Multi-beam digital transmission metasurface adaptive to direct communication of Internet of Vehicles and design method of multi-beam digital transmission metasurface

Abstract

The invention discloses a multi-beam digital transmission metasurface design method adaptive to direct communication of the Internet of Vehicles. The metasurface works in a 5.9 GHz frequency band and is composed of 40 * 40 double-C-shaped slot loading units, 2-bit transmission phase coding is achieved by adjusting inner-layer slot parameters of the units, and the transmission amplitude is superior to-2dB. According to the design, a quadrant partition beam forming method is adopted, an array is divided into four sub-regions, superposition codes of a focusing phase and a specific deflection phase are loaded respectively, and therefore four symmetrically-distributed high-gain beams are synchronously generated. Simulation results show that main beams of the array respectively point to azimuth angles of 45 degrees, 135 degrees, 225 degrees and 315 degrees, pitch angles are all 30 degrees, the maximum gain reaches 14.2 dBi, the narrow-beam and low-sidelobe characteristics are achieved, and the problem of efficient coverage of one source and multiple directions in an Internet of Vehicles scene is effectively solved.

Description

Technical Field

[0001] This invention relates to the fields of wireless communication and electromagnetic metamaterials, specifically to a multi-beam digital transmissive metasurface adapted for vehicle-to-everything (V2X) direct communication and its design method. Background Technology

[0002] Vehicle-to-everything (V2X) is a key area for the deep integration of intelligent transportation and next-generation communication technologies. Its direct communication technology is the core support for realizing autonomous driving and collaborative traffic management. As the technology evolves to higher levels, the demand for low latency, high reliability, and wide coverage in V2X communication is becoming increasingly urgent. Currently, V2X direct communication mainly operates in the 5.9GHz frequency band. This band not only faces the problem of limited spectrum resources, but also suffers from severe signal attenuation in complex scenarios such as high-speed vehicle movement and non-line-of-sight propagation, making it difficult to guarantee communication quality.

[0003] Existing solutions primarily rely on traditional antenna technology. However, achieving multi-beam coverage or high-gain transmission typically requires large-scale active arrays, resulting in high system costs, enormous power consumption, and bulky size, making them unsuitable for the stringent miniaturization and lightweight requirements of vehicle terminals or roadside equipment. On the other hand, while smart metasurface technology is gradually being introduced into the vehicle-to-everything (V2X) field due to its low cost and low power consumption, current mainstream research focuses primarily on reflective architectures. Reflective metasurfaces can only modulate signals within a half-space, failing to achieve through-transmission, and their beam control freedom is relatively limited, making it difficult to meet the requirements of omnidirectional coverage and dynamic beam switching in V2X scenarios. Therefore, designing a passive device capable of efficient transmission and flexible multi-beam generation in this frequency band has become a pressing issue in the current technological field. Summary of the Invention

[0004] To overcome the existing problems and shortcomings, this invention proposes a multi-beam digital transmissive metasurface adapted for vehicle-to-everything (V2X) direct communication, comprising:

[0005] Dielectric substrate;

[0006] Metal patterned layers attached to the upper and lower surfaces of the dielectric substrate;

[0007] The metasurface is composed of several transmissive metasurface units arranged in a rectangular array;

[0008] The metal pattern layer of the transmissive metasurface unit includes a double C-shaped slot loading structure, wherein the upper surface integrates an outer arc slot and an inner arc slot, and the metal pattern on the lower surface is an anti-symmetric form of the upper surface structure.

[0009] The rectangular array is divided into four quadrant subarrays with the center as the origin. Each quadrant subarray independently generates a beam pointing in a specific direction through phase coding, thereby achieving multi-beam transmission synchronously in the 5.9GHz vehicle-to-everything (V2X) direct communication band.

[0010] Furthermore, the dielectric substrate is made of RT5880 material with a dielectric constant of [missing information]. Loss tangent The thickness is 5mm;

[0011] The transmissive metasurface unit exhibits a transmission amplitude better than -2dB in the 5.9GHz band, and the difference in transmission amplitude between different phase coding states is less than 0.5dB.

