An active metamaterial with an encoded switch control array and method of fabrication

Abstract

The application discloses an active metamaterial with a coding switch control array and a preparation method. The metamaterial comprises, from top to bottom, a dielectric layer, a controllable super surface layer, an air layer, a reflection layer and an independent switch feed control layer; the controllable super surface layer comprises metal strip patch unit structures which are alternately connected and distributed in a rectangular array, and PIN diodes loaded in gaps between adjacent metal strips; the independent switch feed control layer is composed of an anode feed line, a cathode feed line and a coding switch control array; the PIN diodes are connected with predetermined electrodes in the controllable super surface layer through the anode and cathode feed lines via metal through holes. The application solves the problems of narrow working bandwidth and single function of traditional electromagnetic regulation and control devices, and the dual-mode working characteristics can effectively adapt to complex electromagnetic environment changes, thereby providing core technical support for the development of a new generation of intelligent skin, a reconfigurable antenna system and a multifunctional radar cover, and having a wide application prospect in the field of military and civilian integration.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic wave absorption stealth protection technology, specifically relating to an electromagnetic multifunctional active metamaterial that integrates broadband active wave absorption and coded control of broadband radar cross-section reduction. Background Technology

[0002] Electromagnetic metamaterials are artificial materials composed of artificially designed resonant units, possessing tunable equivalent dielectric constants and permeabilities. This property endows them with electromagnetic wave manipulation capabilities far exceeding those of natural materials, making them valuable for applications in electronic communication technology, electromagnetic protection, aerospace, and antenna systems. Active metamaterial technology based on tunable devices can dynamically adjust the electromagnetic response characteristics of materials by precisely controlling external excitation signals. This enables electromagnetic functions such as frequency-tunable absorption, multi-beaming, and effective reduction of radar cross-section (RCS), demonstrating significant strategic application potential in military stealth and communications.

[0003] Chinese Patent CN111755833B discloses a multi-band active metamaterial absorber. This absorber consists of a dielectric substrate, a metasurface metal resonant array layer printed on the top surface of the dielectric substrate, a varactor diode loaded on the metasurface metal resonant array layer, and a metal ground layer printed on the back of the dielectric substrate. The absorption frequency band can be continuously tuned by adjusting the bias voltage of the varactor diode. However, this resonant unit structure does not fully utilize the spatial coupling effect, resulting in a limited absorption bandwidth and a lack of active control over polarization characteristics. Chinese Patent CN118367362A discloses an active metamaterial tunable absorber based on ITO and a varactor diode. From top to bottom, it consists of an active tunable metasurface, an ITO thin film layer, a dielectric substrate, a connecting cylinder, air, the dielectric substrate again, and a metal reflective layer. By changing the bias voltage of the varactor diode, the absorption frequency can be adjusted, achieving dynamic adjustment in the 2-5 GHz frequency band, which can address more complex electromagnetic environment problems. The process is highly complex, and the limited capacitance adjustment range of the varactor diode leads to bottlenecks in improving absorption efficiency and bandwidth. Furthermore, the aforementioned solutions all employ a global voltage control mode, with all units tuned synchronously, making it difficult to achieve local adaptive responses to complex electromagnetic environments. Therefore, it is necessary to achieve continuous intelligent control of the feed voltage to solve the problem of intelligent broadband absorption in coded metamaterials. Summary of the Invention

[0004] Purpose of the invention: To address the shortcomings of existing technologies, this invention provides an active metamaterial with an coded switch control array and its fabrication method, realizing a broadband electromagnetic multifunctional controllable active metamaterial that integrates broadband active absorption and coded modulation of broadband radar cross-section reduction.

