Miniaturized single-layer double-frequency broadband rectification metasurface

Abstract

The invention belongs to the field of wireless electromagnetic energy transmission, and particularly relates to a miniaturized single-layer double-frequency broadband rectification metasurface which comprises a metasurface unit, an LC filtering unit, a dielectric layer and a metal floor. The metasurface unit is positioned above the dielectric layer and consists of a metal patch, a diode and a metal through hole; the LC filtering unit is composed of an inductor located between the adjacent metasurface units and a capacitor located on the edge of the dielectric layer. The metal floor is positioned below the dielectric layer; the metal patch comprises an outer side metal patch and an inner side metal patch, the outer side metal patch is composed of a square frame and a horn-shaped patch, the inner side metal patch is composed of four axisymmetric exponential arrows and a square patch, the outer side metal patch and the inner side metal patch are connected through a diode, and the inner side metal patch is connected to the metal floor through a metal through hole. The rectification metasurface can realize energy absorption in frequency bands of 2.45 GHz and 5.6 GHz-6. 6 GHz and convert the energy into direct current, covers a 2.45 GHz WIFI frequency band, part of 5G frequency bands and most of 6G frequency bands, and has polarization insensitivity and wide-angle stability.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless electromagnetic energy transmission, and in particular to a miniaturized single-layer dual-frequency broadband rectifying metasurface. Background Art

[0002] Wireless energy transmission technology enables electromagnetic energy transmission through free space. Energy harvesting technology utilizes wireless energy transmission technology to collect electromagnetic energy from free space in a targeted or random manner, achieving wireless power transmission, thereby saving energy and reducing electromagnetic pollution. Low-power devices such as Bluetooth headsets, electronic watches, and VR glasses can all utilize energy harvesting technology to collect electromagnetic energy from Bluetooth, Wi-Fi, 4G / 5G, and other sources in their environment, allowing them to charge continuously around the clock. This not only avoids repeated wired charging but also improves energy efficiency.

[0003] Rectennas are a common method for achieving energy reception and conversion. Traditional rectennas consist of antennas, power combining networks, and rectifier circuits. Although they can achieve high efficiency, wide bandwidth, and a wide range of input power stability, when the polarization angle and angle of incidence of the incident wave change, the rectification efficiency will be seriously affected. In addition, the energy reception efficiency of traditional rectennas is limited by the aperture. Sometimes, in order to improve the energy reception efficiency, the aperture of the antenna has to be increased.

[0004] At present, with the development of metasurfaces, suitable metasurface structures can break through the limitations of aperture on energy absorption efficiency. Moreover, metasurfaces can more effectively control the amplitude, phase, and polarization of electromagnetic waves, achieving polarization insensitivity and a wider angle of incidence absorption. Therefore, the integration of metasurfaces with rectifier circuits has become a research focus. Researchers have made various attempts to improve the performance of rectifier metasurfaces, designing single-band rectifier metasurfaces, multi-band rectifier metasurfaces, and broadband rectifier metasurfaces. However, in order to match impedance and take into account low-frequency signals, multi-band rectifier metasurfaces often require increasing unit size and adding air layers. Broadband rectifier metasurfaces can increase the energy absorption bandwidth, but current broadband research is mostly in the high-frequency band and lacks the inclusion of low-frequency bands. Therefore, research on small-sized dual-band broadband rectifier metasurfaces that take into account both high and low frequencies is very necessary. Summary of the Invention

[0005] (1) Technical problems solved

[0006] In response to the shortcomings of the existing technology, the present invention provides a miniaturized single-layer dual-band broadband rectifying metasurface to solve the problems of the existing rectifying metasurface unit being large in size, narrow in bandwidth, and unable to take into account both high and low frequency bands at the same time.

[0007] (2) Technical solution

[0008] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0009] A miniaturized single-layer dual-band broadband rectifying metasurface includes a metasurface unit, an LC filter unit, a dielectric layer, and a metal floor layer. The metasurface unit is located above the dielectric layer and consists of a metal patch, a diode, and a metal through-hole. The LC filter unit consists of an inductor located between adjacent metasurface units and a capacitor and a resistor at the edge of the dielectric substrate. The metal floor layer is located below the dielectric layer. The metal patch includes an outer metal patch and an inner metal patch, wherein:

[0010] The outer metal patch consists of a square frame and four trumpet-shaped patches. The square frame is located at the outer edge of the metal patch. The four trumpet-shaped patches are located in the horizontal and vertical directions of the square frame respectively. The edge of the trumpet-shaped patch is an outer exponential curve. The outer exponential curve extends outward from the diode connection end to the square frame.

