Three-frequency polarization insensitive energy collection metasurface device

Abstract

The invention provides a three-frequency polarization insensitive energy collection metasurface device, and belongs to the technical field of wireless energy collection. The energy collection metasurface device comprises a plurality of metasurface unit structures, wherein each metasurface unit structure comprises a metal floor layer, a dielectric layer and a metal metasurface unit which are stacked in sequence; the metal metasurface unit comprises a cross structure and four concave split-ring resonators, the cross structure divides the surface of the dielectric layer into four square areas, each split-ring resonator is located in the corresponding square area, and a gap exists between the split-ring resonator and the cross structure; the four split-ring resonators are rotationally and symmetrically distributed relative to the geometric center of the cross-shaped structure; and the cross structures in the adjacent metasurface unit structures are connected through diodes. Resonance intensity and energy collection efficiency can be improved, triple-frequency energy collection is realized, polarization is not sensitive, the structure of the device is simplified, loss is reduced, low profile and miniaturization are realized, and energy recycling is facilitated.

Description

Technical Field

[0001] This application relates to the field of wireless energy harvesting technology, and in particular to a three-frequency polarization-insensitive energy harvesting metasurface device. Background Technology

[0002] As wireless network deployments become more sophisticated, and considering the feasibility of energy harvesting—such as the significant contributions of wind and hydropower to the power system—energy can also be harvested using wireless sensor networks, i.e., electromagnetic waves. Whether electromagnetic waves originate from nature or are converted from energy sources in nature by humans, they can be recycled and converted back into usable energy. Related technologies will utilize energy harvesting devices based on metasurface units to collect radio frequency wireless energy.

[0003] However, most radio frequency wireless energy harvesting devices in related technologies are single-frequency or dual-frequency and polarization-sensitive, resulting in low energy harvesting efficiency. Furthermore, these technologies require metasurface units to be integrated with rectifier circuits and impedance matching layers to power external loads, increasing structural complexity and affecting the device's thickness and size. Therefore, there is an urgent need for a technical solution that can achieve more resonant points, is polarization-insensitive, and simplifies the structure of the energy harvesting device. Summary of the Invention

[0004] This application provides a three-frequency polarization-insensitive energy harvesting metasurface device, which can improve the resonance intensity, increase the energy harvesting efficiency, achieve three-frequency energy harvesting and polarization insensitivity, and at the same time facilitate the simplification of the device structure, reduce losses, and achieve low profile and miniaturization, thus enabling energy reuse. The technical solution includes at least the following: On one hand, an energy harvesting metasurface device is provided, comprising multiple metasurface unit structures. Each metasurface unit structure includes a metal ground layer, a dielectric layer, and metal metasurface units stacked sequentially. Each metal metasurface unit includes a cross structure and four concave split-ring resonators (SRRs). The cross structure divides the surface of the dielectric layer into four square regions. Each SRR is located in a corresponding square region and has a gap with the cross structure. The four SRRs are rotationally symmetrical about the geometric center of the cross structure, which is the intersection of the cross structures. Adjacent cross structures in the metasurface unit structures are connected by diodes. The energy harvesting metasurface device is used to harvest radio frequency energy in the 2.6 GHz to 2.7 GHz, 5.8 GHz to 6 GHz, and 8.3 GHz to 8.4 GHz frequency bands and can directly power an external load.

[0005] Optionally, the open-ended resonant ring is an axisymmetric structure with uniform width, including a square open-ended ring structure and two inner folded arm structures. The two inner folded arm structures are located inside the square open-ended ring structure and are respectively connected to the two open ends of the square open-ended ring structure.

[0006] Optionally, the distance between the open resonant ring and the cross structure is 0.05 mm to 0.15 mm; the distance between the open resonant ring and the boundary of the metasurface unit structure is 0.05 mm to 0.15 mm.

[0007] Optionally, the width of the open resonant ring is 0.8 mm to 0.9 mm; the distance between the two inner folded arm structures is 0.3 mm to 0.4 mm; and the distance between the side opposite the opening end of the square open ring structure and the end of the inner folded arm structure away from the opening end is 0.1 mm to 0.2 mm.

