A reconfigurable electromagnetic metasurface with joint amplitude and phase control

Abstract

The present invention relates to a reconfigurable electromagnetic metasurface with joint amplitude and phase control, which is formed by periodic extension of anisotropic basic units in a two-dimensional plane, and is intended to integrate a variety of near-field and far-field electromagnetic functions. By loading chip resistors and switching diodes along the horizontal and vertical directions of the metasurface units respectively, the metasurface can be made to have polarization-selective joint amplitude and phase control. Under vertically polarized incident waves, by switching the working state of the diodes in each unit, a series of far- and near-field control functions such as dual-beam scanning and reconfigurable focusing can be dynamically and flexibly realized; at the same time, for horizontally polarized incident waves, the metasurface can absorb the incident electromagnetic waves in a broadband and is not affected by the vertically polarized electromagnetic function. The present invention not only integrates dynamic wavefront control and broadband electromagnetic wave absorption functions, but also has the advantages of high integration and high polarization isolation. It is believed that it has important application prospects in the fields of low-scattering antenna arrays, wireless communications, and imaging.

Description

Technical Field

[0001] The present invention belongs to the field of artificial electromagnetic materials, and specifically relates to a reconfigurable electromagnetic metasurface with jointly controlled amplitude and phase. Background Art

[0002] A metasurface is an artificial electromagnetic material composed of subwavelength-sized basic units arranged in a two-dimensional plane. By carefully designing the basic unit structure, a metasurface can possess electromagnetic responses not possessed by natural electromagnetic materials. To simultaneously integrate multiple electromagnetic functions within the same device and improve device integration, many metasurfaces use polarization, frequency, propagation direction, and other basic electromagnetic properties to provide additional information channels. However, most current designs that use polarization multiplexing to achieve multifunctional integration only support phase control within both polarization channels, failing to fully utilize the basic properties of electromagnetic waves.

[0003] Amplitude, another fundamental electromagnetic property, is crucial for effective control in fields such as electromagnetic stealth, electromagnetic compatibility, and energy harvesting. However, most current metasurfaces that utilize polarization multiplexing to achieve joint amplitude and phase control are limited to passive designs. Once fabricated, their electromagnetic functionality cannot be adjusted to suit different application scenarios. Furthermore, most active designs operate only within a narrow frequency band.

[0004] Therefore, there is an urgent need to explore a reconfigurable electromagnetic metasurface that can achieve joint control of amplitude and phase within a wider frequency band, and can flexibly switch between multiple electromagnetic functions, thereby dynamically adapting to different application scenarios. Summary of the Invention

[0005] Purpose of the invention: The purpose of the present invention is to propose a reconfigurable electromagnetic metasurface with joint amplitude and phase control, which can simultaneously integrate functions such as dynamic electromagnetic wave wavefront control and broadband wave absorption.

[0006] Technical solution: To achieve the above-mentioned purpose, the present invention proposes the following technical solution:

[0007] A reconfigurable electromagnetic metasurface with jointly controlled amplitude and phase is formed by periodically extending basic units in an xy two-dimensional plane. Its basic unit structure comprises, from top to bottom, a first metal patch layer, a first dielectric layer, a second metal patch layer, a second dielectric layer, and a third metal patch layer. The first metal patch layer consists of a butterfly-shaped metal patch, two trapezoidal metal patches located on either side of the butterfly-shaped metal patch, and two metal wires located at both ends of the butterfly-shaped metal patch. Two patch resistors are respectively loaded between the butterfly-shaped metal patch and the metal wires, and two switching diodes are respectively loaded between the butterfly-shaped metal patch and the trapezoidal metal patch. The second metal patch layer is connected to the butterfly metal patch in the first metal patch layer through metal vias. The third metal patch layer is connected to the trapezoidal metal patch in the first metal patch layer through metal vias. The second and third metal patch layers are respectively connected to the negative and positive poles of an external circuit to provide bias voltage for the switching diodes.

[0008] Preferably, the butterfly-shaped metal patch in the first metal patch layer is composed of two isosceles triangular metal patches and a rectangular metal patch, wherein the two isosceles triangular metal patches are connected top to top at the center of the basic unit, and the rectangular metal patch is also located at the center of the unit to ensure the connection stability of the two isosceles triangular metal patches, and the trapezoidal metal patch is an isosceles trapezoidal metal patch; the first metal patch layer adopts a butterfly-shaped, trapezoidal and other size gradient designs, which helps to expand the working bandwidth.

