Rotary multi-channel focusing reflection metasurface

Abstract

The invention discloses a rotary multi-channel focusing reflection metasurface, and belongs to the technical field of metasurfaces. The rotary multi-channel focusing reflection metasurface is composed of 225 phase shift units, multi-channel focusing can be achieved through rotation, the manufacturing process is simple, the machining cost is low, and the array is a plane and is easy to disassemble and transfer. The metasurface unit forming the multi-channel focusing reflection metasurface is composed of three layers of metal copper patches and two dielectric layers. The third layer takes metal copper as a floor structure to ensure the reflection coefficient of the unit, the second layer of metal is a Jerusalem cross structure with four accompanying oscillators on the outer side, and the first layer of metal is three x-direction rectangular patches. The metasurface array has the polarization multiplexing characteristic and the frequency multiplexing characteristic, and multi-channel focusing can be achieved by mechanically rotating the metasurface array on the upper layer or the lower layer at different frequency bands.

Description

Technical Field

[0001] The present invention belongs to the field of super surface technology and relates to a rotating multi-channel focusing reflection super surface which can be used for wireless energy transmission in the microwave field. Background Art

[0002] With the rapid development of science and technology and the continuous progress of society, traditional wired power transmission methods can no longer meet people's growing diversified life needs. Therefore, the realization of wireless power transmission (WPT) technology has opened up a broader and more flexible new way for humans to use electrical energy. In the pursuit of long-distance transmission, microwave wireless power transmission technology has shown potential through the far-field radiation mechanism. However, the far-field distance loss caused by the divergent characteristics of the transmitting beam has become a major challenge. In contrast, near-field focusing (NFF) technology can theoretically accurately focus the electromagnetic waves of the transmitting source at a specific point in the near-field area of ​​the antenna radiation, effectively avoiding the energy loss caused by beam divergence. Although NFF has been realized through a variety of antenna structures such as parabolic antennas, lens antennas, and phased array antennas, these traditional methods face problems such as difficult processing, high cost, or high component loss, which limits their widespread application in the field of WPT.

[0003] Electromagnetic wave focusing refers to the convergence of electromagnetic wave energy to the receiving area, which has a wide range of applications in wireless power transmission, optical imaging, MIMO systems, biomedicine and other fields. In the microwave frequency band, the array antenna can achieve the effect of near-field focusing by changing its own arrangement and the phase shift network loaded at the front end. However, the array antenna control network of this method is complex, and it is difficult to achieve energy distribution at each focus. Metasurfaces have unique advantages in manipulating electromagnetic wave characteristics. By designing a sub-wavelength unit structure, they can modulate the amplitude, phase, polarization direction and other characteristics of the input electromagnetic wave. At the same time, they are small in size and simple to process, making them excellent carriers for microwave focusing. However, the traditional focusing metasurface has a single function. Although additional structures can be introduced to design a focusing metasurface with independent control of dual-frequency and dual-polarization modes to achieve the function of four-channel focusing. However, due to the limitation that only two mutually orthogonal polarization directions and two different frequencies can be independently controlled, the number of channels of most dual-frequency and dual-polarization focusing metasurfaces currently studied is difficult to further expand. Summary of the invention

[0004] In view of this, an object of the present invention is to provide a rotating multi-channel focusing reflective metasurface, which realizes more focusing channels by rotating the array, thereby achieving more focusing effects on a single metasurface.

[0005] To achieve the above-mentioned purpose, the present invention provides a rotating multi-channel focusing metasurface unit on the one hand, which includes 3 metal layers and 2 dielectric substrates, and the metal layers are connected by the dielectric substrates; the third layer of the metal layer uses metal copper as the floor structure, the second layer of metal is a Jerusalem cross plus four outer companion oscillator structures, and the first layer of metal consists of three x-direction rectangular patches.

[0008] Furthermore, the dielectric substrate is made of F4B.

[0009] Furthermore, by encoding the parameters of the metal sheet to control the physical size of the metal sheet and the direction of the rotation unit, the metasurface unit can independently control the reflection phase response of the incident electromagnetic waves of two operating frequencies and polarization directions, thereby realizing a five-channel focusing function.

