A broadband energy harvesting and rectifying metasurface based on dual-mode resonators

Abstract

The present invention belongs to the field of energy harvesting technology, and specifically relates to a broadband energy harvesting rectifying metasurface based on a dual-mode resonator, which is composed of a periodic arrangement of basic units, wherein the basic units include a top metal layer, a dielectric layer, and a bottom metal layer etched with patterns, which are stacked in sequence, and the basic units are connected by metal wires and patch inductors; the top metal layer includes a rectangular patch and metal arms arranged at the four corners of the rectangular patch, and the top metal layer is provided with a cross slot connecting the metal arms in pairs, the connection points of the cross slot are connected by metal blocks, and diodes are provided on the arms of the cross slot; the present application has a simple structure, realizes broadband energy harvesting, and has a high absorption efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of energy harvesting technology, and in particular relates to a broadband energy harvesting rectifying metasurface based on a dual-mode resonator. Background Art

[0002] Using ambient energy harvesting technology, devices can capture weak environmental energy, such as electromagnetic, solar, and vibration, and provide it to low-power IoT sensors, improving device maintainability. In RF energy harvesting systems, traditional rectifying antennas are typically used to capture electromagnetic energy and convert it into DC power. However, the introduction of impedance matching and power combining networks introduces additional losses and increases structural complexity. Metasurfaces, composed of regularly or irregularly arranged electromagnetic units, offer advantages such as low cost, simple structure, and flexible design principles, enabling efficient energy collection from incident waves. In recent years, rectifying metasurfaces have been applied to electromagnetic RF energy harvesting and wireless energy transmission, potentially replacing traditional rectifying antennas. Most currently proposed rectifying metasurfaces only receive electromagnetic energy at a single frequency or multiple narrowband frequencies. Given the numerous and fragmented microwave frequency bands used in civilian communications, designing broadband energy harvesting metasurfaces offers a wider range of applications while also avoiding performance degradation caused by slight frequency offsets during fabrication. Therefore, research on broadband rectifying metasurfaces holds significant practical significance and broad application prospects.

[0003] Rectifying metasurfaces have been proposed for a long time. The paper (Rectifying Metasurface With High Efficiency at Low Power for 2.45GHz Band, IEEE Antennas Wireless Propag. Lett., vol. 19, no. 12, pp. 2216–2220, Dec. 2020) uses an inductive-capacitive resonant unit. By adding vias on one side of the unit, RF energy is introduced into the layer where the rectifier circuit is placed, achieving high system efficiency at 2.45GHz. However, it has two dielectric substrate layers and includes an impedance matching network. The DC energy needs to be combined by the power combining network before it can be loaded onto the load, making the structure relatively complex.

[0004] The literature (Compact Dual-Band, Wide-Angle, Polarization-Angle-Independent Rectifying Metasurface for Ambient Energy Harvesting and Wireless Power Transfer, IEEE Trans. Microw. Theory Tech., vol. 69, no. 3, pp. 1518–1528, Mar. 2021.) adopts a single-plane compact photonic bandgap unit structure and places a rectifier diode between the two units to simplify the structure while extending the energy receiving frequency to 2.4 GHz and 5.8 GHz. However, since multi-band impedance matching is a design difficulty, its system efficiency is relatively low. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a broadband energy harvesting rectifying metasurface based on a dual-mode resonator, which has a simple structure, realizes broadband energy harvesting, and has high absorption efficiency.

[0006] The present invention includes a broadband energy harvesting and rectifying metasurface based on a dual-mode resonator. The metasurface is composed of a periodic arrangement of basic units, each of which includes a top metal layer with an etched pattern, a dielectric layer, and a bottom metal layer stacked in sequence. The basic units are connected by metal wires and patch inductors.

[0007] The top metal layer includes a rectangular patch and metal arms arranged at the four corners of the rectangular patch. A cross slot is opened on the top metal layer to connect the metal arms in pairs. The connection points of the cross slot are connected by metal blocks, and diodes are arranged on the arms of the cross slot.

[0008] In one embodiment, a square groove is provided on the cross groove, and the diode is provided in the square groove.

[0009] In one embodiment, the number of the diodes is two, and they are respectively located on diagonal arms of the cross slot.

[0010] In one embodiment, the metal lines are located on the sides of the rectangular patch.

[0011] In one embodiment, there are four metal wires, which are respectively located on four sides of the rectangular patch.

[0012] In one embodiment, the number of the chip inductors is two, which are respectively located on two symmetrical sides of the rectangular patch.

[0013] In one embodiment, a via is provided on the dielectric layer, and a wire is installed in the via for connecting the top metal layer and the bottom metal layer.

[0014] In one embodiment, the number of the via holes is 2.

[0015] In one embodiment, there are two chip inductors, which are located on two symmetrical sides of the rectangular patch; and two vias are located on both sides of the connection line of the two chip inductors.

[0016] In one embodiment, the distal end of the metal arm is pointed.