[0005] Technical Solution: The technical solution to achieve the purpose of this invention is as follows: An active metamaterial with an coded switch control array, comprising, from top to bottom, a dielectric layer, an adjustable metasurface layer, an air layer, a reflective layer, and an independent switch-feed control layer; the adjustable metasurface layer consists of metal strip patch units and diodes alternately connected in a rectangular array, wherein the metal strips of each array unit are arranged in a grid pattern, and a diode is provided at each of the four junctions; the independent switch-feed control layer includes a positive feed wire, a negative feed wire, and an coded switch control array, wherein the positive feed wire is electrically connected to the metal strip connected to the positive terminal of the diode, and the negative feed wire is electrically connected to the metal strip connected to the negative terminal of the diode; the connection method of the positive and negative feed wires enables the four diodes to form a parallel circuit structure; wherein the coded switch control array unit contains two sets of switch control groups for controlling the on / off state of the circuit and indicating the working state of the circuit.

[0006] Preferably, each metal strip on the tunable metasurface layer is connected to an independent switch feed control layer through a metal via; on an array unit, the positions of the metal vias sequentially form a first, second, third and fourth diagonal line, wherein the metal vias at the positions of the first and third diagonal lines are connected to the positive / negative feed lines, and the metal vias at the positions of the second and fourth diagonal lines are connected to the negative / positive feed lines.

[0007] As a preferred embodiment, the adjustable metasurface layer is printed on the bottom of the dielectric layer using a printed circuit board process, and a packaged PIN diode is loaded between the metal strip patch units using a PCB soldering process.

[0008] Preferably, the coded switch control array unit includes two sets of six-pin miniature sliding switches and surface-mount light-emitting diodes connected in series with them. The reflective layer and the independent switch power supply control layer are laminated together using PCB lamination technology.

[0009] Preferably, the array unit has a period size of 18-20 mm, the metal strip has a length of 6.0-8.0 mm, a width of 2.0-3.0 mm, a central slot width of 1.5-2.0 mm, and a metal through hole with a diameter of 0.2-0.3 mm at a distance of 3.0-3.5 mm from the edge of each metal strip.

[0010] Preferably, during operation, a DC voltage is applied to the positive feed line in the independent switch feed control layer, and the negative feed line is grounded; each switch in the coded switch control array is set to be in the closed state, and the resistance value of the PIN diode is changed by adjusting the DC voltage applied to the adjustable metasurface layer, thereby realizing the control of the ultra-wideband absorption performance of the active metamaterial in different wavebands.

[0011] As a preferred method, the reflection characteristics of the tunable metasurface layer are controlled by randomly encoding the coded switch control array, thereby realizing the broadband RCS reduction function of the active metamaterial in the reflection state.

[0012] Preferably, the reflective layer is made of any one of steel, iron, copper, silver, aluminum, or carbon fiber.

[0013] Beneficial effects: Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Excellent electromagnetic wave control performance: By alternately connecting metal strip patch units and diodes and distributing them in a rectangular array, a unique electromagnetic feature is constructed, realizing the linear polarization decoupling and recoupling of electromagnetic waves in the near field region, triggering the multi-polarization conversion effect, which can effectively control the amplitude and phase of the reflected wave, thereby significantly improving the electromagnetic wave interference attenuation capability in a wide frequency band. (2) High flexibility of active control: By introducing active PIN diode devices and independent switch coding design, dynamic control of electromagnetic response is realized, enhancing the adaptability and flexibility of the material in complex electromagnetic environments. (3) Multifunctional integrated design: Integrating multiple electromagnetic wave control functions such as wideband active absorption and coded control of wideband radar cross section (RCS) reduction in the same structure, compared with the prior art, the working frequency band is wider and the functions are more diversified, which can meet the needs of various application scenarios.

[0014] This invention discloses an active metamaterial with an coded switch control array. In the military field, it can be applied to military facilities such as aircraft, vehicles, and ships. By dynamically controlling the electromagnetic response, it effectively reduces the radar cross-section (RCS), improves stealth performance, and adapts to complex and variable electromagnetic environments. In the civilian field, this active metamaterial can be widely used in radar communication, electromagnetic compatibility (EMC), and intelligent stealth technology, providing efficient electromagnetic wave control capabilities for related equipment and improving system performance. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall cross-sectional structure of an active metamaterial embodiment with an coded switch control array according to the present invention.

[0016] Figure 2 This is a schematic diagram of the overall three-dimensional structure of the active metamaterial structural unit with an coded switch control array as described in an embodiment of the present invention.

