A broadband millimeter-wave flat thin transmissive achromatic metasurface unit, lens, and beam deflector

Abstract

The present invention discloses a broadband millimeter-wave, flat, thin, transmissive achromatic metasurface unit, lens, and beam deflector, comprising a first metal layer, a first dielectric layer, a second metal layer, a first adhesive layer, a third metal layer, a second dielectric layer, a second adhesive layer, a fourth metal layer, a third dielectric layer, and a fifth metal layer stacked in sequence. The first and third metal layers are connected by a first metalized blind via, which does not contact the second metal layer; the third and fifth metal layers are connected by a second metalized blind via, which does not contact the fourth metal layer; and a back-drilled via is provided between the third and second dielectric layers. The present invention enables the combined control of the slope and magnitude of the transmission phase curve, with minimal impact on the transmission amplitude. Using the dispersion manipulation unit of the above invention, a two-dimensional, thin, achromatic lens can be customized at 27 to 37 GHz.

Description

Technical Field

[0001] The present invention relates to a broadband millimeter-wave flat thin transmission achromatic metasurface unit, a lens and a beam deflector, and belongs to the technical field of array antenna neighborhood and novel artificial electromagnetic metasurface. Background Art

[0002] In the millimeter-wave frequency range, achromatic devices have broad application prospects in imaging, radar, and wireless communication systems. For example, millimeter-wave achromatic lenses are often embedded in antenna systems to focus or deflect broadband electromagnetic waves carrying information. These lenses can be used to improve the performance of antenna systems, increase antenna gain in ultra-wideband ranges, or suppress dispersion errors in radiated beams. In addition, in millimeter-wave achromatic beam deflector wireless communication systems, angular transmission of electromagnetic signals is achieved over a wide frequency range. Dielectric lenses generally eliminate the dispersion of the transmitted beam by changing the thickness of the dielectric or cascading grating structures. However, changing the thickness will make the thickness of the lens uneven, and cascading multi-layer structures will further increase the thickness of the lens, making it difficult to integrate with wireless systems.

[0003] As a planar metamaterial, electromagnetic metasurfaces can effectively manipulate the polarization, amplitude, frequency, and phase of electromagnetic waves, achieving a variety of remarkable functions such as anomalous refraction, electromagnetic focusing, and polarization control. In recent years, researchers have proposed a design method for achromatic lenses using metasurfaces. Reflective metasurfaces often combine propagation phase and geometric phase to control the dispersion of reflected waves. The repeated transmission of electromagnetic waves between rectangular patches and the reflective floor can constitute the propagation phase. In addition, stacking multiple layers of patches of different shapes and sizes on the reflective floor can introduce different resonant frequencies, further expanding the bandwidth of dispersion control. In fact, when using a reflective metasurface for dispersion control, the electromagnetic wave reflects back and forth between the patch and the floor, generating a resonant phase, which makes the reflective achromatic metasurface inherently have a low-profile characteristic.

[0004] In practical applications, transmissive achromatic metasurfaces can filter incident electromagnetic waves, directly modulate transmitted waves, and have no feed source obstruction. Therefore, they have been more widely used in imaging systems, spatial filtering, wireless communications and other fields. For planar transmissive metasurfaces, electromagnetic waves propagate along equal paths from the incident surface to the exit surface. Since the optical path length of an electromagnetic wave is the integral of its refractive index along the longitudinal propagation path, the equivalent refractive index of the metasurface unit must be independently designed to achieve dispersion control. Currently, most transmissive metasurfaces use methods such as constructing different equivalent dielectric constants or cascading multilayer structures along the longitudinal direction of propagation to control dispersion, which causes the metasurface to have a large and uneven thickness. At present, how to achieve a low-profile and planar transmissive achromatic metalens remains a difficult problem. Summary of the Invention

[0005] Purpose: To overcome the deficiencies in the prior art, the present invention provides a broadband millimeter-wave flat, thin, transmissive achromatic metasurface unit, a lens, and a beam deflector. The metasurface unit has the ability to simultaneously adjust the geometric phase and the transmission phase, and has the advantages of thin thickness, wide operating bandwidth, and precise beam control.

