Reconfigurable metasurface with continuously adjustable phase and multi-stage modulated amplitude

Abstract

The invention discloses a reconfigurable metasurface with continuously adjustable phase and multi-stage modulation amplitude, which is composed of a plurality of metasurface units arranged in an array, and each unit comprises two layers of dielectric plates and three layers of metal structures; a first metal layer is arranged on the upper surface of the first dielectric plate, and the metal layer is a square metal patch; the upper surface of the second dielectric plate is a second metal layer which is a metal floor loaded with slot coupling grooves, and a third metal layer on the lower surface of the second dielectric plate comprises a microstrip line network, a path selection circuit composed of PIN diodes, a phase shifter circuit composed of variable capacitance diodes and inductors and an amplifying circuit loaded with a microwave amplifier. According to the invention, polarization conversion 360-degree reflection phase continuous adjustment and multi-stage modulation of amplitude from enhancement to reduction can be realized; the reflection directional diagram and the reflection intensity can be independently adjusted, dynamic regulation and control of scattering characteristics are achieved, and the method has application value in the fields of electromagnetic compatibility, target detection, electromagnetic environment optimization and the like.

Description

Technical Field

[0001] This invention belongs to the field of artificial electromagnetic metamaterials, and specifically relates to a reconfigurable metasurface with continuously tunable phase and multi-level modulated amplitude. Background Technology

[0002] Electromagnetic scattering manipulation has significant application value in fields such as electromagnetic compatibility, target detection, and electromagnetic environment optimization. Its core requirement lies in achieving high-precision and flexible control over the scattering characteristics of electromagnetic waves. Reconfigurable electromagnetic metasurfaces, by loading tunable components or variable materials, can dynamically control the amplitude, phase, and polarization state of electromagnetic waves under external excitation, providing an effective technical solution to meet the flexibility requirements of scattering manipulation. Electrically reconfigurable electromagnetic metasurfaces often achieve their control function by loading tunable components such as PIN diodes and varactor diodes. However, the introduction of such components leads to signal attenuation during electromagnetic wave transmission, thus affecting the effectiveness and dynamic control range of scattering manipulation. Furthermore, achieving both continuous phase tunability and multi-level precise amplitude modulation is challenging, and they also face problems such as limited control dimensions and insufficient flexibility, making it difficult to meet the fine-grained control requirements of scattering characteristics in complex scenarios.

[0003] Therefore, integrating gain-type components into reconfigurable metasurface design has significant practical application value. By introducing amplifiers into the metasurface, secondary gain of electromagnetic wave signals can be achieved without relying on the power increase of the excitation source, significantly widening the dynamic range of amplitude modulation. Simultaneously, the synergistic control mechanism of using varactor diodes and PIN diodes to achieve continuously adjustable phase, combined with amplifiers to complete multi-level amplitude modulation, can effectively expand the dimensions of metasurface control over electromagnetic waves, improve control accuracy and stability, and enhance the flexibility and controllability of scattering control. In summary, conducting synergistic optimization research on large-range amplitude modulation and continuously adjustable phase has key technical value for solving existing scattering control technical challenges and improving overall control performance. Summary of the Invention

[0004] The purpose of this invention is to provide a reconfigurable metasurface with continuously adjustable phase and multi-level amplitude modulation, which enables polarization scattering enhancement and dynamic control in the reflection region.

[0005] The technical solution to achieve the purpose of this invention is: a reconfigurable metasurface with continuously adjustable phase and multi-level amplitude modulation, comprising multiple metasurface units arranged in an array, characterized in that the metasurface unit comprises, from top to bottom, a first metal layer, a first dielectric substrate, a second metal layer, a second dielectric substrate, and a third metal layer;

[0006] A first metal layer is disposed on the upper surface of the first dielectric substrate and includes a square metal patch;

[0007] The second metal layer is a metal ground plane located on the upper surface of the second dielectric substrate, serving as a ground plane shared by AC and DC, and has two orthogonal slot coupling grooves; the third metal layer is located on the lower surface of the second dielectric substrate, including a microstrip network, a phase shifter circuit for phase modulation, a path selection circuit, and an amplifier circuit for amplitude modulation; the metal microstrip lines are used to couple electromagnetic energy and current flow from the surface mount units of the first metal layer, and PIN diodes and varactor diodes are used as adjustable components to achieve dynamic phase control.

