Divergence angle regulation and control method and vortex beam radar

Abstract

The invention relates to a divergence angle regulation and control method and a vortex beam radar, and relates to the technical field of vortex beam radars. The method comprises the following steps: acquiring a target divergence angle and radar basic parameters; determining a divergence angle control phase based on the target divergence angle and the radar basic parameters; determining a feed source compensation phase based on the distance from the metasurface unit to the feed source; determining a vortex phase based on the position of the metasurface unit; determining a total phase based on the divergence angle control phase, the feed source compensation phase and the vortex phase; and adjusting the unit structure of the corresponding metasurface unit based on the total phase. By loading the divergence angle control phase in the total phase, the beam main lobe divergence angles of different modes can be unified as the target divergence angle, so that the problem that the divergence angles of beams of different modes are different is solved, cooperative receiving of signals, mode decoupling and information reconstruction are facilitated, and the detection precision and the operating distance of the vortex beam radar are improved.

Description

Technical Field

[0001] This application relates to the field of vortex beam radar technology, and in particular to a divergence angle control method and a vortex beam radar. Background Technology

[0002] With the development of radar technology, vortex beam radar has emerged. Vortex beam radar can emit helical phase beams carrying orbital angular momentum (OAM). Its different modes of electromagnetic waves can provide a "fingerprint"-like identification dimension for target response, significantly improving the ability to distinguish and identify small targets, while also possessing excellent anti-jamming and low intercept characteristics. However, in traditional technologies, the beams emitted by vortex beam radars with different orbital angular momentum (OAM) modes have significantly different divergence angles. This inherent difference in beam divergence characteristics leads to inconsistent far-field wavefront distortion and energy distribution, posing significant challenges to coordinated signal reception, mode decoupling, and information reconstruction, severely limiting the radar's detection accuracy and operating range. Summary of the Invention

[0003] Therefore, it is necessary to provide a divergence angle control method and a vortex beam radar that can control the divergence angle of different mode beams to be the same, in order to address the above-mentioned technical problems.

[0004] In a first aspect, this application provides a divergence angle control method. Applied to a vortex beam radar, the vortex beam radar comprising multiple metasurface elements and a feed source, the method includes: acquiring a target divergence angle and fundamental radar parameters; wherein the fundamental radar parameters include wavenumber and element spacing; determining a divergence angle control phase based on the target divergence angle and the fundamental radar parameters; determining a feed source compensation phase based on the distance from the metasurface element to the feed source; determining a vortex phase based on the position of the metasurface element; determining a total phase based on the divergence angle control phase, the feed source compensation phase, and the vortex phase; and adjusting the element structure of the corresponding metasurface element based on the total phase.

[0005] In one embodiment, the step of determining the divergence angle control phase based on the target divergence angle and the radar fundamental parameters includes: using the following formula: Calculate the divergence angle control phase; wherein, The divergence angle controls the phase, k0 is the wavenumber, and d is the cell spacing. The target divergence angle is given.

[0006] In one embodiment, the step of determining the feed source compensation phase based on the distance from the metasurface unit to the feed source includes: the feed source compensation phase is: Where k0 is the wave number, The radial position of the metasurface unit in the array. The axial distance of the feed source.

[0007] In one embodiment, the step of determining the vortex phase based on the position of the metasurface unit includes: the vortex phase being: Where l is the preset modal order, Let be the angular coordinates of the metasurface unit.

[0008] Secondly, this application also provides a vortex beam radar, including multiple metasurface elements and a feed source, wherein the element structure of each metasurface element is obtained by adjusting the divergence angle control method described in the first aspect embodiment above.

[0009] In one embodiment, the metasurface unit includes a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, and a ground layer stacked sequentially. The first metal layer includes a Jerusalem cross structure, and the second metal layer includes a cross structure.

[0010] In one embodiment, the first metal layer is further provided with a metal circular hole, and the Jerusalem cross structure is disposed in the metal circular hole.

[0011] In one embodiment, the second metal layer further includes a plurality of radiating patches disposed at the ends of the cross structure.

[0012] In one embodiment, the surface of the metasurface unit is set to be square, and a plurality of the metasurface units form a square array.

[0013] In one embodiment, the metasurface unit has a length and width of 10 mm and a height of 2 mm; the edge of the square array is composed of 25 of the metasurface units, and the square array has a length and width of 250 mm and a height of 2 mm.