[0006] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is:

[0007] In the first aspect, a broadband millimeter-wave flat thin transmissive achromatic metasurface unit specifically includes: a first metal layer, a first dielectric layer, a second metal layer, a first adhesive layer, a third metal layer, a second dielectric layer, a second adhesive layer, a fourth metal layer, a third dielectric layer, and a fifth metal layer stacked in sequence.

[0008] The first metal layer and the third metal layer are connected through a first metallized blind via, and the first metallized blind via does not contact the second metal layer; the third metal layer and the fifth metal layer are connected through a second metallized blind via, and the second metallized blind via does not contact the fourth metal layer; a back-drilled via is provided between the third dielectric layer and the second dielectric layer.

[0009] As a preferred solution, the first metal layer and the fifth metal layer are arc-shaped metal patches of the same shape, which are used to convert the received left-handed circularly polarized waves into right-handed circularly polarized waves for radiation.

[0010] As a preferred solution, the dielectric constants of the first dielectric layer, the second dielectric layer and the third dielectric layer are 3.50, and the thicknesses are 1 mm, 0.254 mm and 1 mm respectively; the dielectric constants of the first adhesive layer and the second adhesive layer are 3.52, and the thicknesses are 0.2 mm and 0.1 mm respectively.

[0011] As a preferred solution, the third metal layer is configured as a serpentine line structure.

[0012] As a preferred solution, the expression between the serpentine line length of the third metal layer and the slope of the metasurface unit transmission phase curve is as follows:

[0013]

[0014] Where: k represents the slope of the transmission phase curve of the metasurface unit, l is the overall length of the serpentine line, and γ is a constant.

[0015] As a preferred solution, the first metal layer, the third metal layer, the fifth metal layer, the first metalized blind hole and the second metalized blind hole are rotated α degrees to reduce the cross-polarization transmission phase of the metasurface unit by 2α degrees, so that the size of the transmission phase can be controlled.

[0016] In the second aspect, a broadband millimeter-wave flat thin transmission achromatic metasurface lens specifically includes: a dielectric substrate and several metasurface units described in the first aspect.

[0017] In this case, a number of metasurface units are stacked at different radii around a point on a dielectric substrate. The center of each metasurface unit corresponding to each radius falls on the circumference of the circle corresponding to that radius. Based on the phase of each metasurface unit, the rotation angle α of the first, third, and fifth metal layers, as well as the first and second metalized blind vias, and the length l of the serpentine line of the third metal layer are set.

[0018] Among them, the phase of the metasurface unit The expression is as follows:

[0019]

[0020] Where, Indicates the coordinate value of the horizontal coordinate with the endpoint on one side of the dielectric substrate as the origin, represents the operating frequency of the metasurface lens, represents the refraction angle of the transmitted beam, represents the initial phase, represents the speed of light, Represents pi.

[0021] As a preferred solution, the different radii are set to 0.5p, 1.5p, 2.5p, ..., (n-0.5)p, where p is the period of the metasurface unit and n represents a natural number.

[0022] In a third aspect, a broadband millimeter-wave flat, thin, transmissive achromatic metasurface beam deflector is provided, specifically comprising: a dielectric substrate, and several metasurface units described in the first aspect.

[0023] Multiple columns of metasurface units are stacked at equal intervals along the horizontal axis from one side of the dielectric substrate, with each column comprising a plurality of metasurface units. The center point position of each column of metasurface units corresponds to the horizontal axis interval value. Based on the phase of each metasurface unit, the rotation angle α of the first metal layer, the third metal layer, the fifth metal layer, the first metalized blind via, and the second metalized blind via of each metasurface unit is set, as well as the length l of the serpentine line of the third metal layer.

[0024] Among them, the phase of the metasurface unit The expression is as follows:

[0025]

[0026] Where, Indicates the coordinate value of the horizontal coordinate with the endpoint on one side of the dielectric substrate as the origin, represents the operating frequency of the metasurface lens, represents the refraction angle of the transmitted beam, represents the initial phase, represents the speed of light, Represents pi.

