A microwave and millimeter wave two-dimensional beam dynamic scanning array based on liquid crystal metasurface

Abstract

A microwave millimeter wave two-dimensional beam dynamic scanning array based on a liquid crystal metasurface includes an upper substrate, a lower substrate, a liquid crystal upper surface conductive film, a liquid crystal lower surface conductive film, a liquid crystal layer, and a common ground. The liquid crystal upper surface conductive film forms an upper resonance structure and m upper bias circuit lines on the lower surface of the upper substrate. The liquid crystal lower surface conductive film forms a lower resonance structure and n lower bias circuit lines on the upper surface of the lower substrate. The lower bias circuit lines are perpendicular to the upper bias circuit lines. The upper resonance structure and the lower resonance structure are formed at the intersection of the lower bias circuit lines and the upper bias circuit lines. Each upper resonance structure and the corresponding lower resonance structure and the liquid crystal in the middle form an array unit, forming an m×n array in which each array unit can be independently controlled. While realizing the two-dimensional scanning function of the liquid crystal metasurface reflected beam, the required connections for the liquid crystal voltage bias are greatly reduced, reducing the complexity of the structure.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic wave control technology, and in particular to a microwave millimeter wave two-dimensional beam dynamic scanning array based on liquid crystal metasurface. Background Art

[0002] Metasurface is a two-dimensional periodic structure that overcomes the limitations of traditional metamaterials in three-dimensional space. Compared with traditional three-dimensional forms, it has the advantages of low profile, low loss, and easy integration, which greatly promotes the practical engineering application of metamaterials in the industry.

[0003] Inspired by the two definite states of 'on' and 'off' in digital circuit systems, the research group of Professor Cui Tiejun of Southeast University proposed the concept of a discrete digital representation of electromagnetic metasurfaces. For example, a 1-bit metasurface uses '0' and '1' encoding to represent the reflection or transmission phase 0º and 180º of the electromagnetic metasurface unit. Therefore, different coding combinations can represent different combinations of phase responses of electromagnetic metasurface units, and different functional responses will eventually appear corresponding to different phase responses.

[0004] In order to achieve real-time dynamic control of electromagnetic waves, active devices or new materials can be integrated into the metasurface unit, and the phase and amplitude response of the metasurface can be adjusted by adjusting the state of the active devices or materials through a logic controller (FPGA, etc.) and an external bias signal.

[0005] Liquid crystal is an anisotropic material. Under the action of an external electric field, the molecules of the nematic liquid crystal material will deflect in the direction of the electric field due to polarization, thereby changing the dielectric constant. Compared with other electrically controlled materials, liquid crystal materials have lower dielectric losses from microwaves to optical frequencies, and their unique liquid-like form allows them to be flexibly used in various scenarios.

[0006] The existing technology has the problems of immaturity of dynamic electrically adjustable metasurfaces and complex structure of liquid crystal modulated metasurface devices.

[0007] It should be noted that the information disclosed in the above background technology section is only used for understanding the background of the present application, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the invention

[0008] The main purpose of the present invention is to overcome the defects of the above-mentioned background technology and provide a microwave millimeter wave two-dimensional beam dynamic scanning array based on liquid crystal metasurface.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A microwave millimeter wave two-dimensional beam dynamic scanning array based on a liquid crystal metasurface comprises an upper substrate, a lower substrate, a liquid crystal upper surface conductive film, a liquid crystal lower surface conductive film, a liquid crystal layer and a common ground, wherein the liquid crystal upper surface conductive film forms an upper resonant structure and m upper bias circuit lines on the lower surface of the upper substrate, and the liquid crystal lower surface conductive film forms a lower resonant structure and n lower bias circuit lines on the upper surface of the lower substrate, wherein the lower bias circuit lines are perpendicular to the directions of the upper bias circuit lines, and the upper resonant structure and the lower resonant structure are formed at the intersection of the lower bias circuit lines and the upper bias circuit lines, and each upper resonant structure and the corresponding lower resonant structure and the liquid crystal in between form an array unit, forming an m×n array in which each array unit can be independently controlled, wherein at least one of m and n is not less than 2; and the common ground is a bias circuit grounding terminal.

