Antenna for realizing quasi-diffraction-free beam forming and scanning

Abstract

The invention particularly relates to an antenna for realizing quasi-diffraction-free beamforming and scanning, which comprises a phase shift metasurface and a feed horn antenna, and is characterized in that the feed horn antenna directly faces the center of the phase shift metasurface; the phase shift metasurface is of a double-layer dielectric substrate structure with an electromagnetic wave phase shift function, the whole phase shift metasurface is composed of a plurality of phase shift units arranged periodically, and the structure of each phase shift unit comprises an upper layer metal patch, a middle layer metal patch, a lower layer metal patch, an upper layer dielectric substrate and a lower layer dielectric substrate; the phase shift unit is equivalent to a low-pass filtering phase shifter with a phase shift effect, insertion phase shift at different angles can be realized at any position of the phase shift metasurface by setting the sizes of the three layers of metal patches in each phase shift unit on the phase shift metasurface, and then the insertion phase shift at different angles can be realized under the irradiation of the feed horn antenna. And generating phase distribution meeting the ideal phasor shift quantity of the quasi-non-diffraction beam on the outlet surface of the phase shift metasurface so as to generate the quasi-non-diffraction beam. According to the invention, the problem that the starting point of the non-diffraction region of the quasi-non-diffraction wave beam is uncontrollable is solved.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic wave beamforming, and in particular to an antenna for realizing quasi-diffraction-free beamforming and scanning. Background Art

[0002] Bessel beams have the characteristic of focused propagation, allowing them to propagate without diffraction for considerable distances. Spatial beaming of electromagnetic waves has crucial applications, including wireless electromagnetic energy transmission, THz-band spatial waveguides, near-field detection radar, microwave medical devices, high-precision microwave measurement, and even ground-to-air transmission of space solar energy.

[0003] Quasi-non-diffracting beams have been extensively studied in the fields of optics and electromagnetic waves. These beams can be generated using axicon lenses, dielectric integrated waveguides, leaky-wave antennas, and other methods. However, the starting point of the non-diffracting region of existing quasi-non-diffracting beam antennas always begins at the beam-forming device, making it impossible to arbitrarily control the starting point of the non-diffracting region of the quasi-non-diffracting beam, which greatly limits the application scenarios of quasi-non-diffracting beams. Therefore, it is of great significance to design a new quasi-non-diffracting beam-forming device with a simple structure and controllable non-diffracting region of the quasi-non-diffracting beam.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Summary of the Invention

[0005] The present invention provides an antenna for realizing quasi-diffraction-free beam forming and scanning, and is used to solve the problems of uncontrollable starting point of the diffraction-free area of ​​the quasi-diffraction-free beam, complex structure and high processing cost.

[0006] Other features and advantages of the present invention will become apparent from the following detailed description, or may be learned in part by practice of the present invention.

[0007] According to a first aspect of the present invention, an antenna for achieving quasi-diffraction-free beamforming and scanning is provided, comprising a phase-shifting metasurface and a feed horn antenna, the feed horn antenna being directly opposite the center of the phase-shifting metasurface; the phase-shifting metasurface is a double-layer dielectric substrate structure having an electromagnetic wave phase shifting function, comprising a printed circuit upper layer, a dielectric substrate upper layer, a printed circuit middle layer, a dielectric substrate lower layer, and a printed circuit lower layer coaxially stacked from top to bottom, the entire phase-shifting metasurface being composed of a plurality of periodically arranged phase-shifting units, each of which comprises upper, middle, and lower metal patches and upper and lower dielectric substrates; The phase shift unit is equivalent to a low-pass filter phase shifter with a phase shift effect. By setting the size of the three-layer metal patch in each phase shift unit on the phase shift metasurface, an insertion phase shift of 0 degrees, -90 degrees, -180 degrees, and -270 degrees can be achieved at any position of the phase shift metasurface. Then, under the illumination of the fed horn antenna, a phase distribution that meets the ideal phase shift amount of the quasi-diffracting beam is generated on the exit surface of the phase shift metasurface to generate a quasi-diffracting beam.