[0027] As a preferred solution, the interval values ​​of the horizontal axis are set to 0.5p, 1.5p, 2.5p, ..., (n-0.5)p, where p is the period of the metasurface unit and n represents a natural number.

[0028] Beneficial Effects: This invention provides a broadband millimeter-wave, flat, thin, transmissive achromatic metasurface unit, lens, and beam deflector. By designing the unit's overall rotation angle and the length of the transverse serpentine lines in the third metal layer, both the slope and magnitude of the transmission phase curve can be controlled, with minimal impact on the transmission amplitude. Using this dispersion-manipulation unit, a two-dimensional, thin (0.234-0.32λ, where λ represents the millimeter-wave wavelength) achromatic lens and achromatic beam deflector can be customized between 27 and 37 GHz.

[0029] The transmissive achromatic metasurface proposed in this invention has a low profile, a wide bandwidth, and precise dispersion manipulation capabilities, and has potential application value in wireless communications, millimeter-wave imaging, radar, and other fields.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. Compared with other transmissive achromatic metasurfaces in the low-frequency band, the variables optimized by the dispersion control unit of the present invention are only the length of the stripline and the rotation angle of the entire unit. No optimization algorithm is required when fitting the phase curve, which has the advantage of convenience and simplicity.

[0032] 2. Compared with other transmissive achromatic metasurfaces, the dispersion control unit of the present invention has the advantage of a low profile (0.234-0.32λ), making it easier to integrate into broadband imaging and communication systems.

[0033] 3. The metasurface unit converts the incident left-hand circularly polarized wave into a right-hand circularly polarized wave for transmission, and the transmission coefficient in the frequency band from 27 GHz to 37 GHz is greater than 0.88, which has a high transmittance.

[0034] 4. The achromatic metasurface unit of the present invention can fit the required phase curve in the frequency range of 27 GHz to 37 GHz and has a wide working bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the structural explosion of the achromatic metasurface unit.

[0036] Figure 2 Schematic diagram of the structural assembly of the achromatic metasurface unit.

[0037] Figure 3 Schematic diagram of the structure of each metal layer of the achromatic metasurface unit, where: Figure 3 (a) is the structural diagram of the first metal layer. Figure 3 (b) is the structural diagram of the second metal layer. Figure 3 (c) is the structural diagram of the third metal layer. Figure 3 (d) is the structural diagram of the fourth metal layer. Figure 3 (e) is a structural diagram of the fifth metal layer.

[0038] Figure 4 is a schematic diagram of the structure of the metasurface lens, where Figure 4 (a) is the distribution structure diagram of the first metal layer of the metasurface lens. Figure 4 (b) is the distribution structure diagram of the third metal layer of the metasurface lens.

[0039] Figure 5 is a schematic diagram of the structure of the metasurface beam deflector, where: Figure 5 (a) is the distribution structure diagram of the first metal layer of the metasurface beam deflector. Figure 5 (b) is the distribution structure diagram of the third metal layer of the metasurface beam deflector.

[0040] Figure 6 This is a comparison diagram of the phase curves of theoretical calculation and simulation, where: Figure 6 (a) is the phase curve of the metasurface lens. Figure 6 Middle (b) is the phase curve diagram of the metasurface beam deflector.

[0041] Figure 7 This is the cross-sectional electric field distribution diagram of the metasurface lens test, where: Figure 7 (a) is the electric field amplitude distribution diagram of the xoz cross section, Figure 7 (b) is the electric field amplitude distribution diagram of the xoy cross section at z = 80 mm.

[0042] Figure 8 This is a comparison diagram of the simulation and measurement of the far-field pattern of the metasurface beam deflector, where: Figure 8 (a) is the directional pattern at 27 GHz. Figure 8 (b) is the directional pattern at 29GHz. Figure 8 (c) is the directional pattern at 31GHz. Figure 8 (d) is the directional pattern at 33GHz. Figure 8 (e) in the middle is the directional pattern at 35GHz, Figure 8(f) in the middle is the radiation pattern at 37 GHz. DETAILED DESCRIPTION

[0043] The following is a clear and complete description of the technical solutions in the examples of the present invention, in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0044] The present invention will be further described below with reference to specific embodiments.

