A phase-programmable three-dimensional metamaterial unit

Abstract

The present invention discloses a phase-programmable three-dimensional metamaterial unit, which comprises three layers from top to bottom: a three-dimensional structure layer, a dielectric substrate layer and a metal substrate structure layer. The unit's ability to regulate electromagnetic waves is improved by increasing the spatial degree of freedom of the structure, and the three-dimensional structure enables the phase-programmable three-dimensional metamaterial unit to operate in a frequency band of 5.9 GHz to 9 GHz, covering part of the 6 GHz spectrum (5925-7125 MHz), laying a solid foundation for future 5.5G / 6G communications. The phase-programmable three-dimensional metamaterial unit has a strong practical application background, can perform real-time programming and regulation on the reflection phase of electromagnetic waves, and then accurately control the propagation direction of electromagnetic waves, and realize flexible use under various working conditions, thereby reducing material processing loss and improving processing accuracy, providing a means for large-scale production of phase-programmable three-dimensional metamaterial units to reduce production costs.

Description

Technical Field

[0001] The present invention relates to the field of metamaterial technology, and more particularly to a phase-programmable three-dimensional metamaterial unit. Background Art

[0002] With the rapid development of science and technology, especially in the fields of mobile communications, radar technology and optical applications, the demand for precise control of electromagnetic waves has become increasingly significant. Traditional materials have a series of limitations in this regard, and metamaterials, as a cutting-edge technology, provide a revolutionary solution through their unique structure and properties. The microstructure of metamaterials is much smaller than the wavelength involved, which enables them to control electromagnetic waves, covering multiple aspects such as amplitude, phase, polarization and propagation direction. In addition, metamaterials can be divided into two-dimensional metamaterials and three-dimensional metamaterials from the spatial level, among which two-dimensional metamaterials are also called metasurfaces.

[0003] Programmable three-dimensional metamaterial is a new type of metamaterial. Compared with metasurfaces, it has a more complex topological structure and more electromagnetic wave control methods due to the increase in spatial dimensions. It can achieve more precise control over a wider bandwidth of electromagnetic waves. Since programmable three-dimensional metamaterials are equipped with control devices, control signals can be actively applied to change their electromagnetic properties to electromagnetic waves in different usage scenarios. Unlike the PCB board processing method of metasurfaces, the programmable three-dimensional metamaterial processing method is based on electronic additive manufacturing (AME), which can increase the freedom of metamaterial structure. Compared with traditional processing methods, electronic additive manufacturing technology has higher flexibility and precision, can reduce material waste and processing time, and can also achieve more complex structures and shapes.

[0004] In order to meet the needs of mobile networks for coverage, mobility, bandwidth, latency and other aspects, current mobile networks generally adopt a high-low frequency coordinated network layout. However, with the advancement of mobile communications, communication rates continue to increase, bandwidth continues to expand, and frequency bands are gradually developing towards higher frequencies. This has led to a widening gap between the frequency bands responsible for basic coverage and the frequency bands responsible for rate carrying, which has caused a series of problems, such as the discontinuity and large gap in service rate experience. Therefore, it is urgent to find a frequency band in the medium frequency range that takes into account broadband, coverage and capacity. The maximum frequency range of 6GHz is 5925-7125MHz (1.2GHz). As a medium frequency band spectrum with a continuous large bandwidth of 1.2GHz, it is recognized as the golden spectrum in the post-5G and 6G era. On June 27, 2023, the Ministry of Industry and Information Technology issued a new version of the "Regulations on the Allocation of Radio Frequencies of the People's Republic of China", which allocated all or part of 700MHz, that is, 6425-7125MHz, for IMT (International Mobile Communications, including 5.5G / 6G) applications. However, the newly divided electromagnetic wave frequency band will inevitably bring new demands. The market needs electromagnetic metamaterials with excellent performance and low cost to achieve full communication coverage. Therefore, it is necessary to propose a phase-programmable three-dimensional metamaterial unit to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to solve the problem in the prior art that phase-programmable three-dimensional metamaterial units cannot accurately control electromagnetic waves.