[0011] Further:

[0012] The conductive film on the upper surface of the liquid crystal and the conductive film on the lower surface of the liquid crystal are etched metal-plated films.

[0013] The upper substrate and the lower substrate are glass substrates.

[0014] The common is formed on the lower surface of the lower substrate.

[0015] The common ground is a metal ground.

[0016] By applying a DC voltage signal or a pulse width modulation signal to the upper bias circuit connection and the lower bias circuit connection, the orientation of the liquid crystal molecules at the corresponding array unit is changed, thereby changing the dielectric constant of the liquid crystal material.

[0017] The bias is applied to the array row by row or column by column by switching the circuit ports connected to the corresponding bias circuit lines to a low level or a high impedance state.

[0018] A plurality of said m×n arrays are included.

[0019] The liquid crystal layer is a liquid crystal material with a phase dielectric constant in the range of 2.5-10.

[0020] The thickness of the liquid crystal layer is 25-100 microns.

[0021] The present invention has the following beneficial effects:

[0022] The present invention provides a microwave millimeter wave two-dimensional beam dynamic scanning array based on a liquid crystal metasurface, which is provided with m upper bias circuit lines and n lower bias circuit lines in a perpendicular direction, and the upper resonant structure and the lower resonant structure are formed at the intersection of the lower bias circuit lines and the upper bias circuit lines, and each upper resonant structure and the corresponding lower resonant structure and the liquid crystal in the middle form an array unit, thereby forming an m×n array in which each array unit can be independently regulated, and using mutually perpendicular m+n bias circuit lines, the independent regulation of m×n metasurface units can be achieved by adding bias row by row or column by column, and finally the two-dimensional beam scanning function is achieved. With this design, the present invention can greatly reduce the required connection lines for liquid crystal voltage bias under the premise of realizing the two-dimensional scanning function of the liquid crystal metasurface reflection beam, thereby significantly reducing the structural complexity and improving the practicality.

[0023] Compared with the conventional technology, the advantages of the embodiments of the present invention are mainly as follows:

[0024] Each array unit has two voltage bias connections in perpendicular directions. By simply switching the circuit port connected to one of the bias circuit connections to a low level or high impedance state, the effect of enabling / disabling can be achieved, thereby realizing the bias application of the array unit row by row / column by column.

[0025] By applying external bias to the array unit row by row / column by column in a short period of time, the same effect as biasing each unit independently can be achieved. Because for a certain unit, under this biasing method, it is only necessary to ensure that the time for scanning each row / column is consistent with the period of pulse width modulation, and the voltage change of the upper and lower metal coatings is the same as the effect of pulse width modulation.

[0026] Since the bias voltage is added in a row-by-row / column-by-column scanning manner, there is no need for each unit to be independently connected to an external bias line. Only m+n control signals are needed to independently control m×n metasurface units to achieve two-dimensional beam dynamic scanning, which can greatly reduce the complexity of system design and processing.

[0027] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of a microwave and millimeter wave two-dimensional beam dynamic scanning array based on a liquid crystal metasurface according to an embodiment of the present invention.

[0029] Figure 2 It is a cross-sectional view of a two-dimensional beam dynamic scanning array according to an embodiment of the present invention.

[0030] Figure 3 The figure is a schematic diagram of the structure of a two-dimensional beam dynamic scanning array composed of four small arrays according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention.

[0032] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, connection can be used for fixing as well as for coupling or communication.

[0033] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of 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 cannot be understood as a limitation on the present invention.