[0008] In some exemplary embodiments, the ideal phase shift of each phase shift unit of the phase shift metasurface is From formulas (1) to (7), we can get: (1) (2) (3) (4) (5) (6) (7) in, is the operating frequency of the antenna, c is the speed of light in free space, and is the coordinate of the center point of each phase shift unit, F is the distance from the phase center of the feed horn antenna to the phase-shifting metasurface, R is the radius of the phase-shift metasurface, ρ is the distance between each phase shift unit and the center of the phase shift metasurface, θ is the angle between the beam direction and the phase-shifting metasurface, and z 1 are used to control the depth of field of the quasi-non-diffraction beam and the starting point of the quasi-non-diffraction area respectively.

[0009] In some exemplary embodiments, the phase shift units are rectangular or hexagonal; when they are rectangular, the phase shift units are arranged in a pintle shape; when they are hexagonal, the phase shift units are arranged in a honeycomb shape.

[0010] In some exemplary embodiments, the sizes of the metal patches in the phase shift unit corresponding to different phase shift amplitudes are obtained in full-wave simulation software through periodic boundary conditions.

[0011] In some exemplary embodiments, the feed horn antenna is a linearly polarized, circularly polarized, or multi-polarized horn antenna.

[0012] In some exemplary embodiments, within each phase shift unit, the metal patch on the lower layer of the printed circuit and the metal patch on the upper layer of the printed circuit have the same size.

[0013] According to the second aspect of the present invention, a design method for an antenna that realizes quasi-diffraction-free beamforming and scanning is provided. The corresponding phase shift unit is selected according to the phase shift amount, and the phase shift metasurface is arranged to form a desired quasi-diffraction-free beam according to the generated phase distribution. 、 and Achieve quasi-diffraction-free beams in different directions and areas; including: The sizes of the metal patches in the phase shift unit corresponding to different phase shift amplitudes are obtained by simulating in full-wave simulation software using periodic boundary conditions. According to the different positions of each phase shift unit, the ideal phase shift amount of the phase shift unit is calculated according to formulas (1) to (7); Calculate the actual phase shift amount based on the ideal phase shift amount; The sizes of the metal patches corresponding to the phase shift units at different positions are selected based on the actual phase shift amount.

[0014] In some exemplary embodiments, the actual phase shift amount is calculated based on the ideal phase shift amount using the following formula: 90° in, int is the floor function, is the ideal phase shift, is the actual phase shift.

[0015] The antenna for implementing quasi-diffraction-free beamforming and scanning provided by the embodiments of the present invention achieves controllable starting point of the non-diffraction region of the quasi-diffraction-free beam by adjusting the phase distribution of the beamforming plane, achieving a good quasi-diffraction-free beam. This solves the problem of the starting point of the quasi-diffraction-free region in a quasi-diffraction-free beam antenna always being located on the beamforming device. Compared with the existing technology, this antenna has the following advantages: First, the present invention adopts phase-shift metasurface technology and only uses ordinary PCB technology. The phase-shift metasurface is only about 1 mm thick. Second, the starting point of the quasi-diffraction region of the quasi-diffraction beam can be freely set; Third, in terms of implementation effect, due to the extremely thin thickness of the phase-shift metasurface, the dielectric loss is almost negligible; Fourth, mature PCB technology can achieve higher processing precision and is a low-cost solution suitable for mass production. It also has unique advantages in achieving quasi-diffracting beams in microwave, especially millimeter-wave frequency bands. Fifth, compared with various quasi-non-diffracting beam antennas using the aperture generation method, the present invention has a simpler structure, does not require a complex feeding structure, and avoids transmission and mismatch losses.

[0016] Sixth, compared with the axicon lens, leaky wave antenna, dielectric integrated waveguide and other forms in the prior art, the beam-forming planar structure of the present invention is simple, low in cost and easy to process.