[0045] Example 1:

[0046] This embodiment introduces a broadband millimeter wave flat thin transmissive achromatic metasurface unit, such as Figure 1 、 Figure 2 、 Figure 3 As shown, it specifically includes: a first metal layer 1, a first dielectric layer 2, a second metal layer 3, a first adhesive layer 4, a third metal layer 5, a second dielectric layer 6, a second adhesive layer 7, a fourth metal layer 8, a third dielectric layer 9, and a fifth metal layer 10 stacked in sequence.

[0047] Among them, the first metal layer 1 and the third metal layer 5 are connected through a first metallized blind via 11, and the first metallized blind via 11 does not contact the second metal layer 3; the third metal layer 5 and the fifth metal layer 10 are connected through a second metallized blind via 12, and the second metallized blind via 12 does not contact the fourth metal layer 8; a back-drilled via 13 is provided between the third dielectric layer 9 and the second dielectric layer 6.

[0048] Furthermore, the first metal layer 1 and the fifth metal layer 10 are arc-shaped metal patches of the same shape, which are used to convert the received left-handed circularly polarized waves into right-handed circularly polarized waves for radiation.

[0049] Furthermore, the dielectric materials of the first dielectric layer 2, the second dielectric layer 6 and the third dielectric layer 9 are F4B (a composite material based on polytetrafluoroethylene (PTFE)), with a dielectric constant of 3.50 and thicknesses of 1 mm, 0.254 mm and 1 mm respectively; the dielectric constant of the first adhesive layer 4 and the second adhesive layer 7 is 3.52, and the thicknesses are 0.2 mm and 0.1 mm respectively.

[0050] Furthermore, the third metal layer 5 is configured as a serpentine structure.

[0051] Furthermore, the expression between the serpentine length of the third metal layer 5 and the slope of the transmission phase curve of the metasurface unit is as follows:

[0052]

[0053] Where: k represents the slope of the transmission phase curve of the metasurface unit, l is the overall length of the serpentine line, and γ is a constant.

[0054] Furthermore, the first metal layer 1, the third metal layer 5, the fifth metal layer 10, the first metalized blind hole 11 and the second metalized blind hole 12 are rotated α degrees to reduce the cross-polarization transmission phase of the metasurface unit by 2α degrees, so that the size of the transmission phase can be adjusted.

[0055] Example 2:

[0056] This embodiment introduces the working principle of a broadband millimeter-wave flat, thin, transmissive achromatic metasurface unit, which is specifically as follows:

[0057] When a circularly polarized electromagnetic wave is incident on the metasurface unit, the first metal layer 1 performs polarization filtering on the incident wave, that is, the left-handed circularly polarized wave is transmitted (the right-handed circularly polarized wave is reflected); the left-handed circularly polarized electromagnetic wave is transmitted from the first metalized blind hole 11 to the third metal layer 5, and the serpentine line structure of the third metal layer 5 adjusts the dispersion of the guided electromagnetic wave; the guided electromagnetic wave is transmitted from the second metalized blind hole 12 to the fifth metal layer 10, and the right-handed circularly polarized patch efficiently radiates the electromagnetic wave.

[0058] The second metal layer 3 is a metal floor, which can effectively prevent the incident wave from directly interacting with the third metal layer 5 . The fourth metal layer 8 is also a metal floor, which can prevent the electromagnetic wave on the third metal layer 5 from being directly radiated.

[0059] The operating frequency band of the metasurface unit is 27-37 GHz. The transmission amplitude within the operating frequency band is greater than 0.7, and the transmission phase can be fully controlled at 360 degrees. At the same time, the slope of the unit transmission phase curve can be designed.