[0008] Optionally, the width of the cross structure is 1.35 mm to 1.45 mm.

[0009] Optionally, the side length of the metasurface unit structure is 15 mm to 16 mm.

[0010] Optionally, the plurality of metasurface unit structures are arranged in a rectangular array periodically, and the diodes between two adjacent metasurface unit structures arranged in the horizontal direction are installed in the same polarity direction, and the diodes between two adjacent metasurface unit structures arranged in the vertical direction are installed in the same polarity direction.

[0011] Optionally, the diode is a Schottky diode that supports direct rectification of electromagnetic waves at frequencies of 2.6 GHz to 2.7 GHz, 5.8 GHz to 6 GHz, and 8.3 GHz to 8.4 GHz.

[0012] Optionally, the thickness of the metal floor layer and the metal metasurface unit is 35 μm to 36 μm; the thickness of the dielectric layer is 1 mm to 1.525 mm.

[0013] Optionally, the metal floor layer and the metal metasurface unit are both made of copper, silver, or gold; the dielectric layer is made of F4B.

[0014] The beneficial effects of the technical solution provided in this application include at least the following: In this embodiment, the metal metasurface unit includes a cross structure and four concave open resonant rings. The concave open resonant rings increase the current path, coupling area, and coupling strength, thereby facilitating the excitation of more resonant points, increasing the resonance intensity, and improving energy harvesting efficiency. The cross structure divides the surface of the dielectric layer into four square regions. Each open resonant ring is located in a corresponding square region and has a gap with the cross structure. This decouples the resonant frequencies, increases the degree of freedom, and facilitates tri-frequency energy harvesting. The four open resonant rings are rotationally symmetrical about the geometric center of the cross structure, which is the intersection of the cross structure. This allows the energy harvesting metasurface device to simultaneously collect both transverse electric waves (TE waves) and transverse magnetic waves (TM waves), thus better achieving polarization insensitivity. The cross structures in adjacent metasurface unit structures are connected by diodes. When the metal metasurface unit receives electromagnetic waves and generates induced alternating current due to electromagnetic resonance, it can be rectified by the diodes. In other words, the embodiments of this application, by designing the structure of the metal metasurface unit, change the current distribution and natural mode field distribution on the metal metasurface unit. At the same time, by using diodes for direct rectification, there is no need for complex rectification circuits or impedance matching layers, which helps to simplify the structure of the device, reduce losses, and achieve low profile and miniaturization. Ultimately, the energy harvesting metasurface device can harvest radio frequency energy in the 2.6GHz to 2.7GHz, 5.8GHz to 6GHz, and 8.3GHz to 8.4GHz frequency bands and can directly power external loads. It has the good characteristics of tri-band energy harvesting and polarization insensitivity, which facilitates the reuse of energy. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of a three-frequency polarization-insensitive energy harvesting metasurface device provided in an embodiment of this application.

[0017] Figure 2 This is a three-dimensional structural diagram of the metasurface unit structure provided in the embodiments of this application.

[0018] Figure 3 This is a top view of the metasurface unit structure provided in the embodiments of this application.

[0019] Figure 4 This is a side view of the metasurface unit structure provided in the embodiments of this application.

[0020] Figure 5 This is a schematic diagram of the physical structure of a three-frequency polarization-insensitive energy harvesting metasurface device provided in an embodiment of this application.

[0021] Figure 6 This is a graph showing the input reflection coefficient S11 of the metasurface unit structure provided in this application for transverse electromagnetic waves of different frequencies.

[0022] Figure 7 This is a graph showing the absorption rate of transverse electromagnetic waves of different frequencies by the metasurface unit structure provided in the embodiments of this application.

[0023] Figure 8 These are the S11 curves of the metasurface unit structure provided in this application for input reflection coefficients of transverse electric waves and transverse magnetic waves of different frequencies.

[0024] Figure 9 This is a curve showing the input reflection coefficient S11 of the metasurface unit structure provided in this application for electromagnetic waves at different azimuth angles.

[0025] Figure 10 This is a simulated radiation gain pattern of the metasurface unit structure provided in the embodiments of this application.