[0034] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0035] See also Figure 1 and Figure 2The embodiment of the present invention provides a microwave millimeter wave two-dimensional beam dynamic scanning array based on a liquid crystal metasurface, comprising an upper substrate (such as an upper glass substrate 201), a lower substrate (such as a lower glass substrate 205), a liquid crystal upper surface conductive film (such as a liquid crystal upper surface metal coating 202), a liquid crystal lower surface conductive film (liquid crystal lower surface metal coating 204), a liquid crystal layer 203 and a common ground (such as a metal ground 206), wherein the liquid crystal upper surface conductive film forms an upper resonant structure 103 and m upper bias circuit connections on the lower surface of the upper substrate, and the liquid crystal lower surface The conductive film forms a lower resonant structure and n lower bias circuit lines on the upper surface of the lower substrate, the lower bias circuit lines are perpendicular to the direction of the upper bias circuit lines, the upper resonant structure and the lower resonant structure are formed at the intersection of the lower bias circuit lines and the upper bias circuit lines, each upper resonant structure and the corresponding lower resonant structure and the liquid crystal in the middle form an array unit, forming an m×n array in which each array unit can be independently controlled, wherein at least one of m and n is not less than 2; the common ground is the bias circuit grounding terminal. The m×n array can be, for example, a 16×16 array or a 32×32 array, etc., and the present invention does not limit the number of array units. In addition, the number of row and column bias circuit lines of the m×n array can be the same or different.

[0036] In the two-dimensional dynamic scanning array of the liquid crystal metasurface of the present invention, m upper bias circuit lines and n lower bias circuit lines are arranged in a perpendicular direction, and the upper resonant structure and the lower resonant structure are formed at the intersection of the lower bias circuit line and the upper bias circuit line, and each upper resonant structure and the corresponding lower resonant structure and the liquid crystal in the middle form an array unit, thereby forming an m×n array in which each array unit can be independently regulated, and using mutually perpendicular m+n bias circuit lines, the independent regulation of m×n metasurface units can be realized by adding bias row by row or column by column, and finally the two-dimensional beam scanning function is realized. With this design, the present invention can greatly reduce the connection required for the liquid crystal voltage bias under the premise of realizing the two-dimensional scanning function of the liquid crystal metasurface reflection beam, thereby significantly reducing the structural complexity and improving the practicality.

[0037] In a preferred embodiment, the conductive film on the upper surface of the liquid crystal and the conductive film on the lower surface of the liquid crystal are etched metal films. In addition to metals, the conductive film can also be made of other conductive materials, such as conductive polymers, transparent conductive oxides, etc.

[0038] In a preferred embodiment, the upper substrate and the lower substrate are glass substrates. In addition to glass materials, other materials suitable for transmitting electromagnetic waves can also be used to make the substrates.

[0039] In a preferred embodiment, the common ground is formed on the lower surface of the lower substrate.

[0040] In a more preferred embodiment, the common ground formed on the lower surface of the lower substrate is a metal ground. As a common ground terminal of the bias circuit, the metal ground formed on the lower surface of the lower substrate can also reduce the leakage of electromagnetic waves and environmental interference, enhance the robustness of the metasurface array, and use the metal ground as a heat dissipation surface.

[0041] In some embodiments, the orientation of liquid crystal molecules at the corresponding array unit may be changed to thereby change the dielectric constant of the liquid crystal material by applying a DC voltage signal or a pulse width modulation signal to the upper bias circuit connection and the lower bias circuit connection.

[0042] In some embodiments, bias can be applied to the array row by row or column by column by switching the circuit ports connected to the corresponding bias circuit wiring to a low level or a high impedance state.

[0043] See also Figure 3 In some embodiments, the microwave millimeter wave two-dimensional beam dynamic scanning array based on liquid crystal metasurface may include a combination of multiple m×n arrays to form a larger array.

[0044] In a preferred embodiment, the liquid crystal layer is a liquid crystal material with a phase dielectric constant in the range of 2.5-10, thereby better forming a microwave and millimeter wave two-dimensional beam dynamic scanning array. More preferably, the thickness of the liquid crystal layer is 25-100 microns.

[0045] The specific embodiments of the present invention are further described below.