[0011] The inner metal patch consists of four axially symmetrical exponential arrows and a central square patch. The edge of each exponential arrow is an inner exponential curve. The four exponential arrows are placed between adjacent trumpet-shaped patches at 45 degrees, with the head end connected to the central square patch and the end loaded with a rectangular patch. The central square patch is located at the center of the metasurface unit, and the four corners of the square patch are connected to the four exponential arrows. A metal through-hole is provided in the center of the patch, which is connected to the metal floor layer.

[0012] The outer metal patch and the inner metal patch are connected by a diode, the outer metal patch is the positive electrode, and the inner metal patch is the negative electrode;

[0013] The diodes are respectively located between the outer metal patch and the inner metal patch in a vertical manner, and each metasurface unit has a diode placed in the horizontal and vertical directions respectively.

[0014] Furthermore, the LC filter unit includes an inductor located between adjacent metasurface units, two rectangular patches located at the edge of the dielectric substrate, and capacitors and resistors placed in parallel with each other; the inductor is located at the center of the adjacent metasurface units, connecting each metasurface unit to form a DC channel; the rectangular patch includes a positive electrode patch and a negative electrode patch, the positive electrode patch is connected to the metasurface unit at the edge through the inductor, and a metal through hole 2 is provided at the end of the negative electrode patch to connect to the metal floor.

[0015] Furthermore, the side length of the metasurface unit is 15.5mm-16.5mm.

[0016] In the outer metal patch, the side length of the square frame is 15mm-16mm, the width is 0.8-1.2mm, and the outer exponential curve formula of the trumpet-shaped patch edge is y=0.2e 420x .

[0017] In the inner metal patch, the inner exponential curve formula of the exponential arrow edge is y=0.2e 580x The rectangular patch at the end of the exponential arrow is 1mm-1.5mm long and 0.7mm-1.3mm wide, the side length of the central square patch is 1.2mm-1.7mm, and the radius of the metal through hole is 0.2mm-0.3mm.

[0018] Furthermore, the positive electrode patch in the LC filter unit is 10mm-12mm long and 1mm-1.2mm wide, the negative electrode patch is 8mm-10mm long and 1mm-1.2mm wide, and the radius of the metal through hole is 0.2mm-0.3mm.

[0019] Furthermore, the dielectric layer has a thickness of 2.5 mm to 3.5 mm, a relative dielectric constant of 2.5 to 2.8, and a loss tangent of 0.001 to 0.002.

[0020] Furthermore, the metal patch and the metal floor layer are both made of gold or copper, and have a thickness of 0.032 mm to 0.037 mm.

[0021] Furthermore, the rectifying metasurface is a periodically arranged structure, with the number of periodic rows being ≥4 and the number of periodic columns being ≥4.

[0022] (3) Beneficial effects

[0023] Compared with the existing technology, the present invention provides a miniaturized single-layer dual-band broadband rectifying metasurface with the following advantages:

[0024] By designing symmetrical inner and outer metal patches with exponential curves, energy absorption efficiency peaks of not less than 97% and 98%, and rectification efficiency peaks of 65% and 60% are achieved in the 2.45GHz and 5.6GHz-6.6GHz frequency bands, respectively. The energy absorption efficiency exceeds 90% in the 5.6GHz-6.6GHz frequency band, and the total absorption-rectification efficiency exceeds 40%. In addition, absorption stability with an incident polarization angle of 0°-90° is achieved in the designed frequency band. For electromagnetic waves with oblique incidence at different angles of incidence, efficient absorption of not less than 80% can be achieved for electromagnetic waves with an oblique incidence of 60°. Compared with current rectifying metasurfaces, the present invention covers the 2.45GHz WIFI band, part of the 5G band and most of the 6G band, which is superior to other single-band rectifying metasurfaces and can be used in complex electromagnetic environments for wireless energy transmission and energy collection.