[0026] Figure 11 This is a top view of the metasurface unit structure in the energy harvesting device of Comparative Example 1.

[0027] Figure 12 This is a graph showing the S11 curve of the input reflection coefficient of electromagnetic waves of different frequencies for the metasurface unit structure of Comparative Example 1.

[0028] Figure 13 The graphs show the reflection coefficients (S11) of the metasurface unit structure in Comparative Example 1 for input transverse electric and transverse magnetic waves of different frequencies.

[0029] Figure 14 This is a top view of the metasurface unit structure in the energy harvesting device of Scale 2.

[0030] Figure 15 This is a graph showing the S11 curve of the input reflection coefficient of electromagnetic waves of different frequencies for the metasurface unit structure of Comparative Example 2.

[0031] Figure label: 1: Metasurface unit structure; 2: Diode; 10: Metal ground layer; 20: Dielectric layer; 30: Metal metasurface unit; 31: Cross structure; 32: Open resonant ring; 321: Square open ring structure; 322: Inner folded arm structure. Detailed Implementation

[0032] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the element or object preceding “comprising” or “including” encompasses the element or object listed following “comprising” or “including” and its equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” “right,” etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0033] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0034] Figure 1 This is a schematic diagram of the structure of a three-frequency polarization-insensitive energy harvesting metasurface device provided in an embodiment of this application. Figure 1 As shown, the energy harvesting metasurface device includes multiple metasurface unit structures 1.

[0035] Figure 2 This is a three-dimensional structural diagram of the metasurface unit structure provided in the embodiments of this application. Figure 3 This is a top view of the metasurface unit structure provided in the embodiments of this application. Figure 4 This is a side view of the metasurface unit structure provided in an embodiment of this application. See also... Figures 1 to 4 The metasurface unit structure 1 includes a metal ground layer 10, a dielectric layer 20, and a metal metasurface unit 30 stacked sequentially. The metal metasurface unit 30 includes a cross structure 31 and four concave open resonant rings 32. The cross structure 31 divides the surface of the dielectric layer 20 into four square regions. Each open resonant ring 32 is located in a corresponding square region and has a gap with the cross structure 31. The four open resonant rings 32 are rotationally symmetrical about the geometric center of the cross structure 31, which is the intersection of the cross structures 31. Adjacent cross structures 31 in the metasurface unit structure 1 are connected by diodes 2. The energy harvesting metasurface device is used to harvest radio frequency energy in the 2.6GHz to 2.7GHz, 5.8GHz to 6GHz, and 8.3GHz to 8.4GHz frequency bands and can directly power an external load.

[0036] In this embodiment, the metal metasurface unit 30 includes a cross structure 31 and four concave open resonant rings 32. The concave open resonant rings 32 can increase the current path, coupling area, and coupling strength, thereby facilitating the excitation of more resonant points, improving the resonance intensity, and enhancing energy harvesting efficiency. The cross structure 31 divides the surface of the dielectric layer 20 into four square regions. Each open resonant ring 32 is located in a corresponding square region and has a gap with the cross structure 31. This decouples the resonant frequencies, increases the degree of freedom, and facilitates tri-frequency energy harvesting. The four open resonant rings 32 are rotationally symmetrical about the geometric center of the cross structure 31, with the geometric center of the cross structure 31 being its intersection. This allows the energy harvesting metasurface device to simultaneously collect both TE and TM polarized waves, thereby better achieving polarization insensitivity. The cross structures 31 in adjacent metasurface unit structures 1 are connected by diodes 2. When the metal metasurface unit 30 receives electromagnetic waves and generates induced alternating current due to electromagnetic resonance, it can be rectified by the diodes 2. In other words, by designing the structure of the metal metasurface unit 30, this embodiment of the application changes the current distribution and natural mode field distribution on the metal metasurface unit 30. At the same time, it uses diode 2 for direct rectification, eliminating the need for complex rectification circuits or impedance matching layers. This simplifies the structure of the device, reduces losses, and achieves low profile and miniaturization. Ultimately, the energy harvesting metasurface device can harvest radio frequency energy in the 2.6GHz to 2.7GHz, 5.8GHz to 6GHz, and 8.3GHz to 8.4GHz frequency bands and can directly power external loads. It has the good characteristics of tri-band energy harvesting and polarization insensitivity, which facilitates the reuse of energy.