[0006] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0007] A phase programmable three-dimensional metamaterial unit comprises a three-dimensional structure layer, a dielectric substrate layer and a metal substrate structure layer arranged from top to bottom;

[0008] The three-dimensional structural layer includes four stepped metal structures, two metal feed lines, two square metal patches and diodes fixed on the square metal patches. The four stepped metal structures are equidistantly distributed around the center line of the dielectric substrate layer. The two square metal patches are respectively fixed on two adjacent stepped metal structures and another two adjacent stepped metal structures. Each of the stepped metal structures is provided with n layers of steps and the height of the steps increases step by step from the center of the unit to the outside. The two ends of the diode are fixed on the two square metal patches. The two metal feed lines are respectively fixed on the bottom of the two adjacent stepped metal structures and another two adjacent stepped metal structures. The stepped metal structure, the square metal patch, the diode and the metal feed line are all attached to the dielectric substrate layer, and the metal substrate structural layer is attached to the dielectric substrate layer.

[0009] Furthermore, a spatial rectangular coordinate system is established with the center of the upper surface of the phase-programmable three-dimensional metamaterial unit as the coordinate origin, the positive direction of the z-axis is perpendicular to the upper surface of the unit, the positive direction of the y-axis is horizontally to the right, and the positive direction of the x-axis is vertically downward. The four stepped metal structures are mirror-symmetric about the yoz plane, and the angle between the long side and the yoz plane is θ. The stepped metal structure is provided with n layers of steps and gradually increases from the center of the unit to the outside. The height difference of each layer of steps is d, the step length is t, the step width is w1, and the distance from one end of the stepped metal structure close to the center of the unit to the center point of the unit is s.

[0010] Furthermore, the four step metal structures have a height h1, a length l1, and an angle θ, and the height, length, and angle of the step metal structures respectively satisfy h1=n×d, l1=n×t, and 30°≤θ≤60°.

[0011] Furthermore, the four stepped metal structures are made of metal with high conductivity.

[0012] Furthermore, the two metal feed lines are rectangular metal lines that are mirror-symmetric about the yoz plane, the length, width and height of the metal feed lines are p, wb and hs respectively, the distance between the two metal feed lines is ls, and ls satisfies (s+l1)sinθ>ls>s×sinθ.

[0013] Furthermore, the two square metal patches are mirror-symmetrical about the yoz plane, the length, width and height of the two square metal patches are l2, w2 and ht respectively, and the distance between the two square metal patches is st.

[0014] Furthermore, the length, width and height of the dielectric substrate layer are p, p and h2 respectively, and the dielectric substrate layer is closely attached to the lower side of the three-dimensional structure layer.

[0015] Furthermore, the center point of the diode coincides with the center normal of the upper surface of the dielectric substrate layer, the diode is attached to the top of the dielectric substrate layer, and the on and off states of the bias voltage of the diode are respectively on state and off state.

[0016] Furthermore, the metal substrate structure layer is attached below the dielectric substrate layer, the length, width and height of the metal substrate structure layer are p, p and h3 respectively, and the material of the metal substrate structure layer is a metal with high conductivity.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention designs a phase-programmable three-dimensional metamaterial unit, which increases the spatial freedom of the structure by changing the structure from a two-dimensional material to a three-dimensional material, and improves the unit's ability to regulate electromagnetic waves through the mutual cooperation of the three-dimensional structure layer, the dielectric substrate layer, and the metal substrate structure layer;

[0019] 2. The present invention installs a diode on the phase-programmable three-dimensional metamaterial unit and controls the current on and off through an external FPGA circuit, so as to program and control the reflection phase of the electromagnetic wave in real time, thereby accurately controlling the propagation direction of the electromagnetic wave and realizing flexible use under various working conditions;

[0020] 3. The present invention designs the stepped metal structure in the phase-programmable three-dimensional metamaterial unit into a stepped shape, so that the unit can meet the requirements of the electronic additive manufacturing (AME) process, thereby reducing the processing loss of the material and improving the processing accuracy, thereby providing a way to reduce the production cost for the large-scale production of the phase-programmable three-dimensional metamaterial unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the three-dimensional structure of a phase-programmable three-dimensional metamaterial unit provided in an embodiment of the present invention;

[0022] Figure 2 An S11 amplitude curve diagram of a phase programmable three-dimensional metamaterial unit in a frequency range of 5.9 GHz to 9 GHz provided by an embodiment of the present invention;

[0023] Figure 3 The S11 phase curve diagram of the phase programmable three-dimensional metamaterial unit provided in an embodiment of the present invention in the frequency range of 5.9 GHz to 9 GHz;

[0024] Figure 4 This is a graph of the equivalent dielectric constant ε and magnetic permeability μ of the phase-programmable three-dimensional metamaterial unit provided in an embodiment of the present invention in the frequency range of 5.9 GHz to 9 GHz.