[0025] By designing a miniaturized single-layer dual-band broadband rectifying metasurface, the rectifying metasurface unit size of the present invention is only 0.13λ×0.13λ, and the thickness is only 0.024λ, where λ is the wavelength of the lowest absorption frequency. Both the unit size and thickness are lower than those of other current dual-band / broadband rectifying metasurfaces.

[0026] Under the premise of miniaturizing the size of the rectifying metasurface, the present invention still has a dual-band broadband working frequency band and a high overall absorption-rectification efficiency, which is not possessed by other current rectifying metasurfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the unit structure of a miniaturized single-layer dual-band broadband rectifying metasurface of the present invention;

[0028] Figure 2 for Figure 1 A top view of

[0029] Figure 3 Schematic diagram of the overall 4×4 array miniaturized single-layer dual-band broadband rectifying metasurface in an embodiment of the present invention;

[0030] Figure 4 Graph showing how the S parameters and absorption efficiency of the rectifying metasurface unit vary with frequency in an embodiment of the present invention;

[0031] Figure 5 Graph showing variations in absorption efficiency versus frequency for different polarization angles in an embodiment of the present invention;

[0032] Figure 6 Graph showing how the absorption efficiency changes with frequency at different incident angles according to an embodiment of the present invention;

[0033] Figure 7 Graph showing the variation of the total wave absorption-rectification efficiency of the rectifying metasurface with frequency in an embodiment of the present invention.

[0034] In the figure: 1. Metasurface unit; 2. LC filter unit; 3. Dielectric layer; 4. Metal floor layer; 5. Metal patch; 6. Diode; 7. Metal through-hole 1; 8. Inductor; 9. Capacitor; 10. Resistor; 11. Outer metal patch; 12. Inner metal patch; 13. Square frame; 14. Trumpet-shaped patch; 15. Outer exponential curve; 16. Exponential arrow; 17. Center square patch; 18. Inner exponential curve; 19. Rectangular patch; 20. Positive patch; 21. Negative patch; 22. Metal through-hole 2. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0036] Example

[0037] In this experimental example, simulation software was used to analyze the miniaturized single-layer dual-band broadband rectifying metasurface prepared in this embodiment to explain the working characteristics of the structure.

[0038] A miniaturized single-layer dual-band broadband rectifying metasurface is proposed in Example 1 of the present invention. The rectifying metasurface includes a metasurface unit 1, an LC filter unit 2, a dielectric layer 3, and a metal floor layer 4. The metasurface unit 1 is located above the dielectric layer 3 and consists of a metal patch 5, a diode 6, and a metal through-hole 7. The LC filter unit 2 consists of an inductor 8 located between adjacent metasurface units 1 and a capacitor 9 and a resistor 10 at the edge of the dielectric layer 3. The metal floor layer 4 is located below the dielectric layer 3. The metal patch 5 includes an outer metal patch 11 and an inner metal patch 12, wherein:

[0039] The outer metal patch 11 is composed of a square frame 13 and four horn-shaped patches 14. The square frame 13 is located at the outer edge of the metal patch 5. The four horn-shaped patches 14 are respectively located in the horizontal and vertical directions within the square frame 13. The edge of the horn-shaped patch 14 is an outer exponential curve 15. The outer exponential curve 15 extends outward from the connection end of the diode 6 to the square frame 13. The square frame 13 can achieve resonance at a low frequency of 2.45 GHz. At the same time, the outer exponential curve 15 effectively extends the current path, thereby miniaturizing the size of the metasurface.

[0040] The inner metal patch 12 is composed of four axially symmetrical exponential arrows 16 and a central square patch 17. The edge of each exponential arrow 16 is an inner exponential curve 18. The four exponential arrows 16 are placed between adjacent horn-shaped patches 14 at a 45° angle, with the head end connected to the central square patch 17 and the end loaded with a rectangular patch 19. The central square patch 17 is located at the center of the metasurface unit 1, and the four corners of the central square patch 17 are connected to the four exponential arrows 16. A metal through hole 7 is provided in the center of the central square patch 17 to connect to the metal floor layer 4.