[0046] In some embodiments, a reflective metasurface array based on a liquid crystal metasurface for realizing dynamic scanning of microwave and millimeter wave two-dimensional beams includes m×n array units. The reflective metasurface array includes an upper glass substrate, a lower glass substrate, a metal coating on the upper surface of the liquid crystal, a metal coating on the lower surface of the liquid crystal, a liquid crystal layer, and a metal ground. The metal coating on the upper surface of the liquid crystal is etched on the lower surface of the upper glass substrate, including a resonant structure and a bias circuit connection; the metal coating on the lower surface of the liquid crystal is etched on the upper surface of the lower glass substrate, including a resonant structure and a bias circuit connection, and the bias circuit connection is perpendicular to the bias circuit connection direction of the metal coating on the upper surface of the liquid crystal; the metal ground is etched on the lower surface of the lower glass substrate. Each array unit has two mutually perpendicular bias circuit connections. By applying a DC voltage or a pulse width modulation signal to the two bias circuit connections, the orientation of the liquid crystal molecules can be changed, thereby changing the dielectric constant of the liquid crystal material. By simply switching one of the circuit ports connected to the bias circuit to a low level or high impedance state, the effect of enabling / disabling can be achieved, thereby applying bias to the array row by row / column by row. In the above scheme, only m+n control signals are needed to independently control m×n metasurface units to achieve two-dimensional beam dynamic scanning, which can greatly reduce the complexity of system design and processing.

[0047] Figure 1 It is a schematic diagram of a microwave millimeter wave two-dimensional beam dynamic scanning array based on a liquid crystal metasurface of the present invention. 101 represents a DC bias contact connected to the metal coating on the upper surface of the liquid crystal; 102 represents a DC bias contact connected to the metal coating on the lower surface of the liquid crystal; 103 represents a resonant structure of the metal coating on the upper surface of the liquid crystal; 104 represents a DC bias connection part of the metal coating on the upper surface of the liquid crystal; 105 represents a metal coating on the lower surface of the liquid crystal, including a resonant structure and a DC bias connection part, which is perpendicular to the metal coating on the upper surface and is not in the same layer.

[0048] Figure 2 201 represents the upper glass substrate, 202 represents the metal coating on the upper surface of the liquid crystal, 203 represents the liquid crystal layer, 204 represents the metal coating on the lower surface of the liquid crystal, 205 represents the lower glass substrate, and 206 represents the metal ground.

[0049] like Figure 3 As shown, further, the four microwave millimeter wave two-dimensional beam dynamic scanning arrays based on liquid crystal metasurfaces of the embodiment of the present invention can be combined into a large array again, thereby obtaining a greater degree of freedom in beam control without reducing the control performance of the array unit itself.

[0050] In the present invention, the two-dimensional scanning function of the beam of the metasurface array is achieved by independently regulating the reflection phase of each array unit, and the reflection phase regulation of each unit is achieved by changing the dielectric constant of the liquid crystal layer through an external voltage.

[0051] In the present invention, there is no limit to the number of array units. Preferably, it can be 16×16 or 32×32 units. At this time, the voltage bias lines used to change the dielectric constant of the liquid crystal layer are reduced from hundreds of general two-dimensional scanning metasurfaces to dozens, greatly reducing the processing difficulty and cost.

[0052] like Figure 1 As shown, in the present invention, the shape of the metal coating on the upper and lower surfaces of the liquid crystal of the array unit is not limited, but the same layers need to be separated in pairs and different layers need to be perpendicular to each other. Preferably, the metal coating on the lower surface of the liquid crystal can be a metal ground similar to a slit.

[0053] The present invention has no restrictions on the material of the liquid crystal layer and the thickness of the liquid crystal layer. Preferably, a liquid crystal material dedicated to microwave and millimeter waves with a phase dielectric constant in the range of 2.5-10 can be selected. Preferably, the thickness of the liquid crystal layer can be 25-100 microns.

[0054] Compared with the conventional technology, the advantages of the embodiments of the present invention are mainly as follows:

[0055] Each array unit has two voltage bias connections in perpendicular directions. By simply switching the circuit port connected to one of the bias circuit connections to a low level or high impedance state, the effect of enabling / disabling can be achieved, thereby realizing the bias application of the array unit row by row / column by column.