[0008] Compared with the prior art, the present invention has the following beneficial effects:

[0009] 1) In the range of 3.9 GHz to 4.2 GHz, it can realize the amplification of reflected electromagnetic energy, with an amplification amplitude of more than 6 dB in each phase state.

[0010] 2) While ensuring stable amplification characteristics, it can achieve 360-degree continuous phase change, and the phase of the emitted electromagnetic wave can be continuously adjusted.

[0011] 3) The amplitude control range is independent of the phase control, which can realize a variety of amplitude and phase state combinations, and the scattering pattern has dynamic reconfigurable characteristics.

[0012] 4) The frequency of this invention is easy to move and the cost is low, and it has potential application prospects in fields such as dynamic control of electromagnetic scattering and optimization of space electromagnetic environment. Attached Figure Description

[0013] Figure 1 The following is a schematic diagram of the reconfigurable metasurface structure according to an embodiment of the present invention. (a) is a 3D structural schematic diagram, and (b) and (c) are planar schematic diagrams of the second metal layer and the third metal layer, respectively.

[0014] Figure 2 The following are simulation results of the reconfigurable metasurface unit in the embodiment of the present invention: (a) shows the simulation curves of the polarization reflection amplitude and reflection phase under various phase states, and (b) shows the simulation curves of the polarization reflection amplitude and reflection phase under various amplitude states.

[0015] Figure 3 The following are simulated scattering patterns of a reconfigurable metasurface array according to an embodiment of the present invention. (a), (b), (c), and (d) are scattering patterns of symmetrical dual-beam, single-beam, asymmetrical dual-beam, and random scattering patterns under various amplitude states. Detailed Implementation

[0016] This invention proposes a reconfigurable metasurface with continuously adjustable phase and multi-level amplitude modulation, comprising multiple arrayed metasurface units. From top to bottom, each metasurface unit includes a first metal layer, a first dielectric substrate, a second metal layer, another second dielectric substrate, and a third metal layer. The first metal layer, located on the upper surface of the first dielectric substrate, includes square metal patches. The second metal layer, a metal ground plane, is located on the upper surface of the second dielectric substrate and serves as a shared ground plane for both AC and DC signals, and includes two orthogonal slot coupling slots. The third metal layer, located on the lower surface of the second dielectric substrate, includes a microstrip line network, a phase shifter circuit for phase control, a path selection circuit, and an amplifier circuit for amplitude modulation. When an x-polarized electromagnetic wave is incident perpendicularly on the metasurface, the spatial electromagnetic wave is received and coupled by the patch units of the first metal layer to form a surface current. This current is coupled to the microstrip line network of the third metal layer via the slot coupling slots. The current flows sequentially through a PIN diode, a phase shifter circuit, and an amplifier circuit on one side, and then radiates to the patch units through the orthogonal slot coupling slots. At this point, by reversing the operating states of the two PIN diodes, the electromagnetic signal is coupled through a reverse microstrip line path to the slot coupling groove and then to the patch radiating unit, resulting in 1-bit phase modulation of the emitted electromagnetic wave. Switching the varactor diode capacitance value allows for continuous phase adjustment within a 0-180 degree range. Combining the path selection circuit and the phase shifter circuit enables 360-degree full phase coverage. Simultaneously, controlling the operating state of the amplifier circuit allows for efficient amplification of the incident electromagnetic energy and dynamic amplitude adjustment. Therefore, by properly controlling the bias voltage applied to the amplifier circuit, PIN diodes, and varactor diodes, independent amplitude and phase control of the electromagnetic metasurface can be achieved, enabling continuous phase adjustment and multi-level amplitude modulation.

[0017] Scattering dynamics are achieved by combining phase encoding and multi-level reflection amplitude.

[0018] Preferably, an air layer is loaded between the first dielectric substrate and the second dielectric substrate to expand the working bandwidth.

[0019] Preferably, the slot coupling groove loaded in the second metal layer is an H-shaped slot coupling groove, which is used for electromagnetic energy coupling and broadband impedance matching.