[0041] The outer metal patch 11 and the inner metal patch 12 are connected by a diode 6, with the outer metal patch 11 being the positive electrode and the inner metal patch 12 being the negative electrode. This design directly integrates the radiation patch with the rectifier circuit, eliminating the power synthesis network, and by adjusting the edge exponential curvature of the outer metal patch 11 and the inner metal patch 12, broadband energy absorption can be achieved.

[0042] The diodes 6 are vertically located between the outer metal patch 11 and the inner metal patch 12, and each metasurface unit 1 has a diode 6 placed in the horizontal and vertical directions respectively. The above-mentioned arrangement of the diodes 6 can achieve polarization-insensitive absorption of the incident wave, and can achieve efficient and stable absorption efficiency between the polarization angles of 0-90°.

[0043] Preferably, the LC filter unit 2 includes an inductor 8 located between adjacent metasurface units 1, two rectangular patches 19 located at the edge of the dielectric layer 3, and a capacitor 9 and a resistor 10 placed in parallel with each other; the inductor 8 is located at the center of the adjacent metasurface units 1, connecting each metasurface unit 1 to form a DC channel; the rectangular patch 19 includes a positive electrode patch 20 and a negative electrode patch 21, the positive electrode patch 20 is connected to the metasurface unit 1 at the edge through the inductor 8, and a metal through hole 22 is set at the end of the negative electrode patch 21 to connect to the metal floor layer 4.

[0044] Preferably, the side length of the metasurface unit 1 is 16.5 mm.

[0045] Preferably, in the outer metal patch 11, the side length of the square frame 13 is 15.9 mm, the width is 1.1 mm, and the formula of the outer exponential curve 15 at the edge of the trumpet-shaped patch 14 is y=0.2e 420x .

[0046] Preferably, in the inner metal patch 12, the formula of the inner exponential curve 18 at the edge of the exponential arrow 16 is y=0.2e580x, the rectangular patch 19 at the end of the exponential arrow 16 is 1.2 mm long and 1.1 mm wide, the side length of the central square patch 17 is 1.6 mm, and the radius of the metal through hole 7 is 0.2 mm.

[0047] Preferably, the positive electrode patch 20 in the LC filter unit 2 is 10 mm long and 1 mm wide, the negative electrode patch 21 is 8 mm long and 1 mm wide, and the radius of the second metal through hole 22 is 0.25 mm.

[0048] Preferably, the dielectric layer 3 has a thickness of 3 mm, a relative dielectric constant of 2.65, and a loss tangent of 0.0013.

[0049] Preferably, the metal patch 5 and the metal floor layer 4 are both made of gold or copper, and have a thickness of 0.035 mm.

[0050] Figure 3 The 4×4 array miniaturized single-layer dual-band broadband rectifying metasurface designed for the embodiment of the present invention has 4 periodic rows and 4 periodic columns, and an LC filter unit 2 is provided at the top edge of the dielectric layer 3.

[0051] Figure 4 This is a graph showing how the S parameters and absorption efficiency of the rectifying metasurface unit vary with frequency in an embodiment of the present invention. It can be seen that in the 2.45 GHz and 5.6 GHz-6.6 GHz frequency bands, the S parameters are both lower than -15 dB and the absorption efficiency is close to 100%, indicating that the present invention has good matching characteristics and excellent absorption characteristics within the dual-band broadband range.

[0052] Figure 5 The figure shows the variation of the absorption efficiency with frequency for different polarization angles in an embodiment of the present invention. It can be seen that when the polarization angle varies in the range of 0°-90°, the absorption efficiency can reach more than 96% in the designed frequency band, indicating that the present invention has polarization-insensitive absorption stability.

[0053] Figure 6 The graph below shows the variation of the absorption efficiency with frequency for different incident angles in an embodiment of the present invention. It can be seen that when the incident angle varies from 0° to 60°, when the incident angle is 0-45°, the absorption efficiency is not less than 90%, and when the incident angle reaches 60°, the absorption efficiency is not less than 80%, indicating that the present invention still has wide incident angle stability when operating under dual-band broadband conditions.

[0054] Figure 7 This is a graph showing how the total absorption and rectification efficiency of the rectifying metasurface varies with frequency in an embodiment of the present invention. It can be seen that the peak value of the total absorption and rectification efficiency can reach over 60% in the designed frequency band, and it still has a total absorption and rectification efficiency of 40% when operating in a high-frequency broadband mode. While miniaturizing the unit size, it still has broadband and high-efficiency absorption and rectification efficiency, which is not available in other rectifying metasurfaces.