[0025] Figure numerals: 1. stepped metal structure; 2. square metal patch; 3. metal feed line; 4. diode; 5. dielectric substrate layer; 6. metal substrate structure layer. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In this embodiment, please refer to Figure 1-4 , a phase programmable three-dimensional metamaterial unit, comprising a phase programmable three-dimensional metamaterial unit, wherein the phase programmable three-dimensional metamaterial unit comprises a three-dimensional structure layer, a dielectric substrate layer 5 and a metal substrate structure layer 6 arranged from top to bottom;

[0028] The three-dimensional structural layer includes four stepped metal structures 1, two metal feed lines 3, two square metal patches 2 and a diode 4 fixed on the square metal patches 2. The four stepped metal structures 1 are equidistantly distributed around the center line of the dielectric substrate layer 5. The two square metal patches 2 are respectively fixed on two adjacent stepped metal structures 1 and another two adjacent stepped metal structures 1. Each of the stepped metal structures 1 is provided with n layers of steps and the height of the steps increases step by step from the center of the unit to the outside. The two ends of the diode 4 are fixed on the two square metal patches 2. The two metal feed lines 3 are respectively fixed on the bottom of the two adjacent stepped metal structures 1 and another two adjacent stepped metal structures 1. The stepped metal structure 1, the square metal patch 2, the diode 4 and the metal feed line 3 are all attached to the dielectric substrate layer 5. The metal substrate structural layer 6 is attached to the dielectric substrate layer 5.

[0029] Reference Figure 1 , taking the center of the upper surface of the phase programmable three-dimensional metamaterial unit as the coordinate origin, establishing a spatial rectangular coordinate system, perpendicular to the upper surface of the unit outward as the positive direction of the z axis, horizontally to the right as the positive direction of the y axis, and vertically downward as the positive direction of the x axis, wherein the angle between the long sides of the four stepped metal structures 1 and the yoz plane is 30°≤θ≤60°, and the optimal angle between the long sides of the four stepped metal structures 1 and the yoz plane can be selected as θ=45°, the stepped metal structure 1 has n layers of steps that gradually increase from the center of the unit to the outside, the height difference of each layer of steps is d=0.5mm, and the step length of the steps is t =1mm, the step width is w1=0.5mm, the height is h1=6mm, the length is l1=3mm, the distance from the end of the step metal structure 1 close to the unit center to the unit center point is s=0.707mm, the material of the step metal structure 1 can be silver, the four step metal structures are made of high conductivity metal, such as any one of silver, aluminum, titanium alloy and other metals, and the processing methods are selective laser melting (SLM), direct energy deposition (DED), powder bed photopolymerization (PBF), fused filament fabrication (FFF), electron beam melting (EBM), etc.;

[0030] Reference Figure 1 , the square metal patch 2 is mirror-symmetrical about the yoz plane, the length, width and height of the square metal patch 2 are l2=1.4, w2=0.52mm, ht=0.2mm respectively, and the distance between the two square metal patches 2 is st=0.3mm;

[0031] Reference Figure 1, the metal feed line 3 is two rectangular metal wires mirror-symmetrical about the yoz plane, the length, width and height of the metal feed line 3 are p=15mm, wb=0.2mm, hs=0.2mm respectively, the distance between the two metal feed lines 3 is ls=7.8mm, and (s+l1)sinθ>ls>s×sinθ is satisfied;

[0032] Reference Figure 1 , the length, width and height of the dielectric substrate layer 5 are p=15mm, p=15mm, h2=3.3mm respectively, the dielectric substrate layer 5 is closely attached to the lower side of the three-dimensional structure layer, the relative dielectric constant of the dielectric substrate layer 5 is ε1, and the relative dielectric constant is ε1=2.43. The material of the dielectric substrate layer 5 can be polypropylene (PP), polycarbonate (PC), thermoplastic polyurethane (TPU), polyamide (PAEK), acrylonitrile butadiene styrene copolymer (ABS), etc., and the processing method adopts fused deposition modeling, light curing, composite additive manufacturing and other methods;

[0033] Reference Figure 1 The center point of the diode 4 coincides with the center normal of the upper surface of the dielectric substrate layer 5, and is attached to the top of the dielectric substrate layer 5. The bias voltage on and off states of the diode 4 are respectively on and off.

