Ampitude and phase independent controlled double-layer all-metal huygens super surface unit and antenna

Abstract

The application relates to the technical field of super surfaces, and discloses a double-layer full-metal Huygens super surface unit with independent amplitude and phase control and an antenna. The double-layer full-metal Huygens super surface unit with independent amplitude and phase control does not need a dielectric substrate, can avoid the problem of antenna performance decline caused by the dielectric constant change of the dielectric substrate under extreme environments such as high temperature and high power radiation, and simultaneously reduces the cost. The double-layer structure can effectively reduce the profile height and reduce transmission loss. By arranging the inner concentric folding split ring grooves and the outer concentric split ring grooves with specific structures on the metal plate, on the basis of realizing 360-degree transmission phase control and keeping the transmission amplitude higher than -2 dB, independent control of the phase and the amplitude can also be realized, the deficiency that the existing double-layer full-metal transmission type super surface can only be phase-controlled is made up, and the complex wave front control requirements such as sidelobe suppression, high-precision beam forming, complex amplitude vector holography and the like can be met.

Description

Technical Field

[0001] This invention belongs to the field of metasurface technology, specifically a bilayer all-metal Huygens metasurface unit and antenna with independent amplitude and phase control. Background Technology

[0002] Metasurfaces are artificial two-dimensional materials composed of subwavelength structural units, possessing the unique ability to flexibly control the phase, amplitude, and polarization state of electromagnetic waves. Among them, Huygens metasurfaces, based on Huygens' principle, can achieve highly efficient and nearly arbitrary electromagnetic wavefront manipulation by simultaneously controlling the responses of equivalent electric and magnetic dipoles. They have been widely used in fields such as ultrathin metallic lenses, high-gain low-profile antennas, vortex beam generation, and polarization conversion.

[0003] Based on the different directions of electromagnetic wave manipulation, metasurfaces can be divided into transmissive and reflective types. Transmissive metasurfaces, because their feed and emitted waves are located in different spatial regions, can effectively avoid feed obstruction problems and have become a research hotspot. Currently, most research on transmissive metasurfaces focuses on phase manipulation, achieving 360° phase control through unit structure design, thereby realizing basic functions such as beamforming and beam scanning. However, in complex wavefront manipulation such as sidelobe suppression, high-precision beamforming, and complex amplitude vector holography, it is necessary to simultaneously and independently control both phase and amplitude.

[0004] Most existing amplitude and phase independent modulation schemes rely on dielectric substrates. However, the dielectric constant of dielectric substrates is prone to change under extreme environments such as high temperature and high power radiation, leading to a decrease in antenna performance. Furthermore, dielectric substrates are expensive. The academic community generally believes that at least three metal layers are needed to achieve 360° transmission phase shift and a transmission amplitude better than -3dB for electromagnetic waves. However, multi-layer structures introduce problems such as increased profile height and exacerbated transmission loss. To address this, Chinese patent document CN115207638A discloses a transmission array and antenna based on an all-metal Huygens metasurface. This transmission array adopts a double-layer all-metal structure with an air layer in between, eliminating the need for a dielectric substrate. By using different gap positions on the upper and lower metal patches, when electric and magnetic dipoles are formed on the upper and lower Huygens metasurfaces, surface currents in opposite directions are generated in the upper and lower layers, simultaneously producing Huygens resonance. This achieves 360° transmission phase modulation while maintaining a transmission amplitude higher than -3dB. 2dB. Although the above-mentioned double-layer all-metal transmissive metasurface avoids the problems of dielectric substrates and multilayer structures, it can only achieve phase control. Summary of the Invention

[0005] This invention provides a double-layer all-metal Huygens metasurface element and antenna with independent amplitude and phase control, which solves the problems of existing independent amplitude and phase control using a dielectric substrate, which easily leads to changes in the dielectric constant and causes a decrease in antenna performance, and the problem that without using a dielectric substrate, it is impossible to simultaneously control the phase and amplitude independently.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A phase- and amplitude-independently modulated double-layer all-metal Huygens metasurface unit includes multiple periodically distributed transmission units. Each transmission unit includes two metal plates with an air layer between them. Each metal plate has concentrically folded annular grooves etched into it. Each concentrically folded annular groove includes two first arc-shaped grooves with opposite and symmetrical arc openings. The two first arc-shaped grooves are not connected. The ends of the first arc-shaped grooves are connected to rectangular grooves parallel to the lines of symmetry of the two first arc-shaped grooves. The rectangular grooves do not extend beyond the outer edge of the first arc-shaped grooves. The two rectangular grooves are not connected. Concentrically divided annular grooves are provided outside the concentrically folded annular grooves. Each concentrically divided annular groove includes two second arc-shaped grooves with opposite and symmetrical arc openings. The two second arc-shaped grooves are not connected. The lines of symmetry of the first and second arc-shaped grooves coincide.

