A folded reflectarray antenna based on dual-metasurfaces

Abstract

The application provides a kind of folded reflectarray antenna based on double metasurface, comprising: feed antenna;Reflective metasurface is connected to the periphery of the feed antenna, comprising a plurality of equidistant arrangement of reflective metasurface unit;Polarization grid array is spaced apart on the side of reflective metasurface, at least part of the polarization grid array forms corresponding to cover the first transmission area of the reflective metasurface;Transmissive metasurface is spaced apart on the side of the polarization grid array away from the reflective metasurface, at least part of the transmissive metasurface forms corresponding to cover the second transmission area of the first transmission area, and the transmissive metasurface includes a plurality of equidistant arrangement of transmissive metasurface unit at least in the second transmission area.The above scheme can twice adjust the phase of electromagnetic wave radiated by traditional folded reflectarray antenna, and finally realize the expansion of gain bandwidth of folded reflectarray antenna.

Description

Technical Field

[0001] This invention relates to the field of folded reflective antennas, and more particularly to a folded reflective array antenna based on dual metasurfaces. Background Technology

[0002] Achieving broadband directional radiation remains a major challenge in the field of foldable reflective array antennas. Many foldable reflective array antennas with broadband characteristics have been proposed, and achieving broadband directional radiation mainly relies on designing broadband metasurface elements and metasurface optimization design methods based on array theory. However, the design freedom of the reflective metasurfaces used in current foldable reflective array antennas is limited, resulting in a relatively narrow bandwidth for directional radiation, which requires further improvement. Summary of the Invention

[0003] The main objective of this invention is to provide a folded reflective array antenna based on dual metasurfaces, which solves the problems of narrow gain bandwidth and broadband radiation dependence on broadband radiating elements in existing folded reflective array antennas.

[0004] In a first aspect, the present invention provides a folded reflective array antenna based on a dual metasurface.

[0005] A folded reflective array antenna based on dual metasurfaces, comprising:

[0006] Feed antenna;

[0007] A reflective metasurface, which is connected to the periphery of the feed antenna, includes several equally spaced reflective metasurface units;

[0008] A polarization grating array is spaced apart on one side of the reflective metasurface, and at least a portion of the polarization grating array forms a first transmission region corresponding to and covering the reflective metasurface;

[0009] A transmissive metasurface is spaced apart on the side of the polarization grating array away from the reflective metasurface. At least a portion of the transmissive metasurface forms a second transmissive region corresponding to and covering the first transmissive region. The transmissive metasurface includes at least a plurality of equally spaced transmissive metasurface units within the second transmissive region.

[0010] In some embodiments, the phase compensation required for each of the transmissive metasurface units within the second transmission region is obtained by calculating the electric field phase at the center position of the transmissive metasurface unit at multiple frequencies to be optimized and the reference phase at the corresponding frequencies using the finite-time integration method; wherein...

[0011] Phase compensation required at (x,y) in the second transmission region:

[0012] in This represents the electric field phase calculated by the finite-time integration method at the second transmission region (x,y) at the i-th frequency point. This represents the reference phase at the i-th frequency point.

[0013] In some embodiments, the reference phase at each frequency point It is obtained by optimizing the weighted phase optimization function based on the illumination factor; The weighted phase optimization function based on the illumination factor includes:

[0014]

[0015] Where s (i) w represents the correction weight related to the electrical size of the transmissive metasurface aperture at the i-th frequency point. (i) (x,y) represents the irradiation weight of the transmissive metasurface unit at the second transmissive region (x,y), w (i) (x,y) is taken as the normalized transmission electric field modulus calculated by the finite-time integration method at (x,y) in the second transmission region, and φ realized(i) (x,y) represents the phase compensation achieved by the transmissive metasurface unit at the second transmissive region (x,y).

[0016] In some embodiments, the overall optimization objective function for each of the transmissive metasurface units arranged within the second transmissive region is:

[0017]

[0018] In some embodiments, the phase compensation required by each reflective metasurface unit in the orthogonal direction on the reflective metasurface is divided into:

[0019]

[0020] Where k is the wavenumber at the operating frequency, and d(i,j) is the distance from the phase center of the feed antenna to the geometric center of the (i,j)th reflective metasurface element. Let (x(i,j),y(i,j)) represent the radiation direction of the beam, and (x(i,j),y(i,j)) represent the coordinates of the geometric center of the (i,j)th reflective metasurface unit.

[0021] The objective function for minimizing the phase compensation error in the orthogonal directions of each reflective metasurface unit on the reflective metasurface is:

[0022] Δφ min (i,j)=|φ x (l x ,l y )-φ x (i,j)|+|φ y (l y,l x )-φ y (i,j)|

[0023] Where φ x (l x ,l y φ represents the phase compensation achieved by the (i,j)th metasurface unit in the x-direction. y (l y ,l x ) represents the phase compensation achieved by the (i,j)th metasurface unit in the y-direction.