[0034] Reference Figure 1 The length, width and height of the metal substrate structure layer 6 are p=15 mm, p=15 mm, and h3=0.035 mm, respectively. The metal substrate structure layer 6 is attached to the bottom of the dielectric substrate layer 5. The material of the metal substrate structure layer 6 is silver. The material of the metal substrate structure layer 6 is a metal with high conductivity, such as any one of silver, aluminum, titanium alloy, etc. The processing method is selective laser melting (SLM), direct energy deposition (DED), powder bed photocuring (PBF), fused filament fabrication (FFF), electron beam melting (EBM), etc.;

[0035] From the electromagnetic field theory, we know that when an infinite three-dimensional metamaterial with a thickness of d is placed in free space, S11 represents the total reflection coefficient of the dielectric plate in free space, and S21 represents the total transmission coefficient. When the electromagnetic wave is incident perpendicular to the surface of the metamaterial, the electromagnetic wave will experience countless reflections and transmissions inside the medium, and the coefficient of each reflection and transmission can be expressed by the expression:

[0036]

[0037]

[0038] Where Γ represents the reflection coefficient of electromagnetic waves propagating to the metamaterial, T represents the transmission coefficient of electromagnetic waves between the two surfaces of the metamaterial with a thickness of d, and it is assumed that the relative dielectric constant and magnetic permeability of the three-dimensional metamaterial are ε r and μ r , k0 represents the wave number of electromagnetic waves in free space, then the expressions of reflection coefficient and transmission coefficient are:

[0039]

[0040]

[0041] Solving the above formula we can get

[0042]

[0043] Therefore, knowing only S11 and S21 and the thickness d, the equivalent relative permittivity and magnetic permeability of the three-dimensional metamaterial can be calculated as ε r and μ r , thereby precisely controlling the electromagnetic characteristics of three-dimensional metamaterials.

[0044] In the design of the phase programmable three-dimensional metamaterial unit, the main function of the diode 4 is to act as a controllable nonlinear element to change the working state of the phase programmable three-dimensional metamaterial unit, thereby adjusting the electromagnetic properties of the metamaterial. As an electronic component that only allows current to flow in one direction, the on (or off) state of the diode 4 can be controlled by applying different bias voltages. When the diode 4 is on, the current can flow through the diode 4, and when the diode 4 is off, the current cannot flow through the diode 4. By changing the working state of the diode 4, the electromagnetic response of the phase programmable three-dimensional metamaterial unit can be changed, thereby changing the electromagnetic characteristics of the entire three-dimensional metamaterial.

[0045] The working state of the diode 4 is dynamically controlled by an external FPGA circuit to achieve real-time regulation of the metamaterial. By changing the bias voltage of the diode 4, real-time regulation of the three-dimensional metamaterial can be achieved.

[0046] The following is a further description of the technical effects of the present invention in conjunction with simulation experiments:

[0047] 1. Experimental conditions and contents:

[0048] The modulator unit is simulated using the simulation software CST, and the simulation boundary conditions are set to periodic boundary conditions.

[0049] The reflection amplitude characteristics of the three-dimensional metamaterial unit of the embodiment of the present invention are simulated, and the results are as follows: Figure 2 shown.

[0050] The reflection phase characteristics of the three-dimensional metamaterial unit of the embodiment of the present invention are simulated, and the results are as follows: Figure 3 shown.

[0051] The equivalent dielectric constant of the three-dimensional metamaterial unit of the embodiment of the present invention is simulated, and the results are as follows: Figure 4 shown.

[0052] 2. Experimental results analysis

[0053] Reference Figure 2 As shown, the operating frequency band of the phase programmable three-dimensional metamaterial unit in this document is 5.9GHz~9GHz, which just covers the 6GHz spectrum (5925-7125MHz) allocated in the new version of the "Radio Frequency Division Regulations of the People's Republic of China" issued by the Ministry of Industry and Information Technology on June 27, 2023, laying a solid foundation for future 5.5G / 6G communications and has a strong practical application background. The phase programmable three-dimensional metamaterial unit is a curve diagram of the reflection amplitude parameter of the unit when the diode 4 works in the on and off states. Figure 2 In the figure, Frequency is the frequency in GHz, S-parameter is the scattering parameter in dB, and the unit's operating frequency band is 5.9GHz-9GHz. At the center frequency of 7.5GHz, the reflection coefficient of the reflection unit in the off state |S11|=-0.715dB, and the reflection coefficient of the reflection unit in the off state |S11|=-0.754dB;