[0017] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are incorporated into and constitute a part of this specification, illustrate embodiments consistent with the present invention, and together with the description, serve to explain the principles of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and it is clear that those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0019] Figure 1 is a side view schematic diagram of the antenna of the present invention; Figure 2 is a side view schematic diagram of the phase-shift metasurface in Example 1 of the present invention; Figure 3 Schematic diagram of the distribution of phase shift units on the upper and lower layers of the phase shift metasurface printed circuit in Example 1 of the present invention; Figure 4 Schematic diagram of the distribution of phase shift units in the middle layer of the phase shift metasurface printed circuit in Example 1 of the present invention; Figure 5 2. It is a front view of the phase shift unit on the phase shift metasurface of the present invention; Figure 6 1. It is a simulation diagram of the longitudinal and cross-sectional electric field intensity of the quasi-diffracting beam generated in Example 1 of the present invention; Figure 7 This is a comparison diagram of the axial electric field intensity of the quasi-non-diffracting beam generated by the present invention and the axial electric field intensity of the quasi-non-diffracting beam with a fixed starting point of the quasi-non-diffracting region; Among them: 1 is the beam-forming plane, 2 is the feed horn antenna, 1 is the upper layer of the printed circuit, 21 is the upper layer of the high-frequency dielectric substrate, 12 is the middle layer of the printed circuit, 22 is the lower layer of the high-frequency dielectric substrate, 13 is the lower layer of the printed circuit, and 111, 121, and 131 are metal patches arranged in the upper, middle, and lower layers of the printed circuit respectively. DETAILED DESCRIPTION

[0020] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be embodied in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0021] In addition, the accompanying drawings are merely schematic illustrations of the present invention and are not necessarily drawn to scale. Identical reference numerals in the figures denote identical or similar parts, and thus repetitive descriptions thereof will be omitted. Some of the blocks shown in the accompanying drawings are functional entities that do not necessarily correspond to physically or logically separate entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0022] Related art has disclosed an antenna for generating a Bessel beam. This invention generates a Bessel beam with controllable depth of field by varying the phase distribution of the beamforming plane. However, the antenna in this invention can only generate a Bessel beam perpendicular to the beamforming plane, and the starting point of the non-diffraction region cannot be controlled and remains located on the beamforming plane.

[0023] The prior art also discloses an antenna for generating an arbitrarily directed Bessel beam. This invention generates an arbitrarily directed Bessel beam by rotating two beamforming planes. Similarly, the starting point of the non-diffraction region of the Bessel beam generated by the antenna in this invention is located on the beamforming plane.

[0024] The prior art also discloses a paper titled "Multitarget wireless power transfer system using metasurface for quasi-Bessel beams with large half-power beam length," which proposes a wireless energy transmission system. Based on the desired quasi-Bessel beam, the metasurface's phase distribution is calculated. A horn antenna illuminates the metasurface to generate a quasi-Bessel beam, which wirelessly transmits energy to multiple targets. However, the quasi-Bessel beam generated by the method proposed in this paper has a starting point located on the metasurface, resulting in lower energy efficiency than a quasi-non-diffracting beam with an adjustable starting point.

[0025] The prior art also discloses a paper titled "Quasi-Nondiffractive Multibeam Antennas Based on Phase Shift Surfaces," which proposes a method for generating quasi-nondiffraction multibeams. This method uses a horn antenna to illuminate a phase-shifted surface to generate quasi-nondiffraction multibeams. Each beam can be independently controlled, and interference between beams is reduced by introducing optimized phases. However, the starting point of the quasi-nondiffraction multibeams generated by this method always lies on the phase-shifted surface, making it impossible to control the starting point of the quasi-nondiffraction region of the quasi-nondiffraction beam.

[0026] The prior art also discloses a non-diffracting phase-shifting metasurface antenna with deflectable beam direction. This invention achieves a specific non-diffracting beam through the phase distribution on the phase-shifting metasurface. Similarly, the antenna in this invention can only generate a non-diffracting beam perpendicular to the phase-shifting metasurface, and the starting point of the non-diffracting region cannot be controlled and always remains on the phase-shifting metasurface.