[0014] The aforementioned divergence angle control method and vortex beam radar adjust the unit structure of the corresponding metasurface unit by using the divergence angle control phase, feed compensation phase, and total phase determined by the vortex phase. The divergence angle control phase is determined by the target divergence angle and the radar's basic parameters. By loading this phase term into the total phase, the divergence angles of the main lobe of different modes of beams can be unified to the target divergence angle, thereby solving the problem of different divergence angles of different modes of beams. This facilitates coordinated signal reception, mode decoupling, and information reconstruction, and improves the detection accuracy and range of the vortex beam radar. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the divergence angle control method in one embodiment;

[0016] Figure 2 This is a schematic diagram of a metasurface unit in one embodiment;

[0017] Figure 3 for Figure 2 A schematic diagram of the first metal layer in the middle;

[0018] Figure 4 for Figure 2 A schematic diagram of the second metal layer in the middle;

[0019] Figure 5 for Figure 2 A schematic diagram of the layer structure of the surface unit of the Chinese Super League;

[0020] Figure 6 This is a schematic diagram of the inter-frequency crosstalk characteristics of a metasurface unit in one embodiment;

[0021] Figure 7 The image shows the reflection amplitude and phase curves of the metasurface unit with different structural sizes in one embodiment.

[0022] Figure 8 This is a schematic diagram of a vortex beam radar in one embodiment;

[0023] Figure 9 This is a schematic diagram of the phase distribution corresponding to each metasurface unit in one embodiment;

[0024] Figure 10 This is a schematic diagram of the simulated electric field distribution in one embodiment;

[0025] Figure 11 This is a schematic diagram illustrating the simulated characteristics of a vortex beam in one embodiment.

[0026] Explanation of reference numerals in the attached figures:

[0027] First metal layer 210, first dielectric layer 220, second metal layer 230, second dielectric layer 240, ground layer 250, Jerusalem cross structure 211, metal circular hole 212, cross structure 231, radiation patch 232. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0029] The divergence angle control method provided in this application is applied to the radar structure design of vortex beam radar. The vortex beam radar is a reflective metasurface vortex radar, comprising multiple metasurface elements and a feed source. The multiple metasurface elements form a metasurface, serving as a carrier for electromagnetic wave radiation / reception. During the transmission phase, the incident wave emitted by the feed source reaches the metasurface element. The metasurface element generates a preset phase delay through its own element structure, thereby achieving built-in phase control. The phase-controlled electromagnetic wave is reflected by a metal base plate, and the metasurface element radiates it into space. The wavelets radiated by each metasurface element coherently superimpose in the far field, forming an L-order vortex beam with a spiral phase wavefront, a central phase singularity, and a ring-shaped energy distribution. During the reception phase, the echo of the vortex beam reflected by the target illuminates the metasurface. The metasurface element reverses the phase control, converging the echo to the feed source. The feed source receives the converged signal and transmits it to the receiver. After demodulation, filtering, and amplification, the signal processing unit can extract the target information.

[0030] In one embodiment, such as Figure 1 As shown, a method for controlling the divergence angle is provided, including but not limited to the following steps:

[0031] Step S110: Obtain the target divergence angle and basic radar parameters.

[0032] Specifically, when adjusting the divergence angle, the target divergence angle and basic radar parameters are first obtained. The target divergence angle is the desired divergence angle of the vortex beam output by the vortex beam radar, which can be set according to specific usage requirements. A smaller divergence angle results in a more focused beam, higher energy density, and is more suitable for long-range precision detection; a larger divergence angle provides a wider coverage area and is more suitable for short-range multi-target search. Among the basic radar parameters, the wave number... ,in, The wavelength is denoted by d; the cell spacing d is the center-to-center distance between adjacent metasurface cells.

[0033] Step S120: Determine the divergence angle control phase based on the target divergence angle and radar basic parameters.

[0034] Specifically, after obtaining the target divergence angle and basic radar parameters, the divergence angle control phase is determined based on these parameters. In a metasurface element array, electromagnetic wave propagation generates a spatial phase difference. Without intervention, the spatial phase difference between different mode OAM beams will be different, resulting in divergence angle differences. By determining the divergence angle control phase, this spatial phase difference can be counteracted, allowing all mode beams to form an equiphase surface in the target direction, thereby locking a unified divergence angle.

