Dual-fed quasi-non-diffracting bessel vortex wave generation method and transceiving system

Abstract

This invention discloses a method and transceiver system for generating quasi-diffraction-free Bessel vortex waves using a dual-feed, common-aperture system. It addresses issues in existing technologies such as easy beam diffusion, lack of amplitude-phase co-control, and absence of online transceiver link verification. The generation method includes multi-feed configuration and mode setting, coordinated solution of vortex and Bessel phases, construction of a joint amplitude-phase target field, and beam generation through metasurface element parameter design and selective excitation based on PCB technology. The transceiver system sequentially connects modules for feed placement, target beam construction, element parameter mapping, array construction, beam generation, and transceiver link measurement. This invention also includes online verification. The combined amplitude-phase control, end-to-end transceiver link, and online verification of this invention form a complete technical closed loop. The generated beam exhibits characteristics such as quasi-diffraction-free operation, stable long-distance transmission, and high mode isolation, making it suitable for MIMO multi-antenna wireless transmission scenarios and supporting robust communication in multi-mode parallel transmission and complex electromagnetic environments.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, mainly involving electromagnetic metasurfaces and radio electromagnetic wave modulation. Specifically, it is a method for generating quasi-diffraction-free Bessel vortex waves with dual feed sources and common aperture, as well as a transceiver system. This invention realizes a complete closed loop from design analysis to experimental verification and transceiver link testing of quasi-diffraction-free Bessel vortex beams. It has strong engineering feasibility, is suitable for MIMO multi-antenna wireless transmission scenarios, and supports multi-mode parallel transmission, beam directional coverage, and robust communication in complex electromagnetic environments. Background Technology

[0002] Orbital angular momentum (OAM) vortex electromagnetic waves, due to their helical phase structure and modal orthogonality, represent an important technological direction for improving wireless communication capacity. Traditional OAM vortex beams exhibit rapid main lobe diffusion and significant energy dispersion during free-space propagation, making stable transmission over medium to long distances difficult. In contrast, Bessel beams possess quasi-diffraction-free characteristics, maintaining main lobe structure and energy concentration within a certain distance range. Superimposing helical phases onto Bessel beams creates Bessel-OAM vortex beams, possessing both multimode and quasi-diffraction-free characteristics, offering potential feasibility for stable vortex communication. However, for engineering applications in commonly used microwave frequency bands, existing technologies have not yet achieved mature and simple processes for generating multimode Bessel-OAM beams, and a complete method for constructing and analyzing a transceiver link is lacking. Based on objective engineering needs, researchers have launched this research.

[0003] In their 2022 paper, "Multi-Orbital-Angular-Momentum-ModeVortex Wave Multiplexing and Demultiplexing with Shared-Aperture Reflective Metasurfaces," F. Qiang et al. proposed a method for OAM beam multiplexing based on compensated phase superposition of multiple feed sources and common aperture reflective metasurfaces. By constructing the interference phase distribution between multiple sets of target OAM modes and reference waves from each feed source, they achieved the generation of multimode vortex electromagnetic waves and the multiplexing and demultiplexing of multiple OAM signals on the same reflective artificial electromagnetic surface. However, the phase modulation method of this scheme is mainly aimed at helical phase OAM beams, and therefore still has limitations in terms of propagation stability.

[0004] In their 2016 patent, "Lens and Method for Generating Bessel Beams Carrying Orbital Angular Momentum Based on Metasurfaces," Wu Qun et al. proposed a method to generate Bessel-type electromagnetic beams carrying orbital angular momentum by simultaneously loading axial conical and helical phases in the phase design using a double-layer metal metasurface. This method achieves Bessel vortex waves with quasi-diffraction-free characteristics. However, this scheme mainly targets the generation of a single Bessel-OAM beam and does not achieve multiplexing and transmission of multimode vortex waves under the same aperture.

[0005] In the 2024 paper "ABroadband Transmissive Metasurface for Non-Diffractive THz OAM Multiplexing and Communication" published in IEEE Transactions on Antennas and Propagation, the authors used a transmissive Huygens metasurface to control the phase of the electromagnetic wavefront. They directly introduced Bessel phase and superimposed a spiral phase distribution in the phase design, realizing the generation and multiplexing of Bessel-type quasi-diffraction-free vortex electromagnetic beams carrying orbital angular momentum. However, this scheme mainly relies on the phase control mechanism and does not involve independent adjustment of the amplitude distribution. Moreover, its operating frequency band is mostly concentrated in the terahertz band, which is difficult to popularize due to atmospheric loss and processing requirements. This is significantly different from the commonly used frequency band and application scenarios targeted by this invention.

[0006] In summary, while some progress has been made in the research on vortex electromagnetic waves and quasi-diffraction-free propagation in existing technologies, the following shortcomings remain at the engineering implementation level: Firstly, existing technical solutions are mostly designed for specific high-frequency bands, with wavefront control primarily based on phase adjustment. This fails to fully utilize the degree of freedom in aperture amplitude distribution control, leading to significant structural modifications and parameter reconfiguration required when migrating to microwave bands and implementing them using printed circuit board technology, resulting in high engineering adaptation costs. Secondly, existing verification is mostly limited to local performance testing of the beam generation stage or link, lacking research on integrated antenna architecture design at both transmitting and receiving ends, as well as quantitative prediction methods for effective working distance. Furthermore, end-to-end system-level experimental closed-loop verification is incomplete, and online verification is lacking. How to simultaneously achieve high-quality beam generation, amplitude-phase joint control, and system-level performance verification within a unified technical framework remains an unsolved technical problem. Summary of the Invention

[0007] The purpose of this invention is to address the problems and shortcomings of existing technologies by proposing a dual-feed common-aperture quasi-diffraction-free Bessel vortex wave generation method and transceiver system with end-to-end transceiver link verification capability. This solves the problems of rapid vortex beam diffusion, difficulty in amplitude and phase joint control, difficulty in balancing process simplicity in commonly used frequency bands, and incomplete system-level transceiver verification in existing technologies.

[0008] This invention relates to a method for generating quasi-diffraction-free Bessel vortex waves using a dual-feed, common-aperture system, characterized by the following steps:

[0009] The transmitting antenna used to generate a quasi-diffraction-free Bessel vortex beam includes a transmissive metasurface and a feed horn antenna. The feed horn antenna provides excitation to the metasurface, which modulates the phase and amplitude of the incident wave and radiates the target Bessel vortex beam.

[0010] (1) Feed configuration and mode parameter setting: The feed is arranged above the transmissive metasurface antenna. Each horn antenna feed is optimized and experimentally calibrated by jointly optimizing the spatial position parameters of the feed, including the relative offset from the aperture center, feed spacing, installation height and pointing angle, and the orbital angular momentum mode order and excitation configuration corresponding to each feed are determined accordingly.

[0011] (2) Cooperative solution of vortex phase and Bessel phase: Based on the feed excitation distribution and target beam parameters, the compensation phase distribution for forming Bessel vortex beam is jointly solved on the aperture plane. The cooperative solution is constrained by the phase consistency within the same aperture. On the one hand, it ensures that the aperture phase has the spiral phase structure required by the vortex beam, so that the radiation field forms a clear topological charge and phase singularity characteristics. On the other hand, it ensures that the aperture phase meets the Bessel phase characteristics required for quasi-diffraction-free propagation, so that the energy maintains the main lobe shape stability in the specified propagation range in the form of conical wave synthesis, and forms the total aperture phase distribution that meets the requirements of the target Bessel vortex beam.

[0012] (3) Construction of the combined amplitude and phase target field: Based on the obtained total phase distribution of the aperture, the aperture amplitude distribution design is introduced to construct a target aperture field that simultaneously includes amplitude and phase terms. The amplitude distribution is determined based on the modal composition of the target Bessel vortex beam and the amplitude weight of each mode. The amplitude and phase distribution establish a joint mapping relationship between geometric parameters and transmission response, which is used to achieve joint control of the energy ring structure and sidelobe level on the aperture plane, and is combined with the total aperture phase distribution on the aperture plane.

[0013] (4) Setting of metasurface unit parameters based on PCB process: according to the target aperture field The parameters of each unit on the array are inverted and mapped. The structural parameters of the unit are designed using PCB technology, so that each unit can jointly control the phase and amplitude of the transmitted wave within the operating frequency band. The parameter inversion and mapping includes establishing the correspondence between structural parameters and amplitude and phase response based on the unit electromagnetic response database or full-wave simulation results, completing the determination of unit parameters and constructing the antenna array.

[0014] (5) Selective excitation of multiple feed sources to generate target beam: by... Each feed source can be excited individually or simultaneously to generate a single-mode or multi-mode quasi-diffraction-free Bessel vortex wave within the same physical aperture. Selective excitation involves switching each feed source on and off. By selecting to turn on different feed sources individually or in combination, the target mode can be selected and the single-mode and multi-mode radiation states can be switched to generate a Bessel vortex beam that meets the set parameters.

[0015] This invention is also a dual-feed common-aperture quasi-diffraction-free Bessel vortex wave antenna transceiver system. The antenna transceiver system is further constructed according to the dual-feed common-aperture quasi-diffraction-free Bessel vortex wave generation method according to claims 1-5. The system is characterized by being sequentially connected to a feed layout module, a target beam construction module, an element parameter mapping module, a metasurface array construction module, a beam generation module, and a transceiver link measurement module. The system is used to realize the transceiver communication of the generated beam and to test and evaluate its actual link communication performance.

[0016] The feed layout module is used to arrange multiple feeds above the transmissive metasurface. The multiple feeds are arranged symmetrically in pairs with the center of the metasurface as the symmetry reference, and the orbital angular momentum mode order and spatial position parameters corresponding to each feed are determined, so that the illumination of different feeds can achieve selectable mode excitation within the same physical aperture.

[0017] The target beam construction module is used to calculate the compensation phase distribution required for the metasurface aperture surface based on the feed parameters and the target Bessel vortex beam parameters, and to generate the target beam expression. The compensation phase distribution includes feed illumination compensation, beam converging and shaping compensation, Bessel beam modulation compensation, and vortex phase terms, so that the total aperture phase simultaneously meets the requirements of quasi-diffraction-free propagation and vortex phase structure within the same framework.

[0018] The unit parameter mapping module is used to determine the required unit response at each position of the aperture surface according to the target beam, and map the response to the geometric structure parameter distribution of the unit at each position, so that the unit parameter distribution corresponds one-to-one with the target aperture field, so as to meet the requirement of the metasurface to achieve joint control of the phase and amplitude of the transmitted wave in the working frequency band.

[0019] The metasurface array construction module is used to arrange and assign values ​​to metasurface units point by point on the XOY surface according to the obtained geometric parameters, so as to complete the construction of a transmissive metasurface array, making the resulting array meet the requirements of processing consistency and assembly feasibility, and can be directly used for beam generation.

[0020] The beam generation module is used to excite multiple feed sources individually or simultaneously, and to generate single-mode or mixed-mode Bessel vortex beams within the same physical aperture by selectively activating the feed sources, thereby realizing the switchable and combinable generation of beam modes.

[0021] The transceiver link measurement module is used to construct a receiving structure symmetrical to the transmitter, and to observe and measure the propagation stability and link transmission characteristics of the generated Bessel vortex beam by adjusting the distance between the transmitter and receiver, so as to verify the beam-keeping capability in the quasi-diffraction-free propagation range.

[0022] This invention also relates to a method for verifying the communication performance of a quasi-diffraction-free Bessel vortex beam link. Its key feature is that, based on a dual-feed, common-aperture quasi-diffraction-free Bessel vortex wave wireless transceiver system, specifically, the link performance analysis submodule within the transceiver link measurement module verifies the quasi-diffraction transmission performance. This includes verification of beam propagation stability based on discrete spatial field distribution, verification of transmission stability and modal isolation based on end-to-end S-parameters, and verification of stable transmit / receive distance consistency based on a geometric optics empirical model. The method comprises the following steps:

[0023] A. Beam propagation stability verification based on discrete spatial field distribution: along the propagation region between the transmitting and receiving systems. Uniformly arranged along the propagation axis The electric field amplitude at different positions along the propagation axis is extracted from a sampling point. As sampled data, the field shape preservation is calculated using a discrete correlation model:

[0024] ;

[0025] in The correlation coefficient represents the field shape preservation. The higher the value, the smaller the structural attenuation of the OAM beam.

