High-cut-off transflective reconfigurable skin

Abstract

The invention discloses a high-cut-off transflective reconfigurable skin which comprises a plurality of identical and periodically arranged reconfigurable metasurface units, and each reconfigurable metasurface unit comprises glass fiber reinforced plastic, a first reconfigurable layer, a first foam layer, a second metal mesh layer, a second foam layer and a third metal layer which are sequentially arranged from top to bottom. The first reconfigurable layer is of a multi-layer structure and comprises a first annular metal patch, a first dielectric substrate, a second staggered cross-shaped hole type metal patch, a second dielectric substrate, a third inclined rectangular metal offset line, two plated-through holes, four PIN diodes and two inductors, all of which are sequentially stacked. When the radio frequency front-end antenna is in a wave-transparent state, electromagnetic waves can pass through the skin with relatively low insertion loss during incidence, and the receiving / transmitting performance of the radio frequency front-end antenna is not influenced; when the antenna is in a shielding state, high-power attack electromagnetic waves are incident, and the skin can protect the antenna from being influenced.

Description

Technical Field

[0001] The present invention relates to the fields of electromagnetic stealth and novel artificial electromagnetic materials, and in particular to a high-cutoff transmissive and reflective integrated reconfigurable skin. Background Art

[0002] Radar antennas are often significant scatterers in military systems. Conventional dielectric coverings are incapable of reducing radar cross-sections. While using absorbing materials can achieve electromagnetic stealth, this can compromise the antenna system's communication capabilities. However, using a metasurface as a covering allows electromagnetic waves within the antenna's communication band to pass through the radome, thus preventing communication interference. The metasurface's inherent low-scattering shape reflects incoming waves in all directions, eliminating strong scattering in the incoming direction. This reduces the out-of-band single-station RCS of the antenna system and achieves radar stealth. A reconfigurable smart skin is constructed by incorporating tunable components into the metasurface unit and adding a protective layer. The metasurface's pass- and block-states are altered by controlling external excitation. The skin switches operating mode based on the antenna's internal operation. When the antenna is operating, the reconfigurable skin maintains a passband state, minimizing out-of-band RCS and preserving communication. When the antenna is not operating, the skin switches to a blockband state, achieving broadband electromagnetic stealth.

[0003] Based on high-power array antenna applications, the diodes are configured in the off state (OFF) to achieve electromagnetic shielding, while the conductive state (ON) allows for electromagnetic wave transmission. This configuration effectively mitigates the degradation of in-band insertion loss caused by high-power incident electromagnetic waves. Traditional stealth radomes or skins suffer from narrow bandwidth, high insertion loss, slow transmission coefficient variation, and poor high-cutoff characteristics within their operating frequency bands. These factors significantly impact information transmission and make them difficult to adapt to increasingly sensitive detection technologies. Summary of the Invention

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

[0005] The technical solution to achieve the purpose of the present invention is: a high-cutoff transflective integrated reconfigurable skin, comprising: a plurality of identical, periodically arranged reconfigurable metasurface units, each reconfigurable metasurface unit comprising, from top to bottom, a fiberglass reinforced plastic, a first reconfigurable layer, a first foam layer, a second metal grid layer, a second foam layer, and a third metal layer, wherein:

[0006] The first reconfigurable layer is composed of a multi-layer structure, including a first annular metal patch, a first dielectric substrate, a second cross-aperture 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, with a gap formed at the center of each of the four sides, and a PIN diode loaded in each gap;

[0008] The second cross-aperture metal patch is located on the lower surface of the first dielectric substrate. The second cross-aperture metal patch is square, the side length of which is smaller than the periodic size of the reconfigurable skin unit, and a cross-shaped aperture is opened in the central area. The second dielectric substrate is arranged below the second cross-aperture metal patch.

[0009] A third oblique rectangular metal bias line is located on the lower surface of the second dielectric substrate and includes two oblique rectangular metal patches, one located on either side of a diagonal line rotated 45 degrees clockwise. The metal patches are arranged in an alternating pattern of positive and negative electrodes, with the diagonal line rotated 45 degrees clockwise as the dividing line. The four PIN diodes are divided into two groups, one on the left and one on the right, with the two PIN diodes in each group connected in series to form one path, thus forming two independent bias control loops.

[0010] A metallized hole is set 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 adopts a chip inductor, and two inductors are connected in series with a bias control loop respectively to effectively isolate the radio frequency signal.

[0011] Furthermore, the fiberglass reinforced plastic 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 bias line, the two oblique rectangular metal patches are symmetrically distributed about the diagonal line rotated 45 degrees clockwise, and in the second cross-pore type metal patch, the length of the cross pore 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 grid 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 to form a rectangular grid structure.