[0035] Step S130: Determine the feed compensation phase based on the distance from the metasurface unit to the feed source.

[0036] Specifically, since the distance from the feed source to each metasurface unit is different, the time / phase of the electromagnetic wave arriving at each metasurface unit is also different. In order to eliminate this inherent error, the feed source compensation phase is determined according to the distance from the metasurface unit to the feed source, so that the incident wave phase of all metasurface units is consistent.

[0037] Step S140: Determine the vortex phase based on the position of the metasurface unit.

[0038] Specifically, in order to transform an ordinary plane wave into a vortex wave with a helical phase, it is also necessary to endow the beam trajectory angular momentum (OAM) characteristic. The vortex phase is directly related to the position (such as angular position) of the metasurface element, and the vortex phase can be determined based on the position of the metasurface element.

[0039] Step S150: Determine the total phase based on the divergence angle control phase, the feed compensation phase, and the vortex phase.

[0040] Specifically, after determining the divergence angle control phase, feed compensation phase, and vortex phase, they are superimposed and summed to obtain the final total phase, which is the phase requirement of the corresponding metasurface unit.

[0041] Step S160: Adjust the unit structure of the corresponding metasurface unit based on the total phase.

[0042] Specifically, after determining the total phase of the metasurface unit, the corresponding metasurface unit can provide a response to that total phase by adjusting its unit structure. That is, after the electromagnetic wave passes through the metasurface unit, the phase shift equals the total phase. Adjusting the unit structure of the metasurface unit can be done by adjusting parameters such as the shape or size of the metal patch, and the material or thickness of the dielectric substrate.

[0043] The above-mentioned divergence angle control method adjusts the unit structure of the corresponding metasurface unit by using the total phase determined by the divergence angle control phase, the feed compensation phase, and the vortex phase. The divergence angle control phase is determined by the target divergence angle and the radar's basic parameters. By loading this phase term into the total phase, the divergence angle of the main lobe of different modes of beams can be unified to the target divergence angle, thereby solving the problem of different divergence angles of different modes of beams. This facilitates coordinated signal reception, mode decoupling, and information reconstruction, and improves the detection accuracy and range of the vortex beam radar.

[0044] In one embodiment, step S120, which involves determining the divergence angle control phase based on the target divergence angle and the radar's fundamental parameters, includes: using the following formula: Calculate the divergence angle control phase, where, The divergence angle controls the phase, k0 is the wavenumber, and d is the element spacing. The target divergence angle.

[0045] In one embodiment, step S130, the step of determining the feed compensation phase based on the distance from the metasurface unit to the feed source, includes: the feed compensation phase is: Where k0 is the wave number, The radial position of the metasurface element in the array (metasurface cylindrical coordinate system). The axial distance to the feed source is typically a fixed value. In this embodiment, the slant distance from the metasurface unit to the feed source is calculated, and after being converted into a phase difference, the corresponding feed source compensation phase is obtained.

[0046] In one embodiment, step S140, the step of determining the vortex phase based on the position of the metasurface unit, includes: the vortex phase is: Where l is the preset mode order, i.e., the OAM mode order, such as l=1, 2, 3, etc., and different l corresponds to different spiral periods. Here, represents the angular coordinates of the metasurface element in the metasurface cylindrical coordinate system.

[0047] The principle of the divergence angle control method of this application is described in detail below. This application integrates the phased array principle and metasurface phase control technology, dividing the metasurface into an infinitesimal linear array and forming a phase gradient, thereby constructing an equiphase surface for beam control.

[0048] A uniform linear array uses identical radiating elements arranged at equal intervals, and is a linear array with a locally uniform current distribution. The radiation pattern of a uniform linear array using N elements spaced by d. This can be expressed as:

[0049] (1)

[0050] (2)

[0051] in, It is the core variable that determines the shape of the array factor. , Represents spatial phase difference, while It is the excitation phase difference.

[0052] when At that time, the spatial phase difference and the excitation phase difference cancel each other out in the direction of the main lobe. An equiphase surface is formed at this point. Using L'Hôpital's rule, it can be known that... This is when the maximum value is reached, i.e. The maximum direction of the linear matrix.

[0053] (3)

[0054] From equation (2), we can see that and Closely related, can be changed This is used to change the maximum radiation direction and achieve beam control.

