Broadband transflective metasurface for realizing full-space beam forming and reflection RCS reduction

Abstract

The invention discloses a broadband transmission and reflection integrated metasurface capable of simultaneously achieving full-space beam forming and reflection RCS reduction. The metasurface is composed of metasurface units with a broadband 1bit phase regulation function, each unit structure comprises two layers of dielectric substrates and three metal layers, the top layer and the bottom layer are metal gratings which are perpendicular to each other, and the middle layer is of a split ring structure. By adjusting the opening angle of the split ring, stable 180-degree phase regulation and control can be simultaneously realized on the reflected wave and the transmitted wave. A '01...' type coding sequence arrangement unit is adopted to form an array, beam directional forming in a whole space range is realized in a 11-19GHz frequency band, and RCS reduction exceeding 10dB is realized in a reflection space. The invention has the characteristics of wide band, full-space regulation and low radar scattering, and is suitable for a communication and stealth integrated system.

Description

Technical Field

[0001] This invention relates to a broadband metasurface technology capable of simultaneously achieving full-space beamforming and reflection RCS reduction, belonging to the interdisciplinary field of novel artificial electromagnetic materials and antenna technology. Background Technology

[0002] Full-space metasurfaces are a key emerging technology in metasurface and antenna technology. They allow for the modulation of parameters such as amplitude and phase of reflected and transmitted waves, significantly increasing the degree of freedom in controlling electromagnetic waves. This enables the encoding and processing of electromagnetic waves in physical space, achieving functions such as electromagnetic beamforming and beam scanning. However, most full-space metasurfaces require changing the polarization or wavelength of the incident wave to achieve full-space control. Since the incident wave is in the same electromagnetic field environment in most cases, this design method for full-space metasurfaces is difficult to apply.

[0003] In application scenarios, all-space metasurfaces can also provide electromagnetic information control for targets on the other side of obstacles, enabling control of electromagnetic waves both indoors and outdoors. However, all these metasurface designs neglect the security of outdoor communication, because if the beam energy is strong enough, it can be easily detected by long-range radar systems. Therefore, this invention proposes a broadband bilayer metasurface that can achieve directional beamforming in both transmission and reflection spaces, reducing the radar cross section (RCS) by more than 10 dB. Based on these advantages, targets in the transmission and nearby reflection regions can obtain useful information from the metasurface, and due to the reduced RCS, this information cannot be detected by long-range radar. Summary of the Invention

[0004] Technical Problem: The purpose of this invention is to provide a broadband transmissive-reflective metasurface that can simultaneously achieve full-space beamforming and reflection RCS reduction. By changing the size parameters of the metasurface unit, 1-bit phase modulation can be achieved simultaneously across the entire space within a wide bandwidth. Through a 01… encoding design, beamforming across the entire space and RCS reduction of more than 10 dB in the reflection space are achieved.

[0005] Technical solution: The broadband transflective metasurface of the present invention, which simultaneously realizes full-space beamforming and reflection RCS reduction, comprises two parts: the design of the broadband transflective metasurface unit with 1-bit phase modulation and the simultaneous realization of full-space beamforming and reflection RCS reduction through an arraying method in the form of 01… encoding.

[0006] The broadband transflective-reflective integrated 1-bit phase-controlled metasurface unit structure of the present invention includes two dielectric substrates and three metal layers. The three metal layers are separated by the two dielectric substrates. The top layer of the top dielectric substrate has a metal grating placed along the x-axis, and the metal layer between the two dielectric substrates has an open ring structure. The third metal layer is placed on the bottom layer of the bottom dielectric substrate and includes a metal grating orthogonal to the first metal grating.

[0007] The intermediate open ring metal layer is rotated 45° and placed between the two dielectric substrates. The opening angle β of the open ring can be designed independently, and the phase of the electromagnetic wave in the entire space can be controlled by changing the opening angle β.

[0008] The electrical dimension thickness of the metal structure layer ranges from 0.001 wavelengths to 0.1 wavelengths.

[0009] The metal layer is separated by two dielectric substrates, the electrical thickness H of which ranges from 0.001 wavelengths to 0.3 wavelengths.

[0010] The period width P of the dielectric substrate ranges from 0.1 wavelength to 1 wavelength.