[0012] Furthermore, the double C-shaped slot loading structure achieves 2-bit transmission phase encoding by adjusting the geometric parameters of the inner arc slot;

[0013] The radius of the outer arc gap is fixed at 9mm, and the opening angle is fixed at 240°;

[0014] The radius of the inner arc-shaped gap Select between 5.5mm and 7mm, angle of divergence The range of 68° to 160° corresponds to four digital coding states: “00”, “01”, “10”, and “11”, respectively, with corresponding transmission phases of 0°, 90°, 180°, and 270°.

[0015] Furthermore, the rectangular array comprises 40×40 transmissive metasurface units;

[0016] The multi-beam transmission specifically involves the synchronous generation of four symmetrical beams, each with an elevation angle of 30° and azimuth angles of 45°, 135°, 225°, and 315°, respectively, and a main beam gain greater than 14 dBi.

[0017] Furthermore, the antisymmetric form of the lower surface metal pattern is used to cooperate with the upper surface structure to form a virtual current loop on both sides of the dielectric substrate to excite a magnetic response, and a transparent window is formed when the induced magnetic field and the induced electric field are in balance.

[0018] A design method for a multi-beam digital transmissive metasurface adapted for vehicle-to-everything (V2X) direct communication as described in any of the above embodiments, comprising the following steps:

[0019] Step S1: Unit structure optimization; Based on the double C-shaped slot loading structure and its underlying antisymmetric metal pattern, establish the mapping relationship between the geometric parameters of the inner arc slot and the transmission phase and transmission amplitude.

[0020] Step S2: Encoding state filtering; Four sets of geometric parameters with a transmission phase difference of 90° and a transmission amplitude difference of less than 0.5dB are selected from the mapping relationship as the basic states of 2-bit digital encoding.

[0021] Step S3: Array partitioning planning; The metasurface array is physically divided into four quadrant subarrays, and an independent target beam direction is assigned to each quadrant subarray;

[0022] Step S4: Phase calculation and quantization; For each array unit, calculate the focusing phase for converting the spherical wave into a plane wave and the deflection phase for controlling the beam direction, and quantize the two by superimposing them into the digital encoding state described in step S2.

[0023] Step S5: Based on the determined digital encoding state, process a metal pattern layer on the dielectric substrate.

[0024] Furthermore, in step S4, the superposition and quantization of the focusing phase and the deflection phase are performed according to the following formula:

[0025]

[0026] in, unit coordinates The digital encoding status at that point, To focus the phase, For the deflection phase, Quantize indicates that it is mapped to four states: “00”, “01”, “10”, and “11” according to the intervals [0°, 90°), [90°, 180°), [180°, 270°), and [270°, 360°).

[0027] Furthermore, the deflection phase The calculation formula is as follows:

[0028]

[0029] in, For wave number, , The wavelength corresponding to 5.9 GHz, It is a Huygens unit period.

[0030] Beneficial effects:

[0031] This invention significantly improves signal modulation capabilities in the vehicle-to-everything (V2X) communication band by employing a transmissive metasurface unit design with a double-C-shaped slot loading structure. The metasurface unit features anti-symmetrical metal patterns arranged on the upper and lower surfaces of a dielectric substrate. Reverse-flowing currents create virtual current loops on both surfaces to excite a magnetic response. When the induced magnetic and electric fields are balanced, a transparent window is formed, ensuring a transmission amplitude better than -2dB in the 5.9GHz band, with the amplitude difference between different encoding states controlled within 0.5dB. This high transmittance and amplitude consistency guarantee efficient electromagnetic wave energy transmission, solving the problem of severe amplitude attenuation associated with phase modulation in traditional metasurfaces, and laying the energy foundation for long-distance beam transmission.