[0008] Preferably, it includes 15×15 transmission units.

[0009] Preferably, the radius of the first arc-shaped groove is 2 mm smaller than the radius of the second arc-shaped groove.

[0010] Preferably, the distance between the two metal plates is 2.5-3.5 mm.

[0011] Preferably, the distance between the two metal plates is 3mm.

[0012] Preferably, the distance between the two rectangular grooves is g1, and the distance between the ends of the two second arc-shaped grooves is g2, where g2 = 2.5 × g1 - 0.5 mm.

[0013] A transmission array antenna with a phase-independently modulated double-layer all-metal Huygens metasurface element includes a feed horn and the aforementioned phase-independently modulated double-layer all-metal Huygens metasurface element, wherein the phase center of the feed horn is located at the focal point of the transmission array.

[0014] Preferably, the distance between the phase center of the feed horn and the center of the metasurface is F = 170 mm.

[0015] A phase control method for a bilayer all-metal Huygens metasurface unit cell with independent amplitude and phase modulation includes:

[0016] A phase library is established, which includes the radius of the first arc groove, the radius of the second arc groove, the distance between the rectangular grooves, the distance between the ends of the two second arc grooves, and the phase. The interval between adjacent phases is 30°. The phase is adjusted by adjusting the radius of the first arc groove, the radius of the second arc groove, the distance between the rectangular grooves, and the distance between the ends of the two second arc grooves according to the phase library.

[0017] A method for amplitude control of a bilayer all-metal Huygens metasurface unit cell with independent amplitude and phase regulation involves rotating the entire transmission unit cell structure by an angle α. After rotation, the same polarization transmission amplitude is equal to the original transmission amplitude. The amplitude can be continuously adjusted by rotating the unit angle, while maintaining a relatively stable phase.

[0018] Compared with existing technologies, the present invention has the following advantages: The present invention provides a double-layer all-metal Huygens metasurface unit with independent amplitude and phase control. By adopting a structural design of double-layer metal plates and an air layer, it eliminates the need for a dielectric substrate, thus avoiding the antenna performance degradation caused by changes in the dielectric constant of the dielectric substrate under extreme environments such as high temperature and high power radiation. It also reduces costs, and its double-layer structure effectively reduces the profile height and transmission loss. Furthermore, by setting specific inner and outer concentric folded ring slots on the metal plate, it achieves 360° transmission phase control and maintains a transmission amplitude higher than -2dB, while also enabling independent phase and amplitude control. This overcomes the limitation of existing double-layer all-metal transmissive metasurfaces that can only control phase, and can meet the complex wavefront manipulation requirements such as sidelobe suppression, high-precision beamforming, and complex amplitude vector holography. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the antenna structure according to an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of a phase- and amplitude-independently modulated bilayer all-metal Huygens metasurface unit according to an embodiment of the present invention, where a is a front view and b is a top view.

[0021] Figure 3 Table of specific parameter values ​​for the transmission unit in embodiments of the present invention

[0022] Figure 4 This is a schematic diagram of the structure of the transmission unit after rotation according to an embodiment of the present invention.

[0023] Figure 5 The curve shows the transmission response of the unit in the embodiment of the present invention as a function of rotation angle α.

[0024] Figure 6 This is a phase compensation distribution diagram of the metasurface in an embodiment of the present invention.

[0025] Figure 7This is an amplitude distribution diagram of the metasurface in an embodiment of the present invention.

[0026] Figure 8 (a) is the normalized simulation and measured radiation pattern of the metasurface of the present invention at 10 GHz on the xoz surface. Figure 8 (b) is the normalized simulation and measured radiation pattern of the metasurface at 10 GHz of the yoz surface in this invention;

[0027] Figure 9 The surface current distribution of the top and bottom metal plates of the transmission unit in this embodiment of the invention;

[0028] Figure 10 This is the transmission response of the transmission unit in an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0031] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0032] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this invention, it should be noted that unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," and "set up" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components.

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0034] like Figure 2 As shown, this invention provides a phase- and amplitude-independently tunable double-layer all-metal Huygens metasurface unit, comprising multiple periodically distributed transmission units. Each transmission unit includes two metal plates 3, with an air layer between the two metal plates 3. Each metal plate 3 has concentrically folded annular grooves 4 etched into it. Each concentrically folded annular groove 4 includes two first arc-shaped grooves with opposite and symmetrical arc openings, which are not connected. The ends of the first arc-shaped grooves are connected to rectangular grooves parallel to the symmetry lines of the two first arc-shaped grooves. The rectangular grooves do not extend beyond the outer edge of the first arc-shaped grooves, and the two rectangular grooves are not connected. Concentrically folded annular grooves 5 are provided outside the concentrically folded annular grooves 4. Each concentrically folded annular groove 5 includes two second arc-shaped grooves with opposite and symmetrical arc openings, which are not connected. The symmetry lines of the first and second arc-shaped grooves coincide.

