A metamaterial structure based on liquid metal

Abstract

The application discloses a liquid metal-based metamaterial structure, which comprises a dielectric substrate, a spiral microfluidic channel in the dielectric substrate, and liquid metal and mineral oil in the channel. The spiral microfluidic channel is filled with a short circular arc-shaped liquid metal section and a long circular arc-shaped liquid metal section, the two liquid metal sections are separated by mineral oil, and the rest of the microfluidic channel is filled with mineral oil. The technical scheme of the application solves the problem that the polarization conversion metamaterial structure in the prior art can only realize single reflection wave or transmission wave polarization regulation and cannot realize multi-frequency band and multi-functional polarization reconfiguration.

Description

Technical Field

[0001] This invention belongs to the field of artificial electromagnetic metamaterials technology, specifically relating to a metamaterial structure based on liquid metal. Background Technology

[0002] Polarization is a crucial characteristic of electromagnetic waves, playing a vital role in their propagation. In the microwave and optical bands, polarization conversion devices have significant applications in mobile communications, satellite communications, sensing, and spectral analysis. Based on the form of polarization conversion, they are classified into linear-to-linear and linear-to-circular polarization conversions. Based on the direction of electromagnetic wave propagation, they are classified into reflective and transmissive polarization conversion metasurfaces. Currently, most polarization conversion metasurfaces can only achieve polarization control of a single reflected or transmitted wave, significantly limiting the degree of freedom in applications and preventing multi-band, multi-functional polarization control. Achieving control over the polarization of electromagnetic waves through simple periodic structures is an important research topic.

[0003] With the emergence of metamaterials, researchers have applied them to the design of polarization conversion devices. To achieve reconfigurable polarization conversion, various modulated materials or devices, such as conductive polymers, liquid crystal molecules, PIN diodes, and MEMS switches, have been used in metamaterial units. However, these methods often require complex control circuits. Incorporating these complex control circuits into the periodic structure units can severely affect the electromagnetic properties of the metamaterial itself, making the design difficult.

[0004] Using liquid metal to control devices is a novel approach proposed in recent years. Liquid metal is a conductive metal that can flow at room temperature and possesses excellent dynamic reconfigurability. Utilizing the large deformation and fluidity of liquid metal to design metamaterials can yield low-cost reconfigurable characteristics, making it a promising emerging technology. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a metamaterial structure based on liquid metal.

[0006] To achieve the above objectives, the present invention provides the following solution: A metamaterial structure based on liquid metal includes a dielectric substrate, a spiral microfluidic channel in the dielectric substrate, and liquid metal and mineral oil in the channel; wherein the spiral microfluidic channel is filled with a short arc-shaped liquid metal and a long arc-shaped liquid metal, the two segments of liquid metal are separated by mineral oil, and the rest of the microfluidic channel is filled with mineral oil.

[0007] Preferably, when the position of the liquid metal in the microfluidic channel is different, the metamaterial will work in the following four different working states; (1) Working state 1, if the midpoints of the two liquid metal segments are placed in x Axis, Input x Directional polarization of linearly polarized waves will be totally reflected; (2) Working state 2, if the midpoints of the two liquid metal segments are placed y Axis, Input x Directional polarization of linearly polarized waves will be fully transmitted; (3) Working state 3, if the center point of the short arc-shaped liquid metal is placed in the +45° direction and the center point of the long arc-shaped liquid metal is placed in the -135° direction, input x Directional polarization of linearly polarized waves will be converted into bidirectional propagating left-hand circularly polarized waves in the first frequency band and into bidirectional propagating right-hand circularly polarized waves in the third frequency band; (4) Working state 4, if the center point of the short arc-shaped liquid metal is placed in the +135° direction and the center point of the long arc-shaped liquid metal is placed in the -45° direction, input x Directional polarized linear waves will be converted into bidirectional propagating right-hand circularly polarized waves in the first frequency band and into bidirectional propagating left-hand circularly polarized waves in the third frequency band.