[0020] Preferably, the path selection circuit includes a rectangular microstrip line loop and two PIN diodes connected end-to-end, with the two PIN diodes embedded in the rectangular microstrip line loop as switching elements. The middle of the PIN diodes serves as a control electrode, and the other end of the two PIN diodes connected together serves as another control electrode. By applying high and low level signals to the two control electrodes respectively, the two PIN diodes are alternately turned on.

[0021] Preferably, the phase shifter circuit consists of a cascaded π-type circuit composed of four pairs of two varactor diodes and one inductor, with the varactor diodes having the same bias voltage value.

[0022] Preferably, the working polarization of the metasurface is linear polarization.

[0023] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The present invention can be implemented in various forms; the accompanying drawings and exemplary descriptions do not limit the present invention to the following embodiments.

[0024] Example

[0025] Figure 1 This is a schematic diagram of a reconfigurable metasurface with continuously adjustable phase and multi-level amplitude modulation disclosed in an embodiment of the present invention. The unit, from top to bottom, includes a first metal layer, a first dielectric substrate, a second metal layer, another second dielectric substrate, and a third metal layer. The two dielectric substrates are separated by 1mm air gaps. In this embodiment, the first dielectric substrate is an F4B substrate with a dielectric constant of 4.4 and a loss tangent of 0.0025, with a thickness of 1mm. The second dielectric substrate is an F4B substrate with a dielectric constant of 3 and a loss tangent of 0.002, with a thickness of 0.762mm. All metal layers are copper sheets. In this embodiment, the first metal layer is disposed on the upper surface of the first dielectric substrate, including, as shown below... Figure 1 (a) A square metal patch; the second metal layer is a metal ground plane, disposed on the upper surface of the second dielectric substrate. This metal ground plane serves as a shared ground plane for both AC and DC, and is provided with, for example, Figure 1 (b) Two orthogonal H-shaped slot coupling trenches; a third metal layer is disposed on the lower surface of the second dielectric substrate, including a microstrip line network, a path selection circuit for phase modulation, a phase shifter circuit, and an amplifier circuit for amplitude modulation cascaded in sequence; the metal microstrip lines are used to couple electromagnetic energy and current flow from the surface mount units of the first metal layer, and PIN diodes and varactor diodes are used as adjustable components to achieve dynamic phase control; the phase shifter circuit includes eight varactor diodes 3 and four 1.1 nH inductors 4, and the path selection circuit includes two PIN diodes 1 and 2 (MACOM, MADP-14020-000907P). The microstrip line network is used to couple electromagnetic energy and current flow from the surface mount units of the first metal layer, and PIN diodes and varactor diodes are used as adjustable components to achieve dynamic phase control.

[0026] A path selection circuit for phase modulation, a phase shifter circuit, and an amplifier circuit for amplitude modulation are cascaded in sequence; a metal microstrip line is used to couple electromagnetic energy and current flow from the patch cell of the first metal layer; and PIN diodes and varactor diodes are used as adjustable components to achieve dynamic phase control.

[0027] Amplitude multi-stage modulation is achieved by controlling the bias voltage of the amplifier circuit and adjusting its forward transmission coefficient. Amplitude modulation includes multi-stage control from scattering enhancement to scattering reduction.

[0028] This embodiment operates based on the working mechanism of "receiving—path selection circuit—phase shifter circuit—amplification—re-radiation". When an x-polarized electromagnetic wave is incident perpendicularly onto the metasurface, the spatial electromagnetic wave is received and coupled by the patch unit of the first metal layer to form a surface current. This current is coupled to the microstrip line of the third metal layer via a horizontally placed H-shaped slot coupling groove. The current flows sequentially through a PIN diode, a phase shifter circuit, and an amplifier circuit on one side, and then is coupled to the patch unit of the first metal layer for radiation via an orthogonal vertically placed H-shaped slot coupling groove. At this time, by reversing the operating states of the two PIN diodes 1 and 2, the electromagnetic signal is coupled to the slot coupling groove and then to the patch radiating unit via the reverse microstrip line path, resulting in 1-bit phase modulation of the emitted electromagnetic wave. Switching the capacitance value of the varactor diode 3 enables continuous phase adjustment within a range of 0-180 degrees. Combining the path selection circuit and the phase shifter circuit enables 360-degree full phase coverage. Simultaneously, controlling the operating state of the amplifier circuit enables efficient amplification of the incident electromagnetic energy and dynamic amplitude adjustment. Therefore, by properly controlling the bias voltage applied to amplifier circuit 5, PIN diodes 1 and 2, and varactor diode 3, independent amplitude and phase control of the electromagnetic metasurface can be achieved, enabling continuous phase adjustment and multi-level amplitude modulation.

