Reconfigurable metasurface structure with coplanar design of structure and bias line

Abstract

The invention discloses a reconfigurable metasurface structure with a structure and an offset line in coplanar design, and relates to the technical field of artificial electromagnetic material design. A plurality of metal patches are communicated to form metal structures in irregular shapes, and the two metal structures in irregular shapes are symmetrically arranged on a dielectric substrate layer; the variable capacitance diode is embedded between the two irregular-shaped metal structures, and the irregular-shaped metal structures can be dispersed into bias lines, so that the structures and the bias lines are coplanar; when electromagnetic waves are incident to the metasurface structure, the resonance characteristics of the two irregular-shaped metal structures are changed by changing the capacitance of the variable capacitance diode, and the purpose of dynamically controlling the electromagnetic response of the electromagnetic waves is achieved. According to the invention, the structure and the bias line are integrally designed, and the method has a wide application prospect in the fields of adaptive intelligent sensing and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial electromagnetic material design, and in particular to a reconfigurable super surface structure with coplanar design of structure and bias line. Background Art

[0002] Metasurface is a two-dimensional ultra-thin planar metamaterial composed of many artificial microstructures arranged periodically or non-periodically. It can manipulate electromagnetic waves with a higher degree of freedom to achieve the purpose of miniaturization of microwave or optical devices. Through the careful design of the unit structure, the metasurface can modulate parameters such as amplitude, phase, polarization and propagation mode with sub-wavelength resolution, and complete wavefront shaping within the wavelength range. It can realize absorption, superlens, invisibility and holographic imaging to replace traditional microwave and optical devices. In recent years, some multifunctional metasurfaces have been proposed to meet the requirements of high integration of components in practice and have attracted widespread attention from researchers. The proposal of dynamic metasurfaces further expands functions in the time dimension. At present, some control methods are applied to dynamic metasurfaces, including temperature control, light control, electrical control, etc. Electrical control is the most commonly used method to realize dynamic metasurfaces, which mainly uses voltage bias to quickly and conveniently change the electromagnetic response of metasurface units. PIN diodes or varactors are commonly used electronic components in reconfigurable metasurface design.

[0003] In the specific study, a PIN diode was introduced into the coding metasurface to modulate the RCS of the reflector; the on-off state of the diode corresponds exactly to the 0 and 1 states, which can be used to design a 1-bit coded metasurface; based on 1-bit phase modulation, by constructing different coding sequences, functions such as scattering, holography, and beam deflection can be realized; by further optimizing the number and position of the diodes, more coding modes can be designed, such as 2-bit or even multi-bit coding, thereby realizing richer electromagnetic functions; but the on-off state of the PIN diode lacks continuity, which limits the functional design, so the varactor diode is integrated into the metasurface to expand the electromagnetic function.

[0004] However, as the functions become more and more abundant, the external circuits and components of metasurfaces, such as metallized holes and bias lines, are becoming more and more complex, which greatly hinders the large-scale design of metasurfaces, greatly reduces the control performance of metasurfaces, and makes it difficult to achieve dynamic manipulation of the electromagnetic response of electromagnetic waves. Summary of the invention

[0005] The embodiment of the present invention provides a reconfigurable metasurface structure with a coplanar design of structure and bias lines, which can solve the problem in the prior art that as the functions become more and more abundant, the external circuits and components of the metasurface, such as metallized holes and bias lines, become more and more complex, which greatly hinders the large-scale design of the metasurface and significantly reduces the control performance of the metasurface.

[0006] The embodiment of the present invention provides a reconfigurable metasurface structure with coplanar design of structure and bias line, including a metal patch layer, an active device, a dielectric substrate layer and a reflective backplane layer;

[0007] The metal patch layer includes two symmetrically arranged and irregularly shaped metal structures, and is plated on the top surface of the dielectric substrate layer; an active device is embedded between the two irregularly shaped metal structures, and the active device is a varactor diode; the reflective backplane layer is arranged on the bottom surface of the dielectric substrate layer;

[0008] The irregularly shaped metal structure is composed of a plurality of metal patches connected together, and the metal structure is discretized into bias lines; by changing the bias voltage loaded at both ends of the varactor diode to change the capacitance of the varactor diode, the resonance characteristics of the irregularly shaped metal structure discretized into the bias line are changed.