[0026] The better the mode retention, the higher the value of the field pattern retention correlation coefficient, which verifies the structural stability of the Bessel-OAM beam during free space propagation and provides a beam propagation stability index based on discrete spatial field distribution for link evaluation.

[0027] B. Performance verification of transmission stability and modal isolation based on end-to-end S-parameters: under the operating conditions of the transmit and receive antennas

[0028] In this state, the distance between the transmitting and receiving antennas is Extract the scattering parameters from the transmitter to the receiver. The actual availability of the link is evaluated by analyzing the power transmission characteristics between ports; the transceiver system employs an antenna structure capable of distinguishing different orbital angular momentum modes, and the measured... The parameters not only reflect the overall power transmission level, but also characterize the transmit / receive matching degree and mode isolation performance under specific OAM modes; by adjusting the spacing between the transmitter and receiver... Record the ports under the corresponding conditions. Parameter changes, when the target mode corresponds to When the value is high and the coupling of non-target modes is low, it indicates that the transceiver system has good mode selectivity, high transceiver efficiency and good mode isolation at this distance. By analyzing the end-to-end S-parameters of the target mode, the transmission stability and mode isolation performance of the transceiver system at the corresponding distance are verified.

[0029] C. Verification of Stable Transmit / Receive Range Consistency Based on Geometric Optics Empirical Model: Based on Bessel Vortex Waves

[0030] The stable transmission and reception distance of the Bessel-OAM beam, based on its quasi-diffraction-free propagation characteristics, is estimated using the following empirical model:

[0031] ;

[0032] in, Indicates a stable transmission and reception distance. For the designed diffraction-free propagation distance of the Bessel beam, Let be the equivalent radius of the metasurface radiation aperture, and be the Bessel cone angle. These are empirical coefficients related to finite aperture cutoff, orbital angular momentum mode distribution, and transmitter-receiver mode matching conditions; empirical coefficients This is used to characterize the proportion of the practically stable, quasi-diffraction-free propagation range in the theoretical diffraction-free distance, where... By introducing empirical coefficients The study verified the consistency between the measured stable communication range and the theoretical geometric optical boundary, and determined the upper limit of the actual effective working distance of the Bessel-OAM link.

[0033] This invention addresses the technical challenges of metasurface antennas in controlling Bessel beams, including the limited variety of Bessel vortex beam generation methods, insufficient amplitude and phase control capabilities, and an incomplete transmission performance evaluation system. It proposes a Bessel vortex beam generation scheme capable of joint amplitude and phase control. Through microwave PCB design and fabrication, a quasi-diffraction-free Bessel vortex wave was generated using a joint amplitude and phase control unit. A complete Bessel vortex beam transceiver system was constructed, and a method for verifying its transmission performance was established. This not only enables high-quality generation of the target beam but also allows for quantitative evaluation of its beam-keeping properties, modal purity, energy distribution, and transmission stability during transmission.

[0034] The key technology of this invention in solving the above problems lies in achieving controllable superposition and stable multiplexing of multi-feed multi-mode Bessel vortex waves under 10GHz microwave operating conditions; calculating the compensation phase corresponding to each feed and constructing the target beam complex field distribution based on the feed spatial position, target mode parameters and propagation constraints; and then mapping the target complex field to the geometric parameter distribution of metasurface units to achieve joint control of the phase and amplitude of transmitted electromagnetic waves, forming a reusable and scalable multi-mode beam output capability.

[0035] This invention also constructs an integrated transceiver system that coordinates the transmitting and receiving ends. Through link testing and transmission characterization with adjustable transmit-receive distance, the effective transmit-receive distance and quasi-diffraction-free working area are evaluated and verified, realizing a complete technical closed loop from beam design and generation to system implementation and performance verification.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] Achieving Amplitude-Adjustable Bessel Vortex Beam Electromagnetic Radiation: This invention addresses the application requirements of the microwave band by employing a metasurface structure based on mature PCB technology to uniformly control the electromagnetic beam. A co-design mechanism for phase and amplitude is introduced during beam generation, achieving amplitude-adjustable Bessel vortex beam electromagnetic radiation. This scheme achieves quasi-diffraction-free propagation characteristics while also considering the planarity of the device structure, the maturity of the fabrication process, and the low cost of system implementation, realizing the effective generation and combined amplitude-phase control of Bessel vortex beams in the microwave band.

[0038] A Bessel-type vortex beam transceiver system was constructed to achieve efficient and stable transmission: Based on beam generation, a transceiver system suitable for Bessel-type vortex beam transmission was built. This system, through matching design of the electromagnetic functions of the transmitter and receiver, achieves effective transmission, stable reception, and mode coupling control of the target vortex mode, enhancing the mode-keeping capability and energy transfer efficiency of the beam during transmission. A complete system architecture covering beam generation, spatial transmission, and terminal reception is formed, solving the problems of incomplete Bessel-type vortex beam transceiver links and lack of matching design between the transmitter and receiver systems in existing technologies, which hinder stable transmission. This provides a system foundation for the application of Bessel-type vortex beams in wireless transmission and microwave communication scenarios.

[0039] Online verification of transmission performance was achieved: This invention designs a Bessel vortex beam transmission performance verification scheme and establishes a performance verification scheme that is compatible with the beam generation method and transceiver system. By adjusting the transmission distance, collecting link response, and combining electromagnetic field distribution and system transmission parameter analysis, the stable propagation range, link gain, transmission stability, and mode matching effect of the Bessel vortex beam can be quantitatively evaluated. This verification scheme realizes closed-loop verification from theoretical design to experimental measurement and end-to-end link performance analysis, providing a verification basis for the performance evaluation, parameter optimization, and engineering application of the Bessel vortex beam transceiver system. Attached Figure Description

[0040] Figure 1 This is a flowchart of the dual-feed common-aperture quasi-diffraction-free Bessel vortex wave generation method of the present invention;

[0041] Figure 2 This is a block diagram of the design of the dual-feed common-aperture quasi-diffraction-free Bessel vortex wave wireless transceiver system of the present invention;

[0042] Figure 3 This is a schematic diagram of the transmission metasurface unit structure in the antenna design of the present invention, wherein... Figure 3 (a) is a schematic diagram of the unit structure. Figure 3 This is a top view of the splitting ring;

[0043] Figure 4 This diagram illustrates the variation of element transmission amplitude and phase with geometric parameters in the antenna design of this invention. Figure 4 (a) shows the transmission amplitude and transmission phase of the unit as a function of rotation angle. The changing relationship curve, Figure 4 (b) shows the transmission amplitude and phase of the unit cell as a function of the splitting angle. The changing relationship curve;

[0044] Figure 5 This is a diagram showing the calculated amplitude and phase distribution on the antenna aperture surface in this invention. Figure 5 (a) is the amplitude distribution diagram. Figure 5 (b) is the phase distribution diagram;

[0045] Figure 6 This is a schematic diagram of the structure of the dual-feed common-aperture quasi-diffraction-free Bessel vortex wave wireless transmitter of the present invention.

[0046] Figure 7 This is a schematic diagram of the structure of the dual-feed common-aperture quasi-diffraction-free Bessel vortex wave wireless transceiver system of the present invention.

[0047] Figure 8 To illustrate the vortex electric field distribution and OAM mode spectrum obtained by individually exciting the antenna at feed 1 in the simulation of this invention, wherein... Figure 8 For the electric field amplitude distribution, Figure 8 For the electric field phase distribution, Figure 8 The results are from the OAM modal spectrum analysis. Figure 8 This is a diagram of electric field propagation.

[0048] Figure 9 To illustrate the vortex electric field distribution and OAM mode spectrum obtained by individually exciting feed 2 in the antenna simulation of this invention, wherein... Figure 9 For the electric field amplitude distribution, Figure 9 For the electric field phase distribution, Figure 9 The results are from the OAM modal spectrum analysis. Figure 9 This is a diagram of electric field propagation.

[0049] Figure 10 To illustrate the vortex electric field distribution and OAM mode spectrum obtained by simultaneously exciting the antenna at feed 1 and feed 2 in the simulation of this invention, wherein... Figure 10 For the electric field amplitude distribution, Figure 10 For the electric field phase distribution, Figure 10 The results are from the OAM modal spectrum analysis. Figure 10 This is a diagram of electric field propagation.

[0050] Figure 11 This is a graph showing the variation of S-parameters in the antenna transmit / receive link with transmit / receive distance during the simulation of this invention.

[0051] Figure 12 This is a diagram showing the electric field amplitude distribution along the propagation direction of the target Bessel vortex beam in the simulation of this invention.

[0052] Figure 13 This is a graph showing the correlation calculation results of the electric field distribution of the transmitting and receiving antennas at different transmitting and receiving distances in the simulation of this invention. Detailed Implementation

[0053] The embodiments described herein are merely some, not all, of the embodiments of the present invention. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the protection scope of the present invention.

[0054] It should be noted that the step numbers in the specification and claims of this invention are only for the purpose of clearly describing the embodiments of this invention and facilitating understanding, and their order is not limited.

[0055] Example 1: Existing Bessel vortex beam manipulation techniques are mostly geared towards specific high-frequency bands. Their wavefront manipulation methods mainly rely on phase adjustment, failing to fully utilize the degree of freedom in aperture amplitude distribution. As a result, when migrating to the microwave frequency band and implementing them using printed circuit board technology, significant structural modifications are required, leading to high costs. This invention addresses this issue by proposing a dual-feed, common-aperture quasi-diffraction-free Bessel vortex wave generation method.

[0056] This invention is firstly a method for generating quasi-diffraction-free Bessel vortex waves using a dual-feed, common-aperture system. See [link to relevant documentation]. Figure 1 , Figure 1 This is a flowchart of the present invention, which includes the following steps:

[0057] The transmitting antenna used to generate a quasi-diffraction-free Bessel vortex beam includes a transmissive metasurface and a feed horn antenna. The feed horn antenna provides excitation to the metasurface, which modulates the phase and amplitude of the incident wave and radiates the target Bessel vortex beam.

[0058] (1) Feed configuration and mode parameter setting: Feed configuration and mode parameter setting are the foundation for forming a high-quality Bessel vortex beam. This is done on a transmissive metasurface antenna. One horn antenna feed, among which The core purpose of adopting a multi-feed design is to improve the flexibility and controllability of the beam. Each feed can independently excite different orbital angular momentum modes and support the generation of single-mode or multi-mode hybrid beams to meet the application requirements of improving channel capacity. In terms of specific parameter settings, the following aspects need to be focused on:

[0059] Feed position and illumination uniformity: Each feed must be precisely aligned with the aperture center, and the distance between it and the metasurface must be optimized. Too much distance will cause radiation energy attenuation, weakening the aperture illumination effect; too little distance will result in insufficient illumination of the edge elements, affecting beam quality.

[0060] Installation height: The installation height of the feed directly affects the propagation characteristics of the radiated wave. A reasonable height setting can effectively avoid excessive beam divergence or excessive concentration, and is one of the key constraints to ensure radiation performance.

[0061] Feed spacing: The spacing between each feed needs to be precisely calculated to ensure electromagnetic isolation between them, avoid mutual coupling interference, maintain good coherent superposition characteristics, and make full use of limited space resources.

[0062] Feed pointing angle: The radiation pointing angle of the feed should be configured according to the beam target direction to ensure that the radiation fields of each feed can be effectively coherently superimposed in space, and finally form a vortex beam radiation pattern that meets the design requirements.

