Polarization-insensitive dynamically-adjustable metasurface invisible cloak suitable for different backgrounds

Abstract

The polarization-insensitive dynamic adjustable metasurface invisible cloak is suitable for different target terrain backgrounds, independent adjustment of polarization-insensitive amplitude and phase is achieved through innovative design, and the polarization-insensitive dynamic adjustable metasurface invisible cloak is suitable for dynamic invisibility and electromagnetic wave control in a complex environment. The cloak is composed of a plurality of metasurface units arranged in an array mode, each unit comprises a multi-layer metal structure and a dielectric substrate and is integrated with an active adjustable device, and real-time regulation and control over the phase and amplitude of electromagnetic waves are achieved. And by adopting the 90-degree rotational symmetry design, the good adaptability to horizontal polarization and vertical polarization radar waves is ensured. By adjusting the bias voltage, the device can simulate microwave reflection characteristics of different target terrains, and an efficient solution is provided for military stealth, terrain detection and electromagnetic environment simulation. Compared with the prior art, the electromagnetic wave control flexibility and environmental adaptability of the metasurface are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of metasurface technology, and in particular to a polarization-insensitive dynamically adjustable metasurface stealth cloak operating at microwave frequencies and suitable for different target terrain backgrounds. Background Art

[0002] Metasurfaces are composed of periodically or quasi-periodically arranged subwavelength structural units. By precisely controlling the electromagnetic response characteristics of each unit, the phase, amplitude and polarization state of the incident electromagnetic wave can be finely controlled. Through reasonable design, metasurfaces can achieve spatial changes in the equivalent refractive index, thereby guiding electromagnetic waves to propagate along a specific path to avoid interaction with the target object, making the target object invisible in electromagnetic detection.

[0003] Stealth technology has always been one of the hot areas of metasurface research. Traditional stealth technology is usually based on absorbing materials or scattering cancellation principles. By coating functional materials on the target surface, the radar scattering cross section of the target is suppressed to achieve stealth effect. However, these technologies often have the defects of narrow bandwidth and strong dependence on specific detection directions, which makes it difficult to meet the needs of multi-angle and dynamic stealth in complex environments. With the development of metasurface technology, by covering the surface of the target object with metasurface materials, the incident electromagnetic waves can be precisely controlled to achieve stealth effect, which has become the main research direction of current stealth technology. .

[0004] Although metasurface stealth devices have made significant progress in theory and experiment, the existing technology still has many shortcomings. For example, traditional metasurface stealth devices are mostly static designs with single functions and cannot cope with the changing external conditions in complex environments. In scenarios where dynamic stealth is required, existing stealth devices often lack real-time adaptive control capabilities and need to rely on external detectors or manual operations, which are complicated and inefficient to operate. In addition, although existing metasurface technologies have made certain achievements in achieving stealth and electromagnetic wave control, most of them are concentrated on phase control, and the amplitude control capabilities and multi-polarization stealth capabilities are relatively limited. This limitation reduces the flexibility and efficiency of metasurfaces in practical applications, especially in complex terrain environments where accurate simulation of electromagnetic wave reflection characteristics is required. Existing technologies cannot effectively simulate the reflection characteristics of electromagnetic waves on different terrains, which is a major defect in military stealth, terrain detection and wireless communications.

[0005] Therefore, developing a metasurface technology with reconfigurable amplitude and phase, which can dynamically adjust the reflection amplitude and phase and simulate the reflectivity changes of electromagnetic waves in different terrains, will greatly broaden the application prospects of metasurface technology in terrain adaptive stealth, electromagnetic environment simulation and terrain detection. This technology will be able to adjust the electromagnetic response of the metasurface in real time to adapt to various complex and dynamic external environments, providing a new solution for modern electromagnetic applications. Summary of the invention

[0006] Purpose of the invention: In view of the above-mentioned prior art and the defects therein, the present invention proposes a polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different target terrain backgrounds. The stealth cloak has amplitude and phase reconfigurable characteristics and realizes microwave reflection simulation for different terrains.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] The polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different target terrain backgrounds of the present invention comprises a plurality of phase and amplitude adjustable metasurface units arranged in an array, wherein the metasurface unit comprises four layers of metal patches and three layers of dielectric substrates, including two layers of metal control layers loaded with active adjustable devices, and the bias voltage of the adjustable devices is changed to realize the phase and amplitude control of the metasurface unit.