[0009] Preferably, the irregularly shaped metal structure is a copper structure and is plated on the top surface of the dielectric substrate layer using a printed circuit board.

[0010] Preferably, the active device is a SMV1405-079LF varactor diode;

[0011] The varactor diode and the two irregularly shaped metal structures are equivalent to a series circuit including a resistor, an inductor and a capacitor, wherein the resistor is 0.8Ω and the inductor is 0.7nH;

[0012] When the bias voltage loaded on the varactor changes from 30V to 0V, the capacitance changes from 0.63pF to 2.67pF.

[0013] Preferably, the dielectric substrate layer is made of polytetrafluoroethylene plate F4B, whose dielectric constant is ε r =2.65, and the loss tangent is tanδ=0.001, which is used to adjust the impedance of the metasurface structure and change the amplitude and phase of the incident electromagnetic wave.

[0014] Preferably, the reflective backplane layer is made of a copper plate for reflecting incident electromagnetic waves.

[0015] Preferably, when the frequency of the electromagnetic wave incident on the metasurface is 4.5 GHz, the reflection phase of the metasurface structure achieves a phase difference of 180° and a reflection amplitude difference of 1 dB.

[0016] The embodiment of the present invention provides a reconfigurable metasurface structure with coplanar design of structure and bias line. Compared with the prior art, the beneficial effects thereof are as follows:

[0017] The present invention connects a plurality of metal patches to form an irregularly shaped metal structure, symmetrically arranges two irregularly shaped metal structures on a dielectric substrate layer, and embeds a varactor diode between the two irregularly shaped metal structures, so that the irregularly shaped metal structure can be discretized into a bias line, thereby realizing a coplanar design of the structure and the bias line; the metasurface is simplified, and the control performance is greatly improved; and it has broad application prospects in the fields of adaptive intelligent perception and the like.

[0018] Secondly, when an electromagnetic wave is incident on the metasurface structure, the capacitance of the varactor diode is changed, so that the resonant characteristics of the two irregularly shaped metal structures are changed, thereby achieving the purpose of dynamically manipulating the electromagnetic response of the electromagnetic wave. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the overall structure of a reconfigurable metasurface structure with a coplanar design of a structure and a bias line provided in an embodiment of the present invention;

[0020] Figure 2 A schematic diagram of a flow chart of a matrix generation algorithm for top-down connectivity of a reconfigurable metasurface structure with coplanar design of a structure and bias line provided by an embodiment of the present invention;

[0021] Figure 3 A schematic diagram of the principle of a reconfigurable metasurface structure with a coplanar design of a structure and a bias line provided in an embodiment of the present invention;

[0022] Figure 4 A schematic diagram of a design method for a reconfigurable metasurface structure with coplanar structure and bias line design provided in an embodiment of the present invention; (a) is a schematic diagram of the structure and geometric parameters; (b) is a 1 / 4 unit structure and a corresponding two-dimensional matrix;

[0023] Figure 5 A schematic diagram of electromagnetic response of a metasurface unit of a varactor diode of a reconfigurable metasurface structure with a coplanar design of a structure and bias line provided in an embodiment of the present invention in different states; (a) is a schematic diagram of a simulated reflection phase; (b) is a schematic diagram of a simulated reflection amplitude;

[0024] Figure 6 A schematic diagram of test results of a reconfigurable metasurface structure with a coplanar design of a structure and bias lines provided in an embodiment of the present invention; (a) and (b) thereof are schematic diagrams of coding sequences; (c) and (d) thereof are far-field directional diagrams.

[0025] Among them: 1. Metal patch layer, 2. Active devices, 3. Dielectric substrate layer, 4. Reflective backplane layer. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0027] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0028] 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 "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0029] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0031] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0032] See also Figure 1 An embodiment of the present invention provides a reconfigurable metasurface structure with a coplanar design of structure and bias line, which comprises a metal patch layer 1, an active device 2, a dielectric substrate layer 3 and a reflective backplane layer 4 in sequence.