[0055] To simplify the theoretical derivation, assuming a plane wave is incident perpendicularly on the metasurface, the aperture electric field distribution can be described as follows:

[0056] (4)

[0057] in, Let l be the coordinates of the source point in the metasurface cylindrical coordinate system, and l be the mode. The phase distribution of the electric field is the amplitude distribution function, and the phase distribution of the electric field includes the vortex phase. and excitation phase The excitation phase is used to control the divergence angle. Since the amplitude and phase distributions on the metasurface are deterministic, the radiation field generated by the metasurface can be calculated using the Huygens-Fresnel principle:

[0058] (5)

[0059] Where k0 is the free space wavenumber, and C equals This application treats metallic materials as perfect electrical conductors and models the metasurface structure as a reflective metasurface with an infinitely large grounded metal plate. Therefore, the amplitude function can be approximated as a constant, while the effect of the tilt factor C can be neglected. Let... This represents the result of the integral variable, at which point the radiation mode... It can be represented as:

[0060] (6)

[0061] In fact, infinitesimal sector region This can be equivalent to the aforementioned uniform linear array. By establishing the correlation between the radiation pattern and the linear array, the goal of flexibly designing the far-field radiation pattern by adjusting the phase of the linear array can be achieved. Therefore, in the design of metasurface antennas, formula (3) can be applied to the phase design of metasurface OAM, and... As the divergence angle control phase, a feed compensation phase is added. and vortex phase Finally, the total phase required for each metasurface unit is obtained. :

[0062] (7)

[0063] In the design, the target divergence angle can be... The divergence angle can be set arbitrarily. However, divergence angle control under finite frontiers has a convergence limit: at low... Under certain conditions, the actual divergence angle will remain constant due to the minimum divergence angle. This limit stems from the energy requirements of vortex waves and the infinite energy characteristics of non-diffractive beams. Therefore, metasurface design requires a reasonable configuration of vortex modes and array dimensions.

[0064] In one embodiment, this application also proposes a vortex beam radar, including multiple metasurface elements and a feed source, wherein the element structure of each metasurface element is obtained by adjusting the divergence angle control method in the above embodiment.

[0065] In one embodiment, such as Figures 2 to 5 As shown, the metasurface unit includes a first metal layer 210, a first dielectric layer 220, a second metal layer 230, a second dielectric layer 240 and a ground layer 250 stacked in sequence. The first metal layer 210 includes a Jerusalem cross structure 211 and the second metal layer 230 includes a cross structure 231.

[0066] Specifically, the Jerusalem cross structure 211 in the first metal layer 210 increases the electromagnetic coupling path through the short arms at both ends of the horizontal arm, extending the phase coverage to 360° and resulting in a smoother phase response (reducing mode aliasing). The length and width of its short arms can be independently adjusted to flexibly adapt to different frequency bands. The cross structure 231 in the second metal layer 230 typically has a phase coverage range of 180° to 270°. It is used to form a dual-frequency division with the first metal layer 210, avoiding phase response overlap between the two frequency bands, improving frequency isolation, and reducing interference. The ground layer 250 serves as a reflective surface and provides a stable reference potential, ensuring the consistency of the electromagnetic response of the two metal layers. The ground layer 250 can be a complete metal layer, a partially perforated metal layer, or a mesh-like metal layer. The first metal layer 210 and the second metal layer 230 can be made of highly conductive metals, such as copper, aluminum, gold, or silver, while the ground layer 250 can be made of copper, aluminum-magnesium alloy, etc. The first dielectric layer 220 and the second dielectric layer 240 serve as isolation and support to ensure the structural stability of the metasurface unit. The first dielectric layer 220 and the second dielectric layer 240 can be made of polytetrafluoroethylene composite material (F4B), ceramic matrix composite material (Al2O3 ceramic), polyimide (PI), etc.

[0067] In one embodiment, such as Figure 3 As shown, a metal circular hole 212 is also provided on the first metal layer 210, and the Jerusalem cross structure 211 is disposed in the metal circular hole 212. Specifically, in this embodiment, by providing the metal circular hole 212, interlayer interference can be suppressed simultaneously and the reflection efficiency can be improved.

[0068] In one embodiment, such as Figure 4As shown, the second metal layer 230 also includes a plurality of radiating patches 232, which are disposed at the ends of the cross structure 231. Specifically, in this embodiment, by disposing of radiating patches 232 near the ends of the cross structure 231, a parasitic damping structure is formed, thereby enhancing coupling and achieving 360° phase coverage.