[0037] For example, the split-ring resonator 32 is an axisymmetric structure with uniform width, including a square split-ring structure 321 and two inner folded arm structures 322. The two inner folded arm structures 322 are located inside the square split-ring structure 321 and are respectively connected to the two open ends of the square split-ring structure 321. This can effectively increase the current path, coupling area and coupling strength.

[0038] like Figure 3 As shown, both the open ring structure 321 and the inner folding arm structure 322 are composed of rectangular metal strips.

[0039] Optionally, the distance ge between the open resonant ring 32 and the cross structure 31 is 0.05 mm to 0.15 mm. Here, the distance ge between the open resonant ring 32 and the cross structure 31 is also the gap size between the open resonant ring 32 and the cross structure 31. The size of the gap within this range can better decouple the resonant frequencies and is more conducive to realizing three-frequency energy harvesting.

[0040] Optionally, the distance m between the open resonant ring 32 and the boundary of the metasurface unit structure 1 is 0.05 mm to 0.15 mm.

[0041] Optionally, the width d1 of the open-circuit resonator 32 is 0.8 mm to 0.9 mm.

[0042] Optionally, the distance g between the two inner folding arm structures 322 is 0.3 mm to 0.4 mm. Here, the distance g between the two inner folding arm structures 322 is also the distance between the two open ends of the square open ring structure 321.

[0043] Optionally, the distance n between the side opposite the opening end of the square open ring structure 321 and the end of the inner folded arm structure 322 away from the opening end is 0.1 mm to 0.2 mm.

[0044] For example, the cross structure 31 is composed of rectangular metal strips.

[0045] Optionally, the width d2 of the cross structure 31 is 1.35 mm to 1.45 mm.

[0046] For example, the outer contour of the metasurface unit structure 1 is square. Optionally, the side length 'a' of the metasurface unit structure 1 is 15 mm to 16 mm. Here, the side length 'a' of the metasurface unit structure 1 is also the length of the rectangular metal strip that constitutes the cross structure 31.

[0047] like Figure 4 As shown, optionally, the thickness of both the metal floor layer 10 and the metal metasurface unit 30 is h1, where h1 is 35 μm to 36 μm.

[0048] Optionally, the thickness h2 of the dielectric layer 20 is 1 mm to 1.525 mm.

[0049] Within the aforementioned range, the dimensions and thickness parameters of each structure in the metasurface unit structure 1 can achieve tri-frequency energy harvesting, excellent polarization insensitivity, and high energy harvesting efficiency, while simultaneously ensuring a small size and thickness of the metasurface unit structure 1, thereby better achieving low profile and miniaturization. In this embodiment, the side length a of the metasurface unit structure 1 is only 0.14λ, and the total thickness of the metasurface unit structure 1 is only 0.014λ, where λ represents the wavelength of the lowest resonant frequency.

[0050] like Figure 3 and Figure 4 As shown in Table 1, the dimensions and thickness parameters of each structure in the metasurface unit structure 1 of this embodiment can be set as shown in Table 1.

[0051] Table 1

[0052] Optionally, the metal floor layer 10 and the metal metasurface unit 30 are both made of copper, silver, or gold. Preferably, the metal floor layer 10 and the metal metasurface unit 30 are both made of copper. In other embodiments, the metal floor layer 10 and the metal metasurface unit 30 may be made of other good conductive metal materials as needed, and this application does not impose any restrictions on this.

[0053] For example, the dielectric constant of the dielectric layer 20 is 2.65, and the loss tangent is 0.001. For instance, the material of the dielectric layer 20 can be F4B (polytetrafluoroethylene). F4B is well-suited for high-frequency applications, ensuring good high-frequency performance of the device.