[0014] Furthermore, the third metal layer includes a third cross-aperture metal patch, a fourth dielectric substrate, and a second annular metal patch; the third cross-aperture metal patch is arranged on the upper surface of the fourth dielectric substrate, the third cross-aperture metal patch is square, and a cross-shaped aperture is opened in the central area; the second annular metal patch adopts a rectangular ring structure and is arranged on the lower surface of the fourth dielectric substrate, the third cross-aperture metal patch is the same size as the second cross-aperture metal patch, and the second annular metal patch is the same size as the first annular metal patch.

[0015] Furthermore, the reconfigurable metasurface unit is centrally symmetric.

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

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

[0019] Furthermore, when the high-cutoff transflective 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 transflective integrated reconfigurable skin is transparent to the incident electromagnetic waves. When the electromagnetic waves are incident, they can pass through the skin with a low insertion loss, without affecting the receiving / transmitting performance of the RF front-end antenna; when the high-cutoff transflective integrated reconfigurable 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 high-cutoff transflective integrated reconfigurable skin is destroyed, and the skin is in a reflective state within the working frequency band. The skin will protect the antenna from being affected, and the wave-transmitting state is the communication state.

[0020] Compared with existing technologies, this invention offers significant advantages: a high-cutoff, transflective, and reconfigurable skin with a flatter passband, well-rolled sidebands, and wide-band suppression outside the band. Through a multi-layer cascade, multiple transmission poles are introduced within the passband, and multiple transmission zeros are introduced outside the band near the poles to improve passband flatness, sideband roll-off, and out-of-band suppression. The metasurface's pass-stop state can be altered by controlling external excitation, and the operating state can be switched based on the internal antenna's operating conditions. When the antenna is operating, the reconfigurable intelligent skin is in the passband state, which does not affect normal antenna communication and reduces out-of-band RCS. When the antenna is not operating, it switches to the stopband state, achieving broadband electromagnetic stealth. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0022] Figure 2 Schematic diagram of the reconfigurable metasurface unit structure;

[0023] Figure 3 Schematic diagram of a high-cutoff transflective integrated reconfigurable skin array;

[0024] Figure 4 It is a high-cutoff transflective integrated reconfigurable skin with two states of S 21 parameter;

[0025] Figure 5 It is a high-cutoff transflective integrated reconfigurable skin with a 0-40 degree S- 21parameter;

[0026] Figure 6 It is a high-cutoff transflective integrated reconfigurable skin with a 0-40 degree S reflection state. 11 parameter;

[0027] Explanation of symbols:

[0028] 1-Fiberglass, 2-First reconfigurable layer, 3-First foam layer, 4-Second metal grid layer, 5-Second foam layer, 6-Third metal layer DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0030] The high-cutoff, integrated, transflective, and reconfigurable skin of this invention utilizes a multi-layer cascade approach to optimize structural parameters to achieve flat in-band passband, steep sidebands, and high out-of-band cutoff characteristics. Furthermore, active devices are incorporated into the unit structure to achieve switchable passband (in-band) transmission / reflection, enabling real-time switching between the skin's operational and stealth modes.

[0031] like Figure 1 As shown, the present invention provides a high-cutoff transflective integrated reconfigurable skin, which includes a plurality of two-dimensionally equally spaced reconfigurable metasurface units; each reconfigurable metasurface unit includes fiberglass, a first reconfigurable layer, a first foam layer, a second metal grid layer, a second foam layer, and a third metal layer, which are arranged in sequence from top to bottom.

[0032] like Figure 2 As shown, the first reconfigurable layer 2 is composed of a multi-layer structure stacked in sequence, specifically including: a first annular metal patch, a first dielectric substrate, a second cross-aperture metal patch, a second dielectric substrate, a third oblique rectangular metal bias line, and a metallized hole connecting the first annular metal patch and the third oblique rectangular metal bias line, four PIN diodes and two chip inductors.

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

[0034] Conventional high-cutoff, transflective, and integrated reconfigurable skins are typically designed so that when the PIN diode is in the off state, the skin is wave-transmitting; when the PIN diode is in the on state, the skin is in the shielding state. However, under high-power electromagnetic radiation, a high voltage is induced across the PIN diode, causing the originally off diode to conduct, thereby destroying the wave-transmitting state, increasing insertion loss, and degrading communication performance. The non-ideal characteristics of the PIN diode at high power significantly affect the performance of the reconfigurable skin.

[0035] This invention improves the bias characteristics of the PIN diode: when the PIN diode is in the on-state, the skin is in a wave-transmitting state; when the PIN diode is in the off-state, the skin is in a shielding state. This design maintains the wave-transmitting state even when the diode is turned on by the induced voltage under high-power electromagnetic radiation, effectively reducing insertion loss and improving system stability and reliability. This biasing strategy demonstrates improved electromagnetic compatibility and anti-interference capabilities in high-power applications.