[0060] Example 3:

[0061] This embodiment introduces a broadband millimeter wave flat thin transmissive achromatic metasurface lens, such as Figure 4 As shown, it specifically includes: a dielectric substrate 14, and several super-surface units described in Example 1.

[0062] In this example, a plurality of metasurface units are stacked at different radii around a point on the dielectric substrate 14. The center of each metasurface unit corresponding to each radius falls on the circumference of the circle corresponding to each radius. The rotation angle α of the first metal layer, the third metal layer, the fifth metal layer, the first metalized blind via, and the second metalized blind via of each metasurface unit is set based on the phase of the metasurface unit, as well as the length l of the serpentine line of the third metal layer.

[0063] Among them, the phase of the metasurface unit The expression is as follows:

[0064]

[0065] Where, represents the horizontal coordinate in the coordinate system with the center of the circle as the origin, It represents the vertical coordinate in the coordinate system with the center of the circle as the origin. represents the operating frequency of the metasurface lens, represents the focal length of the metasurface lens, represents the speed of light, Represents pi.

[0066] Furthermore, the different radii are set to 0.5p, 1.5p, 2.5p, ..., (n-0.5)p, where p is the period of the metasurface unit and n represents a natural number.

[0067] Furthermore, the period of the metasurface unit represents the side length of the metasurface unit, which is preferably 3.8 mm.

[0068] Furthermore, the dielectric substrate 14 is formed by a first dielectric layer 2 , a first adhesive layer 4 , a second dielectric layer 6 , a second adhesive layer 7 and a third dielectric layer 9 .

[0069] Furthermore, in one embodiment, r is equal to 0.5p, 1.5p, ..., 10.5p in sequence, that is, there are a total of 11 metasurface units. The theoretically calculated phase distribution of these 11 metasurface units is shown in the dot diagram (Ideal Phase) of Figure (6) a. Then, the metasurface units are optimized according to the electromagnetic simulation software to optimize the rotation angle α and the length l of the serpentine line of the 11 units so that the simulated phase fits the ideal phase as much as possible. It should be noted that in this embodiment, F is selected as 80mm and the maximum value of r is 10.5p. In other cases, the range of r and the size of the focal length F can be modified according to needs. For this embodiment, the distribution of α and the length l of the serpentine line of these 11 metasurface units is as shown in Table 1:

[0070] Table 1: α and l of 11 metasurface units for achromatic lenses

[0071] set 1 2 3 4 5 6 7 8 9 10 11 r 0.5p 1.5p 2.5p 3.5p 4.5p 5.5p 6.5p 7.5p 8.5p 9.5p 10.5p α(deg) 2 -2 4 12 7 6 173 161 143 148 156 l(mm) 0.6 0.6 0.58 0.55 0.53 0.5 0.48 0.46 0.45 0.38 0.3

[0072] According to the above table, the corresponding α and l at different r positions are as follows: Figure 4 As shown in (a), Figure 4(b) shows the distribution of the lens's serpentine lines. The stacked metasurface units form a circular structure, and the overall metasurface lens is square, with physical dimensions of 83.6mm × 83.6mm. Because the designed metasurface units have broadband operating characteristics (27-37GHz) and can convert left-handed circularly polarized waves into right-handed circularly polarized waves, when a left-handed circularly polarized electromagnetic wave is incident, the individual metasurface units work together to focus the transmitted broadband right-handed circularly polarized electromagnetic wave at the same focal length F = 80mm, achieving broadband achromatic electromagnetic focusing.

[0073] Example 4:

[0074] This embodiment introduces a broadband millimeter wave planar thin transmissive achromatic beam deflector, such as Figure 5 As shown, it specifically includes: a dielectric substrate 14, and several super-surface units described in Example 1.

[0075] Multiple columns of metasurface units are stacked at equal intervals along the horizontal axis from one side of the dielectric substrate 14, with each column comprising a plurality of metasurface units. The center point position of each column of metasurface units corresponds to the interval value of the horizontal axis. Based on the phase of each metasurface unit, the rotation angle α of the first metal layer, the third metal layer, the fifth metal layer, the first metalized blind via, and the second metalized blind via of each metasurface unit is set, as well as the length l of the serpentine line of the third metal layer.