[0033] The metal patch layer 1 is two symmetrical metal structures discretized into irregular shapes, which can be represented by a 0-1 two-dimensional matrix and plated on the dielectric substrate layer 3 using a printed circuit board process; the metal patch layer 1 integrates the unit structure and the bias line on a plane, and is implemented using metal copper with a thickness of 0.017 mm.

[0034] Active device 2 is a SMV1405-079LF varactor diode; Active device 2 is welded between two irregularly shaped metal patches on metal patch layer 1, and is used to change the resonance characteristics of metal patch layer 1 and manipulate electromagnetic waves; Active device 2 is equivalent to a series circuit of resistance, inductance and capacitance, in which the resistance is 0.8Ω and the inductance is 0.7nH; The capacitance value changes with the change of the loading voltage, and when the bias voltage changes from 30V to 0V, the capacitance can change from 0.63pF to 2.67pF.

[0035] The dielectric substrate layer 3 adopts a dielectric constant ε r =2.65, and polytetrafluoroethylene (F4B) with a loss tangent of tanδ=0.001, which is used to adjust the impedance of the metasurface unit and change parameters such as the amplitude and phase of the electromagnetic wave; one side of the dielectric substrate layer 3 is the metal patch layer 1, and the other side is the reflective backplane layer 4.

[0036] The reflective backplane layer 4 is made of copper and has a thickness of 0.017 mm. It is used to reflect electromagnetic waves and has the same size as the dielectric substrate layer 3 .

[0037] When an electromagnetic wave is incident on the metasurface structure, the capacitance of the varactor is changed by changing the bias voltage loaded across the varactor, causing the resonant characteristics of the two irregularly shaped metal structures to change, thereby achieving dynamic manipulation of the electromagnetic response of the electromagnetic wave.

[0038] like Figure 2As shown in the figure, it is a flowchart of the matrix generation algorithm with top-down connectivity. First, the variables are initialized in the first iteration. The initial point is set to the first point in the upper left corner, and the metal patch is laid, that is, i = 1, P strat =1; the function rand(1,n) represents the random generation of an integer between 1 and n, representing the cutoff point P end Between 1 and n; function Create_patch(i,P strat ,P end ) means that in the i-th row P strat and P end Create a continuous metal patch between the columns; in subsequent iterations, each time a point in the previous column is randomly selected as the middle point P mid , between 1 and the midpoint P mid The initial point P of this column is randomly determined strat , at the middle point P mid The cutoff point P of this column is randomly determined between and n end ; At the initial point P strat With the cut-off point P end A continuous metal patch is created between them; when the m-th row of metal patches is laid out, the iteration ends.

[0039] like Figure 3 As shown in the figure, it is a schematic diagram of the principle of the reconfigurable metasurface structure; using the algorithm Create_patch(i,P strat ,P end ) generates a 1 / 4 metal patch and performs two symmetries to obtain the final metal patch. The metal patch structure is also a bias line, and a varactor is introduced between the two irregular metal patches. The metal patch is connected from top to bottom, which can ensure that an external voltage source is loaded to both ends of the varactor on each unit of the metasurface, control its working state, and generate a phase difference of 180° to achieve 1-bit phase encoding.

[0040] like Figure 4 As shown, (a) and (b) are schematic diagrams of the metasurface unit structure and geometric parameters and the corresponding two-dimensional matrix, respectively; the period of the metasurface unit structure is p = 10 mm; the period of the two-dimensional matrix unit is u = 0.5 mm; the interval between two irregularly shaped metal patches is g = 1 mm; the thickness of the dielectric substrate layer is h = 2 mm; when the two-dimensional matrix unit is encoded as "1", the metal patch is laid, and when the encoding is "0", the metal patch is not laid.

[0041] like Figure 5 As shown in the figure, the simulation results of the electromagnetic response of the reconstructible metasurface unit are shown when the varactor diode is in different working states. It can be seen from the figure that when the frequency is 4.5 GHz, the reflection phase of the metasurface unit achieves a phase difference of about 180°, as shown in Figure 5As shown in (a) in the figure, the reflection amplitude difference is within 1dB, as shown in (b) in Figure (5), which meets the phase modulation condition and can achieve 1-bit phase encoding; the metasurface unit when the varactor diode capacitance C = 1.17pF is encoded as the binary code "0", and the metasurface unit when the varactor diode capacitance C = 2.12pF is encoded as the binary code "1".