[0063] (2) Cooperative solution of vortex phase and Bessel phase: The cooperative solution of vortex phase and Bessel phase constitutes the core of the entire beam generation. First, based on the excitation distribution of the feed and the preset target beam parameters, the required compensation phase distribution needs to be jointly solved on the aperture plane. The key is to ensure that the aperture phase has the spiral phase structure necessary for vortex beams to form a radiation field with clear topological charge and phase singularity characteristics. At the same time, in order to achieve quasi-diffraction-free propagation, the aperture phase must satisfy the Bessel phase characteristics so that the energy maintains the main lobe shape stable in the specified propagation range in the form of a conical wave. This invention adopts the cooperative solution of vortex phase and Bessel phase, which combines the focusing characteristics of vortex beams with the excellent extensibility of Bessel beams. The beam with vortex characteristics can achieve efficient transmission and maintain a high energy density around the focal point, while the characteristics of Bessel waves can effectively suppress divergence. The beam can maintain its shape and energy distribution at the same time during propagation, preventing unnecessary signal loss in long-distance transmission.

[0064] This invention combines the characteristics of vortex phase and Bessel phase to achieve precise beam control in diverse application scenarios. It can also significantly enhance the adaptability and stability of the beam, and the beam can maintain high efficiency under different environments and conditions. It has significant advantages, especially in cases of complex external interference or multipath propagation.

[0065] (3) Amplitude-Phase Joint Target Field Construction: Amplitude-phase joint target field construction is one of the key steps in achieving high-performance beams. In this process, based on the obtained total aperture phase distribution, aperture amplitude distribution design is introduced to form a target aperture field that simultaneously includes amplitude and phase terms. The core is to ensure the coordination between amplitude and phase so that they work together to affect the radiation characteristics. The amplitude distribution is set based on the modal composition of the target Bessel vortex beam and the amplitude weight of each mode. This not only allows for precise control of the energy distribution of each mode but also ensures that an ideal energy distribution is achieved during transmission. This ability to jointly control amplitude allows for flexible adjustment of the beam's energy concentration to meet different application requirements, ensuring optimal signal transmission performance, which is particularly crucial for communication systems. In actual communication scenarios, clear signal transmission and efficient information delivery are essential. By precisely controlling amplitude and phase, the strength of the main signal is enhanced, while the level of sidelobes is effectively suppressed to reduce interference and noise, effectively improving the system's signal-to-noise ratio and helping to ensure the signal quality of each user in a multi-user environment.

[0066] Furthermore, this invention establishes a correspondence between geometric parameters and transmission response, enabling joint control of the energy ring structure and sidelobe levels to generate a stable radiation beam. This joint mapping ensures accurate prediction and adjustment of beam shape and energy distribution during the design process, ultimately achieving the predetermined communication targets. The construction of the amplitude-phase joint target field not only improves beam generation efficiency and quality but also demonstrates its rationality and practicality in modern communication to meet the ever-increasing demands for information transmission.

[0067] (4) Parameter setting of metasurface units based on PCB technology: Parameter setting of metasurface units based on PCB technology is the core step in transforming the theoretical design of amplitude and phase joint control into actual devices. After completing the amplitude and phase distribution design of the target aperture field, it is necessary to invert and map the required phase and amplitude responses at each position on the aperture surface into fabricable unit structure parameters. This process is achieved by establishing a unit electromagnetic response database, that is, by systematically performing full-wave simulation scanning of the key geometric parameters of the unit, establishing a one-to-one correspondence between structural parameters and amplitude and phase responses, so that units at any position on the aperture surface can accurately achieve the required transmission response.

[0068] Existing microwave vortex beam generation schemes mostly rely on three-dimensional metal structures or complex multi-layer cavity designs, which are difficult to manufacture, costly, and incompatible with actual microwave systems. This invention utilizes PCB technology, which, with its planar structure, mature processing flow, and low manufacturing cost, realizes the metasurface array in the form of a printed circuit board, lowering the technological barrier to device manufacturing. More importantly, the high processing precision of the PCB technology ensures the accurate realization of the structural parameters of each unit, enabling the overall amplitude and phase control capability of the array to closely match the theoretical design, thus ensuring the quality of the final radiated beam.

[0069] (5) Selective excitation of the target beam by multiple feed sources: Selective excitation of the target beam by multiple feed sources is the core component of the entire method. This is achieved by selectively exciting the target beam within the same physical aperture. Individual or simultaneous excitation of each feed source generates quasi-diffraction-free Bessel vortex waves in space that satisfy set parameters. The core logic lies in implementing precise on / off gating control of each feed source. That is, by selecting different combinations of on / off feed sources, a specific excitation state is constructed on a single physical aperture surface, realizing the selection of the target mode and the flexible switching between single-mode and multi-mode radiation states.

[0070] This invention addresses the problems of insufficient amplitude control, difficulty in coordinating amplitude and phase design, and poor stability in existing microwave Bessel vortex beam generation methods. It proposes a metasurface control scheme based on PCB technology. By jointly designing the amplitude and phase of electromagnetic waves, precise control of the Bessel vortex beam is achieved, resulting in a beam with a spatial distribution closer to the ideal state and exhibiting good stability and integrity. The use of a planar PCB structure improves the manufacturability, cost advantages, and integration capabilities with existing microwave systems, demonstrating high engineering application value.

[0071] Example 2: The overall scheme of the dual-feed common-aperture quasi-diffraction-free Bessel vortex wave generation method is the same as that of Example 1. Step 1 of this invention is the feed configuration and mode parameter setting, which includes the following steps:

[0072] 1.1 Symmetrical arrangement of feed sources: The number of feed sources is set to... ,in This example assumes ,when These feed sources are named the first feed and the second feed, respectively. They are symmetrically arranged on both sides of the transmissive metasurface along the X-axis, each at a distance R from the center point O of the metasurface. The beam axes of both feeds form the same angle with the Z-axis. In this embodiment, it is set that The two feed sources are symmetrically distributed on both sides of the X-axis, with a distance of 300 mm from the center of the metasurface. This spatially symmetrical arrangement ensures that the two feed sources provide good uniformity of illumination on the metasurface aperture, enabling each unit of the metasurface to obtain relatively balanced energy excitation, and providing good incident field conditions for the subsequent formation of a stable Bessel vortex beam.

[0073] 1.2 Feed Orbit Angular Momentum Mode Setting: The feed orbit angular momentum mode is set according to the target orbit angular momentum mode of the quasi-diffraction-free Bessel vortex wave to be generated. The i-th orbit angular momentum mode is... The position of the i-th feed source is Each feed mode is In spherical coordinates, the beam direction of its emitted wave is... The beam direction is , Indicates pitch angle and , Indicates azimuth and By setting the above parameters appropriately, the electromagnetic waves radiated by the two feed sources can form a controllable phase distribution and energy distribution in space, enabling them to achieve effective coherent superposition at the metasurface aperture.

[0074] This invention employs a dual-feed, common-aperture structure, which not only ensures stable energy irradiation of the metasurface aperture but also enables flexible excitation of different orbital angular momentum modes. The two feeds are symmetrically arranged in space and simultaneously irradiate the metasurface. Their radiation fields create a superposition effect at the metasurface, and after phase modulation by the metasurface units, a quasi-diffraction-free Bessel vortex beam with specific orbital angular momentum characteristics can be formed in space. Compared to a single-feed system, this structure offers greater flexibility and controllability, while also improving the system's mode multiplexing capability to a certain extent, providing an effective technical approach for realizing high-capacity electromagnetic wave communication systems.

[0075] Example 3: The method for generating quasi-diffraction-free Bessel vortex waves with dual feed and common aperture is the same as in Examples 1-2. Step 2 of this invention involves the joint solution of the vortex phase and the Bessel phase, including the following steps:

[0076] First, based on the number of feeders set in step 1... The position coordinates of each feed source Orbital angular momentum mode The target beam is calculated using the following formula, along with parameters such as the direction of the emitted beam. The expression:

[0077]

[0078] In the formula Let these represent the amplitude distribution and phase distribution of the target field, respectively. , , as well as The four types of compensation phases required from the feed horn to the metasurface aperture surface are calculated using the following formulas:

[0079] The first item is the feed compensation phase:

[0080] ;

[0081] Second convergence compensation phase:

[0082] ;

[0083] The third item is phase compensation for Bessel beam modulation:

[0084] ;

[0085] The fourth item is the OAM phase:

[0086] ;

[0087] By constructing a unified phase model that includes feed compensation phase, convergence compensation phase, Bessel beam control compensation phase, and orbital angular momentum (OAM) phase, the coordinated solution and joint control of vortex phase and Bessel phase are realized, as well as the effective generation of aligned, diffraction-free Bessel vortex beams. The calculation methods for each compensation phase are explained below:

[0088] 2.1 Construction of the target radiation field expression: Calculate the required compensation phase on the metasurface aperture surface and determine the target beam expression. The formula is as follows:

[0089] ;

[0090] in, Indicates the amplitude distribution of the target field. This represents the AND and phase distribution of the target field. These correspond to the four types of compensation phases required from the feed horn to the metasurface aperture surface, among which For feed source phase compensation, To converge and compensate for the phase, To compensate for phase in Bessel beam modulation, The vortex phase can be obtained through specific calculations.

[0091] 2.2 Feed Compensation Phase Calculation: The formula for calculating the feed compensation phase in the target radiation field expression is as follows:

[0092] ;

[0093] in, The distance from each unit to the feed source, This represents the position coordinates of the metasurface element. Indicates the first The location coordinates of the feed source Indicates wavelength.

[0094] 2.3 Convergence Compensation Phase Calculation: The formula for calculating the convergence compensation phase in the target radiation field expression is as follows:

[0095] ;

[0096] in, Indicates wave number.

[0097] 2.4 Bessel Beam Modulation and Phase Compensation Calculation: The formula for calculating the Bessel beam modulation compensation phase in the target radiation field expression is as follows:

[0098] ;

[0099] in, This indicates the cone angle used to generate the Bessel beam. The Bessel cone angle refers to the angle formed by the plane wave component that forms the Bessel beam relative to the propagation axis. Its physical meaning is the characteristic of beam energy propagating along the conical wavefront. Adjusting the cone angle can change the lateral energy distribution characteristics and the quasi-diffraction-free propagation range of the Bessel beam.

[0100] 2.5 Vortex Phase Calculation: The formula for calculating the vortex phase in the target radiation field expression is:

[0101] ;

[0102] in, This indicates the order of the OAM modes corresponding to the two feed sources.

[0103] The two-feed mode determined in this example is: The two feeds are symmetrically distributed on both sides of the X-axis, making an angle of 30° with the X-axis, and are 300mm away from the far point. The direction of the emitted beam is... Bezier cone angle Given a value of 10°, substituting the above parameters into the calculation formulas for each compensation phase yields the following compensation phases: , , , .

[0104] This invention uses the target radiation field expression as a unified framework, and incorporates feed compensation, convergence compensation, Bessel control compensation and vortex phase into the total aperture phase. Each phase term is calculated separately and synthesized into the compensation phase distribution required for the aperture, realizing the coordinated design of Bessel phase characteristics and vortex phase structure, so that the same aperture can simultaneously meet the requirements of quasi-diffraction-free propagation and vortex beam.

[0105] Example 4: The method for generating quasi-diffraction-free Bessel vortex waves with dual feed and common aperture is the same as in Examples 1-3. Step 3 of this invention is the construction of the amplitude-phase joint target field, which includes the following steps:

[0106] 3.1 Amplitude and Total Compensation Phase Acquisition: Based on the target aperture surface complex field distribution obtained in step 2. Extract the amplitude distribution of the target field on the aperture plane. and total compensation phase distribution The complex transmission function at each location in the target field can be expressed as a complex number determined by both amplitude and phase terms. Its amplitude distribution constrains the transmission intensity of each element on the aperture surface, while its total compensation phase constrains the phase compensation amount of each element on the aperture surface for electromagnetic waves. The target aperture surface is discretized into several metasurface elements, and the target transmission amplitude and phase corresponding to each element location are obtained as the basis for subsequent element geometric parameter inversion design.