[0009] Preferably, the second metal patch layer is a square metal patch with two circular areas cut out. It is connected to the butterfly-shaped metal patch in the first metal patch layer through a metal via at the center of the basic unit. The center of the circular area cut out of the second metal patch layer is aligned with the center of the metal via connecting the first and third metal patch layers, and the radius of the circular area is slightly larger than the radius of the metal via, thereby isolating the second metal patch layer from the first and third metal patch layers.

[0010] Preferably, the square metal patches constituting the second metal patch layer have dimensions along the x-axis and the y-axis consistent with the dimensions of the basic unit, and can be used to block the transmission of electromagnetic waves, thereby achieving high-efficiency reflection.

[0011] Preferably, the third metal patch layer includes two rectangular metal patches connected to two metal vias, metal wires connecting the metal patches, and fan-shaped branches connected to the metal wires; the third metal patch layer can provide an independent bias circuit for each basic unit, and isolate AC power and conduct DC power by adding fan-shaped branches.

[0012] Preferably, the two switching diodes in the first metal patch layer are loaded in opposite directions along the y-axis, so that the working states of the two diodes remain consistent.

[0013] Under the incidence of vertically polarized electromagnetic waves, by turning on or off the switching diode, the basic unit can present two electromagnetic responses with a phase difference of about 180° within the designed frequency band, thereby forming dynamic control of the 1-bit reflection phase; under the incidence of horizontally polarized electromagnetic waves, the basic unit can absorb the incident wave within a wide band to achieve amplitude control.

[0014] Beneficial Effects: This invention combines chip resistors and switching diodes to form a reconfigurable electromagnetic metasurface with jointly controlled amplitude and phase. When subjected to x-polarized electromagnetic waves, the metasurface absorbs the incident electromagnetic waves over a wide bandwidth, thereby achieving amplitude modulation. When subjected to y-polarized electromagnetic waves, the bias voltage applied to the switching diodes within the basic unit is controlled using a field-programmable gate array (FPGA), enabling two electromagnetic responses with a phase difference of approximately 180° across a wide frequency band. Compared to existing technologies, this invention offers the following advantages:

[0015] 1. The reconfigurable electromagnetic metasurface with joint amplitude and phase control proposed in the present invention can integrate dynamic phase modulation and broadband amplitude modulation in a pair of orthogonal polarization channels, which not only provides additional information channels but also increases the degree of freedom in controlling the basic properties of electromagnetic waves.

[0016] 2. The present invention introduces butterfly-shaped, trapezoidal and other size gradient structures into the first metal patch layer to expand the effective phase control and amplitude control bandwidth.

[0017] 3. By embedding the diode between the butterfly-shaped and trapezoidal metal patches, the present invention can make the electromagnetic impedance of the basic unit along the y-axis direction in both working states approximately a pure imaginary number, thus making it roughly equivalent to a phase shifter; at the same time, by adjusting the resistance value of the patch resistor and the position of the embedded butterfly metal patch and the metal wire, the real part of the electromagnetic impedance of the basic unit along the x-axis direction can be made basically consistent with the free space wave impedance, thereby absorbing the incident electromagnetic waves and reducing electromagnetic wave reflections.

[0018] 4. The present invention further introduces a fan-shaped branch method in the third metal patch layer, which can effectively eliminate the influence of the two metal narrow-strip lines in the third metal patch layer on the metasurface reflection coefficient, thereby realizing independent control of each unit.

[0019] 5. The present invention has the advantages of simple structure, low preparation cost, and low profile. It can be moved from the microwave band to other target frequency bands through proportional scaling and other means. It has good frequency band flexibility and is expected to be used in low-scattering antenna arrays, imaging, wireless communications and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of a metasurface according to an embodiment of the present invention.

[0021] Figure 2 It is a schematic diagram of the three-dimensional structure of the basic unit of an embodiment of the present invention.

[0022] Figure 3 1 is a diagram of the co-polarized reflection amplitude (a) and phase (b) of a basic unit of an embodiment of the present invention when a y-polarized electromagnetic wave is incident.

[0023] Figure 4 This is a diagram of the co-polarized reflection amplitude of the basic unit of the embodiment of the present invention under the incidence of x-polarized electromagnetic waves.