[0017] Figure 3 This is a schematic diagram of the structure of the active metamaterial tunable metasurface layer with an coded switch control array according to an embodiment of the present invention.

[0018] Figure 4 This is a schematic diagram of the positive and negative feed lines in the active metamaterial described in an embodiment of the present invention.

[0019] Figure 5This is a schematic diagram of the power supply control unit structure according to an embodiment of the present invention.

[0020] Figure 6 The present invention relates to the active metamaterial with an coded switch control array described in the embodiments of the present invention, and the simulation results of reflectivity under different resistance loading conditions.

[0021] Figure 7 The present invention relates to the active metamaterial with an coded switch control array described in the embodiments of the present invention, and the measured reflectivity under different DC feed voltages.

[0022] Figure 8 The simulation results of the reflectivity of the active metamaterial with coded switch control array described in the embodiments of the present invention after random coding.

[0023] Figure 9 The measured reflectance of the active metamaterial with coded switch control array described in this embodiment of the invention after random coding.

[0024] Reference numerals: 1-Dielectric layer; 2-Adjustable metasurface layer; 3-Air layer; 4-Reflective layer; 5-Independent switch power supply control layer; 6-Metal wire; 7-Metal via; 8-Metal resonant unit; 9-PIN diode; 10-Positive feed wire; 11-Negative feed wire; 12-Six-pin miniature slide switch; 13-Light emitting diode. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0026] Example 1

[0027] like Figure 1 As shown, the active metamaterial with an coded switch control array disclosed in this embodiment includes, from top to bottom, a dielectric layer 1, an adjustable metasurface layer 2, an air layer 3, a reflective layer 4, and an independent switch-feed control layer 5. The dielectric layer 1 and the adjustable metasurface layer 2 are integrally formed using a PCB lamination process. The reflective layer 4 and the independent switch-feed control layer 5 are also integrally formed using a PCB lamination process. Figure 2 As shown, the adjustable metasurface layer 2 and the independent switch power supply control layer 5 are connected by a thin metal wire 6 through a metal via 7. The thickness d1 of the dielectric layer 1 is 0.5–1.0 mm, and the thickness d2 of the air layer 3 is 3–5 mm. The diameter of the thin metal wire 6 is... and the diameter of the metal through hole 7 All are 0.2–0.3 mm thick. In this example, the thickness d1 of dielectric layer 1 is 0.8 mm, and the thickness d2 of air layer 3 is 4 mm. The diameter of the metal wire 6 is... and the diameter of the metal through hole 7 All are 0.2mm.

[0028] The tunable metasurface layer 2 comprises multiple resonant structural units arranged in an array, uniformly distributed in a 10×10 matrix to form a square periodic array structure. For example... Figure 3 As shown, each resonant structure unit comprises a metal resonant unit 8 consisting of a rectangular array of patch-type short metal strip units and diodes, and four PIN diodes 9. In each unit, the metal strips are arranged in a grid pattern, with a PIN diode 9 at each of the four junctions. The period p of the resonant structure unit is 18–20 mm, the length l of the metal strips is 6.0–8.0 mm, the width w is 2.0–3.0 mm, the width s of the central slot is 1.5–2.0 mm, and a diameter PIN diode 9 is located 3.0–3.5 mm from the edge t of each metal strip. The metal through-holes are 0.2–0.3 mm in diameter. In this example, the period p of the resonant structure unit is 20 mm, the length l of the metal strip is 6.5 mm, the width w is 2 mm, the width s of the central slot is 2 mm, and a diameter is provided at a distance t from the edge t of each metal strip. The metal via is 0.2mm in diameter. PIN diodes 9 are mounted at the midpoints of the metal strips. The PIN diodes 9 are model BAP70-03 and measure 1.8mm × 1.35mm.