[0076] Among them, the phase of the metasurface unit The expression is as follows:

[0077]

[0078] Where, Indicates the coordinate value of the horizontal coordinate with the endpoint on one side of the dielectric substrate as the origin, represents the operating frequency of the metasurface beam deflector, represents the refraction angle of the transmitted beam, represents the initial phase, represents the speed of light, Represents pi.

[0079] Furthermore, the interval values ​​of the horizontal axis are set to 0.5p, 1.5p, 2.5p, ..., (n-0.5)p, where p is the period of the metasurface unit and n represents a natural number.

[0080] Furthermore, the period of the metasurface unit represents the side length of the metasurface unit, which is preferably 3.8 mm.

[0081] Furthermore, the dielectric substrate 14 is formed by a first dielectric layer 2 , a first adhesive layer 4 , a second dielectric layer 6 , a second adhesive layer 7 and a third dielectric layer 9 .

[0082] Furthermore, in one embodiment, x is successively equal to 0.5p, 1.5p, ..., 21.5p, that is, there are 22 types of metasurface units. The theoretically calculated phase distribution of these 22 metasurface units is shown in the dot diagram (Ideal Phase) of Figure (6) b. Then, the metasurface units are optimized according to the electromagnetic simulation software so that the simulated phase fits the ideal phase as much as possible, and the rotation angle α and the length l of the serpentine line of the 22 metasurface units are obtained. It should be noted that in this embodiment, the refraction angle θ of the transmitted electromagnetic beam is t The selected value is 15°, and the maximum value of x is 21.5p. In other cases, the range of x and the refraction angle θ of the transmitted electromagnetic beam can be modified as needed. t For this embodiment, the rotation angle α and the length l of the serpentine line of these 22 units are distributed as shown in Table 2:

[0083] Table 2: α and l of 22 metasurface units for achromatic beam deflectors

[0084] set 1 2 3 4 5 6 7 8 9 10 11 x 0.5p 1.5p 2.5p 3.5p 4.5p 5.5p 6.5p 7.5p 8.5p 9.5p 10.5p α(deg) 178 1 165 19 97 123 122 113 110 100 95 l(mm) 1 0.95 0.94 0.83 0.63 0.55 0.52 0.5 0.47 0.45 0.42

[0085] set 12 13 14 15 16 17 18 19 20 21 22 x 11.5p 12.5p 13.5p 14.5p 15.5p 16.5p 17.5p 18.5p 19.5p 20.5p 21.5p α(deg) 84 91 80 75 76 67 61 46 36 27 41 l(mm) 0.4 0.35 0.33 0.3 0.25 0.23 0.2 0.2 0.18 0.15 0

[0086] According to the α and l corresponding to different x points in the above table, the final stacked metasurface lens is as follows Figure 5 (a), where Figure 5 (b) is the distribution diagram of the serpentine line. The metasurface beam deflector is square in shape and has a physical size of 83.6mm×83.6mm. Because the designed metasurface unit has broadband operating characteristics (27-37GHz), when a left-handed circularly polarized electromagnetic wave is incident, the various units work together to form a phase mutation at the interface, refracting the transmitted broadband right-handed circularly polarized electromagnetic wave at the same transmission angle θ. t =15°, broadband achromatic beam deflection is achieved.

[0087] Example 5:

[0088] This embodiment introduces the simulation of the metasurface lens and beam deflector in embodiments 3 and 4. Figure 6Figure a shows a comparison of the phase curve required by the theory of the metasurface lens and the phase curve obtained by actual simulation. The horizontal axis of the figure shows that the operating frequency range of the unit is 27-37GHz, and the vertical axis is the transmission phase size of the unit, ranging from -750° to 50°. The figure contains a total of 11 phase curves of units, where r represents the radius from the center of the achromatic lens, and p = 3.8mm is the period of the unit. The achromatic lens is composed of a combination of these 11 units. The dot diagram in the figure is the ideal phase distribution required for the achromatic lens, and the solid line is the unit transmission phase curve obtained by electromagnetic simulation. It can be seen that the phase curve obtained by simulation and the ideal phase curve are in good agreement with each other, proving the feasibility of designing achromatic phase for metasurface units.