[0107] 3.2 Unit Design and Parameter Scanning: To meet the target beam amplitude and phase distribution characteristics calculated in step 2, this embodiment uses a metasurface unit combining a split ring and a polarization grating. Figure 3 This is a schematic diagram of the transmission metasurface unit structure of the present invention, showing the overall structure and components of the unit. The metasurface unit consists of a split ring and a polarization gate, with a metal ground plane at the bottom, connected to the ground plane via a dielectric substrate. The unit structure comprises a split ring and a polarization gate. Figure 3 This represents the composition and structure of the metasurface unit. The substrate of this unit is made of F4B material (ε=2.56, tanδ=0.0015), and its physical dimensions are as follows: The width of the metal strip is 1.5mm, the interval between the two metal strips is 1.1mm, the inner and outer radii of the split metal ring are 2.3mm and 3.5mm respectively, and the thickness of each layer of medium is 2mm.

[0108] Figure 3 This is a top view of the split ring, which features separable amplitude and phase controllability, where the transmission phase is mainly determined by the splitting angle of the split ring. The transmission amplitude is controlled by the rotation angle of the splitting ring. In the specific implementation process, the key geometric parameters of the metasurface unit are scanned, that is, the splitting angle with different values ​​is scanned. and rotation angle A comprehensive combination was performed, and the transmission characteristics of the unit under each parameter combination were simulated and analyzed using HFSS full-wave simulation software to obtain different splitting angles. Rotation angle The corresponding transmission phase and transmission amplitude response data are used to establish the split angle. and rotation angle For the corresponding transmission amplitude and transmission phase response databases, please refer to [link / reference]. Figure 4 . Figure 4 This is a graph showing the relationship between the transmission amplitude and phase of a single element and geometric parameters, used to characterize the ability of the element's structural parameters to control electromagnetic transmission characteristics. Among them, Figure 4 (a) is the transmission amplitude of the unit of the present invention. and transmission phase With rotation angle The changing relationship curve; Figure 4 (b) is the unit transmission amplitude and transmission phase With splitting angle The changing relationship curve. (From...) Figure 4 (a) and Figure 4 (b) The correspondence between the geometric parameters of the unit and its electromagnetic transmission characteristics can be established. The unit has excellent amplitude-phase joint control capability, and can achieve flexible and continuous adjustment of the electromagnetic wave phase while ensuring transmission efficiency. It exhibits good design freedom and engineering applicability, forming a response database for phase design, and providing a basis for subsequent unit parameter inversion design based on the target field distribution.

[0109] 3.3 Establishing a joint mapping between geometric parameters and transmission response: Establishing a one-to-one mapping relationship between two types of geometric parameters and their corresponding transmission responses:

[0110] ;

[0111] The target transmission phase and target transmission amplitude required for each element on the target aperture surface are calculated one by one into the corresponding element geometric parameters, that is, the splitting angle corresponding to each element is calculated. and rotation angle See Figure 5 , Figure 5 The diagram shows the calculated amplitude and phase distribution on the antenna aperture surface of this invention. Figure 5 (a) is the amplitude distribution diagram. Figure 5(b) is a phase distribution diagram used to back-calculate the target transmission phase and amplitude required for each element on the target aperture surface, in order to determine the corresponding geometric parameters for each element, including the splitting angle and rotation angle. For any element on the target aperture surface, based on its target transmission amplitude and target transmission phase, the best-matching transmission response combination is found in the response database, and the splitting angle corresponding to that transmission response combination is determined. and rotation angle By repeating the above process for all elements on the entire aperture surface, the parameter arrangement result of the entire metasurface aperture can be obtained.

[0112] 3.4 Inverse calculation of geometric parameters of the target field: Using this mapping relationship, the required phase and amplitude of each element on the target aperture surface are inversely calculated into the corresponding splitting angle. With rotation angle Compared to existing metasurface design methods that only perform phase modulation, this embodiment introduces two independent geometric parameters: the splitting angle. With rotation angle The transmission phase and transmission amplitude are respectively controlled to achieve combined amplitude and phase design of the aperture field, thereby improving the reconstruction accuracy and propagation performance of the target beam. Among these, the splitting angle... The phase compensation capability and rotation angle of the unit are determined by the phase compensation capability. The main factor determining the transmission amplitude distribution of the unit is the splitting angle. With rotation angle The joint inverse calculation can make the aperture field of the metasurface closer to the theoretical target field distribution, thereby improving the beam quality, energy focusing ability and quasi-diffraction-free transmission characteristics of Bessel vortex waves.

[0113] This invention achieves precise joint control of the amplitude and phase of the target aperture field, solving the problems of difficult amplitude adjustment and phase coordination in traditional methods. By introducing two independent parameters, the splitting angle and the rotation angle, the transmission amplitude and phase are controlled separately, enabling the metasurface unit to simultaneously meet amplitude constraints and phase compensation requirements, thereby improving the accuracy of aperture field reconstruction. Combining a parameter-response mapping database with a target field inversion method, efficient design from the target field to structural parameters is achieved. This method effectively improves beam energy concentration, purity, and quasi-diffraction-free characteristics, providing a feasible solution for the stable generation of Bessel vortex beams and their applications in wireless communication and other fields.

[0114] Example 5: The method for generating quasi-diffraction-free Bessel vortex waves with dual feed and common aperture is the same as in Examples 1-4. Step 4 of this invention involves setting the metasurface unit parameters based on PCB technology, including the following steps:

[0115] This embodiment further defines the PCB process parameters, array element arrangement, transmitter assembly, and target beam generation process for the transmissive metasurface. Based on the target aperture field amplitude and phase distribution and element geometric parameter mapping relationship obtained in step 3, a fabricable transmissive metasurface array model is established, and the transmitter system is assembled using a dual-feed common-aperture illumination method to achieve the generation of the target standard non-diffraction Bessel vortex beam.

[0116] 4.1 Array Model Establishment: Using the XOY plane as the array surface, a square transmissive metasurface array model centered at the origin is established. Preferably, in this embodiment, the transmissive metasurface array size is set to 48×48 metasurface units, that is, the entire array surface is composed of 48 rows and 48 columns of units arranged periodically. It should be noted that the 48×48 array size is only a preferred embodiment of the present invention, used to illustrate the engineering feasibility of the technical solution of the present invention, and does not constitute a limitation on the scope of protection of the present invention. Under the premise of meeting the target aperture field reconstruction requirements, the array size, the overall size of the array surface, and the unit period can be adjusted accordingly based on the operating frequency band, aperture size, processing technology capabilities, and application scenario requirements. The square transmissive metasurface is symmetrically arranged with the origin as the center, the overall size of the array surface is set to 360 mm×360 mm, and the unit period is 7.5 mm. The above parameters are mainly determined by comprehensively considering factors such as the array aperture size, unit space sampling accuracy, PCB process feasibility, and target beam generation quality. Each discrete position in the array corresponds to a metasurface unit, which is used to locally modulate the transmission amplitude and compensate the transmission phase of the incident electromagnetic wave, so as to reconstruct the target aperture field as a whole.

[0117] 4.2 Element Parameter Mapping and Arrangement: Based on the target aperture field mapping results obtained in step 3 and the established correspondence between element amplitude and phase response and structural parameters, the PCB element structural parameters corresponding to each metasurface element at each position on the array are determined. These parameters are then assigned point-by-point according to their spatial positions within the array, forming the final transmissive metasurface array. For any metasurface element at any position on the array, the corresponding element structural parameters are calculated from the mapping relationship established in step 3, based on the target transmission amplitude and phase required at that position. These structural parameters are then assigned to the PCB element at that position on the array. Following this method, parameter mapping and arrangement are completed for all 48×48 metasurface elements, ultimately forming a complete transmissive metasurface array to construct a beam transmitting device. The structure is shown in [reference needed]. Figure 6 , Figure 6 This is a schematic diagram of the launching device of the present invention.

[0118] 4.3 Selective Excitation of Feeds: In the transmitting structure of the transmissive metasurface array, two horn feeds are used to illuminate the transmissive metasurface array with a common aperture. By selectively exciting the two horn feeds, the transmissive metasurface array can generate corresponding single-mode or mixed-mode quasi-diffraction-free Bessel vortex beams. When one horn feed is selected for excitation, the transmissive metasurface array generates a corresponding single-mode quasi-diffraction-free Bessel vortex beam under the control of a predetermined aperture field; when both horn feeds are excited simultaneously, the transmissive metasurface array forms a corresponding mixed-mode quasi-diffraction-free Bessel vortex beam within the same physical aperture. Selective excitation involves controlling the switching state of the two horn feeds. By selecting one to be turned on alone or both to be turned on in combination, the target mode can be selected, and the switching between single-mode and mixed-mode radiation states can be achieved, generating a quasi-diffraction-free Bessel vortex beam that meets the set parameter requirements.

[0119] By individually or simultaneously exciting two feed sources, quasi-diffraction-free Bessel vortex waves of single or multimode origin can be generated within the same physical aperture. Selective excitation refers to the selective control of the switching states of the two feed sources. By selecting the individual or combined activation of different feed sources, the target mode can be selected, and the single-mode and multimode radiation states can be switched, generating a Bessel vortex beam that meets the set parameter requirements.

[0120] This invention, based on obtaining the amplitude and phase distribution of the target aperture field and the mapping relationship of the unit geometric parameters, further completes the engineering realization of a transmissive metasurface array. A 48×48 square transmissive metasurface array is constructed, and the structural parameters of each metasurface unit are precisely arranged using PCB technology, effectively realizing the amplitude-phase modulation requirements obtained from the theoretical design in the actual fabricated structure. Simultaneously, by mapping the structural parameters of each unit point-by-point according to the spatial position of the array surface, the entire array surface can achieve precise local amplitude modulation and phase compensation for the incident electromagnetic wave, reconstructing the target aperture field distribution that meets the design requirements. Combined with a dual-feed common-aperture illumination structure, a stable and high-quality quasi-diffraction-free Bessel vortex beam is formed in space.

[0121] This invention addresses the challenges of amplitude-phase coordination in Bessel vortex beam generation, insufficient structural adaptability, and complex multi-mode excitation. By optimizing feed position and modal parameters, it achieves stable excitation of the target vortex mode through multi-feed coordinated operation. A comprehensive phase compensation model is constructed to achieve high-precision fusion of the Bessel beam and vortex phases. An amplitude-phase joint design method is employed to optimize the aperture field distribution, effectively improving beam quality and energy control capabilities. Furthermore, a metasurface structure is implemented using PCB technology, reducing system complexity and manufacturing costs, and enhancing engineering feasibility.

[0122] Example 6: This invention also relates to a dual-feed, common-aperture quasi-diffraction-free Bessel vortex wave antenna transceiver system. The antenna transceiver system is constructed based on the dual-feed, common-aperture quasi-diffraction-free Bessel vortex wave generation method. See [link to relevant documentation]. Figure 2 The system comprises, in sequence, a feed deployment module, a target beamforming module, an element parameter mapping module, a metasurface array construction module, a beam generation module, and a transceiver link measurement module. The system is used to realize the transceiver communication of the generated beam and to test and evaluate its actual link communication performance. The module structure and working principle of the entire system are as follows:

[0123] Feed Layout Module: As the foundational module of the system, the feed layout module of this invention arranges multiple feeds symmetrically in pairs within a specific focal length plane above the transmissive metasurface, with the geometric center of the metasurface as the reference. Each feed is assigned its orbital angular momentum mode order and spatial position parameters. Specifically, this module precisely defines the coordinate position of each feed in three-dimensional space, its tilt angle relative to the metasurface normal, and the corresponding modal information. This ensures that the spherical waves generated by each feed illuminate the metasurface aperture surface with a predetermined incident wavefront, achieving independent or combined excitation of different orbital angular momentum modes within the same physical aperture. Further, the feed layout module transmits the three-dimensional geometric coordinate information and modal setting information of each feed to the target beam construction module and the metasurface array construction module, respectively, as input conditions for subsequent compensation phase calculation, target beam construction, and array arrangement design.