[0032] This invention proposes a quadrant partitioning and digital coding-based design method that achieves low-cost passive multi-beamforming. By dividing the array into four quadrant subarrays and using a specific phase superposition formula to quantize the focusing and deflection phases into four digital states—"00," "01," "10," and "11"—the beam pointing can be precisely controlled. This design can simultaneously generate four symmetrical beams with an elevation angle of 30° and azimuth angles of 45°, 135°, 225°, and 315°, respectively, without the need for a complex feed network. Simulation results show that the main lobe gain of this multi-beam can reach 14.2 dBi, the half-power width is approximately 5.4°–7.2°, and the sidelobe level is generally below -3 dB, with some directions below -6 dB. This high-gain, narrow-beam characteristic can significantly enhance the signal strength in specific directions, effectively combating path loss in vehicular network environments.

[0033] Furthermore, this invention overcomes the limitations of traditional reflective metasurface control paths, achieving "one source, multiple directions" spatial coverage. Four symmetrically distributed high-gain beams can simultaneously cover traffic participants in multiple directions, enabling spatial multiplexing and reducing interference between multiple users while increasing communication capacity. Compared to large-scale active antenna arrays, the single-layer dielectric substrate structure used in this invention offers advantages such as low profile, light weight, and ease of integration, making it more suitable for deployment in space- and power-constrained vehicle-mounted or roadside communication equipment, thus improving the overall performance and reliability of vehicle-to-everything (V2X) direct communication systems. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1This is a schematic diagram of the top metal structure of the transmissive metasurface unit provided in an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the bottom metal structure of the transmissive metasurface unit provided in an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the overall perspective structure of the transmissive metasurface unit provided in an embodiment of the present invention;

[0038] Figure 4 This is a simulation curve of the transmission amplitude of the four digital encoding states ("00", "01", "10", "11") in the embodiment of the present invention.

[0039] Figure 5 This is a simulation curve of the transmission phase of the four digital encoding states ("00", "01", "10", "11") in the embodiment of the present invention.

[0040] Figure 6 This is the original continuous phase compensation distribution map calculated according to the quadrant partitioning method in this embodiment of the invention;

[0041] Figure 7 This is a discrete phase compensation distribution diagram after 2-bit quantization processing in an embodiment of the present invention;

[0042] Figure 8 This is a three-dimensional far-field radiation pattern of a four-beam metasurface array in an embodiment of the present invention;

[0043] Figure 9 These are elevation radiation patterns of the four-beam metasurface array in different azimuth angle sections according to embodiments of the present invention.

[0044] Figure 10 In this embodiment of the invention, the four-beam metasurface array is at a specific pitch angle ( The azimuth radiation pattern below. Detailed Implementation

[0045] The present application will be described below with reference to specific embodiments:

[0046] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Example 1:

[0048] This embodiment provides a multi-beam digital transmissive metasurface adapted for vehicle-to-everything (V2X) direct communication. Its core lies in utilizing digital coding technology to achieve efficient transmission and multi-beam coverage in the 5.9 GHz frequency band. The metasurface consists of several transmissive metasurface units arranged in a rectangular array. Each transmissive metasurface unit adopts a typical three-layer structure, including a middle dielectric substrate and metal pattern layers attached to the upper and lower surfaces of the dielectric substrate.

[0049] Regarding the specific material selection and structural dimensions, the dielectric substrate uses RT5880 material, which has stable performance in the radio frequency and microwave frequency bands, and its dielectric constant is [missing information]. Set to 2.2, loss tangent The substrate thickness is 0.0009. The thickness is set to 5mm. To achieve precise control of the electromagnetic wave phase and maintain high transmittance, the metal pattern layer in this embodiment employs a double-C-shaped slot loading structure. For example... Figure 1 As shown, the top layer (upper surface) of the unit integrates two C-shaped metal slots with the same opening direction, namely the outer arc-shaped slot and the inner arc-shaped slot. Figure 2 As shown, the metal pattern on the bottom layer (lower surface) of the unit is designed in an anti-symmetrical form with the top layer structure, that is, complementary to or opposite to the top layer structure. Metal linewidth. The standard setting is 1mm.

