Miniaturized single-layer dual-band wideband rectifying metasurface

Abstract

The application belongs to the field of wireless electromagnetic energy transmission, and particularly relates to a miniaturized single-layer double-frequency broadband rectifying metasurface which comprises a metasurface unit, an LC filter unit, a dielectric layer and a metal ground plate; the metasurface unit is composed of a metal patch, a diode and a metal via and is located above the dielectric layer; the LC filter unit is composed of an inductor located between adjacent metasurface units and a capacitor at the edge of the dielectric layer; the metal ground plate is located below the dielectric layer; the metal patch comprises an outer metal patch and an inner metal patch, the outer metal patch is composed of a square frame and a horn-shaped patch, the inner metal patch is composed of four axisymmetric exponential arrows and a square patch, the outer metal patch and the inner metal patch are connected by the diode, and the inner metal patch is connected to the metal ground plate by the metal via. The rectifying metasurface can realize energy absorption and conversion into direct current in the frequency bands of 2.45 GHz and 5.6 GHz-6.6 GHz, covers the 2.45 GHz WIFI frequency band, part of the 5G frequency band and most of the 6G frequency band, and has polarization insensitivity and wide-angle stability.

Description

TECHNICAL FIELD

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

[0002] Wireless energy transmission technology can realize electromagnetic energy transmission through free space, and energy harvesting technology can collect electromagnetic energy from free space in a directional or random manner to realize wireless power transmission, thereby achieving the purposes of energy saving and reducing electromagnetic pollution. Low-power devices such as Bluetooth earphones, electronic watches and VR glasses can collect electromagnetic energy such as Bluetooth, WIFI and 4G / 5G in the environment to charge the devices all day long, which not only avoids repeated wired charging, but also improves energy utilization efficiency.

[0003] Rectenna is a common method to realize energy reception and conversion. The traditional rectenna is composed of an antenna, a power combining network and a rectifier circuit. Although it can realize high efficiency, wide bandwidth and large range of input power stability, the rectification efficiency will be seriously affected when the polarization angle and the incident angle of the incident wave change. Moreover, the energy reception efficiency of the traditional rectenna 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, a suitable metasurface structure can break through the limitation of aperture on energy absorption efficiency, and the metasurface can more effectively control the amplitude, phase and polarization of electromagnetic waves, realize polarization insensitivity and wider incident absorption angle. Therefore, the integration of metasurface and rectifier circuit has become a research focus. Researchers have made various attempts to improve the performance of rectifying metasurfaces and designed single-band rectifying metasurfaces, multi-band rectifying metasurfaces and broadband rectifying metasurfaces. However, in order to match the impedance and consider low-frequency signals, multi-band rectifying metasurfaces often need to increase the size of the unit and add air layers; while broadband rectifying metasurfaces can increase the energy absorption bandwidth, but current broadband research is mostly in the high-frequency band, lacking the addition of low-frequency band. Therefore, it is necessary to research dual-frequency broadband rectifying metasurfaces with small size and considering high and low frequencies. SUMMARY

[0005] (I) Technical problems solved

[0006] In view of the deficiencies of the prior art, the present application provides a miniaturized single-layer dual-frequency broadband rectifying metasurface, which solves the problems of large unit size, narrow bandwidth and inability to simultaneously consider high and low frequency bands of existing rectifying metasurfaces.

[0007] (II) Technical solutions

[0008] The application specifically adopts the following technical solutions to achieve the above-mentioned purpose.

[0009] A miniaturized single-layer dual-frequency broadband rectifying metasurface, comprising a metasurface unit, an LC filter unit, a dielectric layer and a metal ground layer, the metasurface unit is composed of a metal patch, a diode and a metal via above the dielectric layer; the LC filter unit is composed of an inductor between adjacent metasurface units and a capacitor and a resistor at the edge of the dielectric substrate; the metal ground layer is below the dielectric layer; the metal patch comprises an outer metal patch and an inner metal patch, wherein:

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

[0011] The inner metal patch is composed of four axisymmetric exponential arrows and a central square patch, the edge of each exponential arrow is an inner exponential curve, the four exponential arrows are respectively placed at 45° between adjacent horn-shaped patches, the leading end is connected with the central square patch, and the trailing end is loaded with a rectangular patch; the central square patch is located at the center of the metasurface unit, the four corners of the square patch are connected with the four exponential arrows, and a metal via one is connected to the metal ground layer at the center of the patch;

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

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

[0014] Further, the LC filter unit comprises an inductor between adjacent metasurface units, two rectangular patches at the edge of the dielectric substrate, and a capacitor and a resistor 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 direct current channel; the rectangular patch comprises a positive patch and a negative patch, the positive patch is connected with the metasurface unit at the edge through the inductor, and the negative patch is connected with the metal ground through a metal via two at the trailing end.

[0015] Further, 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 edge of the horn-shaped patch is y=0.2e 420x .

[0017] 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 central square patch is 1.2mm-1.7mm long, and the metal through hole is 0.2mm-0.3mm in radius.

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

[0019] Further, the thickness of the dielectric layer is 2.5mm-3.5mm, the relative dielectric constant is 2.5-2.8, and the loss tangent is 0.001-0.002.

[0020] Further, the material of the metal patch and the metal ground layer is one of gold or copper, and the thickness is 0.032mm-0.037mm.

[0021] Further, the rectifying metasurface is a periodic arrangement structure, and the number of periodic rows is greater than or equal to 4 and the number of periodic columns is greater than or equal to 4.

[0022] (Three) beneficial effects

[0023] Compared with the prior art, the present application provides a miniaturized single-layer dual-frequency broadband rectifying metasurface, which has the following beneficial effects:

[0024] By designing symmetric 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 at 2.45GHz and 5.6GHz-6.6GHz frequency bands, respectively, wherein the energy absorption efficiency exceeds 90% at 5.6GHz-6.6GHz frequency band, the total absorption-rectification efficiency exceeds 40%, and the absorption stability is achieved at an incident polarization angle of 0°-90° in the designed frequency band. For electromagnetic waves with different incident angles, the high-efficiency absorption of not less than 80% can be achieved for electromagnetic waves with 60° oblique incidence. Compared with the current rectifying metasurface, the present application covers 2.45GHz WIFI frequency band, part of 5G frequency band and most of 6G frequency band, which is superior to other single-frequency rectifying metasurfaces and can be applied in complex electromagnetic environment for wireless energy transmission and energy collection.

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

[0026] The present application still has a dual-frequency broadband operating frequency band and a high-efficiency wave absorption-rectification total efficiency under the premise of miniaturizing the size of the rectifying metasurface, which is not possessed by other current rectifying metasurfaces. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a unit structure schematic diagram of the miniaturized single-layer dual-frequency broadband rectifying metasurface of the present application;

[0028] Figure 2 It is a top view of Figure 1 ;

[0029] Figure 3 It is a whole schematic diagram of the 4x4 array miniaturized single-layer dual-frequency broadband rectifying metasurface in the embodiment of the present application;

[0030] Figure 4 It is a graph of S parameters and wave absorption efficiency of the rectifying metasurface unit varying with frequency in the embodiment of the present application;

[0031] Figure 5 It is a graph of wave absorption efficiency corresponding to different polarization angles varying with frequency in the embodiment of the present application;

[0032] Figure 6 It is a graph of wave absorption efficiency corresponding to different incidence angles varying with frequency in the embodiment of the present application;

[0033] Figure 7 It is a graph of wave absorption-rectification total efficiency of the rectifying metasurface varying with frequency in the embodiment of the present application.

[0034] In the figure: 1, metasurface unit; 2, LC filter unit; 3, dielectric layer; 4, metal ground plane layer; 5, metal patch; 6, diode; 7, metal via one; 8, inductor; 9, capacitor; 10, resistor; 11, outer metal patch; 12, inner metal patch; 13, square frame; 14, horn-shaped patch; 15, outer exponential curve; 16, exponential arrow; 17, center square patch; 18, inner exponential curve; 19, rectangular patch; 20, positive electrode patch; 21, negative electrode patch; 22, metal via two. DETAILED DESCRIPTION

