High cut-through transreflective reconfigurable skin

Abstract

The application discloses a high-cut transmissive and reflective integrated reconfigurable skin, which comprises a plurality of same and periodically arranged reconfigurable metasurface units, each of which comprises, from top to bottom, a glass steel, a first reconfigurable layer, a first foam layer, a second metal mesh layer, a second foam layer and a third metal layer; the first reconfigurable layer is composed of a multilayer structure, comprising a first annular metal patch, a first dielectric substrate, a second staggered cross-shaped aperture type metal patch, a second dielectric substrate and a third oblique rectangular metal bias line which are stacked in sequence, and two metallized holes, four PIN diodes and two inductors; when the application is in a wave-transmissive state, electromagnetic waves can pass through the skin with low insertion loss when being incident, without affecting the receiving / transmitting performance of a radio frequency front-end antenna; when the application is in a shielding state, the skin can protect the antenna from being affected when high-power attack electromagnetic waves are incident.

Description

Technical Field

[0001] This invention relates to the fields of electromagnetic stealth and novel artificial electromagnetic materials, and in particular to a high-cutoff, transflective, and reconfigurable skin. Background Technology

[0002] Radar antennas are typically significant scattering sources in military systems. Conventional dielectric skins cannot reduce radar cross-section. While absorbing materials can achieve electromagnetic stealth, they can interfere with normal communication. However, using metasurfaces as skin allows electromagnetic waves within the antenna's communication band to pass through the radome without affecting communication. Electromagnetic waves outside the communication band are reflected in various directions by the metasurface's low-scattering shape, preventing strong scattering in the direction of arrival and thus reducing the out-of-band monostatic RCS of the antenna system, achieving radar stealth. A reconfigurable smart skin is constructed by introducing tunable devices and adding a protective layer within the metasurface unit. The passband and stopband states of the metasurface are changed by controlling external excitation. The operating state switches according to the internal antenna's status: when the antenna is active, the reconfigurable skin is in passband mode, not affecting normal communication and reducing out-of-band RCS; when the antenna is inactive, it switches to stopband mode, achieving broadband electromagnetic stealth.

[0003] For high-power array antenna applications, electromagnetic shielding is achieved by setting the diodes to the off state (OFF) and the on state (ON) for electromagnetic wave transmission. This configuration effectively suppresses the in-band insertion loss degradation caused by high-power incident electromagnetic waves. Traditional stealth radomes or skins suffer from narrow bandwidth, high insertion loss, slow transmission coefficient changes, and poor high cutoff characteristics within the operating frequency band. These issues significantly impact information transmission and make them vulnerable to increasingly sophisticated detection technologies. Summary of the Invention

[0004] The purpose of this invention is to provide a high-cutoff, reconfigurable, transflective skin to address the issues of in-band flatness, low insertion loss, and high out-of-band cutoff.

[0005] The technical solution for achieving the objective of this invention is as follows: a high-cutoff, transflective, and reconfigurable skin, comprising: a plurality of identical, periodically arranged reconfigurable metasurface units, each reconfigurable metasurface unit comprising, from top to bottom, fiberglass, a first reconfigurable layer, a first foam layer, a second metal mesh layer, a second foam layer, and a third metal layer, wherein:

[0006] The first reconfigurable layer consists of a multi-layer structure, including a first annular metal patch, a first dielectric substrate, a second cross-shaped metal patch, a second dielectric substrate, and a third oblique rectangular metal bias line stacked in sequence, as well as two metallized holes, four PIN diodes, and two inductors.

[0007] The first annular metal patch is a rectangular ring structure located on the upper surface of the first dielectric substrate. A slit is opened at the center of each of its four sides, and a PIN diode is loaded at each slit.

[0008] The second cross-shaped perforated metal patch is located on the lower surface of the first dielectric substrate. The second cross-shaped perforated metal patch is square, and its side length is smaller than the periodic dimension of the reconfigurable skin unit. A cross-shaped perforation is formed in the central region. The second dielectric substrate is disposed below the second cross-shaped perforated metal patch.