[0054] Figure 5 This is a schematic diagram of the physical structure of a three-frequency polarization-insensitive energy harvesting metasurface device provided in an embodiment of this application. See also... Figure 1 and Figure 5 Optionally, multiple metasurface unit structures 1 are arranged in a rectangular array periodically. The diodes 2 between two adjacent metasurface unit structures 1 arranged in the horizontal direction are installed with the same polarity direction, and the diodes 2 between two adjacent metasurface unit structures 1 arranged in the vertical direction are also installed with the same polarity direction. This ensures that the overall current direction is consistent, making it easy to draw current directly from two opposite corners of the device to power external loads.

[0055] In this embodiment, the energy harvesting metasurface device includes four metasurface unit structures 1, which are arranged in a 2×2 grid-shaped rectangular array. Figure 1 and Figure 5 In the horizontal arrangement, the diodes 2 between adjacent metasurface unit structures 1 are installed with the polarity direction of left positive and right negative. That is, in the horizontal plane, the anodes of these diodes 2 are connected to the cross structure in the left metasurface unit structure 1, and the cathodes are connected to the cross structure in the right metasurface unit structure 1. Similarly, the diodes 2 between adjacent metasurface unit structures 1 arranged vertically are installed with the polarity direction of top positive and bottom negative. That is, in the vertical plane, the anodes of these diodes 2 are connected to the cross structure in the upper metasurface unit structure 1, and the cathodes are connected to the cross structure in the lower metasurface unit structure 1. When the metal metasurface unit receives electromagnetic waves and generates induced alternating current due to electromagnetic resonance, after rectification by the diodes 2, the entire device can form a direct current from top to bottom and from left to right. This direct current can be directly led out from the upper left and lower right corners of the device to power external loads. Figure 1 The red lines in the upper left and lower right corners of the device are schematic diagrams of the lead-out lines, which facilitates the reuse of energy.

[0056] It should be noted that the arrangement of the metasurface unit structure 1 and the polarity direction of the diode 2 in this embodiment are only examples. In other embodiments, the number of metasurface unit structures 1, the arrangement of multiple metasurface unit structures 1, and the polarity direction of the corresponding diode 2 can be adjusted according to actual needs, as long as the overall current direction of the device is consistent. For example, there can be more metasurface unit structures 1, and the energy collected can be increased by increasing the number of metasurface unit structures 1. This application does not limit this.

[0057] For example, diode 2 is a Schottky diode that supports direct rectification of electromagnetic waves at frequencies of 2.6 GHz to 2.7 GHz, 5.8 GHz to 6 GHz, and 8.3 GHz to 8.4 GHz.

[0058] The ambient electromagnetic field contains wave components with different polarization directions, namely transverse electromagnetic waves (TEM waves). Figure 6 This is a graph showing the input reflection coefficient S11 of the metasurface unit structure provided in this application for transverse electromagnetic waves of different frequencies. For example... Figure 6 As shown, the metasurface unit structure of this application has three resonant points for TEM waves of different frequencies: S11 = -14.8 dB at 2.68 GHz, S11 = -10.41 dB at 5.94 GHz, and S11 = -14.15 dB at 8.33 GHz. S11 is less than -10 dB at all three resonant points, which means that it can effectively absorb electromagnetic signal energy of the corresponding three frequency bands and realize tri-frequency energy harvesting.

[0059] Figure 7 This is a graph showing the absorption rate of transverse electromagnetic waves of different frequencies for the metasurface unit structure provided in the embodiments of this application. Figure 7 As shown, the metasurface unit structure of this application has absorption rates of 96.7%, 90.9%, and 96.2% at the three resonant points, respectively, indicating high energy harvesting efficiency.

[0060] Figure 8 These are the S11 curves of the metasurface unit structure provided in this application for input reflection coefficients of transverse electric waves and transverse magnetic waves of different frequencies. Figure 8 As shown, the metasurface unit structure of this application has three resonance points for TE and TM waves of different frequencies, and the S11 curves of the two different polarization waves almost overlap, which means that polarization insensitivity is achieved.