[0035] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0036] Embodiment

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

[0038] The miniaturized single-layer dual-frequency broadband rectifying metasurface provided in Embodiment One of the present application comprises a metasurface unit 1, an LC filter unit 2, a dielectric layer 3 and a metal ground layer 4. The metasurface unit 1 is composed of a metal patch 5, a diode 6 and a metal via 1 7 above the dielectric layer 3; the LC filter unit 2 is composed of an inductor 8 between adjacent metasurface units 1 and a capacitor 9 and a resistor 10 at the edge of the dielectric layer 3; the metal ground layer 4 is below the dielectric layer 3; the metal patch 5 comprises 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 peripheral edge of the metal patch 5, and 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, which extends outward from the connection end of the diode 6 to the square frame 13. The square frame 13 can realize resonance at a low frequency of 2.45 GHz, and the outer exponential curve 15 better extends the current path, realizing the miniaturization of the size of the metasurface;

[0040] The inner metal patch 12 is composed of four axisymmetric 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 respectively placed at 45° between adjacent horn-shaped patches 14, with the first end connected to the central square patch 17 and the last end loaded with a rectangular patch 19. The central square patch 17 is located at the center of the metasurface unit 1. The four corners of the central square patch 17 are connected to the four exponential arrows 16, and the center of the central square patch 17 is provided with a metal via 1 7 connected to the metal ground layer 4;

[0041] The outer metal patch 11 and the inner metal patch 12 are connected by the diode 6, the outer metal patch 11 is positive, and the inner metal patch 12 is negative, which directly integrates the radiation patch with the rectifier circuit, eliminates the power synthesis network, and can realize wideband energy absorption by adjusting the edge exponential curvature of the outer metal patch 11 and the inner metal patch 12.

[0042] The diode 6 is arranged in a vertical manner between the outer metal patch 11 and the inner metal patch 12, and one diode 6 is arranged in the horizontal and vertical directions of each metasurface unit 1; the above-mentioned diode 6 arrangement can realize polarization-insensitive absorption of incident waves, and high-efficiency and stable absorption efficiency can be realized 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 arranged in parallel with each other; the inductor 8 is located at the center of the adjacent metasurface unit 1, and connects the metasurface units 1 to form a direct current channel; the rectangular patch 19 includes a positive patch 20 and a negative patch 21, the positive patch 20 is connected to the metasurface unit 1 at the edge through the inductor 8, and the negative patch 21 is connected to the metal floor layer 4 through the metal through hole two 22 arranged at the end.

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

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

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

[0047] Preferably, in the LC filter unit 2, the positive patch 20 has a length of 10mm and a width of 1mm, the negative patch 21 has a length of 8mm and a width of 1mm, and the metal through hole two 22 has a radius of 0.25mm.

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

[0049] Preferably, the material of the metal patch 5 and the metal floor layer 4 is one of gold or copper, and the thickness is 0.035mm.

[0050] Figure 3 The 4*4 array miniaturized single-layer dual-band rectifying metasurface designed for the embodiment of the present application has 4 periodic rows and 4 periodic columns, and LC filter units 2 are arranged at the top edge of the dielectric layer 3.

[0051] Figure 4 As can be seen from the graph of the S parameter and the wave absorption efficiency of the rectifying metasurface unit in the embodiment of the present application varying with the frequency, the S parameter is lower than -15 dB and the wave absorption efficiency is close to 100% in the frequency bands of 2.45 GHz and 5.6-6.6 GHz, indicating that the present application has good matching characteristics and excellent wave absorption characteristics in the dual-band wideband range.

[0052] Figure 5 As can be seen from the graph of the wave absorption efficiency corresponding to different polarization angles varying with the frequency in the embodiment of the present application, when the polarization angle changes in the range of 0°-90°, the wave absorption efficiency can reach more than 96% in the designed frequency band, indicating that the present application has polarization-insensitive absorption stability.

[0053] Figure 6 As can be seen from the graph of the wave absorption efficiency corresponding to different incidence angles varying with the frequency in the embodiment of the present application, when the incidence angle changes in the range of 0°-60°, the absorption efficiency is not less than 90% when the incidence angle is 0-45°, and the absorption efficiency is not less than 80% when the incidence angle reaches 60°, indicating that the present application still has wide-angle stability when working in the dual-band wideband condition.