[0069] In one embodiment, the surface of the metasurface unit is set as a square, and multiple metasurface units form a square array. Specifically, the x-axis and y-axis symmetry of the square units are completely consistent, ensuring that the electromagnetic response (reflection amplitude, phase shift) of the metasurface unit is completely equal when x-polarized and y-polarized electromagnetic waves are incident. Furthermore, the central symmetry of the square allows for a more uniform distribution of vortex phase on the surface of the metasurface unit, avoiding phase abrupt changes in edge regions (such as current concentration along the long edge of a rectangular unit, leading to phase distortion), thereby achieving 360° full phase coverage. In some other embodiments, the surface of the metasurface unit can also be set as circular, rectangular, etc. In some embodiments, the length and width of the metasurface unit are both 10 mm, and the height is 2 mm; the edge of the square array is composed of 25 metasurface units, and the length and width of the square array are both 250 mm, and the height is 2 mm.

[0070] The following describes in detail, with a specific embodiment, a vortex beam radar obtained by adjusting the unit structure of the metasurface unit using the divergence angle control method of this application. The structure of the metasurface unit is configured as follows: Figure 2 The structure shown uses F4B material (dielectric constant 2.65, tangent loss 0.001) for the dielectric layer, and its fixed geometric parameters are shown in the table below:

[0071]

[0072] When adjusting the unit structure of the metasurface element, only the u of Jerusalem cross structure 211 and cross structure 231 is adjusted. x u y d x d y Adjustments were made. The performance of the metasurface unit cells was evaluated using full-wave simulation, such as... Figure 6 As shown in section (a), the analysis of interlayer crosstalk indicates that the length variation of the Jerusalem cross structure 211 has minimal impact on the phase of the second metal layer 230; similarly, as Figure 6 As shown in (b), the effect of the cross structure 231 on the phase of the first metal layer 210 is negligible. The rotationally symmetric design ensures completely consistent performance in the y-polarization direction, thus verifying the independence of dual-frequency operation. Figure 6As shown in (c) and (d), the polarization isolation characteristics can be verified by the current distribution under orthogonal wave excitation at 16 GHz and 8.5 GHz. The mutually orthogonal and isolated electric field distributions under x / y polarization wave incidence demonstrate the excellent polarization isolation performance of the metasurface unit. The metal strip surrounding the Jerusalem cross structure 211 enhances the coupling capability and phase coverage.

[0073] At the same time, such as Figure 7 Figures (a) and (b) show the relationship between amplitude and phase of co-polarized reflection at different sizes when an x-polarized wave is incident. Furthermore, Figure 7 (c) and (d) in the diagram indicate the selection of 8.5 GHz and 16 GHz as the operating center frequencies. This design achieves 360° full-phase coverage and high reflection efficiency while maintaining angle insensitivity. Compared to traditional frequency selective surface (FSS) loading designs, the low-profile configuration of this application not only facilitates array implementation but also possesses excellent frequency reuse and polarization reuse capabilities.

[0074] Using the aforementioned metasurface units employing frequency reuse and polarization reuse techniques, the top-level unit generates two vortex beams with different polarization states in the 6-11 GHz frequency band, while the bottom-level unit generates two vortex beams with similar polarization in the 14-18 GHz frequency band. By applying the beam divergence angle control method of this application, the divergence angle of the vortex beams in different modes is controlled, thereby achieving equal divergence angle generation of multimode vortex beams.

[0075] Specific examples, such as Figure 8 As shown, the fabricated reflective metasurface consists of 25×25 metasurface units with an aperture size of 250×250 mm², and simulations were performed using 8.5 GHz and 16 GHz as center frequencies. A linearly polarized horn antenna with a gain of 10 dB was used as the feed, rotated 45° and placed 300 mm from the array for illumination, generating dual-polarized (x / y) incident waves at 8.5 GHz and 16 GHz respectively. The target divergence angle was set. At 15°, +4th order x-polarized and +3rd order y-polarized orbital angular momentum beams are generated through the upper structure in the 16GHz band, and +1st order x-polarized and +2nd order y-polarized orbital angular momentum beams are generated through the lower structure in the 8.5GHz band. The orbital angular momentum phase design after feed phase compensation is performed using formula (3) to obtain the total phase of the metasurface unit. The final multiplexed aperture phase distribution is as follows: Figure 9 As shown, (a) is the vortex phase, (b) is the feed compensation phase, (c) is the divergence angle control phase, and (d) is the overall phase distribution after synthesis.