[0009] Furthermore, the first layer of the phase and amplitude adjustable metasurface unit from top to bottom is a phase control metal layer, the second layer is a low-loss dielectric layer, the third layer is an amplitude control metal layer, the fourth layer is a low-loss dielectric layer, the fifth layer is a metal reflection layer, the sixth layer is a low-loss dielectric layer, and the seventh layer is a metal bias line. The second low-loss dielectric layer and the third amplitude control metal layer are separated by air.

[0010] Furthermore, the phase control metal layer includes a middle square metal patch and four identical rectangular metal patches around it. The four identical rectangular metal patches are arranged around the square metal patch in a 90° rotational symmetry. Each rectangular metal patch is connected to the middle square metal patch through a varactor diode, and each adjacent rectangular metal patch is connected to each other through metal routing. A metal via is provided at the geometric center of the unit, which is connected to the bottom metal bias line to control the bias voltage of the varactor diode.

[0011] Furthermore, the amplitude control metal layer includes a middle square ring metal patch and four identical rectangular metal patches around it. The four identical rectangular metal patches are arranged 90° rotationally symmetrically around the square metal patch. Each rectangular metal patch is connected to the middle square metal patch through an active adjustable device, and each adjacent rectangular metal patch is connected to each other through metal routing. The four corners of the middle square ring metal patch are provided with metal vias, which are connected to the bottom metal bias line to control the bias voltage of the active adjustable device.

[0012] Compared with the prior art, the present invention has the following beneficial effects:

[0013] (1) The present invention introduces two metal control layers into the metasurface unit and loads active adjustable devices respectively to achieve independent control of the phase and amplitude of electromagnetic wave reflection. This dual-parameter control capability significantly improves the electromagnetic wave control flexibility of the metasurface, breaking through the limitation of traditional stealth metasurfaces that only focus on phase control.

[0014] (2) By changing the bias voltage of the active adjustable device, the electromagnetic response characteristics of the metasurface can be adjusted in real time, enabling it to simulate the reflection characteristics of electromagnetic waves on different terrains. This feature provides an effective solution for dynamic stealth in complex environments and broadens the application scenarios of metasurface technology.

[0015] (3) The metasurface unit of the present invention adopts a 90° rotationally symmetrical design. This geometric characteristic enables its reflection characteristics to be precisely controlled in both horizontal and vertical polarization states, thereby achieving effective stealth against multi-polarized radar waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of the polarization-insensitive dynamically adjustable metasurface stealth cloak applicable to different backgrounds of the present invention;

[0017] Figure 2 A schematic diagram of the unit structure of the polarization-insensitive dynamically adjustable metasurface stealth cloak applicable to different backgrounds of the present invention;

[0018] Figure 3 It is a simulation curve of the reflection amplitude and phase changing with frequency under different capacitance values ​​of the metasurface unit when the PIN diode is in the on state in the embodiment of the present invention;

[0019] Figure 4 It is a simulation curve of the reflection amplitude and phase changing with frequency under different capacitance values ​​of the metasurface unit in the PIN diode cut-off state in the embodiment of the present invention;

[0020] Figure 5 is the incident electromagnetic wave in the embodiment of the present invention at E x Reflected electric field distribution of metal ground, exposed protrusions, and metasurface-covered stealth cloak under polarization;

[0021] Figure 6 is the incident electromagnetic wave in the embodiment of the present invention at E y Reflected electric field distribution of metal ground, exposed protrusions, and metasurface-covered stealth cloak under polarization;

[0022] Figure 7 is the incident electromagnetic wave in the embodiment of the present invention at E x Reflected electric field distribution diagram of sandy ground, exposed protrusions and metasurface-covered stealth cloak under polarization;

[0023] Figure 8is the incident electromagnetic wave in the embodiment of the present invention at E y Reflected electric field distribution of sandy ground, exposed protrusions, and metasurface-covered stealth cloak under polarization. DETAILED DESCRIPTION

[0024] In order to more clearly illustrate the technical problems solved by the present invention, the technical solutions and the advantages thereof, the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0025] In the present invention, the terms "first", "second", "third", etc. are only used to distinguish similar objects, and do not indicate a specific order or sequence, nor can they be understood as indicating or implying relative importance. In the description, the directions or positional relationships indicated by "upper", "lower", "left", "right", "front", and "back" are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, these terms should not be understood as limiting the scope of protection of the present invention. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0026] This embodiment relates to a polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different backgrounds. The key lies in the special structure of the metasurface unit and the loading of active adjustable devices to achieve phase and amplitude control of the incident microwave. In the specific design, a metasurface unit with a multi-layer structure is used, and each unit is loaded with an active adjustable device. By controlling its bias voltage, the real-time adjustment of the electromagnetic wave reflection characteristics is achieved.