[0036] The second cross-aperture metal patch is located on the lower surface of the first dielectric substrate. The second cross-aperture metal patch is square, with a side length less than the periodic dimension of the reconfigurable skin unit. A cross-shaped aperture is defined in the center of the second cross-aperture metal patch. The length of the cross-aperture is equal to the side length of the square metal patch, and the width is half of the side length of the square metal patch. The second dielectric substrate is positioned below the second cross-aperture metal patch, serving as a support layer and providing the necessary mechanical strength to ensure the stability and functionality of the overall structure.

[0037] The third slanted rectangular metal bias line, located on the lower surface of the second dielectric substrate, comprises two slanted rectangular metal patches, one on either side of a 45-degree clockwise diagonal line and symmetrically arranged around that diagonal line. The third slanted rectangular metal bias line uses an alternating positive and negative arrangement to ensure a rational bias current path. The four PIN diodes are divided into two groups, one on the left and one on the right, separated by a 45-degree clockwise diagonal line. The two PIN diodes in each group are connected in series to form one path, creating two independent bias control loops.

[0038] Traditional bias networks in reconfigurable skin arrays present the following challenges: If a PIN diode fails due to an open circuit or damage, it can cause abnormal voltage distribution across the entire bias network, impacting the proper operation of the entire reconfigurable skin array. Furthermore, as the number of cells increases, ensuring proper conduction of all diodes requires a higher bias voltage, potentially as high as 60 to 80 volts. This increases the complexity of the power supply design, while also increasing system power consumption and safety risks.

[0039] The present invention proposes an improved bias network structure, which adopts independent bias paths, so that each bias path works independently, ensuring that their working states do not affect each other. Even if a diode fails, the other diodes can still work normally, which significantly improves the reliability of the system.

[0040] A metallized hole is set 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 adopts a chip inductor, and two inductors are connected in series with a bias control loop respectively to effectively isolate the radio frequency signal.

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

[0042] The third metal layer 6 includes a third cross-aperture metal patch, a fourth dielectric substrate, and a second annular metal patch. The third cross-aperture metal patch is square, with a side length smaller than the periodic size of the reconfigurable skin unit. A cross-shaped aperture is provided in the center of the second cross-aperture 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 is the same size as the first annular metal patch and is a rectangular ring structure, ensuring consistency in their electromagnetic properties. The third cross-aperture metal patch is the same size as the second cross-aperture metal patch and is a structure with a cross-shaped aperture provided in a square metal patch, ensuring symmetry in their electromagnetic properties. This top-to-bottom symmetrical structural design helps expand the bandwidth of the transmission band and reduce the insertion loss within the band, thereby improving the transmission performance of the reconfigurable skin at high cutoff frequencies.

[0043] Furthermore, the reconfigurable metasurface unit adopts a centrosymmetric structural design, significantly improving the stability and consistency of its electromagnetic performance. This centrosymmetric structure enables the unit to exhibit consistent response characteristics when exposed to electromagnetic waves of different polarization directions, thus 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-aperture metal patch, the third oblique rectangular metal bias line, the metallized via connecting the first annular metal patch and the third oblique rectangular metal bias line in the first reconfigurable layer, the four rectangular metal patches in the second metal grid layer, and the third cross-aperture 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, which are easy to bend and not easy to break, and can achieve conformity with the mounting platform and improve the aerodynamics of the mounting platform.

[0046] Furthermore, the first foam layer and the second foam layer are both PMI, which has the characteristics of low dielectric constant and loss tangent, so that the attenuation of the signal when propagating on its surface is smaller, ensuring that the signal can pass through the skin with low loss. The PMI foam material used is a material with a high dielectric constant (ε r =1.07, tanδ=0.001).

[0047] Furthermore, the fiberglass reinforced plastic 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:

[0049] In the first reconfigurable layer, the PIN diode operates in two states: cutoff and conduction, corresponding to zero-bias and forward-bias voltages of 0V and 0.7V, respectively. By controlling the bias voltage, the electromagnetic response of the annular metal patch structure can be switched, thereby dynamically reconfiguring the skin's transmission and reflection properties. When the high-cutoff transflective reconfigurable skin is powered on, the PIN diode conducts, and the first annular metal patch is connected. In this state, the structure is transparent to incident electromagnetic waves, allowing them 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 transflective reconfigurable skin is powered off, the PIN diode is cut off, and the first annular metal patch is disconnected. This destroys the structure's original transparency, and within the operating frequency band, the skin enters a reflective state, protecting the antenna from interference. The wave-transmitting state is the communication state. When the high-cutoff transflective reconfigurable skin is conformally attached to the carrier, it ensures that the normal operation of the radar antenna is not affected, while also maintaining the aerodynamic performance of the cabin, thus providing enhanced stealth capabilities.

[0050] Example

[0051] In order to verify the effectiveness of the solution of the present invention, the following experiment was conducted.

