A polarization-insensitive dynamically tunable metasurface cloak suitable for different backgrounds

Abstract

The application provides a polarization-insensitive dynamic adjustable metasurface cloak suitable for different target terrain backgrounds, realizes independent adjustment of the amplitude and phase of polarization insensitivity through innovative design, and is suitable for dynamic stealth and electromagnetic wave manipulation in complex environments. The cloak is composed of a plurality of array arranged metasurface units, each unit includes a plurality of metal structures and a dielectric substrate, and integrates an active adjustable device to realize real-time control of electromagnetic wave phase and amplitude. The adopted 90° rotational symmetry design ensures good adaptability to horizontal polarization and vertical polarization radar waves. By adjusting the bias voltage, the device can simulate the microwave reflection characteristics of different target terrains, providing an efficient solution for military stealth, terrain detection and electromagnetic environment simulation. Compared with the traditional technology, the application significantly improves the electromagnetic wave manipulation flexibility and environmental adaptability of the metasurface.

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 periodic or quasi-periodic subwavelength structural units. By precisely controlling the electromagnetic response characteristics of each unit, they can finely control the phase, amplitude, and polarization state of the incident electromagnetic wave. Through proper design, metasurfaces can achieve spatial variations in the equivalent refractive index, thereby guiding electromagnetic waves along specific paths to avoid interaction with target objects, rendering them invisible to electromagnetic detection.

[0003] Stealth technology has long been a hot topic in metasurface research. Traditional stealth technologies typically rely on absorbing materials or the principle of scattering cancellation, achieving stealth by coating the target surface with functional materials to suppress the target's radar cross section. However, these technologies often suffer from narrow bandwidth and strong dependence on specific detection directions, making them difficult to meet the requirements of multi-angle and dynamic stealth in complex environments. With the development of metasurface technology, coating the target surface with metasurface materials allows for precise manipulation of incident electromagnetic waves, achieving stealth, and has become a major research focus in stealth technology.

[0004] Although significant progress has been made in the theory and experimentation of metasurface stealth devices, existing technologies still have many shortcomings. For example, traditional metasurface stealth devices are mostly static designs with single functions, and are unable to 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 rely on external detectors or manual operation, which is complex and inefficient. In addition, although existing metasurface technologies have made certain achievements in achieving stealth and electromagnetic wave control, most of them focus on phase control, and their 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 from different terrains, which is a major drawback in military stealth, terrain detection, and wireless communications.

[0005] Therefore, developing a metasurface technology with reconfigurable amplitude and phase, which can dynamically control the reflection amplitude and phase and simulate the changes in the reflectivity of electromagnetic waves due to 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 response to 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 objectives, the present invention adopts the following technical solutions:

[0008] The polarization-insensitive, dynamically adjustable metasurface cloak, suitable for use in various target terrains, comprises an array of phase- and amplitude-adjustable metasurface units. Each unit comprises four layers of metal patches and a three-layer dielectric substrate. Two of these layers are metal control layers loaded with active adjustable devices. Changing the bias voltage of these adjustable devices enables phase and amplitude control of the metasurface units.

[0009] Furthermore, the phase- and amplitude-adjustable metasurface unit comprises, from top to bottom, a phase-control metal layer as the first layer, a low-loss dielectric layer as the second layer, an amplitude-control metal layer as the third layer, a low-loss dielectric layer as the fourth layer, a metal reflective layer as the fifth layer, a low-loss dielectric layer as the sixth layer, and a metal bias line as the seventh layer. 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 central square 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 central square metal patch through a varactor diode, 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 to control the bias voltage of the varactor diode.

[0011] Furthermore, the amplitude control metal layer includes a central 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 central square metal patch through an active adjustable device, and each adjacent rectangular metal patch is connected to each other through metal traces. Metal vias are provided at the four corners of the central square ring metal patch, 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 application realizes independent controllability of electromagnetic wave reflection phase and amplitude by introducing two layers of metal control layers in the metasurface unit, respectively loaded with active adjustable devices. This double-parameter control capability significantly improves the electromagnetic wave manipulation flexibility of the metasurface, breaking through the limitation of traditional stealth metasurface which only focuses on phase control.

[0014] (2) By adjusting the bias voltage of the active adjustable device, the electromagnetic response characteristics of the metasurface can be adjusted in real time, so that it can 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 application adopts 90° rotational symmetry design. This geometric characteristic enables accurate control of its reflection characteristics in both horizontal polarization and vertical polarization states, thereby achieving effective stealth for multi-polarization radar waves. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Structure diagram of the polarization-insensitive dynamic adjustable metasurface stealth cloak suitable for different backgrounds of the present application;

[0017] Figure 2 Unit structure diagram of the polarization-insensitive dynamic adjustable metasurface stealth cloak suitable for different backgrounds of the present application;

[0018] Figure 3 Simulation curve of reflection amplitude and phase of the metasurface unit in the present application under different capacitance values when the PIN diode is in the on state, with frequency as the variable;

[0019] Figure 4 Simulation curve of reflection amplitude and phase of the metasurface unit in the present application under different capacitance values when the PIN diode is in the off state, with frequency as the variable;