[0024] In some embodiments, the transmissive metasurface includes at least two dielectric layers;

[0025] On the surfaces of the two dielectric plates that are far apart from each other, there are a number of parallel metal strips spaced apart, and the metal strips on the two surfaces are orthogonally arranged.

[0026] In some embodiments, the dielectric substrate is configured as two layers, and the metal strip is disposed on the side of the two dielectric substrates that are far apart from each other.

[0027] In some embodiments, the periodic dimension of the transmissive metasurface unit is 9 mm; the width of the metal strip is 0.9 mm; and the gap width between the metal strips is 0.9 mm.

[0028] In some embodiments,

[0029] The transmissive metasurface unit is arranged in an open ring structure, including:

[0030] The two arc segments are located on the same circumference and are symmetrical about the center. The two arc segments are spaced apart in the circumferential direction to form an opening angle. The arc segments are metal structures.

[0031] A connecting strip connects the midpoints of two arc segments radially, and the connecting strip is a square metal structure.

[0032] In some embodiments, the inner diameter of the arc segment is 3.2 mm, the outer diameter of the arc segment is 4.3 mm, and the width of the connecting strip is 1.8 mm.

[0033] The folded reflective array antenna based on dual metasurfaces provided by this invention has an additional transmissive metasurface on the other side of the polarization grating array relative to the reflective metasurface. This allows for the optimization of the transmission phase of each transmissive metasurface unit within the transmissive metasurface, providing additional design freedom. This enables secondary adjustment of the phase of the electromagnetic waves radiated by the traditional folded reflective array antenna, ultimately expanding the gain and bandwidth of the folded reflective array antenna. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the bandwidth-enhanced folded reflective array antenna based on dual metasurfaces in an embodiment of the present invention;

[0035] Figure 2 This refers to the phase compensation in the x-direction for each metasurface unit on the aperture of the reflective metasurface in this embodiment of the invention;

[0036] Figure 3 This refers to the phase compensation in the y-direction for each metasurface unit on the aperture of the reflective metasurface in this embodiment of the invention;

[0037] Figure 4 This refers to the phase compensation error of each metasurface unit on the reflective metasurface in the orthogonal direction in the embodiments of the present invention;

[0038] Figure 5 This is the phase compensation required at 11 GHz for the transmissive polarization conversion metasurface in the embodiments of the present invention;

[0039] Figure 6 This is the phase compensation required at 12 GHz for the transmissive polarization conversion metasurface in the embodiments of the present invention;

[0040] Figure 7 This is the phase compensation required at 13 GHz for the transmissive polarization conversion metasurface in the embodiments of the present invention;

[0041] Figure 8 This refers to the normalized weights of the transmissive polarization conversion metasurface at 11 GHz in this embodiment of the invention.

[0042] Figure 9 This refers to the normalized weights of the transmission-type polarization conversion metasurface at 12 GHz in this embodiment of the invention.

[0043] Figure 10 This refers to the normalized weights of the transmissive polarization conversion metasurface at 13 GHz in this embodiment of the invention.

[0044] Figure 11 This refers to the phase compensation error of the transmissive polarization conversion metasurface at 11 GHz in this embodiment of the invention.

[0045] Figure 12 This refers to the phase compensation error of the transmissive polarization conversion metasurface at 12 GHz in this embodiment of the invention.

[0046] Figure 13 This refers to the phase compensation error of the transmissive polarization conversion metasurface at 13 GHz in this embodiment of the invention.

[0047] Figure 14This is the optimized structural form of the transmission-type polarization conversion metasurface in the embodiments of the present invention;

[0048] Figure 15 This is a three-dimensional schematic diagram of a reflective anisotropic metasurface unit in an embodiment of the present invention;

[0049] Figure 16 This is a top view of a reflective anisotropic metasurface unit in an embodiment of the present invention;

[0050] Figure 17 This is a three-dimensional schematic diagram of a reflective polarization conversion metasurface unit in an embodiment of the present invention;

[0051] Figure 18 This is a top view of the reflective polarization conversion metasurface unit in an embodiment of the present invention;

[0052] Figure 19 The reflection phase and reflection coefficient of the reflective anisotropic metasurface unit under x-polarized wave incident in the embodiments of the present invention;

[0053] Figure 20 The reflection phase and reflection coefficient of the reflective anisotropic metasurface unit under γ-polarized wave incidence in the embodiments of the present invention;

[0054] Figure 21 In the embodiments of the present invention, the reflective anisotropic metasurface unit is used in different l y The following changes l x The reflection phase at that time;

[0055] Figure 22 In the embodiments of the present invention, the reflective anisotropic metasurface unit is used in different l x The following changes l y The reflection phase at that time;

[0056] Figure 23 This refers to the transmission phase of the transmission-type polarization conversion metasurface unit as a function of frequency in the embodiments of the present invention.