[0027] In response to the shortcomings and deficiencies of existing technologies, the present invention provides an antenna that implements quasi-diffraction-free beamforming and scanning. This antenna addresses the problem of uncontrollable starting point of the non-diffraction region of the quasi-diffraction-free beam by adjusting the phase distribution of the beamforming plane to achieve controllable starting point of the non-diffraction region of the quasi-diffraction-free beam. Furthermore, the antenna has a simple structure and low processing cost. This antenna can solve the following technical problems existing in conventional non-diffraction-free beam antennas: 1. With the extensive and in-depth research on quasi-non-diffraction beams in the fields of optics and electromagnetic waves, technologies for generating quasi-non-diffraction beams in the form of axicon lenses, dielectric integrated waveguides, leaky-wave antennas, etc. have been proposed. However, axicon lenses, dielectric integrated waveguides, leaky-wave antennas, etc. have complex structures and high processing costs. Therefore, it is necessary to design a quasi-non-diffraction beam antenna with a simple structure and low processing cost.

[0028] 2. For traditional quasi-non-diffraction beam antennas, the starting point of the quasi-non-diffraction area of ​​the generated quasi-non-diffraction beam always starts from the beam forming device, and the starting point of the non-diffraction area cannot be controlled. For scenarios where the target non-diffraction range is located at a certain distance from the beam forming device, the energy utilization rate is low compared to the quasi-non-diffraction beam antenna with controllable starting point, which greatly limits the actual application scenarios of the quasi-non-diffraction beam.

[0029] The present invention provides a quasi-diffraction-free beam antenna that generates a quasi-diffraction-free region and has a controllable scanning angle, comprising a phase-shifting metasurface and a feed horn antenna, wherein the feed horn antenna is directly opposite the center of the phase-shifting metasurface; the phase-shifting metasurface is a double-layer dielectric substrate structure with an electromagnetic wave phase shifting function, comprising a printed circuit upper layer, a dielectric substrate upper layer, a printed circuit middle layer, a dielectric substrate lower layer, and a printed circuit lower layer coaxially stacked from top to bottom; the entire phase-shifting metasurface is composed of a plurality of periodically arranged phase-shifting units, and the structure of each phase-shifting unit includes upper, middle, and lower metal patches and upper and lower dielectric substrates; Ideal phase shift of each unit of the phase-shift metasurface From formulas (1) to (7), we can get: (1) (2) (3) (4) (5) (6) (7) in, f is the operating frequency of the antenna, c is the speed of light in free space, and is the coordinate of the center point of each phase shift unit, is the distance from the phase center of the feed horn antenna to the phase-shifting metasurface, is the radius of the phase-shift metasurface, ρ is the distance between each phase shift unit and the center of the phase shift metasurface, θ is the angle between the beam direction and the phase-shifting metasurface 1, and They are used to control the depth of field of the quasi-non-diffraction beam and the starting point of the quasi-non-diffraction area. 、 、 、 、 and is an intermediate variable. According to the different positions of each phase shift unit, the phase shift amount of each phase shift unit is calculated according to the above formulas (1) to (7). The corresponding phase shift unit is selected according to the phase shift amount, and the layout is composed of the phase shift metasurface. According to the generated phase distribution, the desired quasi-diffraction-free beam can be generated. In the design, 、 and Achieve quasi-diffraction-free beams in different directions and areas.

[0030] The phase distribution of the phase-shifting metasurface designed in the present invention is derived from the desired quasi-diffraction-free beam through formulas (1) to (7). The difference between the generated quasi-diffraction-free beam and the previous technology is that the starting point of the quasi-diffraction-free area of ​​the quasi-diffraction-free beam can be freely set as needed, rather than being fixed on the beam generating device. The traditional quasi-diffraction-free beam calculation of the ideal phase shift only focuses on the angle between the beam direction and the phase-shifting metasurface and the depth of field of the quasi-diffraction-free beam. The quasi-diffraction-free beam generated by the present invention not only focuses on the angle between the beam direction and the phase-shifting metasurface and the depth of field of the quasi-diffraction-free beam, but also needs to pay attention to the starting point of the quasi-diffraction-free area.