[0020] Figure 5 Reflection electric field distribution diagram of the incident electromagnetic wave in the E x polarization under the metal ground, bare protrusion and covered metasurface stealth cloak in the embodiment of the present application;

[0021] Figure 6 Reflection electric field distribution diagram of the incident electromagnetic wave in the E y polarization under the metal ground, bare protrusion and covered metasurface stealth cloak in the embodiment of the present application;

[0022] Figure 7 Reflection electric field distribution diagram of the incident electromagnetic wave in the E x polarization under the sand ground, bare protrusion and covered metasurface stealth cloak in the embodiment of the present application;

[0023] Figure 8The incident electromagnetic wave in the embodiment of the present invention is 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 precedence, 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 cloak suitable for diverse backgrounds. The key lies in the unique structure of the metasurface units and the incorporation of active tunable devices to achieve phase and amplitude control of incident microwaves. The specific design utilizes a multilayered metasurface structure, each loaded with an active tunable device. By controlling the bias voltage, the system achieves real-time adjustment of electromagnetic wave reflection characteristics.

[0027] like Figure 1 As shown, this embodiment provides a metasurface stealth cloak composed of two 10×10 metasurface unit arrays. The cloak has a triangular raised structure, a 60mm height h, and a 30° tilt angle α. The phase distribution of the cloak is determined based on the generalized Snell's law. Different bias voltages are then applied to units at different locations on the metasurface stealth cloak via underlying bias lines to achieve phase control and ultimately achieve a stealth effect.

[0028] Figure 2 This is a schematic diagram of the structure of the metasurface unit that constitutes the metasurface stealth cloak in this embodiment. The unit exhibits 90° rotational symmetry. 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 reflective 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 square metal patch in the middle 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 diode 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 diode.

[0030] The amplitude control metal layer includes a central 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 central 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 central square ring metal patch, which are connected to the metal bias line at the bottom layer to control the bias voltage of the PIN diode.

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

[0032] The varactor diode is equivalent to an RLC series circuit: a resistor with a constant resistance, an inductor with a constant inductance, and a capacitor with a variable capacitance. By adjusting the capacitance of the varactor diode, the phase of the metasurface unit can be controlled nearly 360 degrees to meet the different phase requirements of the metasurface stealth cloak. Furthermore, by controlling the on and off state of the PIN diode, the overall reflection amplitude of the metasurface unit can be adjusted. Figure 3 For the determined metasurface unit, when the PIN diode is in the on state, 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; Figure 4 The relationship between the varactor diode capacitance and the unit reflection amplitude, and the varactor diode capacitance and unit reflection phase, for the determined metasurface unit, when the PIN diode is in the off state. Within the 2.4 GHz to 5.2 GHz frequency band, when the PIN diode switches from the on state to the off state, the reflection amplitude switches from partial reflection mode to full reflection mode.

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

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

[0035] The foregoing description is merely a specific embodiment of the present invention, which is intended to better illustrate the technical content of the present invention and does not constitute a limitation of the present invention. Any modifications, equivalent substitutions, or improvements made by those skilled in the art without departing from the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A polarization-insensitive dynamically adjustable metasurface stealth cloak suitable for different backgrounds, characterized by: The system comprises several phase- and amplitude-adjustable metasurface units arranged in an array. The metasurface units comprise four layers of metal patches and three layers of dielectric substrates, including two metal control layers loaded with active adjustable devices. Changing the bias voltage of the adjustable devices enables phase and amplitude control of the metasurface units. The stealth cloak independently regulates the phase and amplitude of electromagnetic waves by controlling the active adjustable devices loaded on the metasurface units. This allows for dynamic simulation of the reflection effects of electromagnetic waves under different target terrain backgrounds. The 90° rotationally symmetric design of the metasurface units enables efficient adaptability to radar waves of different polarizations, achieving multi-terrain and multi-polarization stealth. The phase and amplitude adjustable metasurface unit has a first layer from top to bottom consisting of a phase control metal layer, a second layer consisting of a low-loss dielectric layer, a third layer consisting of an amplitude control metal layer, a fourth layer consisting of a low-loss dielectric layer, a fifth layer consisting of a metal reflective layer, a sixth layer consisting of a low-loss dielectric layer, and a seventh layer consisting of a metal bias line; the second layer of low-loss dielectric layer and the third layer of amplitude control metal layer are separated by air; The phase control metal layer includes a central square metal patch and four identical rectangular metal patches surrounding 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 central square metal patch via a varactor diode, and each adjacent rectangular metal patch is connected to each other via metal traces. A metal via is provided at the geometric center of the unit and connected to the metal bias line at the bottom layer to control the bias voltage of the varactor diode. The amplitude control metal layer includes a central 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 central square metal patch through an active adjustable device, and each adjacent rectangular metal patch is connected to each other through metal traces. Metal vias are provided at the four corners of the central square ring metal patch, which are connected to the metal bias line at the bottom layer to control the bias voltage of the active adjustable device.

2. The polarization-insensitive dynamically adjustable metasurface stealth cloak applicable to different backgrounds according to claim 1, characterized in that: The active adjustable devices include but are not limited to PIN diodes, varactor diodes, controllable resistors, and MEMS switches.

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

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

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

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

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

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