[0035] By employing a double-layer metal plate and air layer structural design, no dielectric substrate is required, thus avoiding the antenna performance degradation caused by changes in the dielectric constant of the dielectric substrate under extreme environments such as high temperature and high power radiation. This also reduces costs. The double-layer structure effectively reduces the profile height and transmission loss. Furthermore, by setting specific inner and outer concentric folded ring slots on the metal plate, it achieves 360° transmission phase modulation and maintains a transmission amplitude above -2dB, while also enabling independent phase and amplitude modulation. This overcomes the limitation of existing double-layer all-metal transmissive metasurfaces that only allow phase control, meeting the complex wavefront manipulation requirements such as sidelobe suppression, high-precision beamforming, and complex amplitude vector holography.

[0036] The detailed structure is as follows:

[0037] The metal plate 3 is perforated with an inner layer of concentric folded annular grooves 4 and an outer layer of concentric annular grooves 5. The thickness of the air layer is h = 2.5-3.5 mm, with an optimal h = 3 mm. A 3 mm spacing ensures that the electromagnetic coupling between the upper and lower metal layers is at a moderate level, avoiding the problems of excessively strong coupling due to being too close or too weak coupling due to being too far apart. The thickness of the metal plate 3 is t = 0.4 mm, the side length of the metal plate 3 is p = 14 mm, and the groove width of the concentric folded annular grooves 4 and 5 is w = 1 mm. The outer radius of the concentric folded annular groove 4 is r1, the gap of the concentric folded annular groove 4 in the x-direction is g1, the outer radius of the concentric annular groove 5 is r2, and the gap of the concentric annular groove 5 in the y-direction is g2, where g2 = 2.5 × g1 - 0.5 mm.

[0038] Unit working principle:

[0039] Under y-polarization excitation at 10 GHz, the surface current distribution of the top and bottom metal plates of the cell is as follows: Figure 9 As shown, the induced current is mainly distributed in the opening gap of the concentric folded ring groove 4, and in the gap region between the concentric folded ring groove 4 and the concentric ring groove 5. Specifically, at t=0 and t=T / 2 (T is the excitation signal period), the current flow direction of the top and bottom layers is consistent, forming an electric dipole polarized along the y-direction. At t=T / 4 and t=3T / 4, the reverse surface current induced in the overlapping parallel region of the top and bottom layers, together with the displacement current in the air layer, constitutes a current loop, thereby forming a magnetic dipole polarized along the x-direction. In this way, the orthogonally distributed electric dipoles and magnetic dipoles together constitute a Huygens source.

[0040] This metasurface unit employs a dual-resonant structure design, specifically featuring concentric folded ring grooves 4 in the inner layer and concentric ring grooves 5 in the outer layer. This dual-resonant structure can excite more resonant modes, thereby effectively expanding the phase coverage range of the unit. The unit's transmission response is as follows: Figure 10 As shown, the unit generates four |S21| peaks at f1, f2, f3, and f4, with corresponding values ​​of -0.07dB, -0.7dB, -0.08dB, and -0.06dB, respectively. Therefore, the unit forms a flat passband with high transmission amplitude (<-2dB) over a wide frequency band from 8.4GHz to 12.3GHz, and its transmission phase shift ranges from 10° to -524°, meeting the requirement of 360° phase coverage within the relevant frequency band.

[0041] Working principle of transmissive metasurface antennas:

[0042] like Figure 1As shown, the spherical wave emitted by the feed horn 1 passes through the metasurface 2, and the sidelobe level of the radiated beam is suppressed by Taylor amplitude-weighted joint phase compensation. The target is a sidelobe level of -25 dB along the y-direction at 10 GHz. Figure 6 This is the phase compensation distribution diagram of metasurface 2. Figure 7 This is the amplitude distribution diagram of metasurface 2.

[0043] Figure 8 (a) Figure 8 (b) Normalized simulated / measured radiation patterns of metasurface 2 at 10 GHz for the xoz and yoz planes are presented. The simulated / measured gain and aperture efficiency are 24.6 / 24.2 dBi and 46.9% / 42.3%, respectively. The simulated / measured sidelobe levels in the xoz and yoz planes are -24.1 / -24.3 dB and -24.2 / -24.6 dB, respectively.

[0044] This invention also provides a phase control method for a bilayer all-metal Huygens metasurface unit with independent amplitude and phase regulation, comprising:

[0045] Phase control is achieved by adjusting the geometric parameters r1, g1, r2, g2 of the unit structure to excite Huygens resonance. These parameters directly control the resonance characteristics of the orthogonal electric and magnetic dipoles, thereby achieving a 360° transmission phase shift. To simplify the design process, r2 and r1 are set to a fixed relationship: r2 = r1 – 2mm, effectively reducing the number of optimization parameters. Based on this, a phase library containing 12 discrete phase states is constructed, with adjacent states spaced 30° apart, to discretize the required compensation phase. The structure of this phase library is as follows: Figure 3 As shown.