[0089] Figure 6 Figure b compares the theoretical phase curve required for a metasurface beam deflector with the actual phase curve obtained by simulation. The horizontal axis of the figure indicates the unit's operating frequency range of 27-37 GHz, and the vertical axis shows the unit's transmission phase, ranging from -800° to 400°. The figure contains phase curves for 22 types of units, and the achromatic beam deflector is composed of these 22 units. The dotted plot in the figure shows the ideal phase distribution required for an achromatic beam deflector, and the solid line is the unit transmission phase curve obtained by electromagnetic simulation. It can be seen that the phase curve obtained by unit simulation and the ideal phase curve are in good agreement, demonstrating the feasibility of designing an achromatic beam deflector using metasurface units.

[0090] Figure 7 The near-field test results of the metasurface lens are given, where (a) shows the right-handed circularly polarized electric field amplitude distribution of the xoz cross section with y = 0 mm, where the x-axis ranges from -50 mm to 50 mm, and the z-axis ranges from -10 mm to -150 mm. Figure (b) shows the electric field amplitude distribution of the xoy cross section with z = 80 mm, where the x-axis ranges from -50 mm to 50 mm, and the y-axis ranges from -50 mm to -50 mm. Figure 6 (a) The frequency range is 27 to 37 GHz, with a frequency interval of 2 GHz. It can be seen that from 27 to 37 GHz, and at 27 GHz, 29 GHz, 31 GHz, 33 GHz, 35 GHz, and 37 GHz, the focal spot center on the xoz cross section at each frequency point falls precisely at z = 80 mm. Furthermore, on the xoy cross section at z = -80 mm, the strongest electric field at each frequency point is concentrated at the coordinate center, demonstrating that the lens has excellent two-dimensional achromatic focusing.

[0091] Figure 8 A comparison diagram of the simulation and measurement of the far-field beam of the metasurface beam deflector, where the black line represents the electromagnetic simulation result and the gray line represents the measured result. Figure 7The frequency span of (a) to (f) is 27 GHz to 37 GHz, and the interval is also 2 GHz. The horizontal coordinate range of the far field direction is -90° to +90°, and the normalized intensity range is 0 dB to -50 dB. The test results show that Figure 6 (a) The frequency range is 27 to 37 GHz. Within the frequency range of 27 GHz to 37 GHz, all transmitted beams are precisely pointed within a 15° direction, demonstrating the precise dispersion control capability of the metasurface beam deflector. Furthermore, the 3 dB beamwidth of the far-field beam from 27 GHz to 37 GHz gradually decreases from 7.1° to 6°, and the sidelobe level of all beams remains below -10 dB, demonstrating the excellent performance of the metasurface beam deflector.

[0092] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A broadband millimeter-wave flat, thin, transmissive achromatic metasurface unit, characterized by: Specifically include: A first metal layer, a first dielectric layer, a second metal layer, a first adhesive layer, a third metal layer, a second dielectric layer, a second adhesive layer, a fourth metal layer, a third dielectric layer, and a fifth metal layer are stacked in sequence; The first metal layer and the third metal layer are connected through a first metalized blind via, and the first metalized blind via does not contact the second metal layer; the third metal layer and the fifth metal layer are connected through a second metalized blind via, and the second metalized blind via does not contact the fourth metal layer; a back-drilled via is provided between the third dielectric layer and the second dielectric layer; The first metal layer and the fifth metal layer are arc-shaped metal patches of the same shape, used to convert the received left-hand circularly polarized waves into right-hand circularly polarized waves for radiation; The second metal layer is a metal floor, the fourth metal layer is a metal floor; the third metal layer is configured as a serpentine line structure; The left-handed circularly polarized electromagnetic wave is transmitted from the first metalized blind via to the third metal layer, where the serpentine structure of the third metal layer adjusts the dispersion of the guided electromagnetic wave. The guided electromagnetic wave is transmitted from the second metalized blind via to the fifth metal layer, where the right-handed circularly polarized patch radiates the electromagnetic wave. The first metal layer, the third metal layer, the fifth metal layer, the first metalized blind hole and the second metalized blind hole are rotated to adjust the size of the transmission phase.