[0009] The third oblique rectangular metal bias line is located on the lower surface of the second dielectric substrate. It includes two oblique rectangular metal patches, which are located on both sides of the diagonal in a clockwise rotation of 45 degrees. They are arranged in an alternating positive and negative manner. The four PIN diodes are divided into two groups, left and right, with the diagonal in a clockwise rotation of 45 degrees as the boundary. The two PIN diodes in each group are connected in series to form one circuit, thus forming two independent bias control circuits.

[0010] Each bias control loop has a metallized via at its center, which is electrically connected to the first annular metal patch to realize the transmission control of the bias voltage; the inductor is a surface-mount inductor, and two inductors are connected in series with one bias control loop to effectively isolate the radio frequency signal.

[0011] Furthermore, the fiberglass is made of cyanate quartz cloth prepreg and is bonded to the upper side of the first reconfigurable layer by epoxy resin.

[0012] Furthermore, in the third oblique rectangular metal offset line, the two oblique rectangular metal patches are symmetrically distributed about the diagonal of the direction of clockwise rotation of 45 degrees. In the second cross-shaped metal patch, the length of the cross hole is equal to the side length of the square metal patch, and the width is half the side length of the square metal patch.

[0013] Furthermore, the second metal mesh layer includes four rectangular metal patches and a third dielectric substrate. The four rectangular metal patches are located on the upper surface of the third dielectric substrate and form a rectangular mesh structure.

[0014] Furthermore, the third metal layer includes a third cross-shaped perforated metal patch, a fourth dielectric substrate, and a second annular metal patch; the third cross-shaped perforated metal patch is disposed on the upper surface of the fourth dielectric substrate, and the third cross-shaped perforated metal patch is square with a cross-shaped perforation in the central region; the second annular metal patch adopts a rectangular ring structure and is disposed on the lower surface of the fourth dielectric substrate, the third cross-shaped perforated metal patch and the second cross-shaped perforated metal patch have the same size, and the second annular metal patch and the first annular metal patch have the same size.

[0015] Furthermore, the reconfigurable metasurface units are centrosymmetric.

[0016] Furthermore, the first dielectric substrate, the second dielectric substrate, the third dielectric substrate, and the fourth dielectric substrate are all polyimide dielectric substrates.

[0017] Furthermore, both the first foam layer and the second foam layer are PMI.

[0018] Furthermore, the material of the metal structure is copper.

[0019] Furthermore, when the high-cutoff, transparent-reflective integrated reconfigurable skin is powered on, the PIN diode is turned on, and the first annular metal patch is in a connected state. At this time, the high-cutoff, transparent-reflective integrated reconfigurable skin is transparent to incident electromagnetic waves. When electromagnetic waves are incident, they can pass through the skin with low insertion loss, without affecting the transmit / receive performance of the RF front-end antenna. When the high-cutoff, transparent-reflective integrated reconfigurable skin is not powered on, the PIN diode is turned off, and the first annular metal patch is in a disconnected state. At this time, the original transparent state of the high-cutoff, transparent-reflective integrated reconfigurable skin is destroyed, and the skin is in a reflective state within the operating frequency band. The skin will protect the antenna from being affected. The transparent state is the communication state.

[0020] Compared with existing technologies, the significant advantages of this invention are: the high-cutoff, transflective, and reconfigurable skin has a flatter passband, better roll-off sidebands, and wide-band out-of-band suppression capabilities. Through multi-layer cascading, multiple transmission poles are introduced within the passband, and multiple transmission zeros are introduced near these poles in the out-of-band region to improve passband flatness, sideband roll-off, and out-of-band suppression. The passband and stopband states of the metasurface can be changed by controlling external excitation, switching the operating state according to the internal antenna's operation. When the antenna is active, the reconfigurable smart skin is in the passband state, not affecting normal antenna communication and reducing out-of-band RCS; when the antenna is inactive, it switches to the stopband state, achieving wideband electromagnetic stealth. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the high-cutoff, reconfigurable, transflective integrated skin structure of the present invention.