[0031] The structure of the antenna for implementing quasi-diffraction-free beamforming and scanning in this exemplary embodiment will be described in more detail below with reference to the accompanying drawings and embodiments.

[0032] Example 1 like Figure 1 As shown, this embodiment provides a quasi-diffraction-free beam antenna that generates a quasi-diffraction-free area and a controllable scanning angle, including a phase-shifting metasurface 1 and a feeding horn antenna 2, wherein the feeding horn antenna 2 is directly opposite to the center of the phase-shifting metasurface 1; the phase-shifting metasurface 1 transforms the quasi-spherical wave emitted from the feeding horn antenna 2 into a quasi-diffraction-free beam.

[0033] like Figure 2 As shown, the phase-shift metasurface 1 is a double-layer dielectric substrate structure with electromagnetic wave phase shifting function, including a printed circuit upper layer 11, a dielectric substrate upper layer 21, a printed circuit middle layer 12, a dielectric substrate lower layer 22, and a printed circuit lower layer 13 coaxially stacked from top to bottom. The radius of the two dielectric substrates is 215 mm, the thickness is 0.508 mm, and the relative dielectric constant is 2.2. The entire phase-shift metasurface is composed of a number of periodically arranged phase-shift units. The dimensions of the printed circuit upper layer and the printed circuit lower layer are the same, as shown in FIG. Figure 3 As shown; the shape of the middle layer of the printed circuit is the same as that of the upper layer and the lower layer of the printed circuit, which is a hexagonal structure. Figure 4 The structure of each phase shift unit includes upper, middle and lower three-layer metal patches 111, 121, 131 and upper and lower dielectric substrates 211, 221, as shown Figure 5 As shown in the figure, by designing the side lengths of the three-layer metal patches of the phase shift unit, insertion phase shifts of 0 degrees, -90 degrees, -180 degrees, and -270 degrees can be achieved.

[0034] In terms of working principle, the phase shift unit is equivalent to a low-pass filter phase shifter with a phase shift effect. By setting the size of the three-layer metal patch in each phase shift unit on the phase shift metasurface, an inserted phase shift of 0 degrees, -90 degrees, -180 degrees, and -270 degrees can be achieved at any position of the phase shift metasurface. Then, under the illumination of the fed horn antenna, a phase distribution that meets the ideal phase shift amount of the quasi-diffraction-free beam is generated on the exit surface of the phase shift metasurface to generate a quasi-diffraction-free beam.

[0035] In this example, the radius R of the phase-shift metasurface 1 is 215 mm, and the operating frequency is f 29GHz, the speed of light in free space c is 3×108 m / s, the upper layer 21 of the dielectric substrate and the lower layer 22 of the dielectric substrate are Taconic TLY-5 dielectric plates with a relative dielectric constant of 2.2 and a thickness of 0.508 mm; the feed horn antenna 2 is a standard gain horn antenna with a -10 dB beam width of 64 degrees, and the distance F between the phase center of the feed horn antenna and the center of the phase shift metasurface is 346 mm; the number of quasi-non-diffraction beams in this example is 3, and the angles between the beams and the phase shift metasurface are 45 degrees, 90 degrees, and 135 degrees, respectively. The starting points of the quasi-non-diffraction beams are 100 mm, 100 mm, and 200 mm, respectively, and the depths of field are 200 mm, 400 mm, and 300 mm, respectively. The distances from the center of the dielectric substrate are ρ The ideal phase shift of the phase shift unit is: (1) (2) (3) (4) (5) (6) (7) in, is the operating frequency of the antenna, is the speed of light in free space, and is the coordinate of the center point of each phase shift unit, and the coordinate axis is as follows Figure 3 As shown, F is the distance from the phase center of the feed horn antenna to the phase-shifting metasurface, is the radius of the phase-shift metasurface, ρ is the distance between each phase shift unit and the center of the phase shift metasurface, θ is the angle between the beam direction and the phase-shifting metasurface 1, and They are used to control the depth of field of the quasi-non-diffraction beam and the starting point of the quasi-non-diffraction area respectively.