[0010] Specifically, by independently or simultaneously adjusting the length of the Jerusalem cross plus the four outer companion oscillators and the direction of the rotation unit, the x- and y-polarized incident electromagnetic waves at an operating frequency of 10 GHz can be adjusted to achieve a reflection amplitude greater than 0.85 and a continuous change of the reflection phase between 0° and 180°. By independently or simultaneously adjusting the length of the Jerusalem cross plus the four outer companion oscillators, the x- and y-polarized incident electromagnetic waves at an operating frequency of 14 GHz can be adjusted to achieve a reflection amplitude greater than 0.9 and a continuous change of the reflection phase between 0° and 180°.

[0011] On the other hand, the present invention provides a rotating multi-channel focusing reflective metasurface, which is composed of the above-mentioned multi-channel focusing metasurface unit arrangement. The multi-channel focusing metasurface has polarization multiplexing characteristics and frequency multiplexing characteristics, and realizes independent regulation of electromagnetic response by changing the direction of the metal patch corresponding to the frequency and polarization, has the ability to independently select and convert x-polarization and y-polarization, and can independently regulate the reflection phase response of the incident electromagnetic wave in the x-direction and y-direction at 10GHz and 14GHz, and can realize the focusing function of five channels by rotation, thereby improving the unit's ability to regulate electromagnetic waves and realizing electromagnetic regulation.

[0012] The beneficial effects of the present invention are:

[0013] (1) Compared with the general dual-frequency dual-polarization focusing reflective metasurface, the present invention has more focusing channels and can achieve more focusing effects on a single metasurface.

[0014] (2) The present invention has polarization multiplexing characteristics and frequency multiplexing characteristics. Independent adjustment is achieved by changing the physical parameters corresponding to frequency and polarization. The reflection phase response of the incident electromagnetic wave can be independently controlled in the x-direction and y-direction at 10 GHz and 14 GHz to achieve five different focusing functions. By rotating the three rectangular patches on the first metal plate, the unit's ability to control electromagnetic waves is improved, the focusing channel of the metasurface is expanded, and a more efficient electromagnetic wave focusing function is achieved.

[0015] (3) The physical structure of a rotating multi-channel focusing reflective metasurface proposed in the present invention is composed of a double-layer plate. During testing, the electromagnetic waves can be regulated by mechanical rotation to generate new channels.

[0016] (4) The present invention uses F4B material with a thickness of 1.6 mm as the dielectric substrate, which has a low cost and has the characteristics of miniaturization and integration while maintaining low loss and high performance.

[0017] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0019] Figure 1 A schematic diagram of the three-dimensional structure of a rotating multi-channel focusing reflective metasurface unit proposed in an embodiment of the present invention;

[0020] Figure 2 A schematic front view of the first layer of a rotating multi-channel focusing reflective metasurface unit proposed in an embodiment of the present invention;

[0021] Figure 3 A schematic front view of the second layer of a rotating multi-channel focusing reflective metasurface unit proposed in an embodiment of the present invention;

[0022] Figure 4 is the transmission amplitude and transmission phase diagram of the focused reflective metasurface unit, Figure 4 (a) is the reflection phase difference and reflection amplitude of the unit at 10 GHz. Figure 4 (b) is the reflection phase difference and reflection amplitude of the unit at 14 GHz;

[0023] Figure 5 To focus on the isolation of reflective metasurface units in different frequency bands, Figure 5(a) l1 / l2 and llx / lly isolation at 10 GHz; Figure 5 (b) l1 / l2 and llx / lly isolation at 14 GHz;

[0024] Figure 6 A front structural diagram of a metasurface composed of focusing reflective metasurface units;

[0025] Figure 7 Phase distribution diagram of the five channels of the metasurface composed of focusing reflective metasurface units. Figure 7 (a) and (f) are the phase distribution diagrams when the focus position is (-20, 90, 170) mm. Figure 7 (b) and (g) are the phase distribution diagrams when the focus position is (-20, 90, 170) mm. Figure 7 (c) and (h) are the phase distribution diagrams when the focus position is (30, 90, 170) mm. Figure 7 (d) and (i) are the phase distribution diagrams when the focus position is (-30, 90, 170) mm. Figure 7 (e) and (j) are the phase distribution diagrams when the focus position is (0, 90, 170) mm;