[0008] As a preferred approach, the fluidity of mineral oil and liquid metal is utilized, and the position of the liquid metal is changed by external force, so that when a single linearly polarized electromagnetic wave is incident on the metamaterial structure, it forms a circularly polarized electromagnetic wave that is totally reflected, totally transmitted, or bidirectionally transmitted.

[0009] Preferably, the dielectric substrate has a length and width of P=20mm, a thickness of H=3mm, and a dielectric constant of [missing value]. ε r =2.2; There are 1.5 turns of spiral microfluidic channels in the dielectric substrate, and the spiral radius is... R 1 = 9mm, the diameter of the microfluidic channel Ф 1=0.5mm, pitch S=0.9mm.

[0010] Preferably, the midpoints of both liquid metal segments are placed... x The axis, the metamaterial structure will operate in state 1; the arc length of the elongated liquid metal is (2π - 2π / 2). θ 1- θ 2) ×R 1, among which, θ 1 is the central angle corresponding to the arc length of the mineral oil used to separate the two segments of liquid metal. θ 2 is the central angle of the arc length of the short circular arc liquid metal, that is, the arc length of the short circular arc liquid metal is... θ 2 ×R 1. The length of the mineral oil arc used for isolation between the short-arc liquid metal and the long-arc liquid metal is... θ 1 ×R 1.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: By changing the position of the liquid metal, various functions can be achieved in different frequency bands, including total internal reflection of linear polarization, total transmission of linear polarization, left-hand circular polarization for bidirectional transmission, and conversion from linear polarization to right-hand circular polarization. Compared with control measures using conductive polymer materials, liquid crystal molecules, PIN diodes, MEMS switches, etc., the liquid metal-based reconstruction method does not rely on complex feed networks that may affect performance; instead, performance reconstruction can be achieved through pressure-driven processes. The metamaterial structure described in this invention offers diverse functions, simple control, ease of fabrication, and greatly improves the degree of freedom in application, making it widely applicable in control devices or wireless communication systems. Attached Figure Description

[0012] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the metamaterial structure in an embodiment of the present invention; Figure 2 This is a top view of the metamaterial structure in an embodiment of the present invention; Figure 3 A schematic diagram showing the location of the liquid metal in the metamaterial structure of this invention under four working states; Figure 4 These are simulation results of the magnitudes of the reflection coefficient and transmission coefficient when the metamaterial is operating in state 1 in this embodiment of the invention. Figure 5 These are simulation results of the magnitudes of the reflection coefficient and transmission coefficient when the metamaterial is operating in state 2 in this embodiment of the invention. Figure 6 These are the simulation results of the amplitude and phase of the reflection coefficient and transmission coefficient when the metamaterial is working in state 3 in the embodiments of the present invention; Figure 7 This is the simulation result of the axial ratio when the metamaterial is working in state 3 in the embodiment of the present invention; Figure 8 These are the simulation results of the amplitude and phase of the reflection coefficient and transmission coefficient when the metamaterial is working in state 4 in the embodiments of the present invention; Figure 9 This is the simulation result of the axial ratio when the metamaterial is working in state 4 in the embodiment of the present invention. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] Example 1 This invention provides a metamaterial structure based on liquid metal, comprising a dielectric substrate, a spiral microfluidic channel within the dielectric substrate, liquid metal, and mineral oil. The spiral microfluidic channel is filled with a short arc-shaped section of liquid metal and a long arc-shaped section of liquid metal, separated by mineral oil. The remaining portion of the microfluidic channel is filled with mineral oil.