[0055] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A miniaturized single-layer dual-band broadband rectifying metasurface, characterized by: The invention comprises a metasurface unit, an LC filter unit, a dielectric layer and a metal floor layer. The metasurface unit is located above the dielectric layer and consists of a metal patch, a diode and a metal through-hole. The LC filter unit consists of an inductor located between adjacent metasurface units and a capacitor and a resistor at the edge of the dielectric layer. The metal floor layer is located below the dielectric layer. The metal patch includes an outer metal patch and an inner metal patch, wherein: The outer metal patch consists of a square frame and four trumpet-shaped patches. The square frame is located at the outer edge of the metal patch. The four trumpet-shaped patches are located in the horizontal and vertical directions of the square frame respectively. The edge of the trumpet-shaped patch is an outer exponential curve. The outer exponential curve extends outward from the diode connection end to the square frame. The inner metal patch consists of four axially symmetrical exponential arrows and a central square patch. The edge of each exponential arrow is an inner exponential curve. The four exponential arrows are placed between adjacent trumpet-shaped patches at 45 degrees, with the head end connected to the central square patch and the end loaded with a rectangular patch. The central square patch is located at the center of the metasurface unit, and the four corners of the square patch are connected to the four exponential arrows. A metal through-hole is provided in the center of the patch, which is connected to the metal floor layer. The outer metal patch and the inner metal patch are connected by a diode, the outer metal patch is the positive electrode, and the inner metal patch is the negative electrode; The diodes are respectively located between the outer metal patch and the inner metal patch in a vertical manner, and each metasurface unit has a diode placed in the horizontal and vertical directions respectively.

2. The miniaturized single-layer dual-band broadband rectifying metasurface according to claim 1, characterized in that: The LC filter unit includes an inductor located between adjacent metasurface units, two rectangular patches located at the edge of the dielectric substrate, and capacitors and resistors placed in parallel with each other; the inductor is located at the center of adjacent metasurface units, connecting each metasurface unit to form a DC channel; the rectangular patch includes a positive electrode patch and a negative electrode patch, the positive electrode patch is connected to the metasurface unit at the edge through the inductor, and a metal through hole 2 is set at the end of the negative electrode patch to connect to the metal floor.

3. The miniaturized single-layer dual-band broadband rectifying metasurface according to claim 1, characterized in that: The side length of the metasurface unit is 15.5mm-16.5mm. In the outer metal patch, the side length of the square frame is 15mm-16mm, the width is 0.8-1.2mm, and the outer exponential curve formula of the trumpet-shaped patch edge is y=0.2e 420x . In the inner metal patch, the inner exponential curve formula of the exponential arrow edge is y=0.2e 580x The rectangular patch at the end of the exponential arrow is 1mm-1.5mm long and 0.7mm-1.3mm wide, the side length of the central square patch is 1.2mm-1.7mm, and the radius of the metal through hole is 0.2mm-0.3mm.

4. The miniaturized single-layer dual-band broadband rectifying metasurface according to claim 1, characterized in that: The positive electrode patch in the LC filter unit is 10mm-12mm long and 1mm-1.2mm wide, the negative electrode patch is 8mm-10mm long and 1mm-1.2mm wide, and the radius of the metal through hole is 0.2mm-0.3mm.

5. The miniaturized single-layer dual-band broadband rectifying metasurface according to claim 1, characterized in that: The dielectric layer has a thickness of 2.5 mm to 3.5 mm, a relative dielectric constant of 2.5 to 2.8, and a loss tangent of 0.001 to 0.

002.

6. The miniaturized single-layer dual-band broadband rectifying metasurface according to claim 1, characterized in that: The metal patch and the metal floor layer are both made of gold or copper, and have a thickness of 0.032 mm to 0.037 mm.

7. The miniaturized single-layer dual-band broadband rectifying metasurface according to claim 1, characterized in that: The rectifying metasurface is a periodically arranged structure, with the number of periodic rows being ≥4 and the number of periodic columns being ≥4.

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