[0011] The full-space functionality achieved by this invention includes simultaneously realizing beamforming and RCS reduction of the reflection space throughout the entire space range.

[0012] The beamforming across the entire space range is achieved because the metasurface unit can simultaneously achieve 1-bit phase control of electromagnetic waves in the anti-transmission space, and can be arrayed using 01… type encoding to achieve beam control at any angle.

[0013] The aforementioned reduction in the reflection space RCS is due to the reduction in reflected energy and the scattering of electromagnetic waves by the 01… type encoding method, achieving an RCS reduction of less than 10dB in the broadband direction of the metasurface normal.

[0014] Beneficial effects: Compared with the prior art, the present invention has the following advantages.

[0015] 1. Compared with traditional reflective or transmissive metasurfaces, this invention, through innovative design of unit structure, enables a single metasurface to simultaneously perform independent 1-bit phase encoding on transmitted and reflected waves, thereby achieving simultaneous and active control of the electromagnetic wavefront in the entire space range (i.e., transmission space and reflection space).

[0016] 2. Compared to traditional all-space metasurfaces, this invention not only achieves directional beamforming but also simultaneously significantly reduces the radar cross section (RCS) in the reflection space (below 10 dB in the normal direction). This enables the target area to effectively receive useful signals while significantly reducing the risk of detection by distant radar, achieving "low-observable" communication or detection.

[0017] 3. The metasurface unit of the present invention can maintain a stable 180° phase difference control for transmitted and reflected waves in a wide frequency band of 11-19 GHz, ensuring the effectiveness of beamforming and RCS reduction functions in this frequency band and improving the practicality and adaptability of the system.

[0018] 4. The present invention uses only a sandwich structure of two dielectric substrates and three metal patterns. Compared with the more complex multi-layer structure that may be required to achieve similar functions, it has fewer layers and a simpler structure, which helps to reduce processing difficulty and production costs, and facilitates engineering implementation and large-scale application. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the present invention.

[0020] Figure 2 This is a schematic diagram of the metasurface unit structure in this invention.

[0021] Figure 3 This is a diagram showing the amplitude and phase relationship of transmission and reflection of the metasurface unit in this invention.

[0022] Figure 4 This is a comparison of far-field beam simulation and experiments at three frequency points of 11GHz, 15GHz, and 19GHz in the transmission space of this invention.

[0023] Figure 5 This is a comparison of far-field beam simulation and experiments at three frequency points of 11GHz, 15GHz, and 19GHz in the reflection space of this invention.

[0024] Figure 6 This is a comparison chart of simulated and experimental RCS reduction values ​​in the metasurface normal direction in the 11GHz-19GHz frequency band in the reflection space according to the present invention. Detailed Implementation

[0025] The present invention provides a broadband transmissive-reflective integrated metasurface that can simultaneously achieve full-space beamforming and reflection RCS reduction. The metasurface 1 is used to control and process the transmissive spatial electromagnetic field and the metasurface unit is used to achieve simultaneous 1-bit phase control of electromagnetic waves in the whole space. The metasurface 3 achieves full-space beamforming function in a broadband band and RCS reduction of less than 10dB in the reflection space.

[0026] The full-space beamforming and RCS reduction of less than 10dB in the reflection space can be achieved through a carefully designed array configuration.

[0027] The aforementioned broadband transmissive-reflective metasurface possesses broadband 1-bit phase modulation characteristics for electromagnetic waves across the entire space, achieving stable 1-bit phase modulation within the 11-19 GHz range. This metasurface unit consists of two dielectric substrates 4 and 5, and three metal layers arranged sequentially. Metal layers 7 and 8 are placed above dielectric substrate 4 and below dielectric substrate 5, respectively, and the two metal layers are orthogonal to each other, forming an orthogonal metal grating structure. In metal layer 7, the strip width W2 = 0.6 mm, the distance between adjacent metal strips is 0.8 mm, and the strip length is 6 mm. Metal layer 9 is located between dielectric substrates 4 and 5, with geometric parameters including an inner diameter r1 = 2.45 mm, an outer diameter r2 = 2.75 mm, an aperture angle β = 45°, and an aperture α that can be independently adjusted according to design requirements to achieve simultaneous 1-bit phase modulation of electromagnetic waves across the entire space.