[0026] Figure 8 This is the simulation result diagram of the focusing reflective metasurface. Figure 8 When (a) and (b) are at 10 GHz, the focus can be switched between (-20, 90, 170) mm and (20, 90, 170) mm by rotating the lower layer. Figure 8 When (c) and (d) are at 14 GHz, the focus can be switched between (-30, 90, 170) mm and (-30, 90, 170) mm by rotating the lower layer. Figure 8 (e) When the frequency is 14 GHz, the upper layer can be rotated to focus at the position of (0, 90, 170) mm, achieving dual-frequency five-focus adjustment;

[0027] Fig. 9 Schematic diagram and test results of the rotating multi-channel focusing reflective metasurface. Fig. 9 (a) is a test diagram of the multi-channel focusing reflective metasurface. Fig. 9 (b) The layout of the darkroom test. Fig. 9 (c) is the test result of multi-channel focusing reflection metasurface at 10 GHz. Fig. 9 (d) is the test result of multi-channel focusing reflection metasurface at 14 GHz;

[0028] Figure numerals: 1 - first metal sheet; 2 - second metal sheet; 3 - third metal sheet; 4 - dielectric substrate. DETAILED DESCRIPTION

[0029] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0030] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0031] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0032] A rotating multi-channel focusing reflective metasurface unit provided by an embodiment of the present invention is as follows Figure 1 to Figure 3 As shown, the five-channel focusing reflective metasurface unit is composed of three metal layers 1-3 and two dielectric substrates 4, and the dielectric substrate 4 is located between the metal layers. The metal layers include a first metal sheet 1, a second metal sheet 2, and a third metal sheet 3, wherein the first metal sheet 1 is a rectangular patch of three x-direction strips, and the second metal sheet 2 is a Jerusalem cross-shaped metal sheet with four accompanying oscillator structures on the outside. The two arms of the cross-shaped metal sheet are parallel to the x-axis and the y-axis respectively and are placed in the center of the metal layer, and the four accompanying oscillator metal sheets are placed in positions parallel to the cross-shaped metal sheet. The third metal sheet 3 is a metal ground, which mainly ensures the high reflectivity of the unit.

[0033] The width w3 of the rectangular patch of the first layer is equal to the width w1 of the rectangular patch of the second layer, such as Figure 2As shown in Figure 3, the width of the three rectangular metal strips in the x direction on the first metal layer is w3. The lengths of the two cross-shaped branches on the first metal layer are l1 and l2 respectively, and they are placed in the center of the metal layer along the x and y axes. The lengths of the four accompanying oscillator structure metal sheets are llx and lly respectively, which are parallel to the two cross-shaped oscillators respectively. The width of the oscillators is w1. The above metal sheets generate electromagnetic resonance under the incidence of polarized waves. By adjusting the structural dimensions in the corresponding directions of the corresponding frequency bands, the high reflectivity and phase response in the two polarization directions in the two frequency bands can be independently controlled.

[0034] The operating frequencies of the rotating five-channel focusing reflective metasurface unit are 10 GHz and 14 GHz, and the unit period P is 14 mm; the dielectric substrate material is F4B, the dielectric constant is 2.2, the tangent value of the loss angle is 0.001, and the single layer thickness is 1.6 mm.

[0035] The rotating five-channel focusing metasurface unit has the characteristic of increasing polarization multiplexing by rotation, and can work at 10GHz and 14GHz at the same time, realizing independent regulation of the reflection phase in the x and y polarization directions. At 10GHz, the preferred metal sheet lengths l1 and l2 can be independently or simultaneously regulated, with a regulation size range of 5mm to 7mm, realizing a reflection phase change of 0° to 180°; in addition, the lengths llx and lly of the four accompanying oscillators can be independently or simultaneously regulated with a regulation size range of 5mm to 8mm, realizing a reflection phase change of 0° to 180°, and the reflection amplitude within the regulated range is greater than 0.85; by regulating the length parameters l1, l2, llx and lly of the metal patches in the x and y directions, the unit has different electromagnetic responses under the excitation of incident waves in different frequency bands and different polarization directions. Therefore, the reflective metasurface composed of the rotating five-channel focusing metasurface units can realize five different electromagnetic focusing functions under the incidence of x-polarized and y-polarized waves at 10GHz and 14GHz.

