least one electromagnetic unit are the same or different.

7. A programmable metasurface, characterized in that: It comprises a plurality of programmable metasurface unit chips and a metasurface substrate as described in any one of claims 1 to 6, wherein the plurality of programmable metasurface unit chips are arrayed on the metasurface substrate.

8. The programmable metasurface according to claim 7, characterized in that: The metasurface substrate includes a metal structure and a signal transmission structure. The plurality of programmable metasurface unit chips are detachably mounted on the metal structure. The signal transmission structure is used to provide a control signal for each electromagnetic wave control channel of the plurality of metasurface unit chips, thereby setting their electromagnetic response state.

9. The programmable metasurface according to claim 8, characterized in that: The metal structure includes a top metal layer, a metal layer II, a metal layer III and a bottom metal layer. The signal transmission structure includes a DC bias network arranged on the metal layer III and the bottom metal layer. The top metal layer is used to install the several programmable metasurface unit chips and provide a DC control voltage for the controllable elements of the several programmable metasurface unit chips; the metal layer II serves as the ground plane of the DC signal, and the positive electrodes of all controllable elements are connected to the metal layer II; the multi-channel control voltage is transmitted to the negative electrodes of the controllable elements inside the several programmable metasurface unit chips through the DC bias network and the metal holes arranged on each metal layer.

10. The programmable metasurface according to claim 9, characterized in that: The multi-channel control voltage is generated by a multi-channel programmable driver, which is connected to the metasurface substrate and includes a single-chip microcomputer, an analog multiplexing chip, a bus switching chip, and an input / output expansion chip. The single-chip microcomputer is used to receive external control instructions and parse the metasurface reflection phase distribution information therein, thereby converting them into internal instructions to independently drive each electromagnetic wave control channel of each unit chip through the analog multiplexing chip, the bus switching chip, and the input / output expansion chip.

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