[0046] This invention also provides a method for amplitude control of a bilayer all-metal Huygens metasurface unit cell with independent amplitude and phase regulation, comprising:

[0047] Amplitude control is based on the principle of polarization conversion to control the overall rotation angle of the unit structure. Implementation. The rotated unit structure is as follows: Figure 4 As shown. Analysis of its transmission characteristics reveals that the amplitude of the same-polarization transmission after rotation is [amount missing]. times, and rotation angle The sign of the polarization does not affect the phase characteristics of the same polarization transmission, such as Figure 5 As shown. Therefore, continuous amplitude control can be achieved by rotating the unit angle, while maintaining relative phase stability.

[0048] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0049] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A bilayer all-metal Huygens metasurface unit with independently modulated amplitude and phase, characterized in that, It includes multiple periodically distributed transmission units, each transmission unit includes two metal plates (3), with an air layer between the two metal plates (3), and each metal plate (3) has a concentric folded ring groove (4) etched on it. The concentric folded ring groove (4) includes two first arc grooves with opposite and symmetrical arc openings. The two first arc grooves are not connected. The ends of the first arc grooves are connected to a rectangular groove parallel to the symmetry line of the two first arc grooves. The rectangular groove does not exceed the outer edge of the first arc groove. The two rectangular grooves are not connected. The concentric folded ring groove (4) is provided with a concentric ring groove (5) outside. The concentric ring groove (5) includes two second arc grooves with opposite and symmetrical arc openings. The two second arc grooves are not connected. The symmetry lines of the first arc groove and the second arc groove coincide. The phase is adjusted by adjusting the radius of the first arc groove, the radius of the second arc groove, the distance between the rectangular grooves, and the distance between the ends of the two second arc grooves; Amplitude control is achieved by rotating the angle of the transmission unit.

2. The amplitude- and phase-independently modulated bilayer all-metal Huygens metasurface unit according to claim 1, characterized in that, It includes 15×15 transmission units.

3. The amplitude- and phase-independently modulated bilayer all-metal Huygens metasurface unit according to claim 1, characterized in that, The radius of the first arc-shaped groove is 2 mm smaller than the radius of the second arc-shaped groove.

4. The amplitude- and phase-independently tunable bilayer all-metal Huygens metasurface unit according to claim 1, characterized in that, The distance between the two metal plates (3) is 2.5-3.5 mm.

5. The amplitude- and phase-independently modulated bilayer all-metal Huygens metasurface unit according to claim 4, characterized in that, The distance between the two metal plates (3) is 3mm.

6. The amplitude- and phase-independently modulated bilayer all-metal Huygens metasurface unit according to claim 1, characterized in that, The distance between the two rectangular grooves is g1, and the distance between the ends of the two second arc-shaped grooves is g2, where g2 = 2.5 × g1 - 0.5 mm.

7. A transmission array antenna with a double-layer all-metal Huygens metasurface unit for independent amplitude and phase control, characterized in that, It includes a feed horn and a phase-independently modulated bilayer all-metal Huygens metasurface unit as described in any one of claims 1-6, wherein the phase center of the feed horn is located at the focal point of the transmission array.

8. A transmission array antenna with amplitude and phase independently modulated double-layer all-metal Huygens metasurface unit according to claim 7, characterized in that, The distance between the phase center of the feed horn (1) and the center of the metasurface (2) is F = 170 mm.

9. A phase control method for a bilayer all-metal Huygens metasurface unit with independent amplitude and phase modulation, characterized in that, A bilayer all-metal Huygens metasurface unit with independent amplitude and phase control as described in any one of claims 1-6, comprising: Establish a phase library with respect to the radius of the first arc groove, the radius of the second arc groove, the distance between the rectangular grooves, the distance between the ends of the two second arc grooves, and the phase. The interval between adjacent phases is 30°. Adjust the phase by adjusting the radius of the first arc groove, the radius of the second arc groove, the distance between the rectangular grooves, and the distance between the ends of the two second arc grooves according to the phase library.

10. A method for amplitude and phase independently modulated amplitude control of a bilayer all-metal Huygens metasurface unit, characterized in that, Based on the amplitude-phase independently modulated bilayer all-metal Huygens metasurface unit according to any one of claims 1-6, rotating the entire transmission unit structure by an angle α results in the same polarization transmission amplitude being equal to the original transmission amplitude. The amplitude can be continuously adjusted by rotating the angle of the transmission unit, while maintaining a relatively stable phase.

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