[0042] like Figure 6 As shown, different coding sequences of the reconfigurable metasurface and the corresponding far-field radiation patterns of the electromagnetic wave; (a) and (b) are the comparisons of different coding sequences of the metasurface, and (c) and (d) are the far-field radiation patterns of the electromagnetic wave corresponding to the coding sequences of (a) and (b), respectively; by encoding the metasurface according to different coding sequences, the deflection angle of the reflected electromagnetic wave beam can be changed, thereby achieving the purpose of controlling the scattering pattern of the electromagnetic wave, verifying the feasibility and effectiveness of the structure.

[0043] The metal patch in the present invention is both a structure and a bias line. The metal patch is connected from top to bottom, and the working state of the varactor diode on each unit can be controlled by an external voltage source to generate a phase difference of 180° to achieve 1-bit phase encoding, thereby achieving the purpose of dynamically manipulating the electromagnetic response of electromagnetic waves. The bias integrated design has special application effects such as lightning protection and deicing, and has strong applicability in practice. The designed metasurface is further combined with an intelligent control terminal to realize an intelligent metasurface system to adapt to different environments, and has broad application prospects in fields such as adaptive intelligent perception.

[0044] The present invention integrates the structure and bias line design on the same plane. The metal structure, that is, the bias line, can realize large-scale design of the metasurface and improve the control performance of the metasurface. Electrical control is used to change the working state of the varactor diode and dynamically manipulate the electromagnetic response of the electromagnetic wave.

[0045] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A reconfigurable metasurface structure with coplanar design of structure and bias line, characterized in that: include: Metal patch layer (1), active device (2), dielectric substrate layer (3) and reflective backplane layer (4); The metal patch layer (1) comprises two symmetrically arranged and irregularly shaped metal structures, and is plated on the top surface of the dielectric substrate layer (3); an active device (2) is embedded between the two irregularly shaped metal structures, and the active device (2) is a varactor diode; the reflective backplane layer (4) is arranged on the bottom surface of the dielectric substrate layer (3); The irregularly shaped metal structure is composed of a plurality of metal patches connected together, and the metal structure is discretized into bias lines; by changing the bias voltage loaded at both ends of the varactor diode to change the capacitance of the varactor diode, the resonance characteristics of the irregularly shaped metal structure discretized into the bias line are changed.

2. The reconfigurable metasurface structure with coplanar design of structure and bias line according to claim 1, characterized in that: The irregularly shaped metal structure adopts a copper structure and is plated on the top surface of the dielectric substrate layer (3) using a printed circuit board.

3. The reconfigurable metasurface structure with coplanar design of structure and bias line according to claim 1, characterized in that: The active device (2) is a SMV1405-079LF varactor diode; The varactor diode and the two irregularly shaped metal structures are equivalent to a series circuit including a resistor, an inductor and a capacitor, wherein the resistor is 0.8Ω and the inductor is 0.7nH; When the bias voltage loaded on the varactor changes from 30V to 0V, the capacitance changes from 0.63pF to 2.67pF.

4. The reconfigurable metasurface structure with coplanar design of structure and bias line according to claim 1, characterized in that: The dielectric substrate layer (3) is made of polytetrafluoroethylene plate F4B, whose dielectric constant is ε r =2.65, and the loss tangent is tanδ=0.001, which is used to adjust the impedance of the metasurface structure and change the amplitude and phase of the incident electromagnetic wave.

5. The reconfigurable metasurface structure with coplanar design of structure and bias line according to claim 1, characterized in that: The reflective backplane layer (4) is made of a copper plate and is used to reflect incident electromagnetic waves.

6. The reconfigurable metasurface structure with coplanar design of structure and bias line according to claim 1, characterized in that: When the frequency of the electromagnetic wave incident on the metasurface is 4.5 GHz, the reflection phase of the metasurface structure achieves a phase difference of 180° and a reflection amplitude difference of 1 dB.

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