[0124] Target Beam Construction Module: As the core module of the system, the target beam construction module of this invention generates a complete aperture surface amplitude and phase distribution based on the spatial layout parameters of the feed and the Bessel-OAM parameters of the target Bessel vortex beam, and forms a target beam expression. The target beam construction module includes a basic phase generation submodule, a Bessel vortex phase generation submodule, and a target phase construction submodule. Specifically, the basic phase generation submodule calculates the path difference compensation phase at each position from the feed to the metasurface based on the geometric relationship between the feed position and the metasurface; the Bessel vortex phase generation submodule generates the Bessel control phase and helical phase based on preset Bessel cone angles and orbital angular momentum orders; and the target phase construction submodule superimposes the path difference compensation phase and the Bessel vortex beam control phase, and combines this with the target amplitude distribution to construct a complete target aperture field description.

[0125] The target beam construction module of this invention is used to calculate the total compensated phase distribution required for the metasurface aperture surface based on the feed parameters and the target Bessel vortex beam parameters, and to generate the target beam expression. The total compensated phase distribution simultaneously includes feed illumination compensation, beamforming compensation, Bessel beam manipulation compensation, and vortex phase terms, ensuring that the total aperture phase satisfies both the quasi-diffraction-free propagation requirement and the vortex phase structure requirement within a unified framework. The target aperture surface amplitude and phase distribution output by this module are transmitted to the element parameter mapping module.

[0126] Element Parameter Mapping Module: As the system's parameter solving module, the element parameter mapping module determines the required element response at each location on the metasurface aperture surface based on the amplitude and phase distribution of the target beam. It then maps this response to the geometric parameter distribution of the metasurface elements at the corresponding locations, ensuring a one-to-one correspondence between the element parameter distribution and the target aperture field. Specifically, based on a pre-established database of element amplitude and phase responses, this module uses the rotation and splitting angles of the splitting rings to independently control the transmission amplitude and phase, respectively, and maps the required target amplitude and phase at each aperture grid point to the corresponding element geometric parameters. Finally, the calculated element parameter matrix is ​​transmitted to the metasurface array construction module for subsequent array arrangement and fabrication.

[0127] Metasurface Array Construction Module: As the system's array implementation module, the metasurface array construction module is used to arrange and assign parameters to metasurface elements point-by-point on the XOY plane according to the obtained geometric parameters, completing the construction of a transmissive metasurface array. This ensures the resulting array meets both the target beamforming requirements and the requirements for fabrication consistency and assembly feasibility. Further, based on the geometric parameter matrix output by the element parameter mapping module, this module arranges each metasurface element on the XOY plane to form a complete transmissive metasurface array. Simultaneously, based on the feed position information in the feed placement module, monopole antennas or other suitable feed structures are installed at the corresponding positions on the array to complete the construction of the transmitting structure for generating the target Bessel vortex beam. The metasurface array and its feed layout constructed by this module will serve as the basic structure for the beam generation module, used for the subsequent excitation and radiation of the Bessel vortex beam.

[0128] Beam generation module: As the system's operating module, the beam generation module is used to individually or simultaneously excite multiple feed sources to generate single-mode or mixed-mode Bessel vortex beams within the same physical aperture, enabling switchable and combinable generation of beam modes. Specifically, this module achieves flexible control over different orbital angular momentum mode combinations by adjusting the excitation amplitude and phase of each feed source. When only a single feed source is excited, the system can radiate a Bessel vortex beam of a single order; when multiple feed sources are excited simultaneously, the system can achieve the synthetic radiation of multi-mode mixed Bessel vortex beams under the same common aperture condition. Therefore, the beam generation module can guide the radiated target beam into the transceiver link measurement module to verify its actual propagation performance and communication capabilities.

[0129] Transceiver Link Measurement Module: The transmit / receive link measurement module is used to construct a symmetrical receiver within the propagation area between the transceiver systems. (See also...) Figure 7 , Figure 7 This is a schematic diagram of a wireless transceiver system device. The distance between the transceiver and receiver is set to... The propagation axis is The system establishes a test link along the propagation axis. By adjusting the distance between the transmitter and receiver, the propagation stability, energy concentration, and link transmission characteristics of the generated beam are observed and evaluated to verify its beam-keeping capability and actual communication performance in the quasi-diffraction-free region. Furthermore, the transceiver link measurement module is used to receive, demodulate, and test the link performance of the Bessel vortex beam generated by the system. Evaluation indicators include, but are not limited to, received power distribution, link transmission stability, mode retention capability, bit error rate performance, and communication quality variations at different propagation distances. This enables a comprehensive test and evaluation of the actual link communication performance of this dual-feed, common-aperture quasi-diffraction Bessel vortex wave wireless transceiver system.

[0130] This invention constructs an end-to-end wireless transceiver system suitable for Bessel-type vortex beam transmission based on target beam generation. Through electromagnetic matching design of the transmitter and receiver, the transmitter can directionally radiate a Bessel-type vortex beam with a predetermined orbital angular momentum mode, while the receiver can achieve effective coupling, stable reception, and selective mode response to the target mode, improving mode holding capability, energy transmission efficiency, and communication stability in the end-to-end link. Through the collaborative construction of the transmitter, propagation space, and receiver, end-to-end coverage of the entire process of Bessel-type vortex beam generation, transmission, and reception is achieved, forming a complete end-to-end wireless link system architecture. This provides a system foundation for subsequent end-to-end S-parameter measurement and link communication performance evaluation.

[0131] Example 7: The dual-feed common-aperture quasi-diffraction-free Bessel vortex wave generation method and transceiver system are the same as in Examples 1-6, see [link to example 1-6]. Figure 2The target beamforming module, from phase generation to phase synthesis, is sequentially connected to the basic phase generation submodule, the Bessel vortex phase generation submodule, and the target phase forming submodule. The functions of each submodule are as follows:

[0132] The basic phase generation submodule calculates the path length, path difference, and corresponding phase offset of electromagnetic waves propagating from the feed to each sampling point based on the three-dimensional spatial coordinates of each feed and the position of each sampling unit within the metasurface aperture surface. This generates the basic compensated phase distribution when the feed illuminates the aperture surface. This submodule primarily compensates for wavefront phase inconsistencies caused by incident spherical waves from the feed, establishing a unified phase reference for subsequent target beam manipulation. The results are then output to the Bessel vortex phase generation submodule.

[0133] The Bessel vortex phase generation submodule generates the Bessel control phase based on preset Bessel cone angle parameters and the spiral phase distribution based on preset orbital angular momentum topological charge number. The Bessel control phase imparts axial convergence and quasi-diffraction-free propagation characteristics to the target beam, while the spiral phase introduces the angular phase gradient required for the orbital angular momentum mode. This submodule combines these two types of phases to form the basis for mode control of the target Bessel vortex beam.

[0134] The target phase construction submodule is used to superimpose the basic compensation phase, Bessel-controlled phase, and spiral phase on the metasurface aperture surface to construct the overall design phase distribution corresponding to the target beam. This submodule can fold and quantize continuous phases to form a final design phase spectrum suitable for actual fabrication; and combined with the full-wave simulation electromagnetic response database of the metasurface elements, it performs matching and optimization between the target phase and the element geometric parameters, outputting a geometric parameter distribution file to guide the arrangement of the metasurface array, realizing parameter integration from target beam design to physical structure realization.

[0135] The basic phase generation submodule, the Bessel vortex phase generation submodule, and the target phase construction submodule are sequentially connected, forming a complete processing chain from feed incident compensation and target mode phase generation to overall phase construction and parameter output. Specifically, the basic phase generation submodule establishes the compensation basis for the feed spherical wave; the Bessel vortex phase generation submodule introduces the mode control characteristics required for the target Bessel vortex beam; and the target phase construction submodule achieves the unified synthesis of multiple phase terms and generates target phase design results that can directly guide the arrangement of metasurface units. The target beam construction module can not only generate a target phase distribution that meets the requirements of quasi-diffraction-free propagation based on the feed spatial layout, but also simultaneously introduce the helical phase structure required for the orbital angular momentum mode, providing theoretical and parameter support for the accurate generation of a dual-feed, common-aperture quasi-diffraction Bessel vortex beam.

[0136] The transceiver system built upon the aforementioned target beamforming module integrates the beam generation mechanism at the transmitter with the modal response characteristics at the receiver, creating a closed loop between the transmitter and receiver links in terms of beam type, phase structure, propagation characteristics, and mode matching. The target beam constructed at the transmitter maintains high structural stability during propagation and receives a matching response characteristic at the receiver. This enhances the controllability, stability, and engineering feasibility of Bessel vortex beams in practical transmission scenarios, solving the technical problems of incomplete Bessel vortex beam transceiver links, lack of matching design between transmitter and receiver systems, and difficulty in achieving stable transmission in existing technologies.

[0137] Example 8: The dual-feed common-aperture quasi-diffraction-free Bessel vortex wave generation method and transceiver system are the same as in Examples 1-6, see [link to example 1]. Figure 2 The transmit / receive link measurement module, from data measurement to data analysis, is sequentially connected to the receiver construction submodule, propagation sampling submodule, link power measurement submodule, and link performance analysis submodule. The functions of each submodule are as follows:

[0138] Receiver Construction Submodule: This module constructs a receiving antenna structure that is mirror-symmetrical to the transmitter. Specifically, a spatial propagation link with a spacing of D is established between the transmitter and receiver. At the receiver, a receiving antenna array is constructed that is completely or substantially mirror-symmetrical to the transmitter's metasurface in terms of aperture size, element arrangement, and feed configuration. The receiver construction submodule adjusts the polarization, spatial pointing, and modal response characteristics of the receiving feed to achieve mode, direction, and polarization matching between the target Bessel vortex beams generated by the receiver and transmitter.

[0139] This invention establishes a wireless communication physical link between the transmitter and receiver. Through this mirror-matched receiver structure, the coupling efficiency of the receiver to the target mode beam is improved, interference from non-target modes or incident waves from non-target directions is suppressed, and the mode selectivity and reception stability of the entire transceiver link are enhanced.

[0140] Propagation Sampling Submodule: The propagation sampling submodule of this invention is used to collect spatial electric field data during the propagation of the beam between the transmitting and receiving structures. Specifically, within the quasi-diffraction-free propagation region between the transmitting and receiving structures, multiple detection cross-sections are uniformly arranged along the propagation axis, and N sampling points are uniformly set along the axis within the propagation region. The spatial electric field amplitude vectors at different locations are extracted using a near-field scanning probe or a far-field scanning probe. By collecting and comparing the cross-sectional distribution of the field pattern at different propagation distances, this study analyzes whether the transverse field shape, phase center structure, and energy ring distribution characteristics of the target Bessel vortex beam remain stable during propagation. The propagation sampling submodule is used to quantitatively evaluate the beam's ability to maintain its structural shape, propagation stability, and mode preservation performance in the quasi-diffraction-free region, providing basic spatial field data for subsequent link performance analysis.

[0141] The link power measurement submodule is used to acquire the scattering parameters S and power transmission coefficients between the transmit and receive antenna ports. It focuses on recording the variation curves of link transmission parameters with the transmit-receive distance D to analyze the energy concentration of the target mode beam and the power coupling between different modes. Furthermore, by measuring the port response between the transmitter and receiver, the link gain variation, transmission loss characteristics, and inter-mode crosstalk level of the target Bessel vortex beam at different propagation distances can be quantitatively evaluated. Especially in multi-mode or mixed-mode operation, the link power measurement submodule can also be used to analyze the power coupling degree and isolation effect between different orbital angular momentum modes, determining the mode resolvability and transmission effectiveness of the designed transceiver system under actual communication conditions.