[0036] Figure 4 The figure shows the reflection phase and amplitude changes with the parameters l1, l2, llx and lly, and the reflection phase response of the five-channel focusing metasurface unit in the frequency bands near 10 GHz and 14 GHz. According to the simulation results, Figure 4 As shown in (a), at 10 GHz, the reflection amplitude of the unit is above 0.85 and maintains a stable 180° phase difference; Figure 4 As shown in (b), at 14 GHz, the reflection amplitude of the unit is above 0.9 and maintains a stable phase difference of 180°.

[0037] Figure 5The figure shows the coupling of high and low frequency points. When the reflection phase at 10 GHz is controlled by changing the size of l1 and l2, the phase response at 14 GHz is less than 10°, which is within an acceptable range. x andll y When the size controls the reflection phase at 14 GHz, the phase response at 10 GHz is less than 5°. The phases of both frequencies can be controlled by changing the size of key parameters, and the vertical polarization and horizontal polarization can be independent of each other, achieving four independent phases.

[0038] Figure 6 It is a metasurface composed of rotating five-channel focusing metasurface units; the operating frequency of the metasurface is 10GHz and 14GHz, and the reflective metasurface is composed of 15×15 units, with a square structure and a side length of 210mm.

[0038] Figure 7 Shown is the phase distribution diagram of the five channels of the metasurface composed of five-channel focusing metasurface units. When the y-polarized incident wave irradiates the reflective metasurface, the Jerusalem cross patch of the lower layer can be rotated to focus at (-20, 90, 170) mm and (20, 90, 170) mm at 10 GHz, and the outer companion oscillator patch can be used to focus at (-30, 90, 170) mm and (30, 90, 170) mm at 14 GHz. By rotating the array where the three x-direction rectangular patches of the upper layer are located, the surface current of the lower array can be basically shielded, achieving focusing at (0, 90, 170) mm.

[0039] Figure 8 In the case of fixed vertical polarization irradiation metasurface, at 10 GHz, the focus position can be switched between (-20, 90, 170) mm and (20, 90, 170) mm by rotating the lower layer. At 14 GHz, the focus position can be switched between (-30, 90, 170) mm and (30, 90, 170) mm by rotating the lower layer. At this time, focusing at the position of (0, 90, 170) mm can be achieved by rotating the upper layer, realizing dual-frequency five-focus adjustment.

[0040] Fig. 9 This is a measured image of a five-channel focusing reflective metasurface. The test platform consists of a horn antenna, a five-channel focusing reflective metasurface, a probe, and a vector network analyzer. Finally, through the test, the reflective focusing metasurface can achieve focusing at five positions with good focusing effect, which illustrates the effectiveness of achieving adjustable focus by rotating the array.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A rotating multi-channel focusing metasurface unit, characterized in that: The metasurface unit includes three metal layers and two dielectric substrates, and the metal layers are connected by the dielectric substrates; the third metal layer uses metal copper as a floor structure, the second metal layer is a Jerusalem cross structure with four companion oscillators on the outside, and the first metal layer consists of three x-direction rectangular patches.

2. The multi-channel focusing metasurface unit according to claim 1, characterized in that: By adjusting the physical size of the metal sheet and rotating the first metal layer and the first dielectric substrate, the metasurface unit can independently adjust the reflection phase response of the incident electromagnetic waves of two operating frequencies and polarization directions, thereby realizing a five-channel focusing function.

3. The multi-channel focusing metasurface unit according to claim 2, characterized in that: By independently or simultaneously regulating the length of the Jerusalem cross plus the four outer companion oscillators and rotating the metasurface unit, it is possible to regulate the x- and y-polarized incident electromagnetic waves at an operating frequency of 10 GHz, achieving a reflection amplitude greater than 0.85 and a continuous change of the transmission phase between 0° and 360°.

4. The multi-channel focusing metasurface unit according to claim 2, characterized in that: By independently or simultaneously adjusting and rotating the length of the Jerusalem cross plus the four outer companion oscillators, the metasurface unit can regulate the x- and y-polarized incident electromagnetic waves at an operating frequency of 14 GHz, achieving a reflection amplitude greater than 0.9 and a continuous change of the reflection phase between 0° and 180°.

5. A rotating multi-channel focusing reflective metasurface, characterized in that: The focusing reflective metasurface is composed of an arrangement of multi-channel focusing metasurface units as described in any one of claims 1 to 4.

Images