[0054] Reference Figure 3 As shown, the reflection phase parameter curve of the phase programmable three-dimensional metamaterial unit is a graph when the diode 4 tube is working in the on and off states. Figure 2 In the figure, Frequency is the frequency in GHz, Phase is the unit reflection phase in degrees, and at the center frequency of 7.5 GHz, the reflection phase difference of the reflection unit in the off state is Phase-difference = 192°;

[0055] Reference Figure 3 As shown in the figure, the equivalent dielectric constant and permeability curves of the phase programmable three-dimensional metamaterial unit in the frequency range of 5.9 GHz to 9 GHz, Figure 2 In the figure, Frequency is the frequency in GHz, Epsilon and Mu are the equivalent dielectric constant and magnetic permeability, respectively. At the center frequency of 7.5 GHz, the dielectric constant and magnetic permeability of the reflection unit are shown in the figure.

[0056] The above simulation example analysis shows that the phase of electromagnetic waves can be programmed and controlled in the frequency range of 5.9 GHz to 9 GHz by using the phase-programmable three-dimensional metamaterial unit.

[0057] The above are only some embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A phase programmable three-dimensional metamaterial unit, characterized in that: It includes a three-dimensional structure layer, a dielectric substrate layer and a metal substrate structure layer arranged from top to bottom; The three-dimensional structural layer includes four stepped metal structures, two metal feed lines, two square metal patches and diodes fixed on the square metal patches. The four stepped metal structures are equidistantly distributed around the center line of the dielectric substrate layer. The two square metal patches are respectively fixed on two adjacent stepped metal structures and another two adjacent stepped metal structures. Each of the stepped metal structures is provided with n layers of steps and the height of the steps increases step by step from the center of the unit to the outside. The two ends of the diode are fixed on the two square metal patches. The two metal feed lines are respectively fixed on the bottom of the two adjacent stepped metal structures and another two adjacent stepped metal structures. The stepped metal structure, the square metal patch, the diode and the metal feed line are all attached to the dielectric substrate layer, and the metal substrate structural layer is attached to the dielectric substrate layer.

2. A phase programmable three-dimensional metamaterial unit according to claim 1, characterized in that: A spatial rectangular coordinate system is established with the center of the upper surface of the phase-programmable three-dimensional metamaterial unit as the coordinate origin. The positive direction of the z-axis is perpendicular to the upper surface of the unit, the positive direction of the y-axis is horizontally to the right, and the positive direction of the x-axis is vertically downward. The four stepped metal structures are mirror-symmetric about the yoz plane, and the angle between the long side and the yoz plane is θ. The height difference of each step of the stepped metal structure is d, the step length is t, the step width is w1, and the distance from one end of the stepped metal structure close to the center of the unit to the center point of the unit is s.

3. The phase programmable three-dimensional metamaterial unit according to claim 2, characterized in that: The height, length and angle of the four step metal structures are h1, l1 and θ, and the height, length and angle of the step metal structures respectively satisfy h1=n×d, l1=n×t, and 30°≤θ≤60°.

4. The phase programmable three-dimensional metamaterial unit according to claim 3, characterized in that: The four stepped metal structures are made of metal with high conductivity.

5. The phase programmable three-dimensional metamaterial unit according to claim 4, characterized in that: The two metal feed lines are rectangular metal lines that are mirror-symmetric about the yoz plane. The length, width and height of the metal feed lines are p, wb and hs respectively. The distance between the two metal feed lines is ls, and ls satisfies (s+l1)sinθ>ls>s×sinθ.

6. The phase programmable three-dimensional metamaterial unit according to claim 5, characterized in that: The two square metal patches are mirror-symmetrical about the yoz plane, the length, width and height of the two square metal patches are l2, w2 and ht respectively, and the distance between the two square metal patches is st.

7. The phase programmable three-dimensional metamaterial unit according to claim 1, characterized in that: The length, width and height of the dielectric substrate layer are p, p and h2 respectively, and the dielectric substrate layer is closely attached to the lower side of the three-dimensional structure layer.

8. The phase programmable three-dimensional metamaterial unit according to claim 1, characterized in that: The center point of the diode coincides with the center normal of the upper surface of the dielectric substrate layer, the diode is attached to the top of the dielectric substrate layer, and the on and off states of the bias voltage of the diode are respectively on state and off state.

9. The phase programmable three-dimensional metamaterial unit according to claim 8, characterized in that: The metal substrate structure layer is attached below the dielectric substrate layer. The length, width and height of the metal substrate structure layer are p, p and h3 respectively. The material of the metal substrate structure layer is a metal with high conductivity.

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