[0050] To achieve 2-bit digital encoding, the outer circular arc gap parameter in this unit structure remains fixed, and its radius... It is 9mm, and the angle is... The angle is 240°; however, the geometric parameters of the inner arc gap are variable, and can be adjusted by changing the radius of the inner arc. and Zhang Jiao This is used to change the transmission phase response of the unit. As shown in Table 1, this embodiment selects four specific geometric parameters, which correspond to the digital coding states "00", "01", "10" and "11" respectively.

[0051] Table 1. Structural parameters representing state units “00”, “01”, “10”, and “11”.

[0052] Variables / States "00” "01” "10” "11” rb(mm) 7 5.5 7 5.5 (°) 74 68 99 160

[0053] This anti-symmetric, double-layered metal structure design possesses a unique electromagnetic response mechanism. For example... Figure 3In the overall structure shown, when electromagnetic waves are incident, the top and bottom metal patterns of the four states "00", "01", "10", and "11" exhibit similar electrical resonant frequency responses at 5.9 GHz, but the directions of the induced currents are opposite. This reverse-flowing current forms a virtual current loop between the upper and lower surfaces of the dielectric substrate, thereby exciting orthogonal magnetic fields. When the induced magnetic field and the induced electric field reach equilibrium, they jointly excite Huygens resonance, thus forming a transparent window near the resonant frequency, allowing electromagnetic waves to be transmitted efficiently.

[0054] Figure 4 and Figure 5 The transmission amplitude and transmission phase curves for the four types of coded state units are shown respectively. Combined with... Figure 4 It can be seen that near the 5.9GHz vehicle-to-everything (V2X) direct communication operating frequency, the transmission amplitude of all four states (State 00, State 01, State 10, and State 11) is greater than -2dB, and the maximum amplitude difference between any two states is only 0.5dB, exhibiting excellent amplitude consistency. This characteristic overcomes the defect of traditional metasurfaces, which often suffer from severe amplitude attenuation during phase modulation. Combined with... Figure 5 It can be seen that at the 5.9 GHz frequency point, the transmission phase of the "00" state is close to 0°; the transmission phases of the "01", "10", and "11" states are close to 90°, 180°, and 270°, respectively. This indicates that the phase difference between each pair of the four states is stable at around 90°, which can accurately cover the phase period of [0, 360°], providing a physical basis for achieving high-precision beamforming.

[0055] At the array level, this embodiment constructs a rectangular array containing 40×40 transmissive metasurface units. To achieve "one source, multiple directions" coverage, the rectangular array is designed using quadrant-based beamforming. First, a two-dimensional Cartesian coordinate system is established with the array center as the origin, and the array is physically divided into four independent quadrant subarrays along the X and Y axes. For each quadrant subarray, the focusing phase required to convert the spherical wave emitted by the feed source into a plane wave is calculated first, and then the deflection phase required to point the beam to a specific angle is calculated. Subsequently, the focusing phase and the deflection phase are superimposed to obtain the total phase, and according to the 2-bit phase quantization rule, the continuous phase is discretized and mapped to four states: 0°, 90°, 180°, and 270°. The specific phase compensation and quantization are performed according to the following formula:

[0056]

[0057] Among them, deflection phase The calculation formulas for the four quadrants (corresponding to azimuth angles of 45°, 135°, 225°, and 315°, and elevation angle of 30°) are as follows:

[0058]

[0059] In the formula, wave number ( ), It is a Huygens unit period. Figure 6 The original phase compensation distribution map calculated using the above method is shown, with the color intensity representing the continuous change in phase value; Figure 7 The image shows the phase distribution map finally loaded onto the array after 2-bit quantization. It clearly shows that the array is divided into four regions, exhibiting discrete phase patches. By loading this phase distribution, the array is configured to synchronously generate four symmetrical beams, and the elevation angles of these four beams are... Both are 30°, while the azimuth angle They point to 45°, 135°, 225° and 315° respectively.

[0060] Figure 8 Simulation results of the three-dimensional far-field radiation pattern of this multi-beam metasurface array in the 5.9 GHz band are presented. The figure clearly shows that the red high-gain region is symmetrically distributed, with the four beams pointing diagonally in space, exhibiting a regular shape and concentrated energy. The gain of the main beam region reaches 14.2 dBi, demonstrating the array's excellent energy focusing capability in the target direction.