[0029] The independent switch feed control layer 5 includes a positive feed line 10, a negative feed line 11, and an coded switch control array. The coded switch control array contains multiple feed control units arranged in an array, uniformly distributed in a 10×10 matrix, forming a square periodic array structure. For example... Figure 4 As shown, the positive feed line 10 is electrically connected to the metal strip connecting the positive terminal of the PIN diode 9, and the negative feed line 11 is electrically connected to the metal strip connecting the negative terminal of the PIN diode 9. The connection method of the positive feed line 10 and the negative feed line 11 enables the four PIN diodes 9 to form a parallel circuit structure, ensuring that the operating states of the four PIN diodes 9 can be switched synchronously. Figure 4 The diagram illustrates the specific power supply method. On one array unit, the locations of the metal vias sequentially form first, second, third, and fourth diagonal lines. The metal vias at the first and third diagonal positions connect to the positive feed line 10, and the metal vias at the second and fourth diagonal positions connect to the negative feed line 11. For example... Figure 5As shown, each power supply control unit contains two sets of switch control groups. Each switch control group includes a six-pin miniature slide switch 12 and a light-emitting diode 13 connected in series, used to control the circuit's on / off state and indicate its operating status. In this example, the six-pin miniature slide switch 12 is an MSS6 model, measuring 6.7mm × 4.1mm. The light-emitting diode 13 measures 2mm × 1.2mm.

[0030] During operation, a DC voltage is applied to the positive feed wire in the independent switch power supply control layer, while the negative feed wire is grounded. Each six-pin sliding switch in the coded switch control array is set to the closed state. By adjusting the DC voltage applied to the tunable metasurface layer, the resistance of the PIN diode is changed, thereby achieving ultra-wideband absorption performance modulation of the active metamaterial in the C-band, X-band, and Ku-band. By randomly encoding the coded switch control array, the reflection characteristics of the tunable metasurface layer are controlled, realizing the broadband RCS reduction function of the active metamaterial in the reflection state.

[0031] Example 2

[0032] This embodiment discloses a method for fabricating an active metamaterial with an coded switch control array as described in Embodiment 1, comprising the following steps: using a single-sided copper-clad laminate as a substrate with a copper foil thickness of 0.01–0.05 mm, a predetermined metasurface pattern is formed on the copper foil surface using a photolithography process, including: coating a photoresist, mask alignment and exposure, etching, resist removal and cleaning, and substrate cutting, wherein a diameter is reserved at a designated position of the metasurface pattern. It is a through hole with a diameter of 0.2 to 0.3 mm.

[0033] The PIN diodes, toggle switch elements, and LEDs are manually soldered to their preset positions on the adjustable metasurface layer and the independent switch power supply control layer. Precise alignment of the adjustable metasurface layer and the power supply control layer is achieved using four corner locating pins, maintaining a 3-5mm air gap. (The last sentence appears to be incomplete and possibly refers to a specific process involving a diameter of 1 mm.) The electrical interconnection between each PIN diode electrode and the independent switch feed control layer is achieved by welding 0.2-0.3mm oxygen-free copper wire.

[0034] The dielectric layer can be made of an insulating material board with a flame retardant rating of FR4, which has a dielectric constant of 3.0 to 5.0 and a loss tangent of 0.01 to 0.04.

[0035] In this embodiment, the adjustable metasurface layer is made of metallic copper with a thickness of 0.035 mm (conductivity σ is 5.7 × 10⁻⁶). 7The reflective layer consists of a metal strip pattern (S / m) and BAP70-03 PIN diodes. The coded switch array in the independent switch power supply control layer is composed of a six-pin miniature slide switch (MSS6) and surface-mount LEDs in a 0805 package. The reflective layer can be made of any of the following materials: steel, iron, copper, silver, aluminum, or carbon fiber.