[0017] The beneficial effects of the present invention are:

[0018] 1. Compared with existing rectifying metasurfaces, the present invention adopts a DC feeding structure for eliminating the power synthesis network, which can solve the problems of complex structure and low system efficiency of existing rectifying metasurfaces.

[0019] 2. Compared with the existing single-frequency rectifying metasurface, the present invention adopts a metasurface resonant unit with a metal patch loaded with a metal arm, which generates two resonant modes through the cross slot and its own pattern, and at the same time brings the two resonant points close and merges, realizing broadband energy collection.

[0020] 3. Compared with existing rectifying metasurfaces, the present invention only utilizes metasurfaces that can generate high-impedance modes, allowing them to directly perform impedance matching with the rectifying circuit, simplifying the structure and eliminating the problem of difficulty in achieving high efficiency while eliminating the impedance matching network.

[0021] 4. The rectifying metasurface designed by the present invention uses only one type of dual-mode metasurface resonator unit to achieve broadband characteristics, while being low-cost and easy to integrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the top structure of an embodiment of the present application.

[0023] Figure 2 This is a schematic structural diagram of the basic unit of an embodiment of the present application.

[0024] Figure 3 This is a side view structural diagram of the basic unit of an embodiment of the present application.

[0025] Figure 4 The reflection coefficient and absorptivity of the rectifying metasurface unit in the embodiment of the present application.

[0026] Figure 5 The overall system efficiency of the rectifying metasurface of the embodiment of the present application.

[0027] Figure 6 Sample photos of the examples of this application.

[0028] Figure 7Experimental results of the broadband rectifying metasurface according to the embodiment of the present application: reflection coefficient and absorptivity.

[0029] Figure 8 Experimental results of the broadband rectifying metasurface of the embodiment of this application: overall system efficiency.

[0030] In the figure, 1 is the chip inductor, 2 is the metal arm, 3 is the rectangular patch, 4 is the via position, 5 is the square slot, 6 is the metal line, 7 is the diode, 8 is the metal block, 9 is the cross slot, 10 is the bottom metal layer, 11 is the dielectric layer, 12 is the via, and 13 is the top metal layer. DETAILED DESCRIPTION

[0031] Example 1

[0032] like Figure 1-3 6, a broadband energy harvesting and rectifying metasurface based on a dual-mode resonator is composed of a periodic arrangement of basic units. The basic units include a top metal layer 13 with an etched pattern, a dielectric layer 11, and a bottom metal layer 10 stacked in sequence. The basic units are connected by metal wires 6 and a patch inductor 1.

[0033] The side length of the basic unit is 16mm, and the rectangular patch is located in the center of the basic unit. The top metal layer 13 includes a rectangular patch 3 with a side length of 10mm and metal arms 2 arranged at the four corners of the rectangular patch 3, which are 0.8mm away from the edge of the basic unit. The top metal layer 13 is provided with a cross slot 9 with a spacing of 0.2mm to connect the metal arms 2 in pairs. The connection point position of the cross slot 9 is connected by a metal block 8 with a width of 0.8mm. The size of the arm of the cross slot 9 is set to 1.2×1.3mm 2 The groove 5 has a diode 7 placed therein.

[0034] like Figure 1 、 6 As shown, the number of basic units is 6×6, and the total size of the rectifier metasurface is 96×105×33mm 3 The top metal layer 13 is made of 0.035mm thick copper. The dielectric layer 11 is made of F4B dielectric substrate with a relative dielectric constant of 2.2, a thickness of 3mm, and a loss tangent of 0.001. The bottom metal layer 10 is made of 0.035mm thick copper.

[0035] The basic units are arranged periodically in a rectangular shape, in one direction, e.g. Figure 1 、 6 In the longitudinal direction, each basic unit is connected in series with each other through the metal wire 6 and the patch inductor 1; in the other direction, such as Figure 1 、 6 In the horizontal direction, each metal wire 6 and the chip inductor 1 are connected in parallel to each other.

[0036] The top metal layer 13 does not cover the entire surface of the dielectric layer 11. The basic unit is a square, and the rectangular patch is a square. The metal arm 2 extends outward with the diagonal of the rectangular patch as the center axis. The end of the metal arm 2 is pointed, and the center axis protrudes outward. The vertex of the point is on the diagonal of the rectangular patch 3. The angle between the vertex of the point and the endpoints of the two edge lines of the metal arm 2 is 90 degrees. That is, the line between the vertex of the point and the endpoints of the edge line of the metal arm 2 is parallel to the edge line of the basic unit and also parallel to the side of the rectangular patch 3.

[0037] The cross slots 9 connect the metal arms 2 in pairs. In the specific implementation, the cross slots 9 are all located on the diagonals of the rectangular patches. No slots are cut at the connection points of the diagonals, that is, the center positions of the rectangular patches, leaving a rectangular metal block, that is, the metal block 8.