[0022] Figure 2 This is a schematic diagram of a reconfigurable metasurface unit structure;

[0023] Figure 3 A schematic diagram of a high-cutoff, reconfigurable, transflective skin array.

[0024] Figure 4 For high-cutoff, reconfigurable, one-piece transparent and reflective skin, S-shaped in two states 21 parameter;

[0025] Figure 5 For high-cutoff, reconfigurable transflective skin in a 0-40 degree S-mode, the transflective state is... 21parameter;

[0026] Figure 6 For high-cutoff reconfigurable reconstructable skin with integrated transmissive and reflective properties, the 0-40 degree S-axis is used in the reflective state. 11 parameter;

[0027] Symbol explanation:

[0028] 1-Fiberglass, 2-First reconfigurable layer, 3-First foam layer, 4-Second metal mesh layer, 5-Second foam layer, 6-Third metal layer Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0030] This invention relates to a high-cutoff, reconfigurable, transmissive-reflective integrated skin. It employs a multi-layer cascade method, optimizing structural parameters to achieve a flat in-band passband, steep sidebands, and high out-of-band cutoff. Furthermore, active devices are loaded into the unit structure to enable switchable transmission / reflection in the passband (in-band), thus truly achieving real-time switching between skin operation and stealth mode.

[0031] like Figure 1 As shown, the present invention provides a high-cutoff transflective integrated reconfigurable skin, comprising multiple two-dimensionally equally spaced reconfigurable metasurface units; each reconfigurable metasurface unit comprises, from top to bottom, fiberglass, a first reconfigurable layer, a first foam layer, a second metal mesh layer, a second foam layer, and a third metal layer.

[0032] like Figure 2 As shown, the first reconfigurable layer 2 is composed of multiple layers stacked sequentially, specifically including: a first annular metal patch, a first dielectric substrate, a second cross-shaped metal patch, a second dielectric substrate, a third obliquely placed rectangular metal bias line, and metallized vias connecting the first annular metal patch and the third obliquely placed rectangular metal bias line, four PIN diodes, and two surface-mount inductors.

[0033] The first annular metal patch is a rectangular annular structure disposed on the upper surface of the first dielectric substrate. A slit of equal width is formed at the center of each of its four sides, and a PIN diode is loaded at each slit, thereby realizing reconfigurable control of the electromagnetic response state of the unit.

[0034] In traditional high-cutoff, transparent-reflective integrated reconfigurable skins, the design typically dictates that the skin is transparent when the PIN diode is in the cutoff state, and shielded when the PIN diode is on. However, under high-power electromagnetic radiation, a high voltage is induced across the PIN diode, causing the originally cutoff diode to conduct, thus disrupting the transparent state, increasing insertion loss, and reducing communication performance. The non-ideal characteristics of the PIN diode under high power significantly affect the performance of the reconfigurable skin.

[0035] This invention improves the bias characteristics of PIN diodes: when the PIN diode is in the conducting state, the skin is in a transparent state; when the PIN diode is in the cutoff state, the skin is in a shielded state. This design ensures that even if the diode conducts due to induced voltage under high-power electromagnetic radiation, the transparent state is not disrupted, thereby effectively reducing insertion loss and improving system stability and reliability. This biasing strategy exhibits superior electromagnetic compatibility and anti-interference capabilities in high-power applications.

[0036] The second cross-shaped perforated metal patch is located on the lower surface of the first dielectric substrate. The second cross-shaped perforated metal patch is square, and its side length is smaller than the periodic dimension of the reconfigurable skin unit. A cross-shaped perforation is formed in the central region of the second cross-shaped perforated metal patch. The length of the cross-shaped perforation is equal to the side length of the square metal patch, and the width is half the side length of the square metal patch. The second dielectric substrate is disposed below the second cross-shaped perforated metal patch as a support layer, providing the necessary mechanical strength to ensure the stability and functionality of the overall structure.

[0037] The third oblique rectangular metal bias line is located on the lower surface of the second dielectric substrate and includes two oblique rectangular metal patches, located on either side of a diagonal line rotated 45 degrees clockwise, symmetrically distributed around the diagonal. The third oblique rectangular metal bias line uses an alternating arrangement of positive and negative electrodes to ensure the rationality of the bias current path. Using the diagonal line rotated 45 degrees clockwise as the boundary, the four PIN diodes are divided into left and right groups. The two PIN diodes in each group are connected in series to form one path, forming two independent bias control loops.