[0036] Example 3

[0037] This embodiment describes the tunable ultrawideband microwave absorption function of an active metamaterial with an coded switch control array prepared in Example 2, as detailed below:

[0038] like Figure 6 The figure shows the simulation results of the absorption performance of the active metamaterial described in this embodiment under different resistance loading conditions. When the loading resistance varies from 0Ω to 10000Ω, the reflection loss performance of the active metamaterial in the C, X, and Ku bands shows significant changes, respectively, from R s Switching from total internal reflection state at 0Ω to R s The wideband absorption states at 70Ω, 120Ω, and 190Ω are then switched to R. s The active metamaterial exhibits total internal reflection at 10000Ω. By appropriately adjusting the applied resistance value, the active metamaterial can flexibly switch between different absorption states. Specifically, within the frequency range of 4.8–18 GHz, the absorption rate of the active metamaterial for electromagnetic waves exceeds 90% (reflection loss RL ≤ -10 dB). In a single absorption state, the effective absorption bandwidth of the active metamaterial ranges from a minimum of 5.9 GHz to a maximum of 12.9 GHz.

[0039] like Figure 7 The figure shows the test results of the absorption performance of the active electromagnetic metamaterial described in this embodiment under different DC feed voltage conditions. The results show that by adjusting the feed voltage, the active electromagnetic metamaterial can switch between a reflection state and an absorption state in an adjustable manner. In the frequency range of 5.8–18 GHz, the reflectivity of the active electromagnetic metamaterial can be dynamically adjusted to below 18%, corresponding to an electromagnetic wave absorption rate greater than 82%. Specifically, in the frequency ranges of 6.4–11.1 GHz, 11.5–14.9 GHz, and 16.7–18 GHz, the reflectivity of the active electromagnetic metamaterial can be dynamically adjusted to below 10%, corresponding to an electromagnetic wave absorption rate greater than 90%.

[0040] Example 4

[0041] This embodiment describes the coded modulation broadband RCS reduction function of an active metamaterial design with a coded switch control array prepared in Example 2, as detailed below:

[0042] Based on the relationship between the coding unit period size and the operating frequency band of anomalous reflections, random coding design was carried out for two cases: coding period unit size D of 20mm and 40mm. For example... Figure 8 and Figure 9 The figure shows the simulation and test results of the reflection loss of the active electromagnetic metamaterial described in this embodiment after random coding. When the coding periodic unit size D is 20 mm, due to the random distribution of phase modules caused by the irregular random coding, the absorption rate of the active electromagnetic metamaterial for electromagnetic waves exceeds 90% near the 15 GHz frequency. When the coding periodic unit size D is 40 mm, due to the random distribution of phase modules caused by the irregular random coding, the absorption rate of the active electromagnetic metamaterial for electromagnetic waves exceeds 90% near the 7.5 GHz frequency. The active electromagnetic metamaterial achieves good RCS reduction performance under both coding periodic unit sizes of D=20 mm and D=40 mm.

[0043] In summary, this invention provides the design and fabrication of an active metamaterial with an coded switch control array. The tunable metasurface layer comprises alternating metal strip patch unit structures arranged in a rectangular array, and PIN diodes loaded between adjacent metal strips. The independent switch-feed control layer consists of a positive feed wire, a negative feed wire, and an coded switch control array. The bias voltage of the PIN diodes is provided by an external power supply and connected to predetermined electrodes in the tunable metasurface layer via metal vias through the positive and negative feed wires. Experiments show that this invention achieves active tunable absorption in an ultra-wideband frequency range of 5.8-18 GHz. Simultaneously, by dynamically adjusting the coded sequence, it achieves broadband RCS reduction performance consistent with simulation results near 7.5 GHz and 15 GHz. This invention innovatively solves the technical bottlenecks of narrow operating bandwidth and single function in traditional electromagnetic control devices. Its dual-mode operating characteristics (integrating broadband active absorption and coded broadband RCS reduction) can effectively adapt to complex electromagnetic environment changes, improving the battlefield survivability of electronic equipment. The active electromagnetic metamaterial is realized using printed circuit board technology, which is suitable for mass production. It features miniaturized structure, low cost, and diverse functions, and can be applied to fields such as electromagnetic communication, civilian protection, aerospace, and radar stealth technology.