[0028] The electrical dimension thickness of the metal structure layer ranges from 0.001 wavelengths to 0.1 wavelengths.

[0029] The metal layer is separated by two dielectric substrates, the electrical thickness H of which ranges from 0.001 wavelengths to 0.3 wavelengths.

[0030] The width P of the dielectric substrate ranges from 0.1 wavelength to 1 wavelength.

[0031] This invention discloses a broadband transmissive and reflective integrated metasurface capable of simultaneously achieving full-space beamforming and reflection RCS reduction. It can simultaneously achieve full-space beamforming and RCS reduction of less than 10dB in the reflection space within the 11-19GHz frequency band. In specific implementation, it can be designed and implemented through the following steps:

[0032] Step 1: Based on the above structural parameters, model and simulate the metasurface unit using electromagnetic simulation software, optimize the opening angle α of the opening ring and the size of the metal grating, so as to achieve a stable 180° phase difference between reflected and transmitted waves in the 11-19GHz frequency band, while ensuring that the transmission amplitude is greater than 0.7 and the reflection amplitude is less than 0.6.

[0033] Step 2: Arrange the optimized cells according to a “01…” type coding sequence to form a metasurface array. The codes “0” and “1” correspond to cell states with opening angles α of 70° and 178°, respectively. In these two states, the reflected and transmitted waves are approximately 180° out of phase. The coding sequence forms a phase gradient along the array interface, thereby guiding the reflected and transmitted wave beams to the specified spatial angle.

[0034] Step 3: Using the aforementioned coding array, the metasurface can achieve directional beamforming in both transmission and reflection spaces at frequency points of 11GHz, 15GHz, and 19GHz. For example... Figure 4 and Figure 5 As shown, the simulated and measured far-field beam patterns are in good agreement, verifying the broadband performance of full-space beamforming.

[0035] Step 4: The arrangement of the coding sequence simultaneously significantly disperses the reflected energy in the normal direction, thereby achieving an RCS reduction of over 10dB in the 11-19GHz band. For example... Figure 6 As shown, the simulated and measured RCS reduction values ​​are both higher than 10dB in the normal direction, indicating that the present invention has good stealth performance.

[0036] Step 5: Fabricate the metasurface array using standard PCB or photolithography processes. Common high-frequency substrates such as Rogers 4350B can be used as the dielectric substrate, and copper or aluminum can be used for the metal layer. After fabrication, perform far-field beamforming and RCS tests in a microwave anechoic chamber to verify its full-space beamforming and RCS reduction performance.

[0037] Figure 1 A schematic diagram of a broadband transflective metasurface that can simultaneously achieve full-space beamforming and reflection RCS reduction is presented. This includes a broadband transflective metasurface 1, a metasurface unit structure 2, and simultaneously achieves full-space beamforming function 3 and reflection space RCS reduction function 4.

[0038] Figure 2 The unit structure of this invention is given, comprising two dielectric substrates 5 and 6 and three metal layers. Metal layer 7 contains a grating composed of parallel metal strips, where W2 = 0.6 mm, the distance between two adjacent rectangular patches forming the grating is 0.8 mm, and the length is 6 mm. The metal gratings in metal layers 7 and 8 are orthogonal, and the width of the grating metal portion is equal to the spacing length of the grating metal portion, with an electrical length of 0.001 to 0.005 wavelengths. Metal layer 9 contains an open-loop structure with geometric parameters r1 = 2.45 mm, r2 = 2.75 mm, β = 45°. The opening size α of the open-loop can be independently designed, achieving simultaneous 1-bit phase modulation for electromagnetic waves throughout space. The metal layer material has excellent conductivity, with an electrical thickness ranging from 0.001 wavelengths to 0.1 wavelengths. The metal layers are processed on dielectric substrates with any dielectric constant, with an electrical thickness H ranging from 0.001 wavelengths to 0.3 wavelengths. The period width P of the metal structure layer ranges from 0.1 wavelengths to 1 wavelength.