[0027] like Figure 1 As shown, this embodiment provides a metasurface stealth cloak composed of two 10×10 metasurface unit arrays. The stealth cloak is a triangular convex structure, the height h of the stealth cloak is 60 mm, and the inclination angle α is 30°. The phase distribution of the stealth cloak is determined based on the generalized Snell's law, and then different bias voltages are applied to the units at different positions of the metasurface stealth cloak through the bottom bias line to achieve phase control and finally achieve the stealth effect.

[0028] Figure 2 This is a schematic diagram of the structure of the metasurface unit constituting the metasurface stealth cloak in this embodiment. The unit as a whole has a 90° rotationally symmetrical structure. Specifically, from top to bottom, the first layer is a phase control metal layer, the second layer is a low-loss dielectric layer, the third layer is an amplitude control metal layer, the fourth layer is a low-loss dielectric layer, the fifth layer is a metal reflection layer, the sixth layer is a low-loss dielectric layer, and the seventh layer is a metal bias line. The second low-loss dielectric layer and the third amplitude control metal layer are separated by air.

[0029] The phase control metal layer includes a middle square metal patch and four identical rectangular metal patches 1 around it. The four identical rectangular metal patches are arranged 90° rotationally symmetrically around the square metal patch 5. Each rectangular metal patch is connected to the middle square metal patch through a varactor 2, and each adjacent rectangular metal patch is connected to each other through metal traces. A metal via is provided at the geometric center of the unit, which is connected to the bottom metal bias line 7 to control the bias voltage of the varactor.

[0030] The amplitude control metal layer includes a middle square ring metal patch and four identical rectangular metal patches 1 around it. The four identical rectangular metal patches are arranged 90° rotationally symmetrically around the square metal patch. Each rectangular metal patch is connected to the middle square metal patch through a PIN diode 3, and each adjacent rectangular metal patch is connected to each other through metal traces. Metal vias are provided at the four corners of the middle square ring metal patch, which are connected to the bottom metal bias line to control the bias voltage of the PIN diode.

[0031] Specifically, the metasurface unit period p = 12mm, the unit thickness t = 7mm, the side length of the square metal patch and the long side b of the rectangular metal patch are 6mm, the short side a is 2mm, and the inner side length of the square ring is d = 3mm. The metal material is copper, the low-loss dielectric material is F4B, the dielectric constant is 2.65, and the loss tangent is 0.0012.

[0032] The varactor diode can be equivalent to an RLC series circuit, that is, a resistor with a constant resistance value, an inductor with a constant inductance value, and a capacitor with a capacitance value that varies within a certain range are connected in series. By adjusting the capacitance value of the varactor diode, the phase control of the metasurface unit can be close to 360° to meet the different phase requirements of the metasurface stealth cloak. At the same time, by controlling the on and off of the PIN diode, the overall control of the reflection amplitude of the metasurface unit can be achieved. Figure 3 The relationship curve between the capacitance value of the varactor diode and the unit reflection amplitude and the capacitance value of the varactor diode and the unit reflection phase curve for the determined metasurface unit when the PIN diode is in the on state; Figure 4 The relationship curve between the capacitance of the varactor diode and the unit reflection amplitude and the capacitance of the varactor diode and the unit reflection phase curve for the determined metasurface unit when the PIN diode is in the cut-off state. In the frequency band of 2.4 GHz to 5.2 GHz, when the PIN diode switches from the on state to the off state, the reflection amplitude can switch from the partial reflection mode to the full reflection mode.

[0033] Figure 5 Given an incident 4.5 GHz E x When polarizing a plane electromagnetic wave, the reflected electric field distribution of the invisible cloak when the metal ground, exposed protrusions and covered PIN diodes are in the cut-off state. Figure 6 The incident E at 4.5 GHz y When polarizing a plane electromagnetic wave, the reflected electric field distribution of the invisible cloak when the metal ground, exposed protrusions, and covered PIN diodes are in the cut-off state. The results show that the designed metasurface invisible cloak can simulate the reflection of the metal ground when the PIN diode is cut off, and is insensitive to the polarization of the incident wave.