[0056] By applying external bias to the array unit row by row / column by column in a short period of time, the same effect as biasing each unit independently can be achieved. Because for a certain unit, under this biasing method, it is only necessary to ensure that the time for scanning each row / column is consistent with the period of pulse width modulation, and the voltage change of the upper and lower metal coatings is the same as the effect of pulse width modulation.

[0057] Since the bias voltage is added in a row-by-row / column-by-column scanning manner, there is no need for each unit to be independently connected to an external bias line. Only m+n control signals are needed to independently control m×n metasurface units to achieve two-dimensional beam dynamic scanning, which can greatly reduce the complexity of system design and processing.

[0058] The background section of the present invention may contain background information about the problem or environment of the present invention, but does not necessarily describe the prior art. Therefore, the content included in the background section is not an admission by the applicant that the prior art is available.

[0059] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, it can also make several substitutions or modifications to these described embodiments, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In the absence of mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A microwave millimeter wave two-dimensional beam dynamic scanning array based on liquid crystal metasurface, characterized in that: The invention comprises an upper substrate, a lower substrate, a liquid crystal upper surface conductive film, a liquid crystal lower surface conductive film, a liquid crystal layer and a common ground, wherein the liquid crystal upper surface conductive film forms an upper resonant structure and m upper bias circuit lines on the lower surface of the upper substrate, and the liquid crystal lower surface conductive film forms a lower resonant structure and n lower bias circuit lines on the upper surface of the lower substrate, wherein the lower bias circuit lines are perpendicular to the direction of the upper bias circuit lines, and the upper resonant structure and the lower resonant structure are formed at the intersection of the lower bias circuit lines and the upper bias circuit lines, and each upper resonant structure and the corresponding lower resonant structure and the liquid crystal in the middle form an array unit , forming an m×n array in which each array unit can be independently controlled, wherein at least one of m and n is not less than 2; the common ground is the bias circuit grounding terminal, and the common ground is the metal ground formed on the lower surface of the lower substrate; using mutually perpendicular m+n bias circuit lines, the independent control of the m×n metasurface units is achieved by adding bias row by row or column by column, wherein each of the array units has two mutually perpendicular voltage bias lines, and the bias is applied to the array row by row or column by column by switching the circuit port connected to one of the bias circuit lines to a low level or a high impedance state, ensuring that the time for scanning each row / column is consistent with the period of pulse width modulation.

2. The microwave millimeter wave two-dimensional beam dynamic scanning array based on liquid crystal metasurface according to claim 1, characterized in that: The conductive film on the upper surface of the liquid crystal and the conductive film on the lower surface of the liquid crystal are etched metal-plated films.

3. The microwave millimeter wave two-dimensional beam dynamic scanning array based on liquid crystal metasurface according to claim 1, characterized in that: The upper substrate and the lower substrate are glass substrates.

4. The microwave millimeter wave two-dimensional beam dynamic scanning array based on liquid crystal metasurface according to any one of claims 1 to 3, characterized in that: By applying pulse width modulation signals to the upper bias circuit connection and the lower bias circuit connection, the orientation of the liquid crystal molecules at the corresponding array unit is changed, thereby changing the dielectric constant of the liquid crystal material.

5. The microwave millimeter wave two-dimensional beam dynamic scanning array based on liquid crystal metasurface according to any one of claims 1 to 3, characterized in that: A plurality of said m×n arrays are included.

6. The microwave millimeter wave two-dimensional beam dynamic scanning array based on liquid crystal metasurface according to any one of claims 1 to 3, characterized in that: The liquid crystal layer is a liquid crystal material with a phase dielectric constant in the range of 2.5-10.

7. The microwave millimeter wave two-dimensional beam dynamic scanning array based on liquid crystal metasurface according to claim 6, characterized in that: The thickness of the liquid crystal layer is 25-100 microns.

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