[0036] According to the different positions of each phase shift unit, the phase shift amount of each phase shift unit is calculated according to the above formulas (1) to (7), and the corresponding phase shift unit is selected according to the phase shift amount. The layout forms the phase shift metasurface 1, and the desired quasi-diffraction-free beam can be generated according to the generated phase distribution. θ 、 and z 1. Realize quasi-diffraction-free beams in different directions and different areas.

[0037] The ideal phase shift is the theoretical phase difference between each phase shift unit and the center position of the phase shift metasurface. In this example, the actual phase shift is: 90° in, int is a rounded-down function; by changing the side length of the three-layer metal patch in each phase shift unit, the phase requirement of the quasi-diffraction-free beam at the output surface of the phase-shift metasurface can be met; the metal patch sizes corresponding to the four phase shift amplitudes are obtained in Ansys HFSS full-wave simulation software through periodic boundary conditions; in this embodiment, the relationship between the phase shift amount and the side length of the metal patch is:

[0038] Thus, the design of the phase-shift metasurface is completed. Then, a linearly polarized standard gain horn antenna 2 with a -10 dB beamwidth and a 64-degree beamwidth is applied to the left side of the phase-shift metasurface for feeding. The horn antenna is facing the center of the phase-shift metasurface, as shown in FIG. Figure 1 As shown, a linearly polarized quasi-diffraction-free beam can be generated on the right side of the phase-shifted metasurface.

[0039] like Figure 6 Shown are simulation diagrams of the longitudinal and cross-sectional electric field strength of the quasi-diffracting beam generated by the present invention. It can be seen from the figure that within a range of 500 mm, the electromagnetic wave field intensity distribution is beam-shaped on the propagation axis and is symmetrical along the propagation axis. The field strength remains basically unchanged, and the quasi-diffracting beam is generated within the expected range, meeting the design expectations.

[0040] Example 2 On the basis of Example 1, the number of quasi-non-diffraction beams is changed to 1, generating beam 1 (the starting point of the quasi-non-diffraction area is adjustable) and beam 2 (the starting point of the quasi-non-diffraction area is located on the beam generating device), respectively. The angle between beam 1 and the phase-shift metasurface is 90 degrees, the starting point of the quasi-non-diffraction beam is 200 mm, and the depth of field is 300 mm. The angle between beam 2 and the phase-shift metasurface is 90 degrees, the starting point of the quasi-non-diffraction beam is 0 mm, and the depth of field is 500 mm. Figure 7A graph comparing the axial electric field intensity of the quasi-non-diffracting beam generated by the present invention with that of a beam with a fixed starting point in the quasi-non-diffracting region. As can be seen, within the target area (200 mm to 500 mm), the electric field intensity of the quasi-non-diffracting beam proposed by the present invention is consistently higher than that of a beam with the starting point of the quasi-non-diffracting region located on the generator. This demonstrates that in applications where the target area is far from the generator, the quasi-non-diffracting beam proposed by the present invention offers greater energy and concentration than conventional quasi-non-diffracting beams.

[0041] The present invention relates to a quasi-non-diffraction beam antenna that generates a quasi-non-diffraction region and has a controllable scanning angle. This antenna has a simple structure and a controllable starting point for the non-diffraction region that creates the quasi-non-diffraction beam. This effectively solves the problem of the starting point of the non-diffraction region of the quasi-non-diffraction beam antenna always being located within the beamforming device. It can be applied to indoor near-field communications and near-field wireless energy transmission, improving signal strength and energy efficiency.

[0042] Other embodiments of the present invention will readily occur to those skilled in the art after considering the specification and practicing the invention herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the claims.

[0043] It should be understood that the present invention is not limited to the exact construction described above and shown in the drawings and that various modifications and variations can be made without departing from the scope thereof, which is limited only by the appended claims.