[0017] By utilizing the fluidity of mineral oil and liquid metal, and by using external force to change the position of the liquid metal, a single linearly polarized electromagnetic wave can be incident on a metamaterial structure, resulting in a circularly polarized electromagnetic wave that can be totally reflected, totally transmitted, or propagated bidirectionally. The four specific operating states include: (1) Working state 1, if the midpoints of the two liquid metal segments are placed in x Axis, Input x Directionally polarized linearly polarized waves will be totally reflected; (2) Working state 2, if the midpoints of both liquid metal segments are placed y Axis, Input x Directionally polarized linearly polarized waves will be fully transmitted; (3) Working state 3, if the center point of the short arc-shaped liquid metal is placed in the +45° direction and the center point of the long arc-shaped liquid metal is placed in the -135° direction, input x Directional polarized linear waves will be converted into bidirectional propagating left-hand circularly polarized waves in the first frequency band and into bidirectional propagating right-hand circularly polarized waves in the third frequency band. (4) Working state 4, if the center point of the short arc-shaped liquid metal is placed in the +135° direction, and the center point of the arc-shaped liquid metal in the tank is placed in the -45° direction, input x Directional polarized linear waves will be converted into bidirectional propagating right-hand circularly polarized waves in the first frequency band and into bidirectional propagating left-hand circularly polarized waves in the third frequency band.

[0018] Figure 1 , 2The image shows a specific embodiment of a unit within the metamaterial structure of the present invention. The dielectric substrate of this unit has a length and width of P = 20 mm, a thickness of H = 3 mm, and a dielectric constant of... ε r =2.2. There is a 1.5-turn spiral microfluidic channel in the dielectric substrate, the spiral radius R1 = 9 mm, and the diameter of the microfluidic channel is... Ф 1=0.5mm, pitch S=0.9mm; a short section of liquid metal and a long section of liquid metal are injected into the microfluidic channel, and the rest is filled with mineral oil.

[0019] Figure 3 The diagram shows the location of the liquid metal in the metamaterial structure of this invention under four different operating conditions. Figure 3 As shown in (a), the midpoints of both liquid metal segments are placed... x The axis, the metamaterial structure will operate in state 1; the arc length of the elongated liquid metal is (2π - 2π / 2). θ 1- θ 2) ×R 1, among which, θ 1 is the central angle corresponding to the arc length of the mineral oil used to separate the two segments of liquid metal. θ 2 is the central angle of the short circular arc liquid metal arc length, that is, the mineral oil arc length used for isolation between the short circular arc liquid metal and the long circular arc liquid metal. θ 1 ×R 1. The arc length of the short circular arc-shaped liquid metal is θ 2 ×R 1. In this embodiment, θ 1 = 1 / 3 radian θ 1 = ( π / 2 - 1 / 3) radians, meaning the arc length of the short liquid metal section is approximately 11.14 mm, the arc length of the long liquid metal section is approximately 39.4 mm, and the arc length of the mineral oil used for separation between the two liquid metal sections is 3 mm; For example Figure 3 As shown in (b), the midpoints of both liquid metal segments are placed... y The axis, the metamaterial structure will operate in state 2; such as Figure 3 As shown in (c), with the center point of the short, arc-shaped liquid metal placed at +135° and the center point of the long, arc-shaped liquid metal placed at -45°, the metamaterial structure will operate in state 3; as Figure 3 As shown in (d), with the center point of the long arc-shaped liquid metal placed in the +45° direction and the center point of the short arc-shaped liquid metal placed in the +135° direction, the metamaterial structure will operate in state 4.

[0020] Figure 4The figure shows the simulation results of reflection and transmission when the metamaterial structure of the present invention is operating in state 1. The simulation results show that when... x When polarized electromagnetic waves are incident on the surface of a metamaterial structure, the frequency band with a reflection coefficient modulus greater than -1dB is 4.8-6.3GHz, which means it is operating in a state of total internal reflection.

[0021] Figure 5 The figure shows the simulation results of reflection and transmission when the metamaterial structure of the present invention is operating in state 2. The simulation results show that when... x When polarized electromagnetic waves are incident on the surface of a metamaterial structure, the frequency band with a transmission coefficient modulus greater than -1dB is 3.5-6.3GHz, which means it is operating in a fully transparent state.