[0029] The path selection circuit consists of a rectangular microstrip line loop and two PIN diodes 1 and 2 connected end-to-end. The PIN diodes are embedded in the rectangular microstrip line loop as switching elements. The middle of the PIN diode serves as a control electrode, and the other end of the two PIN diodes connected together serves as another control electrode. By applying high and low level signals to the two control electrodes respectively, the two PIN diodes are alternately turned on.

[0030] The phase shifter circuit consists of a cascaded π-type circuit composed of four pairs of varactor diodes (2 x 3) and one inductor (4). The varactor diodes have the same bias voltage. The varactor diodes are located on both sides of the inductor, 2.1 mm away from it. The inductor is connected in series with the microstrip line circuit, and the capacitor is connected in parallel with the microstrip line circuit.

[0031] In this embodiment, the first metal layer patch unit is 24 mm long, and the dimensions of the H-shaped slot coupling groove are l1=8.8 mm, l2=5 mm, w1=4.4 mm, and w2=3 mm.

[0032] In this embodiment, amplitude multi-level modulation relies on the third metal layer amplifier circuit. A schematic diagram of the amplifier circuit connection is shown below. Figure 1As shown in (c), the microwave amplifier is a GVA-123+ (Mini-Circuits) model, and its peripheral circuitry includes a 6.8nH choke inductor, a 16.5 Ω resistor, a 0.1 uF bypass capacitor, and two 5 pF isolation capacitors. When the bias voltage changes, the change in bias voltage alters the forward transmission coefficient of the microwave amplifier circuit. Therefore, the amplification amplitude of the amplifier circuit can be dynamically adjusted by precisely controlling the bias voltage, thereby achieving multi-level amplitude control from amplitude enhancement to reduction.

[0033] Simulations were performed in the full-wave simulation software CST Microwave Studio. The elements were subjected to periodic boundary conditions along the x and y axes, and open boundary conditions along the z axis. A field-path co-simulation method was used for simulation verification. Figure 1 When the PIN diode (1) in (c) is turned on, and the varactor diode capacitance is set to 0.1 pF, 0.15 pF, 0.2 pF, 0.25 pF, 0.3 pF, 0.35 pF, 0.38 pF, and 0.4 pF respectively, it is set to the "R0"-"R7" state; when Figure 1 When the PIN diode (2) in (c) is turned on, and the varactor diode capacitance values ​​are set to 0.15 pF, 0.2 pF, 0.25 pF, 0.3 pF, 0.35 pF, 0.38 pF, 0.4 pF, and 0.45 pF respectively, it is set to "R8" - "R". 15 "state;

[0034] like Figure 2 As shown in (a), for x-polarized incident electromagnetic waves, the energy can be amplified in the 3.9 GHz ~ 4.2 GHz frequency band, with a reflection amplification greater than 6 dB, and the phase can achieve 360-degree full coverage; as Figure 2 As shown in (b), the scattered energy can achieve multi-level modulation, changing the reflection amplitude while keeping the phase constant. Therefore, amplitude modulation and phase modulation are independent of each other, and multiple combinations of amplitude and phase states can be achieved.

[0035] A 16×16 array of metasurface units was used. The scattering control performance was verified by separately adjusting the phase encoding and unit reflection amplitude of the metasurface. The reflection amplitude of each unit was set to 10 dB (case 1), 0 dB (case 2), and -3 dB (case 3), respectively. Phase encoding was simultaneously adjusted to sequentially achieve symmetrical dual-beam, single-beam, asymmetric dual-beam, and random scattering modes. The scattering patterns corresponding to each beam mode were normalized using the maximum value of the scattering pattern when the unit reflection amplitude was 0 dB as a reference. The results are as follows: Figure 3As shown. By coordinating and controlling the phase encoding and the unit reflection amplitude, the shape and amplitude of the scattering pattern can be dynamically controlled. In summary, this invention, through a cascaded path selection circuit, a phase shifter circuit, and an amplifier circuit, controls the on / off state of the PIN diode, the capacitance value of the varactor diode, and the external bias voltage of the amplifier, thereby achieving continuous control of the phase of the reflected electromagnetic wave and multi-level modulation of its amplitude, and thus realizing flexible and dynamic reconfigurability of the scattering state.