Claims

1. An antenna for achieving quasi-diffraction-free beamforming and scanning, characterized in that: The invention comprises a phase-shift metasurface and a feed horn antenna, wherein the feed horn antenna is directly opposite the center of the phase-shift metasurface; the phase-shift metasurface is a double-layer dielectric substrate structure with an electromagnetic wave phase shifting function, comprising a printed circuit upper layer, a dielectric substrate upper layer, a printed circuit middle layer, a dielectric substrate lower layer, and a printed circuit lower layer coaxially stacked from top to bottom. The entire phase-shift metasurface is composed of a number of periodically arranged phase-shift units, and the structure of each phase-shift unit includes three layers of metal patches, upper, middle, and lower layers, and upper and lower dielectric substrates; The phase shift unit is equivalent to a low-pass filter phase shifter with a phase shift effect. By setting the size of the three-layer metal patch in each phase shift unit on the phase shift metasurface, an insertion phase shift of 0 degrees, -90 degrees, -180 degrees, and -270 degrees can be achieved at any position of the phase shift metasurface. Then, under the illumination of the fed horn antenna, a phase distribution that meets the ideal phase shift amount of the quasi-diffracting beam is generated on the exit surface of the phase shift metasurface to generate a quasi-diffracting beam.

2. The antenna for achieving quasi-diffraction-free beamforming and scanning according to claim 1, wherein: The ideal phase shift of each phase shift unit of the phase shift metasurface From formulas (1) to (7), we can get: (1) (2) (3) (4) (5) (6) (7) in, is the operating frequency of the antenna, c is the speed of light in free space, and is the coordinate of the center point of each phase shift unit, F is the distance from the phase center of the feed horn antenna to the phase-shifting metasurface, is the radius of the phase-shift metasurface, ρ is the distance between each phase shift unit and the center of the phase shift metasurface, is the angle between the beam direction and the phase-shifting metasurface, and They are used to control the depth of field of the quasi-non-diffraction beam and the starting point of the quasi-non-diffraction area respectively.

3. The antenna for achieving quasi-diffraction-free beamforming and scanning according to claim 1, wherein: The phase shift units are rectangular or hexagonal; when they are rectangular, the phase shift units are arranged in a pintle shape; when they are hexagonal, the phase shift units are arranged in a honeycomb shape.

4. The antenna for achieving quasi-diffraction-free beamforming and scanning according to claim 1, wherein: The sizes of the metal patches in the phase shift unit corresponding to different phase shift amplitudes are obtained in the full-wave simulation software through periodic boundary conditions.

5. The antenna for achieving quasi-diffraction-free beamforming and scanning according to claim 1, wherein: The feed horn antenna is a linearly polarized, circularly polarized or multi-polarized horn antenna.

6. The antenna for achieving quasi-diffraction-free beamforming and scanning according to claim 1, wherein: In each phase shift unit, the sizes of the metal patch on the lower layer of the printed circuit and the metal patch on the upper layer of the printed circuit are the same.

7. A method for designing an antenna for achieving quasi-diffraction-free beamforming and scanning according to claim 2, characterized in that: According to the phase shift amount, the corresponding phase shift unit is selected and the layout is composed of the phase shift metasurface. According to the generated phase distribution, the desired quasi-diffraction-free beam can be generated. 、 and Achieve quasi-diffraction-free beams in different directions and areas; including: The sizes of the metal patches in the phase shift unit corresponding to different phase shift amplitudes are obtained by simulating in full-wave simulation software using periodic boundary conditions. According to the different positions of each phase shift unit, the ideal phase shift amount of the phase shift unit is calculated according to formulas (1) to (7); Calculate the actual phase shift amount based on the ideal phase shift amount; The sizes of the metal patches corresponding to the phase shift units at different positions are selected based on the actual phase shift amount.

8. The method for designing an antenna for achieving quasi-diffraction-free beamforming and scanning according to claim 7, wherein: The actual phase shift amount is calculated based on the ideal phase shift amount using the following formula: 90° in, int is the floor function, is the ideal phase shift, is the actual phase shift.

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