[0142] The link performance analysis submodule integrates spatial sampling data and port scattering parameters to perform unified analysis and verification of beam propagation stability, link transmission performance, and stable transmission and reception distance. Specifically, based on discrete correlation models, modal isolation indices, and empirical models based on geometric optics, the submodule comprehensively evaluates the consistency of the beam pattern during propagation, the maintenance of modal purity, the variation of port transmission performance, and their correlation with propagation distance. By jointly analyzing the spatial electric field distribution obtained by the propagation sampling submodule and the scattering parameter results obtained by the link power measurement submodule, the link performance analysis submodule can maintain the target beam's ability within the diffraction-free region, the effective transmission range, and the stable transmission and reception distance. Consistency verification is performed within a reasonable range to achieve a systematic evaluation of the performance of the entire dual-feed common-aperture quasi-diffraction-free Bessel vortex wave wireless transceiver link.

[0143] The receiver construction submodule, propagation sampling submodule, link power measurement submodule, and link performance analysis submodule are sequentially connected to form a complete test process from receiver setup, spatial propagation data acquisition, port power measurement to comprehensive link analysis. This not only enables experimental observation of the spatial propagation characteristics of the target Bessel vortex beam but also allows for quantitative characterization of the transmission performance of actual wireless communication links. The transceiver link measurement submodule can comprehensively test the mode-keeping capability, energy concentration capability, transmission stability, and link effectiveness of the beam generated by this invention in a real propagation environment, providing experimental basis and performance support for the engineering application of dual-feed common-aperture quasi-diffraction-free Bessel vortex beams in wireless transmission and microwave communication.

[0144] Example 9: This invention also provides a method for verifying the link communication performance of a quasi-diffraction-free Bessel vortex beam. This method is based on the aforementioned dual-feed, common-aperture quasi-diffraction Bessel vortex beam wireless transceiver system. Specifically, the link performance analysis submodule in the transceiver link measurement module verifies the quasi-diffraction transmission performance. The verification method of this invention focuses on the propagation stability, mode maintenance capability, end-to-end energy transmission capability, and stable communication distance of the Bessel-OAM beam in a practical wireless link. By constructing a receiving system matched to the transmitter, and combining spatial field sampling, port parameter measurement, and theoretical model analysis, the link communication performance of the generated Bessel vortex beam is systematically verified. The quasi-diffraction-free Bessel vortex beam link communication performance verification method includes the following steps:

[0145] A. Beam propagation stability verification based on discrete spatial field distribution: along the propagation region between the transmitting and receiving systems. Uniformly arranged along the propagation axis There are 1 sampling points, among which Extracting the electric field amplitude at different positions along the propagation axis As sampling data, Given the distance between the transmitter and receiver, in this example, sampling is performed every 2000 mm, with the sampling axis being the z-axis. Based on the sampled data, the field pattern preservation is calculated using a discrete correlation model. After obtaining the above discrete spatial field distribution data, the field pattern preservation of the beam during propagation is calculated using the following discrete correlation model based on the sampled data:

[0146] ;

[0147] Discrete correlation models are used to measure the similarity between the field distribution at different propagation locations and the reference field distribution. The calculated field pattern preservation correlation coefficient serves as an important indicator for evaluating beam structure preservation capabilities. The higher the value, the less structural decay and the better mode retention of the OAM beam during propagation; conversely, the lower the value, the more obvious field distortion, energy diffusion or mode degradation of the target beam during propagation.

[0148] Furthermore, by comparing the cross-sectional electric field distribution at different propagation positions between the transceiver systems, the stability of the target Bessel-OAM beam's field structure characteristics within the quasi-diffraction-free propagation range can be quantitatively assessed. These characteristics include, for example, the central hollow structure, ring-shaped energy distribution, phase singularity position, and transverse field envelope shape. When the field pattern preservation correlation coefficient remains high throughout a relatively long propagation range, it indicates that the Bessel-OAM beam generated by this invention possesses good free-space propagation stability and can meet the link transmission's requirements for mode preservation capability. Verification of beam propagation stability based on discrete spatial field distribution provides a quantitative indicator reflecting the target beam's spatial structure preservation capability for link evaluation, serving as an important basis for determining the quasi-diffraction-free propagation range.

[0149] B. Performance verification of transmission stability and modal isolation based on end-to-end S-parameters: After completing the spatial field sampling...

[0150] Following the analysis, the actual transmission performance of the transceiver link was further verified through port parameter measurement. Specifically, with the transceiver antennas in operation, the distance between the transmitter and receiver was set to D, the scattering parameter S between the transmitter and receiver was extracted, and the actual usable energy of the link was evaluated by analyzing the port power transmission coefficient.

[0151] Preferably, in this embodiment, the interval distance D between the transmitter and receiver is gradually changed, and the port parameter changes under different distance conditions are recorded in predetermined step sizes. In this embodiment, D is 100mm, that is, the transmit and receive antenna port parameters are extracted every 100mm to obtain the S-parameter curve from the transmitter to the receiver under the corresponding conditions. By analyzing the magnitude of the parameter change with the propagation distance, the energy transmission efficiency and link stability of the target beam in different propagation intervals can be determined.

[0152] This invention employs a transmit / receive antenna structure capable of distinguishing different OAM modes, and simultaneously evaluates power transmission, mode matching, and mode isolation performance through end-to-end S-parameters. When the target mode's S-parameters are high and the non-target mode coupling is low, it indicates that the system possesses good transmission efficiency and mode selectivity. Measurement analysis under different distances and modal conditions verifies the transmission performance of the OAM beam and the system's stability. Furthermore, by comparing the differences in target and non-target mode parameters, crosstalk immunity can be assessed.

[0153] C. Consistency Verification of Stable Transmit / Receive Distance Based on Geometric Optics Empirical Model: After completing the above verification and port parameters...

[0154] After verification, based on the quasi-diffraction-free propagation characteristics of the Bessel-OAM beam, the stable transmission and reception distance of the Bessel-OAM beam was theoretically estimated, and the consistency between the theoretical results and the experimental test results was compared to verify the actual effective communication distance of the transmission and reception system. ,in, Indicates a stable transmission and reception distance. For the designed diffraction-free propagation distance of the Bessel beam, Let be the equivalent radius of the metasurface radiation aperture, and be the Bessel cone angle. These are empirical coefficients related to finite aperture cutoff, orbital angular momentum mode distribution, and transmitter-receiver mode matching conditions; empirical coefficients This is used to characterize the proportion of the practically stable, quasi-diffraction-free propagation range in the theoretical diffraction-free distance, where... In this embodiment By introducing empirical coefficients The study verified the consistency between the measured stable communication range and the theoretical geometric optical boundary, and determined the upper limit of the actual effective working distance of the Bessel-OAM link.

[0155] This invention combines spatial field distribution stability, end-to-end S-parameters, and geometric optics prediction results to comprehensively evaluate the performance of quasi-diffraction-free Bessel vortex beam links, addressing the lack of systematic transmission performance verification in existing technologies. Through field shape preservation, mode transmission efficiency and isolation performance, and consistency analysis of stable transmission and reception distances, the effectiveness of the system in quasi-diffraction-free transmission, mode preservation, and link communication is verified. This establishes a systematic performance evaluation method for Bessel-OAM wireless links, providing a basis for performance verification, parameter optimization, and engineering applications of related transceiver systems.

[0156] The technical effects of the present invention will be further illustrated below through simulation and its results:

[0157] Example 10: The dual-feed common-aperture quasi-diffraction-free Bessel vortex wave generation method, transceiver system, and link communication performance verification method are the same as in Examples 1-9.

[0158] Simulation conditions: The simulation software used was the commercial software HFSS; the aforementioned transmissive metasurfaces were set to consist of identical structures but different dimensions, arranged periodically along the x and y axes. It consists of a metasurface unit, with two horn antennas above the metasurface as feed sources. The two horn feed antennas are symmetrically distributed about the x-axis, and an observation surface is provided to observe the electric field distribution.

[0159] The metasurface unit consists of a dielectric substrate, split rings, and a metal polarization gate. The dielectric substrate is a cubic solid dielectric material, and the height of the dielectric substrate is... The range of values ​​is .

[0160] The polarization gate and the splitting ring are copper foils printed on the lower and middle surfaces of the dielectric substrate, respectively. The substrate is made of F4B material (ε=2.56, tanδ=0.0015), with a side length of... The height of the dielectric substrate .

[0161] The observation surfaces are planes perpendicular to and parallel to the metasurface, used to observe the electric field distribution and trends.

[0162] A standard vortex electromagnetic wave was introduced as a control. By comparing its electric field amplitude distribution, phase distribution, and OAM mode spectrum, the correctness of the vortex wave generation of the designed metasurface was verified.

[0163] Simulation content: For standard vortex electromagnetic waves, the feed 1 of the metasurface antenna designed in this invention is individually excited to generate a +1 mode Bessel vortex electromagnetic wave. The electric field distribution is observed on the designated observation surface, and the modal spectrum distribution is calculated from the extracted data. (See [link to simulation]). Figure 8 , Figure 8 This is the vortex electric field distribution and OAM mode spectrum obtained by individually exciting the feed source 1 of this invention.

[0164] Simulation results and analysis: Figure 8 (a) shows the electric field amplitude distribution. A clear hollow ring structure can be observed. The electric field intensity in the central region is close to zero, exhibiting typical vortex wave amplitude characteristics. Figure 8 (b) shows the electric field phase distribution, with the phase exhibiting a continuous spiral change along the azimuth direction, consistent with the phase characteristics of a +1 mode vortex electromagnetic wave. Comparison with the amplitude and phase distribution of a standard +1 mode vortex wave reveals that the electromagnetic wave generated by this invention exhibits a high degree of consistency with the theoretical model in terms of spatial distribution characteristics, verifying the effectiveness of the designed metasurface in controlling the phase of electromagnetic waves. OAM modal spectrum analysis was performed on the simulation results, such as... Figure 8 As shown in (c), it can be seen that the +1 mode accounts for 98%, which is much higher than other mode components, indicating that the generated vortex wave has high mode purity and stray modes are effectively suppressed. Figure 8 (d) is a schematic diagram of the electric field propagation process. As can be seen from the figure, the beam maintains a relatively stable lateral distribution shape during propagation, with minimal diffusion, demonstrating good quasi-diffraction-free characteristics. This indicates that the metasurface can not only effectively generate specific OAM modes but also possesses excellent beam manipulation capabilities.

[0165] Example 11: The dual-feed common-aperture quasi-diffraction-free Bessel vortex wave generation method, transceiver system, and link communication performance verification method are the same as in Examples 1-9. The simulation conditions are the same as in Example 10.

[0166] Simulation content: The feed 2 of the metasurface antenna designed in this invention is individually excited to generate a -1 mode Bessel vortex electromagnetic wave, and its electric field distribution is observed on the designated observation surface. Data is extracted to calculate the mode spectrum distribution. See [link to simulation]. Figure 9 , Figure 9 These are the vortex electric field distribution and OAM mode spectrum obtained by individually exciting feed 2.

[0167] Simulation results and analysis: Figure 9 (a) shows the electric field amplitude distribution. A clear hollow ring structure can be observed. The electric field intensity in the central region is close to zero, exhibiting typical vortex wave amplitude characteristics. Figure 9 (b) shows the electric field phase distribution, with the phase exhibiting a continuous spiral change along the azimuth direction, consistent with the phase characteristics of a -1 mode vortex electromagnetic wave. Comparison with the amplitude and phase distribution of a standard -1 mode vortex wave reveals that the electromagnetic wave generated by this invention exhibits a high degree of consistency with the theoretical model in terms of spatial distribution characteristics, verifying the effectiveness of the designed metasurface in controlling the phase of electromagnetic waves. OAM modal spectrum analysis was performed on the simulation results, such as... Figure 9 As shown in (c), it can be seen that the -1 mode accounts for 99%, which is much higher than other mode components, indicating that the generated vortex wave has high mode purity and stray modes are effectively suppressed. Figure 9 (d) is a schematic diagram of the electric field propagation process. As can be seen from the figure, the beam maintains a relatively stable lateral distribution shape during propagation, with minimal diffusion, demonstrating good quasi-diffraction-free characteristics. This indicates that the metasurface can not only effectively generate vortex waves of specific modes but also possesses excellent beam manipulation capabilities.