[0052] In this embodiment, the reconfigurable metasurface is composed of 20*20 periodic units, and the array size is 130mm×130mm. Figure 3 As shown, the bias voltage uniformly controls the 20*20 period unit.

[0053] The simulation software CST Studio Suite 2022 is used with the boundary condition of unit cell and frequency domain solver to model and simulate the designed skin. The lumped port is used to equate the cut-off and conduction states of the PIN diode, as shown in the following example: Figure 4 When powered on, the high-cutoff transflective reconfigurable skin achieves an insertion loss of less than 1dB in the 2.78-3.41GHz band and a high cutoff of greater than 20dB in the 4-10GHz band. When powered off, the reconfigurable skin achieves an insertion loss greater than 3dB in the band and a high cutoff greater than 20dB in the band. Furthermore, TE and TM polarizations remain consistent.

[0054] like Figure 5 As shown, when the high-cutoff transflective integrated reconfigurable skin is powered on, the angle is 0-40 0 When S 21 The curve remains basically consistent, showing good angular stability.

[0055] like Figure 6 As shown, when the high-cutoff transflective integrated reconfigurable skin is not powered, the angle is 0-40 0 When S 11 The curves are basically consistent, and the reflection effect is better in the range of 3.5-10GHz, showing a good reflection effect.

[0056] Working principle: The present invention changes the pass-resistance state of the skin by controlling external excitation. The working state is switched according to the working condition of the internal antenna. When the antenna is working, the reconfigurable intelligent skin is in the passband state, which does not affect the normal communication of the antenna and reduces the out-of-band RCS; when the antenna is not working, it switches to the stopband state to achieve broadband electromagnetic stealth. Compared with the existing technology, the present invention can achieve in-band wave transmission and reflection state switching, and has a high cutoff characteristic out of the band to achieve low out-of-band RCS. It has a better stealth effect. In addition, its electromagnetic wave dynamic control ability and self-sensing ability are broadband, polarization-insensitive, and angle-insensitive. Compared with existing electromagnetic protection devices, the bias network of the present invention is sophisticated in design, with the advantages of high stability, strong practicality, and a wide range of applications.

[0057] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, 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 above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A high-cutoff transflective integrated reconfigurable skin, characterized in that: include: A plurality of identical, periodically arranged reconfigurable metasurface units, each of which comprises, from top to bottom, a fiberglass reinforced plastic layer, a first reconfigurable layer, a first foam layer, a second metal grid layer, a second foam layer, and a third metal layer, wherein: The first reconfigurable layer is composed of a multi-layer structure, including a first annular metal patch, a first dielectric substrate, a second cross-aperture 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, with a gap formed at the center of each of the four sides, and a PIN diode loaded in each gap; The second cross-aperture metal patch is located on the lower surface of the first dielectric substrate. The second cross-aperture metal patch is square, the side length of which is smaller than the periodic size of the reconfigurable skin unit, and a cross-shaped aperture is opened in the central area. The second dielectric substrate is arranged below the second cross-aperture metal patch. A third oblique rectangular metal bias line is located on the lower surface of the second dielectric substrate and includes two oblique rectangular metal patches, one located on either side of a diagonal line rotated 45 degrees clockwise. The metal patches are arranged in an alternating pattern of positive and negative electrodes, with the diagonal line rotated 45 degrees clockwise as the dividing line. The four PIN diodes are divided into two groups, one on the left and one on the right, with the two PIN diodes in each group connected in series to form one path, thus forming two independent bias control loops. A metallized hole is set 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 adopts a chip inductor, and two inductors are connected in series with a bias control loop respectively to effectively isolate the radio frequency signal.

2. The high-cutoff transflective integrated reconfigurable skin according to claim 1, characterized in that: The fiberglass reinforced plastic 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 integrated reconfigurable skin according to claim 1, characterized in that: In the third oblique rectangular metal bias line, the two oblique rectangular metal patches are symmetrically distributed about the diagonal line rotated 45 degrees clockwise. In the second cross-pore type metal patch, the length of the cross pore 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 integrated reconfigurable skin according to claim 1, characterized in that: The second metal grid 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 to form a rectangular grid structure.

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

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

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

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

10. The high-cutoff transflective integrated reconfigurable skin according to claim 1, characterized in that: When the high-cutoff transflective 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 transflective integrated reconfigurable skin is transparent to the incident electromagnetic waves. When electromagnetic waves are incident, they can pass through the skin with low insertion loss, without affecting the receiving / transmitting performance of the RF front-end antenna; when the high-cutoff transflective integrated reconfigurable 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 high-cutoff transflective integrated reconfigurable skin is destroyed. The skin is in a reflective state within the working frequency band. The skin will protect the antenna from being affected. The wave-transmitting state is the communication state.

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