[0076] Simulations were performed using the CST time-domain solver, with a 400×400mm² observation surface set at 300mm. Figure 10 The results show the transverse electric field and phase distribution. (a) and (b) are the phase distribution at 8.5 GHz; (c) and (d) are the phase distribution at 16 GHz; (e) and (f) are the amplitude distribution at 8.5 GHz; and (g) and (h) are the amplitude distribution at 16 GHz. They exhibit typical π to 4π phase periodicity and a ring-shaped amplitude zero consistent with theoretical predictions. Crucially, Figure 10 The toroidal energy distribution radii corresponding to different modes in (e) to (h) remain consistent, verifying the effectiveness of the divergence angle design in this application. Furthermore, the phenomenon that the energy distribution radius increases with the topological charge number is consistent with the physical characteristics of orbital angular momentum. Figure 11 As shown in (a), its normalized radiation pattern further confirms that all four channels achieve an equal divergence angle of 15°. This is further confirmed by extracting the electric field data of the main radiation region (e.g., Figure 10 The purity of the vortex beam (as shown) was evaluated, and quantitative analysis was performed using the orbital angular momentum spectrum decomposition method. The simulation results are as follows: Figure 11 As shown in (b), the mode purity is for modes l=1, 2, 3, and 4, respectively. All modes exhibit high mode purity, indicating that the divergence angle control method of this application does not affect the mode purity while maintaining constant angle changes.

[0077] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0078] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0079] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0080] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for controlling the divergence angle, characterized in that, The method, applied to a vortex beam radar comprising multiple metasurface elements and a feed source, includes: Obtain the target divergence angle and basic radar parameters; wherein, the basic radar parameters include: wave number and cell spacing; The divergence angle control phase is determined based on the target divergence angle and the radar's basic parameters; The feed compensation phase is determined based on the distance from the metasurface unit to the feed source; The vortex phase is determined based on the position of the metasurface unit; The total phase is determined based on the divergence angle control phase, the feed compensation phase, and the vortex phase; The unit structure of the metasurface unit corresponding to the total phase adjustment.

2. The divergence angle control method according to claim 1, characterized in that, The step of determining the divergence angle control phase based on the target divergence angle and the radar fundamental parameters includes: By the following formula: Calculate the divergence angle control phase; wherein, The divergence angle controls the phase, k0 is the wavenumber, and d is the cell spacing. The target divergence angle is given.

3. The divergence angle control method according to claim 1, characterized in that, The step of determining the feed compensation phase based on the distance from the metasurface unit to the feed source includes: The feed compensation phase is: Where k0 is the wave number, The radial position of the metasurface unit in the array. The axial distance of the feed source.

4. The divergence angle control method according to claim 1, characterized in that, The step of determining the vortex phase based on the position of the metasurface unit includes: The vortex phase is: Where l is the preset modal order, Let be the angular coordinates of the metasurface unit.

5. A vortex beam radar, characterized in that, It includes multiple metasurface units and a feed source, wherein the unit structure of each metasurface unit is obtained by adjusting the divergence angle control method according to any one of claims 1 to 4.

6. The vortex beam radar according to claim 5, characterized in that, The metasurface unit includes a first metal layer, a first dielectric layer, a second metal layer, a second dielectric layer, and a ground layer stacked sequentially. The first metal layer includes a Jerusalem cross structure, and the second metal layer includes a cross structure.

7. The vortex beam radar according to claim 6, characterized in that, The first metal layer is also provided with a metal circular hole, and the Jerusalem cross structure is disposed in the metal circular hole.

8. The vortex beam radar according to claim 6, characterized in that, The second metal layer also includes a plurality of radiating patches, which are disposed at the ends of the cross structure.

9. The vortex beam radar according to claim 6, characterized in that, The surface of the metasurface unit is set to be square, and multiple metasurface units form a square array.

10. The vortex beam radar according to claim 9, characterized in that, The metasurface unit has a length and width of 10 mm and a height of 2 mm; the edge of the square array is composed of 25 metasurface units, and the square array has a length and width of 250 mm and a height of 2 mm.

Images