[0061] Figure 9 This is a graph showing the input reflection coefficient S11 of the metasurface unit structure provided in this application for electromagnetic waves at different azimuth angles. (See graph for example.) Figure 9As shown, the metasurface unit structure of this application exhibits three resonance points for electromagnetic waves with different azimuth angles phi. Furthermore, the S11 curves almost overlap when the azimuth angles phi are 0°, 30°, 60°, and 90°, indicating that it is insensitive to the azimuth angle phi. Here, the azimuth angle phi refers to the angle between the incident direction of the electromagnetic wave and the plane of the array, measured counterclockwise from the +x axis.

[0062] Figure 10 This is a simulated radiation gain pattern of the metasurface unit structure provided in the embodiments of this application. For example... Figure 10 As shown, the gain pattern of the metasurface unit structure of this application is spherical, radiating uniformly in the horizontal and vertical directions, with a maximum gain of 20.02dB. It has omnidirectional characteristics and can stably collect radio frequency signals from different incident directions in complex electromagnetic environments.

[0063] Furthermore, the sensitivity and operating range of the energy harvesting metasurface device provided in this application embodiment were tested. The energy harvesting metasurface device in this application can still operate normally and output DC voltage even with radio frequency signals as low as -19dBW. With an input power of 19dBW, it can output 12V DC voltage. At a distance of 1m from the wireless energy transmitter, it can still output 4V DC voltage; at a distance of 3m from the wireless energy transmitter, it still outputs DC voltage. It is evident that the energy harvesting metasurface device provided in this application can operate normally with relatively low input power and a large spatial range, exhibiting high sensitivity and a large operating range.

[0064] To verify the excellent characteristics of the tri-frequency polarization-insensitive energy harvesting metasurface device of this application, the following description is provided in conjunction with different comparative examples.

[0065] Figure 11 This is a top view of the metasurface unit structure in the energy harvesting device of Scale 1. (Example:) Figure 11 As stated, Comparative Example 1 adopts the same as Figure 3 Similar metasurface unit structures to the embodiments shown, Comparative Example 1 and Figure 3 The only difference in the embodiments shown is that: in Comparative Example 1, the four open resonant rings are axially symmetrically distributed, the opening direction of the two open resonant rings on the left is to the right, and the opening direction of the two open resonant rings on the right is to the left. In addition, there is no gap between the open resonant rings and the cross structure in Comparative Example 1, that is, the distance ge between the open resonant rings and the cross structure is 0.

[0066] Figure 12 This is a graph showing the S11 curves of the input reflection coefficient of electromagnetic waves of different frequencies for the metasurface unit structure in Comparative Example 1. Figure 12 As shown, the metasurface unit structure in Comparative Example 1 has only one resonant point with a resonant frequency of 5.92 GHz and S11 = -11.87 dB, which can only achieve single-frequency energy harvesting.

[0067] Figure 13 The graphs show the reflection coefficients (S11) of the metasurface unit structure in Comparative Example 1 for input transverse electric and transverse magnetic waves of different frequencies. Figure 13 Part (a) shows the S11 curves of the input reflection coefficient for TE waves of different frequencies. Figure 13 Part (b) shows the S11 curves of the input reflection coefficient for TM waves of different frequencies. For example... Figure 13 As shown, the metasurface unit structure of Comparative Example 1 has a resonant frequency shift to 6.62 GHz when TE wave is incident, with a corresponding S11 = -19.5 dB; when TM wave is incident, the resonant frequency shifts to 4 GHz, with a corresponding S11 = -6.9 dB. This means that the metasurface unit structure of Comparative Example 1 is selective for the polarization direction of the incident wave and is polarization sensitive.

[0068] Figure 14 This is a top view of the metasurface unit structure in the energy harvesting device of Scale 2. (Example:) Figure 14 As shown, Comparative Example 2 adopts the same as... Figure 3 Similar metasurface unit structures to the embodiments shown, Comparative Example 2 and Figure 3 The only difference in the embodiments shown is that there is no gap between the open resonant ring and the cross structure in Comparative Example 2, that is, the distance ge between the open resonant ring and the cross structure is 0.