[0038] Traditional bias networks in reconfigurable skin arrays suffer from the following problems: when a PIN diode becomes open-circuited or fails, it can cause abnormal voltage distribution across the entire bias network, affecting the normal operation of the entire reconfigurable skin array. Furthermore, as the number of cells increases, to ensure all diodes conduct properly, the system needs to provide higher bias voltages, potentially as high as 60 to 80 volts. This not only increases the complexity of power supply design but also raises system power consumption and safety risks.

[0039] This invention proposes an improved bias network structure that employs independent bias paths, enabling each bias path to operate independently and ensuring that their operating states do not affect each other. Even if one diode fails, the other diodes can still operate normally, significantly improving the reliability of the system.

[0040] Each bias control loop has a metallized via at its center, which is electrically connected to the first annular metal patch to realize the transmission control of the bias voltage; the inductor is a surface-mount inductor, and two inductors are connected in series with one bias control loop to effectively isolate the radio frequency signal.

[0041] The second metal mesh layer 4 includes two parallel rectangular metal patches and two mutually orthogonal rectangular metal patches, a third dielectric substrate, and four rectangular metal patches located on the upper surface of the third dielectric substrate, forming a rectangular mesh structure.

[0042] The third metal layer 6 includes a third cross-shaped perforated metal patch, a fourth dielectric substrate, and a second annular metal patch. The third cross-shaped perforated metal patch is square, with a side length smaller than the periodic dimension of the reconfigurable skin unit. A cross-shaped perforation is formed in the central region of the second cross-shaped perforated metal patch. The second annular metal patch adopts a rectangular ring structure and is disposed on the lower surface of the fourth dielectric substrate. The second annular metal patch and the first annular metal patch have the same size and are both rectangular ring structures to ensure consistency in their electromagnetic characteristics. The third cross-shaped perforated metal patch and the second cross-shaped perforated metal patch have the same size and are both structures with cross-shaped perforations formed in a square metal patch to ensure symmetry in their electromagnetic characteristics. This symmetrical structural design helps to expand the bandwidth of the transmission band and reduce in-band insertion loss, thereby improving the transmission performance of the reconfigurable skin at high cutoff frequencies.

[0043] Furthermore, the reconfigurable metasurface unit adopts a centrosymmetric structure design, which significantly improves the stability and consistency of its electromagnetic properties. This centrosymmetric structure enables the unit to exhibit consistent response characteristics under electromagnetic wave irradiation with different polarization directions, thereby achieving polarization insensitivity.

[0044] Furthermore, the metal structure material of the reconfigurable skin unit is copper. Specifically, the first annular metal patch, the second cross-shaped perforated metal patch, the third oblique rectangular metal offset line, and the metallized holes connecting the first annular metal patch and the third oblique rectangular metal offset line in the first reconfigurable layer, the four rectangular metal patches in the second metal mesh layer, and the third cross-shaped perforated metal patch and the second annular metal patch in the third metal layer are all made of copper.

[0045] Furthermore, the first dielectric substrate, the second dielectric substrate, the third dielectric substrate, and the fourth dielectric substrate are all polyimide dielectric substrates. This material is characterized by being flexible and not easily broken, which can achieve conformal integration with the mounting platform and improve the aerodynamics of the mounting platform.

[0046] Furthermore, both the first and second foam layers are PMI (Polydimer Magnetic Material), a material characterized by low dielectric constant and low loss tangent, resulting in less signal attenuation during propagation on its surface and ensuring low-loss signal transmission through the skin. The PMI foam material used is a high dielectric constant material (ε... r =1.07, tanδ =0.001).

[0047] Furthermore, the fiberglass is made of cyanate quartz cloth prepreg and is bonded to the upper side of the first reconfigurable layer by epoxy resin.