[0039] Figure 3The transmissive amplitude and phase of the metasurface unit of the present invention are given when the opening size α of the open ring is 70° and 178° in the transmission and reflection states, respectively. It can be seen that the metasurface unit can achieve a stable 180° phase difference in the transmissive range within the 11-19 GHz frequency band, and the transmission amplitude is greater than 0.7, the maximum reflection amplitude is less than 0.6, and the average value is about 0.25.

[0040] Figure 4 The simulation and experimental comparison figures of the far-field beamforming of this invention at three frequency points (11 GHz, 15 GHz, and 19 GHz) in the transmission space are presented. It can be seen that the experimental and simulation results agree well, and beamforming can be achieved in a wide bandwidth within the transmission space.

[0041] Figure 5 The simulation and experimental comparison figures of the far-field beamforming of this invention at three frequency points (11 GHz, 15 GHz, and 19 GHz) in the reflection space are presented. It can be seen that the experimental and simulation results agree well, and beamforming can be achieved in a wide bandwidth within the reflection space.

[0042] Figure 6 A comparison of simulated and experimental RCS reduction values ​​in the normal direction of the metasurface in the reflection space of this invention is presented in the 11GHz-19GHz frequency band. It can be seen that the RCS reduction value of this metasurface in the reflection space is higher than 10dB in all reflection spaces.

Claims

1. A broadband transreflective metasurface that enables full-space beamforming and reflective RCS reduction, characterized in that, The application relates to a metasurface array (1) comprising a plurality of transreflective metasurface units (2) and a 01... type coding sequence arranged by the plurality of metasurface units; the metasurface unit (2) can simultaneously and stably control the reflection wave and the transmission wave of the incident electromagnetic wave in the 11-19 GHz frequency band; the metasurface array (1) can simultaneously realize beam forming (3) in the whole space range and realize RCS reduction (4) of more than 10 dB in the reflection space through the arrangement of the 01... type coding sequence. The metasurface unit (2) keeps the polarization state of the reflection wave consistent with that of the incident wave and realizes polarization flip of the transmission wave; and the reflection wave and the transmission wave corresponding to different coding states are 180 degrees out of phase.

2. The wideband transmissive and reflective unifying metasurface for full spatial beamforming and reflection RCS reduction of claim 1, wherein: The metasurface unit (2) comprises a top layer metal grating (7), a first dielectric substrate (4), an intermediate layer metal open ring structure (9), a second dielectric substrate (5) and a bottom layer metal grating (8) arranged in sequence from top to bottom; the extension direction of the top layer metal grating (7) and the bottom layer metal grating (8) is orthogonal to each other; and the opening angle of the intermediate layer metal open ring structure (9) is adjustable.

3. The wideband transmissive and reflective unifying metasurface for full spatial beamforming and reflection RCS reduction according to claim 1 or 2, characterized in that: The electric size thickness of the top layer metal grating (7), the intermediate layer metal open ring structure (9) and the bottom layer metal grating (8) is 0.001 wavelength to 0.1 wavelength; the electric size thickness of the first dielectric substrate (4) and the second dielectric substrate (5) is 0.001 wavelength to 0.3 wavelength; and the period width of the metasurface unit (2) is 0.1 wavelength to 1 wavelength.

4. The wideband transmissive and reflective unifying metasurface for full spatial beamforming and reflection RCS reduction of claim 3, wherein: The 01... type coding sequence is arranged along the interface of the metasurface array (1) to form a phase gradient, so as to guide the reflection wave beam and the transmission wave beam to a specified spatial angle.

5. The wideband transmissive and reflective unifying metasurface for full spatial beamforming and reflection RCS reduction of claim 1, wherein: The metasurface array (1) realizes whole space beam forming in the 11-19 GHz frequency band.

6. The wideband transmissive and reflective unifying metasurface for full spatial beamforming and reflection RCS reduction of claim 5, wherein: Through the arrangement of the 01... type coding sequence, the metasurface array (1) realizes RCS reduction in the reflection space normal direction.

7. The wideband transmissive and reflective unifying metasurface for full spatial beamforming and reflection RCS reduction of claim 1, wherein: The metasurface array (1) realizes RCS reduction of less than 10 dB in the reflection space normal direction in the 11-19 GHz frequency band.

8. The wideband transmissive and reflective unifying metasurface for full spatial beamforming and reflection RCS reduction of claim 7, wherein: ​

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