[0036] This invention provides a reconfigurable electromagnetic metasurface that combines continuously adjustable phase and multi-level amplitude modulation, enabling high-precision and flexible control of electromagnetic wave scattering characteristics. By constructing an external control circuit, this invention can achieve functions such as rapid beamforming and scattering modulation, and is expected to be applied in fields such as electromagnetic compatibility, target detection, and electromagnetic environment optimization. Furthermore, the components used in this invention are replaceable, facilitating adjustment; the metasurface structure possesses frequency-shiftable characteristics, allowing for convenient adjustment of the operating frequency band by changing the parameters and thickness of the dielectric substrate and the dimensional parameters of each electromagnetic structure.

[0037] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. In other words, any simple equivalent transformations and modifications made based on the claims and description of the present invention should be considered within the scope of protection of this patent. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A reconfigurable metasurface with continuously tunable phase and multi-level amplitude modulation, comprising a plurality of metasurface units arranged in an array, characterized in that, The metasurface unit comprises, from top to bottom, a first metal layer, a first dielectric substrate, a second metal layer, a second dielectric substrate, and a third metal layer; A first metal layer is disposed on the upper surface of the first dielectric substrate and includes a square metal patch; The second metal layer is a metal floor, located on the upper surface of the second dielectric board, and serves as a ground plane shared by AC and DC. It has two orthogonal slot coupling grooves. The third metal layer is disposed on the lower surface of the second dielectric substrate and includes a microstrip line network, a phase shifter circuit for phase modulation, a path selection circuit, and an amplifier circuit for amplitude modulation. Metal microstrip lines are used to couple electromagnetic energy and current flow from the surface-mount units of the first metal layer, while PIN diodes and varactor diodes are used as adjustable components to achieve dynamic phase control.

2. The reconfigurable metasurface with continuously adjustable phase and multi-level amplitude modulation according to claim 1, characterized in that, The first metal layer has a square metal patch for receiving and radiating electromagnetic waves. Below it, the second metal layer has orthogonal H-shaped slot coupling grooves for coupling electromagnetic energy from the metal patch to the microstrip network of the third metal layer.

3. The reconfigurable metasurface with continuously adjustable phase and multi-level amplitude modulation according to claim 1, characterized in that, The path selection circuit includes a rectangular microstrip line loop and two PIN diodes connected end to end. The PIN diodes are embedded in the rectangular microstrip line loop as switching elements. The middle of the PIN diode serves as a control electrode, and the other end of the two PIN diodes connected together serves as another control electrode. By applying high and low level signals to the two control electrodes respectively, the two PIN diodes can be turned on alternately.

4. The reconfigurable metasurface with continuously adjustable phase and multi-level amplitude modulation according to claim 1, characterized in that, The phase shifter circuit consists of a cascaded π-type circuit composed of four pairs of two varactor diodes and one inductor.

5. The reconfigurable metasurface with continuously adjustable phase and multi-level amplitude modulation according to claim 1, characterized in that, 360-degree continuous phase adjustment is achieved by combining a path selection circuit and a phase shifter circuit.

6. The reconfigurable metasurface with continuously tunable phase and multi-level amplitude modulation according to claim 1, characterized in that, Amplitude multi-stage modulation is achieved by controlling the bias voltage of the amplifier circuit and adjusting its forward transmission coefficient. Amplitude modulation includes multi-stage control from scattering enhancement to scattering reduction.

7. The reconfigurable metasurface with continuously tunable phase and multi-level amplitude modulation according to claim 1, characterized in that, An air layer is loaded between the first dielectric substrate and the second dielectric substrate.

8. The reconfigurable metasurface with continuously tunable phase and multi-level amplitude modulation according to claim 1, characterized in that, The working polarization is linear polarization.

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