[0054] Figure 7 As can be seen from the graph of the wave absorption-rectification total efficiency of the rectifying metasurface varying with the frequency in the embodiment of the present application, the peak value of the wave absorption-rectification total efficiency can reach more than 60% in the designed frequency band, and the wave absorption-rectification total efficiency is still 40% when working in the high-frequency wideband, which means that the present application still has wideband high-efficiency wave absorption-rectification efficiency while the unit size is miniaturized, which is not possessed by other rectifying metasurfaces.

[0055] Finally, it should be noted that: the above only describes the preferred embodiments of the present application and is not used to limit the present application, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments or make equivalent replacement for some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A miniaturized single-layer dual-frequency broadband metasurface, characterized in that: The application relates to a rectifying metasurface, which comprises a metasurface unit, an LC filter unit, a dielectric layer and a metal floor layer. The outer metal patch is composed of a square frame and four horn-shaped patches, the square frame is located at the peripheral edge of the metal patch, the four horn-shaped patches are respectively located in the horizontal and vertical directions within the square frame, the edge of the horn-shaped patch is an outer exponential curve, and the outer exponential curve extends outward from the connecting end of the diode to the square frame. The inner metal patch is composed of four axisymmetric exponential arrows and a central square patch, the edge of each exponential arrow is an inner exponential curve, the four exponential arrows are respectively placed at 45 DEG between adjacent horn-shaped patches, the leading end is connected with the central square patch, and the trailing end is loaded with a rectangular patch; the central square patch is located at the central position of the metasurface unit, the four corners of the square patch are connected with the four exponential arrows, and a metal through hole one is arranged in the center of the patch and connected to the metal floor layer. The outer metal patch and the inner metal patch are connected by the diode, the outer metal patch is the positive electrode, and the inner metal patch is the negative electrode. The diode is arranged in a vertical manner between the outer metal patch and the inner metal patch, and one diode is arranged in the horizontal and vertical directions of each metasurface unit.

2. The miniaturized single-layer dual-frequency broadband rectifying metasurface of claim 1, wherein: The LC filter unit comprises an inductor between adjacent metasurface units, two rectangular patches at the edge of the dielectric substrate, and a capacitor and a resistor arranged in parallel with each other; the inductor is located at the central position of the adjacent metasurface units, connects the metasurface units, and forms a direct current channel; the rectangular patch comprises a positive electrode patch and a negative electrode patch, the positive electrode patch is connected with the metasurface unit at the edge through the inductor, and the negative electrode patch is provided with a metal through hole two connected with the metal floor.

3. The miniaturized single-layer dual-band wideband rectifying metasurface of claim 1, wherein: The side length of the metasurface unit is 15.5mm-16.5mm, In the outer metal patch, the square frame side length is 15mm-16mm, the width is 0.8-1.2mm, the outer exponential curve formula of the edge of the horn-shaped patch 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 has a length of 1mm-1.5mm and a width of 0.7mm-1.3mm, the central square patch has a side length of 1.2mm-1.7mm, and the metal through hole has a radius of 0.2mm-0.3mm.

4. The miniaturized single-layer dual-frequency broadband rectifying metasurface of claim 1, wherein: The positive electrode patch in the LC filter unit has a length of 10mm-12mm and a width of 1mm-1.2mm, the negative electrode patch has a length of 8mm-10mm and a width of 1mm-1.2mm, and the metal through hole two has a radius of 0.2mm-0.3mm.

5. The miniaturized single-layer dual-frequency broadband rectifying metasurface of claim 1, wherein: The thickness of the dielectric layer is 2.5mm-3.5mm, the relative dielectric constant is 2.5-2.8, and the loss tangent is 0.001-0.

002.

6. The miniaturized single-layer dual-frequency broadband rectifying metasurface of claim 1, wherein: The material of the metal patch and the metal floor layer is one of gold and copper, and the thickness is 0.032mm-0.037mm.

7. The miniaturized single-layer dual-frequency broadband rectifying metasurface of claim 1, wherein: The rectifying metasurface is a periodic arrangement structure, and the number of periodic rows is greater than or equal to 4, and the number of periodic columns is greater than or equal to 4.

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