[0069] Figure 15 This is a graph showing the S11 curves of the input reflection coefficient of electromagnetic waves of different frequencies for the metasurface unit structure in Comparative Example 2. Figure 15 As shown, the first resonant frequency of the metasurface unit structure in Comparative Example 2 is 2.7 GHz, with a corresponding S11 = -0.5048 dB. The input reflection coefficient is relatively large, resulting in poor energy harvesting. The second resonant frequency is 6.34 GHz, with a corresponding S11 = -18.1333 dB. This is equivalent to the existence of only one resonant point, and there is mutual interference between different resonant frequencies.

[0070] Through the above Figures 6 to 15 Analysis shows that the energy harvesting metasurface device provided in this application embodiment can have a stable three-frequency resonant frequency within a wide incident azimuth angle, improve energy harvesting efficiency, realize three-frequency energy harvesting and is polarization insensitive, which facilitates energy reuse and has good application prospects in the fields of Internet of Things, radio frequency identification (RFID), wireless sensor network (WSN) and energy harvesting and recovery.

[0071] The above description is merely an optional embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An energy harvesting metasurface device, characterized in that, It includes multiple metasurface unit structures, wherein the metasurface unit structure comprises a metal ground layer, a dielectric layer and metal metasurface units stacked sequentially; The metal metasurface unit includes a cross structure and four concave open resonant rings. The cross structure divides the surface of the dielectric layer into four square regions. Each open resonant ring is located in a corresponding square region and has a gap with the cross structure. The four open resonant rings are rotationally symmetrical about the geometric center of the cross structure, which is the intersection of the cross structure. The cross-shaped structures in adjacent metasurface unit structures are connected by diodes. The energy harvesting metasurface device is used to harvest radio frequency energy in the 2.6 GHz to 2.7 GHz, 5.8 GHz to 6 GHz and 8.3 GHz to 8.4 GHz frequency bands and can directly power external loads.

2. The energy harvesting metasurface device according to claim 1, characterized in that, The open resonant ring is an axisymmetric structure with uniform width, including a square open ring structure and two inner folded arm structures. The two inner folded arm structures are located inside the square open ring structure and are respectively connected to the two open ends of the square open ring structure.

3. The energy harvesting metasurface device according to claim 2, characterized in that, The distance between the open resonant ring and the cross structure is 0.05 mm to 0.15 mm; The distance between the open resonant ring and the boundary of the metasurface unit structure is 0.05 mm to 0.15 mm.

4. The energy harvesting metasurface device according to claim 2, characterized in that, The width of the open resonant ring is 0.8 mm to 0.9 mm; The distance between the two inner folding arm structures is 0.3 mm to 0.4 mm; The distance between the side opposite the opening end of the square open ring structure and the end of the inner folding arm structure away from the opening end is 0.1 mm to 0.2 mm.

5. The energy harvesting metasurface device according to claim 2, characterized in that, The width of the cross structure is 1.35 mm to 1.45 mm.

6. The energy harvesting metasurface device according to claim 2, characterized in that, The side length of the metasurface unit structure is 15mm to 16mm.

7. The energy harvesting metasurface device according to any one of claims 1 to 6, characterized in that, The multiple metasurface unit structures are arranged in a rectangular array periodically. The diodes between two adjacent metasurface unit structures arranged in the horizontal direction are installed in the same polarity direction, and the diodes between two adjacent metasurface unit structures arranged in the vertical direction are installed in the same polarity direction.

8. The energy harvesting metasurface device according to claim 7, characterized in that, The diode is a Schottky diode that supports direct rectification of electromagnetic waves at frequencies of 2.6 GHz to 2.7 GHz, 5.8 GHz to 6 GHz, and 8.3 GHz to 8.4 GHz.

9. The energy harvesting metasurface device according to any one of claims 1 to 6, characterized in that, The thickness of both the metal floor layer and the metal metasurface unit is 35 μm to 36 μm; The thickness of the dielectric layer is 1 mm to 1.525 mm.

10. The energy harvesting metasurface device according to any one of claims 1 to 6, characterized in that, Both the metal floor layer and the metal metasurface unit are made of one of copper, silver, or gold. The material of the dielectric layer is F4B.

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