[0061] To analyze beam performance in more detail, Figure 9 The azimuth angle is given Pitch angle pattern in a plane (normalized amplitude distribution). Four curves at pitch angles... High-gain main lobes were observed in the vicinity, with a main lobe amplitude of approximately 14 dBi and a half-power width (HPBW) of approximately 5.4°–7.2°. Furthermore, the sidelobe amplitudes outside the main lobe were generally below -3 dB, and in some directions below -6 dB. This directly verifies that the four beams possess excellent directivity and sidelobe suppression capabilities at the preset elevation angles. Figure 10 This demonstrates a fixed pitch angle. The absolute value diagram of the azimuth direction at time is shown. It can be clearly observed that there are distinct main beams in all four azimuth directions: 45°, 135°, 225°, and 315°. The main lobe amplitude is maintained at approximately 14 dBi, while the sidelobe level is controlled below -5 dB. The above simulation data fully demonstrates that the multi-beam digital transmission metasurface proposed in this embodiment can meet the stringent requirements of vehicle-to-everything (V2X) direct communication for high gain, narrow beamwidth, and multi-directional coverage.

[0062] Example 2:

[0063] This embodiment provides a design method for a multi-beam digital transmissive metasurface adapted to vehicle-to-everything (V2X) direct communication. This method is based on the quadrant-partitioned beamforming principle and can quickly achieve the directional generation of four beams. The specific steps are as follows:

[0064] Step 1: Constructing a transmissive metasurface digital coding unit library

[0065] RT5880 was selected as the dielectric substrate material, and the operating frequency was set to 5.9GHz. A double C-slot loaded metal layer structure was designed, keeping the outer C-slot parameters constant while varying the radius of the inner C-slot. and Zhang Jiao As variables, four unit structures with transmission amplitudes better than -2dB and transmission phases close to 0°, 90°, 180°, and 270° were selected through electromagnetic simulation scanning and defined as digital encoding states "00", "01", "10", and "11" respectively, and a digital encoding unit library was established.

[0066] Step 2: Establish the array coordinate system and divide the region

[0067] Construct a 40×40 two-dimensional planar array and establish a Cartesian coordinate system with the array's geometric center as the origin (0,0). Physically divide the array into four quadrants, namely the first to the fourth quadrant, with each quadrant serving as an independent subarray responsible for generating a beam in a specific direction.

[0068] Step 3: Calculate the compensated phase distribution of the target beam

[0069] The directions of the four target beams are set as follows: elevation angle Keep it consistent, azimuth angle These correspond to 45°, 135°, 225°, and 315° respectively.

[0070] For any position in the array The unit, its required total compensation phase From the focused phase and beam deflection phase These are superimposed. To achieve symmetrical four-beam splitting, the required phase of each element in the array is calculated using the following formula:

[0071]

[0072] Among them, deflection phase Calculate according to the quadrant position of the unit, as follows:

[0073]

[0074] In the above formula, The free-space wavenumber corresponding to 5.9 GHz. It is a Huygens unit period.

[0075] Step 4: Perform 2-bit phase quantization and array generation

[0076] Based on the continuous phase distribution calculated in step three Based on the principle of proximity, it is mapped to the four discrete states "00", "01", "10", and "11" established in step one. The quantization rules are as follows:

[0077] If the phase value is or The interval is mapped to 0° (state "00");

[0078] If the phase value is The interval is mapped to 90° (state "01");

[0079] If the phase value is The interval is mapped to 180° (state "10");

[0080] If the phase value is The interval is mapped to 270° (state "11").

[0081] After quantization is completed, the corresponding physical unit model is called according to the encoding state of each position to generate the final multi-beam digital transmission metasurface array.