[0034] Figure 7 Given an incident 4.5 GHz E x When polarizing a plane electromagnetic wave, the reflected electric field distribution of the sandy ground, exposed protrusions, and the invisible cloak when the covered PIN diode is in the on state. Figure 8 The incident E at 4.5 GHz y When polarizing plane electromagnetic waves, the reflected electric field distribution of the invisibility cloak when the sandy ground, exposed protrusions, and covered PIN diodes are in the off state. The results show that when the PIN diode integrated on the metasurface invisibility cloak switches from the on state to the off state, the reflected electric field intensity of the metasurface cloak decreases, which can simulate the reflection of other target terrains (such as the sandy ground given in this embodiment) and is insensitive to polarization.

[0035] The above description is only a specific implementation of the present invention, the purpose is to better illustrate the technical content of the present invention, and does not constitute a limitation of the present invention. For those skilled in the art, any modification, equivalent replacement or improvement made without departing from the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different backgrounds, characterized in that: It includes several phase and amplitude adjustable metasurface units arranged in an array, and the metasurface unit includes four layers of metal patches and three layers of dielectric substrates. Two of them are metal control layers loaded with active adjustable devices, and the bias voltage of the adjustable devices is changed to achieve phase and amplitude control of the metasurface unit. The invisibility cloak realizes independent regulation of the phase and amplitude of electromagnetic waves by controlling the active adjustable devices loaded on the metasurface unit, and can dynamically simulate the reflection effect of electromagnetic waves under different target terrain backgrounds. It also realizes efficient adaptability to radar waves of different polarizations through the 90° rotational symmetry design of the metasurface unit, realizing multi-terrain and multi-polarization stealth.

2. The polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different backgrounds according to claim 1, characterized in that: The first layer of the phase and amplitude adjustable metasurface unit from top to bottom is a phase control metal layer, the second layer is a low-loss dielectric layer, the third layer is an amplitude control metal layer, the fourth layer is a low-loss dielectric layer, the fifth layer is a metal reflection layer, the sixth layer is a low-loss dielectric layer, and the seventh layer is a metal bias line. The second low-loss dielectric layer and the third amplitude control metal layer are separated by air.

3. The polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different backgrounds according to claim 1, characterized in that: The phase control metal layer includes a middle square metal patch and four identical rectangular metal patches around it. The four identical rectangular metal patches are arranged around the square metal patch in a 90° rotational symmetry. Each rectangular metal patch is connected to the middle square metal patch through a varactor diode, and each adjacent rectangular metal patch is connected to each other through metal routing. A metal via is provided at the geometric center of the unit and is connected to the bottom metal bias line to control the bias voltage of the varactor diode.

4. The polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different backgrounds according to claim 1, characterized in that: The amplitude control metal layer includes a middle square ring metal patch and four identical rectangular metal patches around it. The four identical rectangular metal patches are arranged around the square metal patch in a 90° rotational symmetry. Each rectangular metal patch is connected to the middle square metal patch through an active adjustable device, and each adjacent rectangular metal patch is connected to each other through metal routing. The four corners of the middle square ring metal patch are provided with metal vias, which are connected to the bottom metal bias line to control the bias voltage of the active adjustable device.

5. The polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different backgrounds according to claim 4, characterized in that: The active adjustable devices include but are not limited to PIN diodes, varactor diodes, controllable resistors, and MEMS switches.

6. The polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different backgrounds according to claim 1, characterized in that: The metasurface unit period p is 10 to 14 mm.

7. The polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different backgrounds according to claim 1, characterized in that: The length b of the super surface unit rectangular metal patch is 5 to 8 mm.

8. The polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different backgrounds according to claim 1, characterized in that: The width a of the super surface unit rectangular metal patch is 1 to 4 mm.

9. The polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different backgrounds according to claim 1, characterized in that: The inner side length d of the square ring of the super surface unit is 2.5-5 mm.

10. The polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different backgrounds according to claim 1, characterized in that: The thickness t of the super surface unit is 6 to 10 mm.

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