[0024] Figure 5 These are the front (a) and back (b) views of a processed sample according to an embodiment of the present invention.

[0025] Figure 6 Graphs showing test results of a sample according to an embodiment of the present invention generating dual beams with scanning angles of (a) 9.2° and (b) 18.9°.

[0026] Figure 7 This is a schematic diagram of the test results of the sample of an embodiment of the present invention achieving reconfigurable focusing in the y-polarization channel, (a) illustrates the focusing path, and (b)-(h) illustrate the focusing points at each moment.

[0027] Figure 8 This is a test result diagram of the sample of an embodiment of the present invention, which shows that when the y-polarization channel realizes reconfigurable focusing, the x-polarization channel realizes broadband absorption. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should be understood that the present invention may be implemented in various forms, and the following exemplary and non-limiting embodiments shown in the drawings and described below are not intended to limit the present invention to the specific embodiments described.

[0029] like Figure 1 As shown in FIG, an embodiment of the present invention provides a reconfigurable electromagnetic metasurface with jointly controlled amplitude and phase, which is formed by periodically extending basic units in the xy two-dimensional plane. The basic unit structure is as follows: Figure 2 As shown, from top to bottom, there are the first metal patch layer, the first dielectric layer, the second metal patch layer, the second dielectric layer, and the third metal patch layer. The first metal patch layer consists of a butterfly-shaped metal patch 1, two trapezoidal metal patches 2, and two narrow metal strip lines 3. Two chip resistors are loaded between the butterfly metal patch 1 and the narrow metal strip lines 3, and two switching diodes are loaded between the butterfly metal patch 1 and the trapezoidal metal patch 2. The second and third metal patch layers are connected to the negative and positive electrodes of the external circuit, respectively, to provide bias voltage for the diodes.

[0030] In this example, the second metal patch layer consists of a square metal patch with two circular areas cut out. A metal via connects the center of the square metal patch in the first metal patch layer to the butterfly-shaped metal patch in the first metal patch layer. The center of the circular area cut out of the second metal patch layer aligns with the center of the metal via connecting the first and third metal patch layers. The radius of the circular area is slightly larger than the radius of the metal via, thus isolating the second metal patch layer from the first and third metal patch layers. To minimize electromagnetic wave transmission and achieve high-efficiency reflection, the square metal patch in the second metal patch layer covers the entire basic unit.

[0031] The third metal patch layer consists of fan-shaped branches, two rectangular metal patches, and narrow metal strips. The two rectangular metal patches are connected to the trapezoidal metal patches in the first metal patch layer through metal vias. The vertex of the fan-shaped branches is connected to the narrow metal strip extending along the x-axis at the center of the unit. The narrow metal strip extending along the y-axis of each unit is staggered to provide independent bias circuits for each unit.

[0032] In this embodiment, the dielectric layer is made of F4B material with a dielectric constant of 3.5 and a loss tangent of 0.0018, and the metal patches are copper. The thickness of the first dielectric layer is 4 mm, and the thickness of the second dielectric layer is 0.5 mm. The basic unit period is 12 mm, the length of the narrow metal strip line in the first metal patch layer is 8.8 mm, the height of the trapezoidal metal patch is 3.5 mm, the bottom base is 8 mm, and the total width of the butterfly-shaped metal patch is 6.6 mm.

[0033] Under the incident y-polarized electromagnetic wave, with the unit cell as the boundary between the x-axis and the y-axis, the simulation results of the reflection amplitude corresponding to the metasurface unit when the diode is turned on (coded as 1) or cut off (coded as 0) are as follows Figure 3 As shown. In the frequency range of 5.9-7.5GHz, the phase difference between the two working states is kept within 180° ± 20°, and the reflection amplitude is always kept above -1dB. Under the incident x-polarized electromagnetic wave, as shown Figure 4 As shown in the figure, within the range of 4.8 - 9.8 GHz, the reflection amplitude of both working states is below -10 dB, thus achieving broadband absorption.

[0034] In this embodiment, 24 × 24 units are used as an example for sample processing and experimental description. Figure 5 As shown. By adopting different phase encoding distributions, the metasurface can achieve far-field dual-beam scanning ( Figure 6 ), near-field reconfigurable focusing ( Figure 7 ) and other functions; and the orthogonal polarization always maintains wave absorption ( Figure 8 ).