[0022] Figure 6 The image shows the metamaterial structure of the present invention operating in state 3. x Simulation results of reflection and transmission coefficients when polarized electromagnetic waves are incident on a metamaterial structure. (Figure shows...) R xx The incident wave is x Polarization and reflected waves are x The amplitude of the polarization reflection coefficient R yx The incident wave is x Polarization and reflected waves are y The magnitude of the reflection coefficient of polarization; T xx The incident wave is x Polarization and transmission waves are x The amplitude of the transmission coefficient of the polarization component. T yx The incident wave is x Polarization and transmission waves are y The amplitude of the transmission coefficient of the polarization component; r xx and r yx In the reflected wave x polarization components and y Phase of the reflection coefficient of the polarization component It is the phase difference between the two components; t xx and t yx In transmitted waves x polarization components and y The transmission coefficient phase of the polarization component. It is the phase difference between the two components. Figure 6 The result of (a) shows that the amplitudes of the two components in the reflected wave are approximately equal; Figure 6The result of (c) shows that the amplitudes of the two components in the transmitted wave are equal. exist Figure 6 The first frequency band in (b), ,Right now x Phase lead of polarization components y The polarization component has a phase of 90°, therefore the reflected wave is a right-hand circularly polarized wave; in the third frequency band, ,Right now x Phase lag of polarization components y The polarization component has a phase of 90°, therefore the reflected wave is a left-handed circularly polarized wave.

[0023] exist Figure 6 The first frequency band in (d), ,Right now x Phase lag of polarization components y The polarization component has a phase of 90°, therefore the transmitted wave is a right-hand circularly polarized wave; in the third frequency band, ,Right now x Phase lead of polarization components y The polarization component has a phase of 90°, therefore the transmitted wave is a left-handed circularly polarized wave.

[0024] Figure 7 The figure shows the simulation results of the axial ratio of reflected and transmitted waves when the metamaterial structure of the present invention is operating in state 3. The axial ratio of the reflected wave is less than 3 in the two frequency bands of 2.96-3.48 GHz and 6.05-6.5 GHz; the axial ratio of the transmitted wave is less than 3 in the two frequency bands of 3-3.55 GHz and 5.9-6.55 GHz.

[0025] Figure 8 The image shows the metamaterial structure of the present invention operating in state 4. x Simulation results of reflection and transmission when polarized waves are incident on metamaterial structures. Figure 8 The result in (a) shows that the incident wave is x In polarized waves and reflected waves x polarization components and y The amplitudes of the reflection coefficients of the polarization components are approximately equal. Figure 8 The results in (b) show that in the first frequency band, ,Right now x Phase lag of polarization components y The polarization component has a phase of 90°, therefore the reflected wave is a left-handed circularly polarized wave; in the third frequency band, ,Right now x Phase lead of polarization components yThe polarization component has a phase of 90°, therefore the reflected wave is a right-hand circularly polarized wave. Figure 8 The results in (c) indicate that in the transmitted wave x polarization components and y The amplitudes of the polarization components are nearly equal; Figure 8 The results in (d) show that in the first frequency band, ,Right now x Phase lag of polarization components y The polarization component has a phase of 90°, therefore the transmitted wave is a left-handed circularly polarized wave; in the third frequency band, ,Right now x Phase lead of polarization components y The polarization component has a phase of 90°, therefore the transmitted wave is a right-hand circularly polarized wave.

[0026] Figure 9 The figure shows the simulation results of the axial ratio of reflected and transmitted waves when the metamaterial structure of the present invention is operating in state 4. The axial ratio of the reflected wave is less than 3 in the two frequency bands of 2.95-3.5GHz and 5.94-6.55GHz; the axial ratio of the transmitted wave is less than 3 in the two frequency bands of 3.05-3.55GHz and 5.9-6.5GHz.