[0168] Example 12: The dual-feed common-aperture quasi-diffraction-free Bessel vortex wave generation method, transceiver system, and link communication performance verification method are the same as in Examples 1-9. The simulation conditions are the same as in Example 10.

[0169] Simulation content: Simultaneous excitation of feed 1 and feed 2 of the metasurface antenna designed in this invention to generate... Modal Bessel vortex electromagnetic waves were observed, and their electric field distribution was observed on a designated observation surface. Data was extracted to calculate the modal spectrum distribution. (See [reference]). Figure 10 , Figure 10 The diagram shows the vortex electric field distribution and OAM mode spectrum obtained by simultaneously exciting feed 1 and feed 2.

[0170] Simulation Results and Analysis: When two feed sources are simultaneously excited, the output electromagnetic field of the metasurface exhibits a superposition of +1 and −1 modes, as shown in the following figures. Figure 10 As shown. Figure 10(a) shows the electric field amplitude distribution. The electric field distribution exhibits obvious interference characteristics. The ring structure is distorted, and there are enhancement and weakening regions along a specific direction, indicating that spatial superposition and interference occur between different modes. Figure 10 (b) shows the electric field phase distribution. The phase distribution no longer exhibits a unidirectional spiral structure, but rather a symmetrically distributed phase distortion region, reflecting the characteristics of the superposition of +1 and −1 mode phases. This phase structure indicates the simultaneous presence of positive and negative topological charge components in the electromagnetic field. Further OAM mode spectrum analysis is performed, such as... Figure 10 As shown in (c), it can be seen that the +1 and −1 modes have a high proportion, at 47% and 52% respectively, and their strengths are similar. The proportion of other higher-order modes is relatively low, indicating that the structure can achieve effective reuse and coexistence of dual modes under doubly fed excitation. Figure 10 (d) shows the electric field propagation diagram. The mixed-mode beam can still maintain a relatively stable spatial structure distribution during propagation and exhibits obvious symmetry. Compared with the spiral propagation characteristics of a single mode, the field distribution formed after mode superposition is more balanced, demonstrating good propagation stability under dual-mode multiplexing conditions.

[0171] Example 13: The dual-feed common-aperture quasi-diffraction-free Bessel vortex wave generation method, transceiver system, and link communication performance verification method are the same as in Examples 1-9. The simulation conditions are the same as in Example 10.

[0172] Simulation content: Simultaneous excitation of feed 1 and feed 2 of the metasurface antenna designed in this invention to generate... Modal Bessel vortex electromagnetic waves further alter the spacing between the transmitting and receiving antennas. Extract the data from the transmitter to the receiver every 100mm from the transmit and receive antenna ports. For the parameters and their changing trends, see 11. Figure 11 It is a graph showing how the S-parameters change with the transmission distance in the transmit / receive link.

[0173] Simulation Results and Analysis: From Figure 11 As can be seen from this, within a certain propagation range, the distance between the transmitting and receiving horns of the corresponding mode... The low attenuation rate indicates that the Bessel vortex wave constructed in this invention exhibits good energy preservation characteristics and quasi-diffraction-free propagation behavior in a matched mode link; while the gradual decrease in the curve with increasing propagation distance reflects the natural cumulative trend of link transmission loss. (The text also mentions different modes, but this seems unrelated to the previous sentences and may be a separate point.) The curve remains at a low level overall, indicating that the isolation of non-corresponding mode links is good, which can effectively suppress inter-mode crosstalk and ensure the independence and reliability of multimode Bessel vortex waves under common aperture transmission conditions.

[0174] Example 14: The dual-feed common-aperture quasi-diffraction-free Bessel vortex wave generation method, transceiver system, and link communication performance verification method are the same as in Examples 1-9. The simulation conditions are the same as in Example 10.

[0175] Simulation content: Under the above conditions, feed 1 and feed 2 of the metasurface antenna designed in this invention are simultaneously excited to generate... The amplitude variation of the electric field in the modal Bessel vortex electromagnetic wave is sampled and measured along the main propagation axis of the beam to obtain the curve (see [reference]). Figure 12 As shown, Figure 12 This is a diagram showing the electric field amplitude distribution along the propagation direction of the target Bessel vortex beam.

[0176] Simulation Results and Analysis: From Figure 12 As can be seen, the electric field intensity of the Bessel vortex wave is high near the transmitting end, and a clear main lobe peak can be observed. As the propagation distance increases, the electric field amplitude gradually decreases, but the rate of decrease is relatively slow, indicating that the beam maintains good energy concentration and spatial structure stability during propagation.

[0177] Example 15: The dual-feed common-aperture quasi-diffraction-free Bessel vortex wave generation method, transceiver system, and link communication performance verification method are the same as in Examples 1-9. Simulation conditions are the same as in Example 10.

[0178] Simulation content, Simulation 6: Under the above conditions, the amplitude variation curve of the sampled electric field is analyzed using a matching receiver method. The curve showing the variation of the matching amplitude with the transmission / reception distance is shown below. Figure 13 , Figure 13 This is a graph showing the correlation calculation results of the electric field distribution of the transmitting and receiving antennas at different transmitting and receiving distances.

[0179] Simulation results and analysis: Figure 13 It is evident that, within a certain propagation range, the matching reception amplitude between the transmitting and receiving horns of the corresponding mode is relatively high, and... The diffraction-free ranges determined in the parameters are basically consistent, indicating that the Bessel vortex wave of the present invention has good energy preservation characteristics and quasi-diffraction-free propagation behavior in the matched mode link.

[0180] In summary, this invention presents a dual-feed, common-aperture quasi-diffraction-free Bessel vortex wave generation method and transceiver system. It solves the problems of existing metasurface antennas in Bessel vortex beam manipulation and transmission, such as limited generation methods, insufficient amplitude and phase control capabilities, incomplete transceiver links, and a lack of effective performance evaluation. The generation method of this invention includes: feed configuration and mode parameter setting; joint solution of vortex phase and Bessel phase; joint amplitude and phase target field construction; metasurface element parameter setting based on PCB technology; and selective excitation of the target beam by multiple feeds. The transceiver system of this invention is sequentially connected to an active deployment module, a target beam construction module, an element parameter mapping module, a metasurface array construction module, a beam generation module, and a transceiver link measurement module. The verification methods of this invention include: beam propagation stability verification based on discrete spatial field distribution; transmission stability and modal isolation performance verification based on end-to-end S-parameters; and stable transmission and reception distance consistency verification based on a geometric optics empirical model.

[0181] This invention belongs to the field of electromagnetic beam manipulation and wireless communication technology, and relates to a method and transceiver system for generating quasi-diffraction-free Bessel vortex waves using a dual-feed, common-aperture system. It aims to solve problems in existing technologies such as easy beam diffusion, difficulty in amplitude and phase co-control, complex engineering implementation, and incomplete system-level transceiver verification. The transmissive metasurface antenna designed in this invention achieves efficient generation, manipulation, and stable transmission of quasi-diffraction-free Bessel vortex beams through a dual-feed structure. The two feeds can excite Bessel vortex modes of different orders, enabling flexible switching between single-mode and mixed-mode operation. Verified through a symmetrical transceiver link, the generated beam exhibits quasi-diffraction-free characteristics, stable long-distance transmission, and low inter-mode coupling within a certain propagation distance. It demonstrates good energy concentration, structural stability, and modal isolation, effectively suppressing inter-mode crosstalk. This constitutes a complete technical closed loop from beam design and generation to system implementation and performance verification, suitable for MIMO multi-antenna wireless transmission scenarios, supporting multi-mode parallel transmission, beam-oriented coverage, and robust communication in complex electromagnetic environments.

Claims

1. A method for generating quasi-diffraction-free Bessel vortex waves with dual feed sources and common aperture, characterized in that, The steps include the following: The transmitting antenna used to generate the quasi-diffraction-free Bessel vortex beam Bessel–OAM includes a transmissive metasurface and a feed horn antenna. The feed horn antenna provides excitation to the metasurface, which modulates the phase and amplitude of the incident wave and radiates the target Bessel vortex beam. (1) Feed configuration and mode parameter setting: The feed is arranged above the transmissive metasurface antenna. Each horn antenna feed is optimized and experimentally calibrated by jointly optimizing the spatial position parameters of the feed, including the relative offset from the aperture center, feed spacing, installation height and pointing angle, and the orbital angular momentum mode order and excitation configuration corresponding to each feed are determined accordingly. (2) Cooperative solution of vortex phase and Bessel phase: Based on the feed excitation distribution and target beam parameters, the compensation phase distribution for forming Bessel vortex beam is jointly solved on the aperture plane. The cooperative solution is constrained by the phase consistency within the same aperture. On the one hand, it ensures that the aperture phase has the spiral phase structure required by the vortex beam, so that the radiation field forms a clear topological charge and phase singularity characteristics. On the other hand, it ensures that the aperture phase meets the Bessel phase characteristics required for quasi-diffraction-free propagation, so that the energy maintains the main lobe shape stability in the specified propagation range in the form of conical wave synthesis, and forms the total aperture phase distribution that meets the requirements of the target Bessel vortex beam. (3) Construction of the combined amplitude and phase target field: Based on the obtained total aperture phase distribution, the aperture amplitude distribution design is introduced to construct a target aperture field that simultaneously includes amplitude and phase terms. The amplitude distribution is determined based on the modal composition of the target Bessel vortex beam and the amplitude weight of each mode. The amplitude-phase distribution establishes a joint mapping relationship between geometric parameters and transmission response, which is used to achieve joint control of the energy ring structure and sidelobe level on the aperture plane, and is uniformly combined with the total aperture phase distribution on the aperture plane. (4) Setting of metasurface unit parameters based on PCB process: according to the target aperture field The parameters of each unit on the array are inverted and mapped, and the structural parameters of the unit are designed using PCB technology. This enables the unit to jointly control the phase and amplitude of the transmitted wave within the operating frequency band. The parameter inversion and mapping includes establishing the correspondence between structural parameters and amplitude and phase responses based on the unit electromagnetic response database or full-wave simulation results, completing the determination of unit parameters and constructing the antenna array. (5) Selective excitation of multiple feed sources to generate target beam: By using the aforementioned Each feed source is excited individually or simultaneously to generate a single-mode or multi-mode quasi-diffraction-free Bessel vortex wave within the same physical aperture. The selective excitation is the switching of each feed source. By selecting the individual or combined activation of different feed sources, the target mode can be selected and the single-mode and multi-mode radiation states can be switched to generate a Bessel vortex beam that meets the set parameters.

2. The method for generating quasi-diffraction-free Bessel vortex waves with dual feed sources and common aperture as described in claim 1, characterized in that, Step 1, which describes the feed configuration and modal parameter setting, includes the following steps: 1.1 Symmetrical arrangement of feed sources: The number of feed sources is set to... ,in ,when These are named the first feed and the second feed, respectively. The two feeds are symmetrically arranged on both sides of the transmissive metasurface along the X-axis, each at a distance R from the center point O of the metasurface, and at an angle of [missing information - likely a specific angle]. ; 1.2 Feed Orbital Angular Momentum Mode Setting: Based on the target orbital angular momentum mode of the quasi-diffraction-free Bessel vortex wave to be generated, the orbital angular momentum mode orders of the first and second feeds are determined respectively; let the order of the first feed be... The orbital angular momentum modes of the feed are of ,in , The feed sources are numbered, and the modal orders of different feed sources are different.