[0035] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0036] The above is merely a preferred embodiment of the present invention. The same structure can be used to flexibly design the operating frequency band of the reconfigurable electromagnetic metasurface unit with joint amplitude and phase control by proportionally scaling the unit size, and can even be directly extended to the millimeter wave band, infrared, terahertz, and visible light bands. Obviously, after understanding the content and principles of the present invention, professionals in this field may make various modifications and changes in form and details without departing from the principles and structure of the present invention. However, any simple equivalent changes and modifications made in accordance with the claims and the content of the invention description shall still fall within the scope of the patent coverage of the present invention.

Claims

1. A reconfigurable electromagnetic metasurface with joint amplitude and phase control, characterized in that: The invention is formed by periodically extending a basic unit in a two-dimensional plane; the basic unit structure comprises, from top to bottom, a first metal patch layer, a first dielectric layer, a second metal patch layer, a second dielectric layer and a third metal patch layer; the first metal patch layer is composed of a butterfly-shaped metal patch (1), two trapezoidal metal patches (2) located on both sides of the butterfly-shaped metal patch (1) and two metal wires (3) located at both ends of the butterfly-shaped metal patch (1); two patch resistors are respectively loaded between the butterfly-shaped metal patch (1) and the metal wires (3); two switching diodes are respectively loaded between the butterfly-shaped metal patch (1) and the trapezoidal metal patch (2); the second metal patch layer is connected to the butterfly-shaped metal patch (1) through a metal via; the third metal patch layer is connected to the trapezoidal metal patch (2) through a metal via; the second and third metal patch layers are respectively connected to the negative pole and the positive pole of the external circuit, and are used to provide a bias voltage for the switching diode.

2. The reconfigurable electromagnetic metasurface with jointly controlled amplitude and phase according to claim 1, characterized in that: The butterfly-shaped metal patch (1) in the first metal patch layer is composed of two isosceles triangular metal patches and a rectangular metal patch, wherein the two isosceles triangular metal patches are connected top to top at the center of the basic unit, and the rectangular metal patch is also located at the center of the unit to ensure the connection stability of the two isosceles triangular metal patches, and the trapezoidal metal patch (2) is an isosceles trapezoidal metal patch.

3. The reconfigurable electromagnetic metasurface with jointly controlled amplitude and phase according to claim 1, characterized in that: The second metal patch layer is a square metal patch with two circular areas dug out, and is connected to the butterfly metal patch (1) in the first metal patch layer through a metal via at the center of the basic unit.

4. The reconfigurable electromagnetic metasurface with jointly controlled amplitude and phase according to claim 3, characterized in that: The center of the circular area dug out of the second metal patch layer is consistent with the center of the metal via connecting the first and third metal patch layers, and the radius of the circular area is larger than the radius of the metal via, thereby isolating the second metal patch layer from the first and third metal patch layers.

5. The reconfigurable electromagnetic metasurface with jointly controlled amplitude and phase according to claim 3, characterized in that: The square metal patches constituting the second metal patch layer are consistent in size with the basic unit.

6. The reconfigurable electromagnetic metasurface with jointly controlled amplitude and phase according to claim 1, characterized in that: The third metal patch layer includes two rectangular metal patches connected to two metal vias, metal wires connecting the metal patches, and fan-shaped branches connected to the metal wires.

7. The reconfigurable electromagnetic metasurface with jointly controlled amplitude and phase according to claim 6, characterized in that: The third metal patch layer provides an independent bias circuit for each basic unit, and isolates the alternating current and conducts the direct current by adding the fan-shaped branches.

8. The reconfigurable electromagnetic metasurface with jointly controlled amplitude and phase according to claim 1, characterized in that: The two switching diodes in the first metal patch layer are reversely loaded so that the working states of the two diodes remain consistent.

9. The reconfigurable electromagnetic metasurface with jointly controlled amplitude and phase according to claim 1, characterized in that: When a vertically polarized electromagnetic wave is incident, by turning on or off the switching diode, the basic unit can present two electromagnetic responses with a phase difference of 180° within the designed frequency band, thereby forming dynamic control of the 1-bit reflection phase.

10. The reconfigurable electromagnetic metasurface with jointly controlled amplitude and phase according to claim 1, characterized in that: When horizontally polarized electromagnetic waves are incident, the basic unit absorbs the incident waves within the designed frequency band to achieve amplitude control.

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