[0027] In summary, the metamaterial structure proposed in this invention is a multi-band, multi-polarization, and multi-propagation characteristic reconfigurable metamaterial. By externally pushing the position of the liquid metal in the spiral microfluidic channel within the structure, four working states can be achieved: the first state is realized... x The directional linearly polarized wave is totally reflected; the second state is realized. x The directional linearly polarized wave is fully transmitted; the third state is achieved in two separate frequency bands. x The directional linearly polarized wave is converted into bidirectional propagating right-handed and left-handed circularly polarized waves; the fourth state is achieved in two frequency bands respectively. x The linearly polarized wave is converted into bidirectional propagating left-handed and right-handed circularly polarized waves. Therefore, the metamaterial structure described in this invention achieves multi-polarization and reconfigurable transmission characteristics, and can be widely used in control devices or wireless communication systems.

[0028] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A metamaterial structure based on liquid metal, characterized in that, The invention includes a dielectric substrate, a spiral microfluidic channel in the dielectric substrate, and liquid metal and mineral oil in the channel; wherein the spiral microfluidic channel is spiral along the thickness H direction of the dielectric substrate, and the channel is filled with a short arc-shaped liquid metal and a long arc-shaped liquid metal, the two liquid metal sections are separated by mineral oil, and the rest of the microfluidic channel is filled with mineral oil. Using the center point of the metamaterial unit as the origin of the rectangular coordinate system, the coordinate system... x The axis and the horizontal edge of the element are parallel, coordinate system y The axis and the vertical edge of the unit are parallel; when the position of the liquid metal in the microfluidic channel is different, the metamaterial will work in the following four different working states; (1) Working state 1, if the midpoints of the two liquid metal segments are placed in x Axis, Input x Directional polarization of linearly polarized waves will be totally reflected; (2) Working state 2, if the midpoints of the two liquid metal segments are placed y Axis, Input x Directional polarization of linearly polarized waves will be fully transmitted; (3) Working state 3, if the center point of the short arc-shaped liquid metal is placed in the +45° direction and the center point of the long arc-shaped liquid metal is placed in the -135° direction, input x Directional polarization of linearly polarized waves will be converted into bidirectional propagating left-hand circularly polarized waves in the first frequency band and into bidirectional propagating right-hand circularly polarized waves in the third frequency band; (4) Working state 4, if the center point of the short arc-shaped liquid metal is placed in the +135° direction and the center point of the long arc-shaped liquid metal is placed in the -45° direction, input x Directional polarized linear waves will be converted into bidirectional propagating right-hand circularly polarized waves in the first frequency band and into bidirectional propagating left-hand circularly polarized waves in the third frequency band.

2. The metamaterial structure based on liquid metal as described in claim 1, characterized in that, By utilizing the fluidity of mineral oil and liquid metal, and by using external force to change the position of the liquid metal, a single linearly polarized electromagnetic wave can be incident on a metamaterial structure to form a circularly polarized electromagnetic wave that is totally reflected, totally transmitted, or bidirectionally transmitted.

3. The metamaterial structure based on liquid metal as described in claim 2, characterized in that, The dielectric substrate has a length and width of P=20mm, a thickness of H=3mm, and a dielectric constant of [missing value]. ε r =2.2; There are 1.5 turns of spiral microfluidic channels in the dielectric substrate, the spiral radius R1 = 9 mm, and the diameter of the microfluidic channel is... Ф 1=0.5mm, pitch S=0.9mm.

4. The metamaterial structure based on liquid metal as described in claim 3, characterized in that, Place the midpoints of both liquid metal segments on x The axis, the metamaterial structure will operate in state 1; the arc length of the elongated liquid metal is (2π - 2π / 2). θ 1- θ 2) × R 1, among which, θ 1 is the central angle corresponding to the arc length of the mineral oil used to separate the two segments of liquid metal. θ 2 is the central angle of the arc length of the short circular arc liquid metal, that is, the arc length of the short circular arc liquid metal is... θ 2 ×R 1. The length of the mineral oil arc used for isolation between the short-arc liquid metal and the long-arc liquid metal is... θ 1 ×R 1.

Images