[0082] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

Claims

1. A multi-beam digital transmissive metasurface adapted for vehicle-to-everything (V2X) direct communication, characterized in that, include: Dielectric substrate; Metal patterned layers attached to the upper and lower surfaces of the dielectric substrate; The metasurface is composed of several transmissive metasurface units arranged in a rectangular array; The metal pattern layer of the transmissive metasurface unit includes a double C-shaped slot loading structure, wherein the upper surface integrates an outer arc slot and an inner arc slot, and the metal pattern on the lower surface is an anti-symmetric form of the upper surface structure. The rectangular array is divided into four quadrant subarrays with the center as the origin. Each quadrant subarray independently generates a beam pointing in a specific direction through phase coding, thereby achieving multi-beam transmission synchronously in the 5.9GHz vehicle-to-everything (V2X) direct communication band.

2. The multi-beam digital transmissive metasurface adapted for vehicle-to-everything (V2X) direct communication as described in claim 1, characterized in that: The dielectric substrate is made of RT5880 material with a dielectric constant of [missing information]. Loss tangent The thickness is 5mm; The transmissive metasurface unit exhibits a transmission amplitude better than -2dB in the 5.9GHz band, and the difference in transmission amplitude between different phase coding states is less than 0.5dB.

3. The multi-beam digital transmissive metasurface adapted for vehicle-to-everything (V2X) direct communication as described in claim 1, characterized in that: The double C-shaped slot loading structure achieves 2-bit transmission phase encoding by adjusting the geometric parameters of the inner arc slot; The radius of the outer arc gap is fixed at 9mm, and the opening angle is fixed at 240°; The radius of the inner arc-shaped gap Select between 5.5mm and 7mm, angle of divergence The range of 68° to 160° corresponds to four digital coding states: "00", "01", "10", and "11", with corresponding transmission phases of 0°, 90°, 180°, and 270°, respectively.

4. The multi-beam digital transmissive metasurface adapted for vehicle-to-everything (V2X) direct communication as described in claim 1, characterized in that: The rectangular array contains 40×40 transmissive metasurface units; The multi-beam transmission specifically involves the synchronous generation of four symmetrical beams, each with an elevation angle of 30° and azimuth angles of 45°, 135°, 225°, and 315°, respectively, and a main beam gain greater than 14 dBi.

5. The multi-beam digital transmissive metasurface adapted for vehicle-to-everything (V2X) direct communication as described in claim 1, characterized in that: The antisymmetric form of the lower surface metal pattern is used to cooperate with the upper surface structure to form a virtual current loop on both sides of the dielectric substrate to excite a magnetic response, and to form a transparent window when the induced magnetic field and the induced electric field are in balance.

6. A design method for a multi-beam digital transmissive metasurface adapted for vehicle-to-everything (V2X) direct communication as described in any one of claims 1-5, characterized in that, Includes the following steps: Step S1: Unit structure optimization; Based on the double C-shaped slot loading structure and its underlying antisymmetric metal pattern, establish the mapping relationship between the geometric parameters of the inner arc slot and the transmission phase and transmission amplitude. Step S2: Encoding state filtering; Four sets of geometric parameters with a transmission phase difference of 90° and a transmission amplitude difference of less than 0.5dB are selected from the mapping relationship as the basic states of 2-bit digital encoding. Step S3: Array partitioning planning; The metasurface array is physically divided into four quadrant subarrays, and an independent target beam direction is assigned to each quadrant subarray; Step S4: Phase calculation and quantization; For each array unit, calculate the focusing phase for converting the spherical wave into a plane wave and the deflection phase for controlling the beam direction, and quantize the two by superimposing them into the digital encoding state described in step S2. Step S5: Based on the determined digital encoding state, process a metal pattern layer on the dielectric substrate.

7. The design method according to claim 6, characterized in that, In step S4, the superposition and quantization of the focusing phase and the deflection phase are performed according to the following formula: ； in, unit coordinates The digital encoding status at that point, To focus the phase, For the deflection phase, Quantize indicates that it is mapped to four states "00", "01", "10", and "11" according to the intervals [0°, 90°), [90°, 180°), [180°, 270°), and [270°, 360°).

8. The design method according to claim 7, characterized in that, The deflection phase The calculation formula is as follows: ; in, For wave number, , The wavelength corresponding to 5.9 GHz, It is a Huygens unit period.

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