Claims

1. An active metamaterial with an coded switch control array, characterized in that, The metamaterial consists of a dielectric layer, a tunable metasurface layer, an air layer, a reflective layer, and an independently switchable power supply control layer from top to bottom. The tunable metasurface layer is composed of metal strip patch units and diodes connected alternately in a rectangular array. The metal strips of each array unit are arranged in a grid pattern, and a diode is set at each of the four junctions. The independent switch power supply control layer includes a positive feed line, a negative feed line, and an coded switch control array. The positive feed line is electrically connected to the metal strip connecting the positive terminal of the diode, and the negative feed line is electrically connected to the metal strip connecting the negative terminal of the diode. The adjustable metasurface layer and the independent switch power supply control layer are connected by thin metal wires through metal vias. The connection method of the positive and negative feed lines enables the four diodes to form a parallel circuit structure. The coded switch control array unit contains two sets of switch control groups, which are used to control the on / off state of the circuit and indicate the working status of the circuit. Each metal strip on the tunable metasurface layer is connected to an independent switch feed control layer through a metal via; on an array unit, the positions of the metal vias sequentially form the first, second, third and fourth diagonal lines, wherein the metal vias at the positions of the first and third diagonal lines are connected to the positive / negative feed lines, and the metal vias at the positions of the second and fourth diagonal lines are connected to the negative / positive feed lines.

2. The active metamaterial with an coded switch control array according to claim 1, characterized in that, The adjustable metasurface layer is printed on the bottom of the dielectric layer using printed circuit board technology, and a packaged PIN diode is loaded between the metal strip patch units through PCB soldering technology.

3. The active metamaterial with an coded switch control array according to claim 1, characterized in that, The coded switch control array unit contains two sets of six-pin miniature sliding switches and surface-mount LEDs connected in series with them. The reflective layer and the independent switch power supply control layer are laminated together using PCB lamination technology.

4. The active metamaterial with an coded switch control array according to claim 1, characterized in that, The array unit has a period of 18-20 mm, the metal strip has a length of 6.0-8.0 mm, a width of 2.0-3.0 mm, a central slot width of 1.5-2.0 mm, and a metal through hole with a diameter of 0.2-0.3 mm at a distance of 3.0-3.5 mm from the edge of each metal strip.

5. An active metamaterial with an coded switch control array according to claim 1, characterized in that, During operation, a DC voltage is applied to the positive feed line in the independent switch power supply control layer, and the negative feed line is grounded; each switch in the coded switch control array is set to be in the closed state; by adjusting the DC voltage applied to the adjustable metasurface layer, the resistance value of the PIN diode is changed, thereby realizing the control of the ultra-wideband absorption performance of the active metamaterial in different wavebands.

6. The active metamaterial with an coded switch control array according to claim 1, characterized in that, By randomly encoding the coded switch control array, the reflection characteristics of the tunable metasurface layer can be controlled, thereby realizing the broadband RCS reduction function of the active metamaterial in the reflection state.

7. The active metamaterial with an coded switch control array according to claim 1, characterized in that, The reflective layer can be made of any one of steel, iron, copper, silver, aluminum, or carbon fiber.

8. A method for fabricating an active metamaterial with an coded switch control array according to any one of claims 1-7, characterized in that, Includes the following steps: Using a single-sided copper-clad laminate as the substrate, a predetermined metasurface pattern is formed on the surface of the copper foil using photolithography, including: coating photoresist, mask alignment and exposure, etching and forming, removing the photoresist and cleaning, and cutting the substrate. A through hole with a diameter of 0.2~0.3mm needs to be reserved at the designated position of the metasurface pattern. The PIN diodes, toggle switch elements, and light-emitting diodes are respectively assembled in the preset positions of the adjustable metasurface layer and the independent switch power supply control layer; the adjustable metasurface layer and the power supply control layer are precisely aligned by four corner positioning pins, and an air gap of 3~5mm is maintained. The electrical interconnection between each PIN diode electrode and the independent switch power supply control layer is achieved by welding together oxygen-free copper wire with a diameter of 0.2~0.3mm.

9. The method for fabricating an active metamaterial with an coded switch control array according to claim 8, characterized in that, The tunable metasurface layer consists of a metal strip pattern made of copper with a thickness of 0.01~0.05mm and PIN diodes.

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