3. The method for generating quasi-diffraction-free Bessel vortex waves with dual feed sources and common aperture as described in claim 1, characterized in that, Step 2, which involves the joint solution of the vortex phase and the Bessel phase, includes the following steps: 2.1 Construction of the target radiation field expression: Calculate the required compensation phase on the metasurface aperture surface and determine the target beam expression. The formula is as follows: ； in, Indicates the amplitude distribution of the target field. This represents the AND and phase distribution of the target field. These correspond to the four types of compensation phases required from the feed horn to the metasurface aperture surface, among which For feed source phase compensation, To converge and compensate for the phase, To compensate for phase in Bessel beam modulation, The vortex phase can be obtained through specific calculations; 2.2 Feed Compensation Phase Calculation: The formula for calculating the feed compensation phase in the target radiation field expression is as follows: ； in, This represents the position coordinates of the metasurface element. Indicates the first The location coordinates of the feed source Indicates wavelength; 2.3 Convergence Compensation Phase Calculation: The formula for calculating the convergence compensation phase in the target radiation field expression is as follows: ； in, Indicates wave number; 2.4 Bessel Beam Modulation and Phase Compensation Calculation: The formula for calculating the Bessel beam modulation compensation phase in the target radiation field expression is as follows: ； in, Indicates the cone angle used to generate the Bessel beam; 2.5 Vortex Phase Calculation: The formula for calculating the vortex phase in the target radiation field expression is: ； in, This indicates the order of the OAM modes corresponding to the two feed sources; The above steps use the target radiation field expression as a unified framework, and simultaneously incorporate feed compensation, convergence compensation, Bessel control compensation and vortex phase into the total aperture phase. Each phase term is calculated separately and synthesized into the compensation phase distribution required for the aperture, realizing the coordinated design of Bessel phase characteristics and vortex phase structure, so that the same aperture can simultaneously meet the requirements of quasi-diffraction-free propagation and vortex beam.

4. The method for generating quasi-diffraction-free Bessel vortex waves with dual feed sources and common aperture as described in claim 1, characterized in that, Step 3, the construction of the combined amplitude and phase target field, includes the following steps: 3.1 Amplitude and Total Compensation Phase Acquisition: Based on Obtain its amplitude distribution With total compensation phase ; 3.2 Unit Design and Parameter Scanning: A combination of split-ring and polarization grating units is used, which has the characteristic of separable amplitude and phase control. The transmission phase is mainly determined by the splitting angle of the split-ring. The transmission amplitude is controlled by the rotation angle of the splitting ring. The control system performs parameter scanning on the key geometric parameters of the element and obtains a response database between the splitting angle, rotation angle and the element's transmission phase and transmission amplitude through full-wave simulation. 3.3 Establishing a joint mapping between geometric parameters and transmission response: Establishing a one-to-one mapping relationship between two types of geometric parameters and their corresponding transmission responses: ； 3.4 Inverse calculation of geometric parameters of the target field: Using this mapping relationship, the required phase and amplitude of each element on the target aperture surface are inversely calculated into the corresponding splitting angle. With rotation angle .

5. The method for generating quasi-diffraction-free Bessel vortex waves with dual feed sources and common aperture as described in claim 1, characterized in that, Step 4, which describes the parameter setting for the metasurface unit based on PCB technology, includes the following steps: 4.1 Establishment of array surface model: Using the XOY plane as the array surface, establish a square transmissive metasurface array centered on the origin of the coordinate system, with the array size set to 48×48 metasurface units; 4.2 Element parameter mapping and arrangement: Based on the target aperture field mapping results obtained in step 3, determine the PCB element structure parameters corresponding to each element on the array surface, and assign values ​​point by point according to the array position to form the final transmissive metasurface array.

6. A dual-feed, common-aperture quasi-diffraction-free Bessel vortex wave antenna transceiver system, further constructing the antenna transceiver system according to the dual-feed, common-aperture quasi-diffraction-free Bessel vortex wave generation method described in claims 1-5, characterized in that... The system is sequentially connected to a feed deployment module, a target beam construction module, a unit parameter mapping module, a metasurface array construction module, a beam generation module, and a transceiver link measurement module. The system is used to realize the transceiver communication of the generated beam and to test and evaluate its actual link communication performance. The feed layout module is used to arrange multiple feeds symmetrically in pairs with the geometric center of the metasurface as a reference in a specific focal length plane above the transmissive metasurface. By precisely defining the coordinate position of each feed in three-dimensional space and the tilt angle relative to the normal of the metasurface, the spherical waves generated by each feed are irradiated onto the aperture surface with a specific incident wavefront, thereby realizing independent or combined excitation of different orbital angular momentum modes within the same physical aperture. The target beam construction module is used to calculate the compensation phase distribution required for the metasurface aperture surface based on the feed parameters and the Bessel-OAM parameters of the target Bessel vortex beam, and to generate the target beam expression. The compensation phase distribution includes feed illumination compensation, beam converging and shaping compensation, Bessel beam modulation compensation, and vortex phase terms, so that the total aperture phase simultaneously meets the requirements of quasi-diffraction-free propagation and vortex phase structure within the same framework. The unit parameter mapping module is used to determine the required unit response at each position of the aperture surface according to the target beam, and map the response to the geometric structure parameter distribution of the unit at each position, so that the unit parameter distribution corresponds one-to-one with the target aperture field, so as to meet the requirement of the metasurface to achieve joint control of the phase and amplitude of the transmitted wave in the working frequency band. The metasurface array construction module is used to arrange and assign values ​​to metasurface units point by point on the XOY surface according to the obtained geometric parameters, so as to complete the construction of a transmissive metasurface array, making the resulting array meet the requirements of processing consistency and assembly feasibility, and can be directly used for beam generation. The beam generation module is used to excite multiple feed sources individually or simultaneously, and to generate single-mode or mixed-mode Bessel vortex beams within the same physical aperture by selectively activating the feed sources, thereby realizing the switchable and combinable generation of beam modes. The transceiver link measurement module is used to construct a symmetrical receiving end within the propagation region between transceiver systems and along the propagation axis. Establish a test link by adjusting the distance between the transmitter and receiver. The propagation stability, energy concentration, and link transmission characteristics of the beam were observed to verify the beam-keeping capability in the quasi-diffraction-free region.

7. The dual-feed common-aperture quasi-diffraction-free Bessel vortex wave wireless transceiver system according to claim 6, characterized in that, The target beamforming module is sequentially connected to a basic phase generation submodule, a Bessel vortex phase generation submodule, and a target phase forming submodule, from phase generation to phase synthesis. The basic phase generation submodule is used to calculate the propagation path difference generated by electromagnetic waves propagating from the feed source to each point on the metasurface based on the three-dimensional spatial coordinates of each feed source and the geometric position of each sampling unit in the metasurface aperture plane; by extracting the phase offset corresponding to each path length, a basic compensation phase distribution is generated to compensate for the wavefront distortion of the incident spherical wave. The Bessel vortex phase generation submodule is used to generate a conical wave with a convergent-axis characteristic based on a preset Bessel cone angle parameter, and to generate a spiral phase distribution that varies linearly with the spatial azimuth angle by combining a preset orbital angular momentum topological charge number. The submodule determines the physical basis for the beam to have quasi-diffraction-free propagation capability and a rotating phase structure by synthesizing the above two phase terms. The target phase construction submodule is used to spatially linearly superimpose the basic compensation phase, Bessel control phase, and spiral phase term on the metasurface aperture surface. By performing phase folding and quantization on the superimposed continuous phase, it is limited to a single periodic phase range to construct the final design phase spectrum. Then, combined with the full-wave simulation electromagnetic response database of the metasurface unit, the target phase at each grid point coordinate is matched and optimized with the geometric structural parameters of the unit to generate a geometric parameter distribution file that guides the arrangement of the metasurface physical array.

8. The dual-feed common-aperture quasi-diffraction-free Bessel vortex wave wireless transceiver system according to claim 6, characterized in that, The transceiver link measurement module, from data measurement to data analysis, is sequentially connected to a receiver construction submodule, a propagation sampling submodule, a link power measurement module, and a link performance analysis module. The receiver construction submodule is used to construct a receiving antenna structure that is mirror-symmetrical to the transmitter. The spacing distance D between the transmitter and receiver metasurfaces is mirror-symmetrical to the transmitter metasurface in terms of aperture size, element arrangement and feed arrangement. The polarization state and spatial pointing of the receiving feed are adjusted to establish an end-to-end wireless communication physical link that matches the transmitter mode. The propagation sampling submodule is used to collect electric field propagation data. Multiple detection planes are uniformly set along the propagation axis within a quasi-diffraction-free region between the transmitting and receiving structures. The spatial electric field amplitude vector at different locations is extracted using a sampling point and a near-field or far-field scanning probe. By comparing the cross-sectional characteristics of the field pattern at different propagation distances, the beam's ability to maintain its structural shape during propagation is quantitatively evaluated. The link power measurement submodule is used to obtain scattering parameters between the transmit and receive antenna ports. and power transfer coefficient, recorded Parameters vary with transmit / receive interval The variation curves of the target mode are analyzed to determine the energy concentration of the target mode and the power coupling degree between different modes. The link performance analysis submodule is used to integrate spatial sampling data with port data. Parameters, based on discrete correlation models, modal isolation indices, and empirical models based on geometric optics, are used to assess beam structure stability, transmission performance, and stable transmit / receive distance. Consistency verification.

9. A method for verifying the communication performance of a quasi-diffraction-free Bessel vortex beam link, characterized in that, Based on the dual-feed common-aperture quasi-diffraction-free Bessel vortex wave wireless transceiver system, specifically, the link performance analysis submodule in the transceiver link measurement module verifies the quasi-diffraction transmission performance. This includes verification of beam propagation stability based on discrete spatial field distribution, verification of transmission stability and modal isolation performance based on end-to-end S-parameters, and verification of stable transmit / receive distance consistency based on a geometric optics empirical model. The steps include: A. Beam propagation stability verification based on discrete spatial field distribution: along the propagation region between the transmitting and receiving systems. Uniformly arranged along the propagation axis The electric field amplitude at different positions along the propagation axis is extracted from a sampling point. As sampled data, the field shape preservation is calculated using a discrete correlation model: ； in The correlation coefficient represents the field shape preservation. The higher the value, the smaller the structural attenuation of the OAM beam. The better the mode retention, the higher the value of the field pattern retention correlation coefficient, which verifies the structural stability of the Bessel-OAM beam during free space propagation and provides a beam propagation stability index based on discrete spatial field distribution for link evaluation. B. Performance verification of transmission stability and modal isolation based on end-to-end S-parameters: under the operating conditions of the transmit and receive antennas In this state, the distance between the transmitting and receiving antennas is Extract the scattering parameters from the transmitter to the receiver. The actual availability of the link is evaluated by analyzing the power transmission characteristics between ports; since the transceiver system uses an antenna structure capable of distinguishing different orbital angular momentum modes, the measured... The parameters not only reflect the overall power transmission level, but also characterize the transmit / receive matching degree and mode isolation performance under specific OAM modes; by adjusting the spacing between the transmitter and receiver... Record the ports under the corresponding conditions. Parameter changes, when the target mode corresponds to When the value is high and the coupling of non-target modes is low, it indicates that the transceiver system has good mode selectivity, high transceiver efficiency and good mode isolation at this distance. By analyzing the end-to-end S-parameters of the target mode, the transmission stability and mode isolation performance of the transceiver system at the corresponding distance are verified. C. Verification of Stable Transmit / Receive Range Consistency Based on Geometric Optics Empirical Model: Based on Bessel Vortex Waves The stable transmission and reception distance of the Bessel-OAM beam, based on its quasi-diffraction-free propagation characteristics, is estimated using the following empirical model: ； in, Indicates a stable transmission and reception distance. For the designed diffraction-free propagation distance of the Bessel beam, Let be the equivalent radius of the metasurface radiation aperture, and be the Bessel cone angle. These are empirical coefficients related to finite aperture cutoff, orbital angular momentum mode distribution, and transmit / receive mode matching conditions; the empirical coefficients This is used to characterize the proportion of the practically stable, quasi-diffraction-free propagation range in the theoretical diffraction-free distance, where... By introducing empirical coefficients The study verified the consistency between the measured stable communication range and the theoretical geometric optical boundary, and determined the upper limit of the actual effective working distance of the Bessel-OAM link.

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