[0048] The working principle is as follows:

[0049] In the first reconfigurable layer, the PIN diode operates in two states: cutoff and conduction, with zero-bias and forward bias voltages of 0V and 0.7V respectively. By controlling the bias voltage, the electromagnetic response state of the annular metal patch structure can be switched, thus enabling dynamic reconfigurability of the skin's transmission and reflection characteristics. When the high-cutoff reconfigurable transparent-reflective skin is powered on, the PIN diode conducts, and the first annular metal patch is in a connected state. At this time, the structure is transparent to incident electromagnetic waves, allowing the electromagnetic waves to pass through the skin with low insertion loss, without affecting the transmit / receive performance of the RF front-end antenna. When the high-cutoff reconfigurable transparent-reflective skin is not powered on, the PIN diode is cut off, and the first annular metal patch is in a disconnected state. At this time, the original transparent state of the structure is destroyed, and the skin is in a reflective state within the operating frequency band. The skin protects the antenna from being affected; this transparent state is the communication state. When the high-cutoff reconfigurable transparent-reflective skin is conformally fitted to a corresponding carrier, it can ensure that the normal operation of the radar antenna is not affected, nor the aerodynamics of the cabin, thus providing good stealth capabilities.

[0050] Example

[0051] To verify the effectiveness of the present invention, the following experiment was conducted.

[0052] In this embodiment, the reconfigurable metasurface is composed of 20*20 periodic units, with an array size of 130mm×130mm, such as... Figure 3 As shown, the bias voltage is uniformly controlled for the 20*20 periodic unit.

[0053] Using the simulation software CST Studio Suite 2022, with unit cell boundary conditions and a frequency domain solver, the designed skin was modeled and simulated. Lumped ports were used to represent the cutoff and conduction states of the PIN diode, such as... Figure 4 As shown. When powered on, the high-cutoff reconfigurable transparent-reflective skin achieves a cutoff of less than 1dB insertion loss in the in-band (2.78-3.41GHz) and greater than 20dB out-of-band (4-10GHz). When not powered on, the reconfigurable skin exhibits a cutoff of greater than 3dB in the in-band and greater than 20dB out-of-band. Furthermore, the TE polarization and TM polarization remain consistent.

[0054] like Figure 5 As shown, when the high-cutoff reconfigurable transflective skin is powered on, the angle is between 0-40 degrees. 0 At that time, S 21 The curves remain largely consistent, demonstrating good angular stability.

[0055] like Figure 6 As shown, when the high-cutoff reconfigurable transparent-reflective skin is not powered on, the angle is between 0-40 degrees. 0 At that time, S 11 The curves remained largely consistent, with good reflection performance in the 3.5–10 GHz range, demonstrating excellent reflection capabilities.

[0056] Working Principle: This invention changes the pass / stop state of the skin by controlling external excitation. The operating state switches according to the internal antenna's activity. When the antenna is active, the reconfigurable smart skin is in passband mode, not affecting normal antenna communication and reducing out-of-band RCS. When the antenna is inactive, it switches to stopband mode, achieving broadband electromagnetic stealth. Compared with existing technologies, this invention can achieve in-band transmission and reflection switching, and has high out-of-band cutoff characteristics, achieving low out-of-band RCS. It has a better stealth effect. Furthermore, its electromagnetic wave dynamic control capability and self-sensing capability are both broadband, polarization-insensitive, and angle-insensitive. Compared with existing electromagnetic protection devices, this invention has a sophisticated bias network design, high stability, strong practicality, and wide applicability.