2. The broadband millimeter-wave flat, thin, transmissive achromatic metasurface unit according to claim 1, characterized in that: The dielectric constants of the first dielectric layer, the second dielectric layer and the third dielectric layer are 3.50, and their thicknesses are 1 mm, 0.254 mm and 1 mm respectively; the dielectric constants of the first adhesive layer and the second adhesive layer are 3.52, and their thicknesses are 0.2 mm and 0.1 mm respectively.

3. The broadband millimeter-wave flat, thin, transmissive achromatic metasurface unit according to claim 1, characterized in that: The expression between the serpentine length of the third metal layer and the slope of the metasurface unit transmission phase curve is as follows: ； Where: k represents the slope of the transmission phase curve of the metasurface unit, l is the overall length of the serpentine line, and γ is a constant.

4. The broadband millimeter-wave flat, thin, transmissive achromatic metasurface unit according to claim 1, characterized in that: The first metal layer, the third metal layer, the fifth metal layer, the first metalized blind hole and the second metalized blind hole are rotated α degrees to reduce the cross-polarization transmission phase of the metasurface unit by 2α degrees, so that the size of the transmission phase can be adjusted.

5. A broadband millimeter-wave flat, thin, transmissive achromatic metasurface lens, characterized by: Specifically include: A dielectric substrate, and several metasurface units according to any one of claims 1 to 4; In which, with a point on the dielectric substrate as the center of a circle, a plurality of metasurface units are stacked at different radii around the same center; the center of the metasurface unit corresponding to each radius falls on the circumference corresponding to each radius; according to the phase of each metasurface unit, the rotation angle α of the first metal layer, the third metal layer, the fifth metal layer, the first metalized blind via, and the second metalized blind via of each metasurface unit, as well as the length l of the serpentine line of the third metal layer, are set; Among them, the phase of the metasurface unit The expression is as follows: ； Where, Indicates the coordinate value of the horizontal coordinate with the endpoint on one side of the dielectric substrate as the origin, represents the operating frequency of the metasurface lens, represents the refraction angle of the transmitted beam, represents the initial phase, represents the speed of light, Represents pi.

6. The broadband millimeter-wave flat, thin, transmissive achromatic metasurface lens according to claim 5, characterized in that: The different radii are set to 0.5p, 1.5p, 2.5p, ..., (n-0.5)p, where p is the period of the metasurface unit and n represents a natural number.

7. A broadband millimeter-wave planar thin-type transmissive achromatic metasurface beam deflector, characterized by: Specifically include: A dielectric substrate, and several metasurface units according to any one of claims 1 to 4; Multiple columns of metasurface units are stacked at equal intervals along the horizontal axis from one side of the dielectric substrate, and each column of metasurface units is provided with a number of metasurface units; the center point position of each column of metasurface units corresponds to the interval value of the horizontal axis; according to the phase of each metasurface unit, the rotation angle α of the first metal layer, the third metal layer, the fifth metal layer, the first metalized blind via, and the second metalized blind via of each metasurface unit is set, as well as the length l of the serpentine line of the third metal layer; Among them, the phase of the metasurface unit The expression is as follows: ； Where, Indicates the coordinate value of the horizontal coordinate with the endpoint on one side of the dielectric substrate as the origin, represents the operating frequency of the metasurface lens, represents the refraction angle of the transmitted beam, represents the initial phase, represents the speed of light, Represents pi.

8. The broadband millimeter-wave planar thin transmissive achromatic metasurface beam deflector according to claim 7, characterized in that: The interval values ​​of the horizontal axis are set to 0.5p, 1.5p, 2.5p, ..., (n-0.5)p, where p is the period of the metasurface unit and n represents a natural number.

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