[0038] The cross slot 9 is provided with a square slot 5, and the diode 7 is disposed within the square slot 5. There are two diodes 7, one located on a diagonal arm of the cross slot 9. Metal wires 8 are located on the sides of the rectangular patch. There are four metal wires 6, one located on each of the four sides of the rectangular patch. There are two chip inductors 1, one located on two symmetrical sides of the rectangular patch.

[0039] The dielectric layer 11 is provided with a via 12 with a diameter of 0.3 mm, located 5 mm from the edge of the basic unit. A wire is installed in the via 12 to connect the top metal layer 13 to the bottom metal layer 10. There are two vias 12. There are two chip inductors 1, located on two symmetrical sides of the rectangular patch; two vias 12 are located on either side of the line connecting the two chip inductors 1.

[0040] In the broadband rectifier metasurface unit, diode 7 is connected in parallel in the gap between the rectangular patches. Due to the potential difference between the two ends of diode 7, a rectifier circuit equivalent to a Class-F structure is formed, where RF AC energy is converted into pulsating DC energy. The metasurface impedance is tuned to an impedance conjugate with the rectifier diode impedance, allowing direct impedance matching between the two without introducing an additional matching network. For the metasurface units in the column direction, they are connected by patch inductors 1, and DC power can be directly extracted from the unit surface, eliminating the power synthesis network.

[0041] The broadband rectifying metasurface introduces two resonant modes, whose reflection coefficients are as follows: Figure 4 As shown in the figure, the center frequencies of the two resonant modes are 5.65 GHz and 6.2 GHz respectively. At the same time, the two resonant points are brought close to each other and merged, achieving broadband energy harvesting. In the entire passband, the absorption efficiency of the metasurface exceeds 90%. The system efficiency peak is located at 6.05 GHz, as shown in the figure. Figure 5 shown.

[0042] The experimental results are as follows Figure 7 As shown in Figure 2, the measured frequency range of the rectifying metasurface is 5.32-6.66 GHz, with a bandwidth of 22.37%. The system efficiency is shown in Figure 2. Figure 8 As shown in Figure 2, the system can capture incident energy with a maximum efficiency of 74.5%. The measurement results prove that the proposed rectifying metasurface can efficiently capture electromagnetic energy in the environment over a wide frequency band and transfer it to the load.

[0043] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of protection of the present application is limited to these examples. In line with the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0044] The one or more embodiments of this application are intended to encompass all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this application should be included in the scope of protection of this application.

Claims

1. A broadband energy harvesting and rectifying metasurface based on a dual-mode resonator, characterized by: The device is composed of a periodic arrangement of basic units, wherein the basic units include a top metal layer (13) etched with a pattern, a dielectric layer (11) and a bottom metal layer (10) stacked in sequence, and the basic units are connected via metal wires (6) and a patch inductor (1); The top metal layer (13) includes a rectangular patch (3) and metal arms (2) arranged at the four corners of the rectangular patch (3). The top metal layer (13) is provided with a cross slot (9) for connecting the metal arms (2) in pairs. The connection points of the cross slot (9) are connected through a metal block (8). A diode (7) is provided on the arm of the cross slot (9).

2. The broadband energy harvesting rectifying metasurface based on a dual-mode resonator according to claim 1, characterized in that: A square groove (5) is provided on the cross groove (9), and the diode (7) is provided in the square groove (5).

3. The broadband energy harvesting rectifying metasurface based on a dual-mode resonator according to claim 1, characterized in that: There are two diodes (7), which are respectively located on diagonal arms of the cross slot (9).

4. The broadband energy harvesting rectifying metasurface based on a dual-mode resonator according to claim 1, wherein: The metal wire (6) is located on the side of the rectangular patch (3).

5. The broadband energy harvesting rectifying metasurface based on dual-mode resonators according to claim 4 is characterized in that: There are four metal wires (6), which are respectively located on the four sides of the rectangular patch (3).

6. The broadband energy harvesting rectifying metasurface based on dual-mode resonators according to claim 5, characterized in that: The number of the patch inductors (1) is two, and they are respectively located on two symmetrical sides of the rectangular patch (3).

7. The broadband energy harvesting rectifying metasurface based on a dual-mode resonator according to any one of claims 1 to 6, characterized in that: A via (12) is provided on the dielectric layer (11), and a wire is installed in the via (12) for connecting the top metal layer (13) and the bottom metal layer (10).

8. The broadband energy harvesting rectifying metasurface based on a dual-mode resonator according to claim 7, characterized in that: The number of the via holes (12) is 2.

9. The broadband energy harvesting rectifying metasurface based on dual-mode resonators according to claim 8, characterized in that: There are two chip inductors (1), which are respectively located on two symmetrical sides of the rectangular patch (3); and two vias (12) are located on both sides of the connection line of the two chip inductors (1).

10. The broadband energy harvesting rectifying metasurface based on a dual-mode resonator according to any one of claims 1 to 6, characterized in that: The end of the metal arm (2) is pointed.

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