[0057] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A high-cutoff, transflective, reconfigurable integrated skin, characterized in that, include: Several identical, periodically arranged reconfigurable metasurface units, each reconfigurable metasurface unit comprising, from top to bottom, fiberglass, a first reconfigurable layer, a first foam layer, a second metal mesh layer, a second foam layer, and a third metal layer, wherein: The first reconfigurable layer consists of a multi-layer structure, including a first annular metal patch, a first dielectric substrate, a second cross-shaped metal patch, a second dielectric substrate, and a third oblique rectangular metal bias line stacked in sequence, as well as two metallized holes, four PIN diodes, and two inductors. The first annular metal patch is a rectangular ring structure located on the upper surface of the first dielectric substrate. A slit is opened at the center of each of its four sides, and a PIN diode is loaded at each slit. The second cross-shaped perforated metal patch is located on the lower surface of the first dielectric substrate. The second cross-shaped perforated metal patch is square, and its side length is smaller than the periodic dimension of the reconfigurable skin unit. A cross-shaped perforation is formed in the central region. The second dielectric substrate is disposed below the second cross-shaped perforated metal patch. The third oblique rectangular metal bias line is located on the lower surface of the second dielectric substrate. It includes two oblique rectangular metal patches, which are located on both sides of the diagonal in a clockwise rotation of 45 degrees. They are arranged in an alternating positive and negative manner. The four PIN diodes are divided into two groups, left and right, with the diagonal in a clockwise rotation of 45 degrees as the boundary. The two PIN diodes in each group are connected in series to form one circuit, thus forming two independent bias control circuits. A metallized via is provided at the center of each bias control loop, which is electrically connected to the first annular metal patch to realize the transmission control of the bias voltage; the inductor is a surface-mount inductor, and two inductors are connected in series with one bias control loop respectively to effectively isolate the radio frequency signal; When the high-cutoff, reconfigurable, transparent skin is powered on, the PIN diode is turned on, and the first annular metal patch is in a connected state. At this time, the high-cutoff, reconfigurable, transparent skin is transparent to incident electromagnetic waves, allowing the electromagnetic waves to pass through the skin with low insertion loss, without affecting the transmit / receive performance of the RF front-end antenna. When the high-cutoff, reconfigurable, transparent skin is not powered on, the PIN diode is turned off, and the first annular metal patch is in a disconnected state. At this time, the original transparent state of the high-cutoff, reconfigurable, transparent skin is destroyed, and the skin is in a reflective state within the operating frequency band. The skin protects the antenna from being affected. The transparent state is the communication state.

2. The high-cutoff, transflective, reconfigurable skin according to claim 1, characterized in that, The fiberglass is made of cyanate quartz cloth prepreg and is bonded to the upper side of the first reconfigurable layer by epoxy resin.

3. The high-cutoff, transflective, reconfigurable skin according to claim 1, characterized in that, In the third oblique rectangular metal offset line, two oblique rectangular metal patches are symmetrically distributed about the diagonal of the direction of clockwise rotation of 45 degrees. In the second cross-shaped metal patch, the length of the cross hole is equal to the side length of the square metal patch, and the width is half the side length of the square metal patch.

4. The high-cutoff, transflective, reconfigurable skin according to claim 1, characterized in that, The second metal mesh layer includes four rectangular metal patches and a third dielectric substrate. The four rectangular metal patches are located on the upper surface of the third dielectric substrate and form a rectangular mesh structure.

5. The high-cutoff, transflective, reconfigurable integrated skin according to claim 1, characterized in that, The third metal layer includes a third cross-shaped metal patch, a fourth dielectric substrate, and a second annular metal patch; the third cross-shaped metal patch is disposed on the upper surface of the fourth dielectric substrate, and the third cross-shaped metal patch is square with a cross-shaped hole in the central region. The second annular metal patch adopts a rectangular ring structure and is disposed on the lower surface of the fourth dielectric substrate. The third cross-shaped metal patch has the same size as the second cross-shaped metal patch, and the second annular metal patch has the same size as the first annular metal patch.

6. The high-cutoff, transflective, reconfigurable integrated skin according to claim 1, characterized in that, The reconfigurable metasurface unit is centrosymmetric.

7. The high-cutoff, transflective, reconfigurable skin according to claim 1, characterized in that, The first dielectric substrate, the second dielectric substrate, the third dielectric substrate, and the fourth dielectric substrate are all polyimide dielectric substrates.

8. The high-cutoff, transflective, reconfigurable skin according to claim 1, characterized in that, Both the first foam layer and the second foam layer are PMI.

9. The high-cutoff, transflective, reconfigurable integrated skin according to claim 1, characterized in that, The metal structure is made of copper.

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