[0057] Figure 24 This refers to the transmission coefficient of the transmission-type polarization conversion metasurface unit as a function of frequency in the embodiments of the present invention.

[0058] Figure 25 This is the radiation pattern of the bandwidth-enhanced folded reflective array antenna at 10.5 GHz in an embodiment of the present invention;

[0059] Figure 26 This is the radiation pattern of the bandwidth-enhanced folded reflective array antenna at 11.5 GHz in an embodiment of the present invention;

[0060] Figure 27This is the radiation pattern of the bandwidth-enhanced folded reflective array antenna at 12.5 GHz in an embodiment of the present invention;

[0061] Figure 28 The radiation pattern of the bandwidth-enhanced folded reflective array antenna at 13.5 GHz in this embodiment of the invention is shown.

[0062] Figure 29 This refers to the gain of the bandwidth-enhanced folding reflective array antenna as a function of frequency in this embodiment of the invention.

[0063] Figure 30 The aperture efficiency of the bandwidth-enhanced folded reflective array antenna as a function of frequency in this embodiment of the invention;

[0064] Figure label:

[0065] 1. Reflective metasurface; 2. Reflective metasurface element; 3. Polarization grating array; 4. Transmissive polarization conversion metasurface; 5. Transmissive polarization conversion metasurface element; 6. Feed antenna; 7. Support column; 8. Single-layer dielectric substrate; 9. First dielectric substrate; 10. Second dielectric substrate.

[0066] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0067] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0068] Reference Figure 1 A folded reflective array antenna based on a dual metasurface, comprising:

[0069] Feed antenna 6;

[0070] A reflective metasurface 11 is connected to the periphery of the feed antenna 6 and includes a plurality of equally spaced reflective metasurface units 2;

[0071] A polarization grating array 3 is spaced apart on one side of the reflective metasurface 11, and at least a portion of the polarization grating array 3 forms a first transmission region corresponding to and covering the reflective metasurface 11;

[0072] A transmissive metasurface 4 is spaced apart on the side of the polarization grating array 3 away from the reflective metasurface 1. At least a portion of the transmissive metasurface 4 forms a second transmissive region corresponding to and covering the first transmissive region. The transmissive metasurface 4 includes at least a plurality of equally spaced transmissive metasurface units 5 within the second transmissive region.

[0073] This configuration, with an additional transmissive metasurface 4 on the other side of the polarization grating array 3 relative to the reflective metasurface 1, allows for optimized design of the transmission phase of each transmissive metasurface unit 5 within the transmissive metasurface 4, providing additional design freedom. This enables secondary adjustment of the electromagnetic wave phase radiated by the traditional folded reflective array antenna, ultimately expanding the gain bandwidth of the folded reflective array antenna.

[0074] Furthermore, regarding the arrangement of the transmissive metasurface unit 5 on the transmissive metasurface 4, in some preferred embodiments, the phase compensation required for each of the transmissive metasurface units 5 within the second transmission region is obtained by calculating the electric field phase at the center position of the transmissive metasurface unit 5 at multiple frequencies to be optimized and the reference phase at the corresponding frequencies using the finite-time integration method; wherein...

[0075] Phase compensation required at (x,y) in the second transmission region:

[0076] In the above formula, This represents the electric field phase calculated by the finite-time integration method at the second transmission region (x,y) at the i-th frequency point. This represents the reference phase at the i-th frequency point.

[0077] Among them, the reference phase at each frequency point It is obtained by optimizing the weighted phase optimization function based on the illumination factor; The weighted phase optimization function based on the illumination factor includes:

[0078]

[0079] In the above formula, s (i) w represents the correction weight related to the electrical dimensions of the 4-aperture transmissive metasurface at the i-th frequency point. (i) (x,y) represents the irradiation weight of the transmissive metasurface unit 5 at the second transmissive region (x,y), w (i) (x,y) is taken as the normalized transmission electric field modulus calculated by the finite-time integration method at (x,y) in the second transmission region, and φ realized(i) (x,y) represents the phase compensation achieved by the transmissive metasurface unit 5 at the second transmissive region (x,y).

[0080] Therefore, based on the above calculation relationships, the overall optimization objective function for each of the transmissive metasurface units 5 arranged in the second transmissive region is:

[0081]

[0082] Furthermore, regarding the arrangement of the reflective metasurface units on the reflective metasurface 1, in some preferred embodiments, the phase compensation required for each reflective metasurface unit on the reflective metasurface 1 in the orthogonal direction is as follows:

[0083]

[0084] Where k is the wavenumber at the operating frequency, and d(i,j) is the distance from the phase center of the feed antenna 6 to the geometric center of the (i,j)th reflective metasurface element. Let (x(i,j),y(i,j)) represent the radiation direction of the beam, and (x(i,j),y(i,j)) represent the coordinates of the geometric center of the (i,j)th reflective metasurface unit.

[0085] The objective function for minimizing the phase compensation error in the orthogonal directions of each reflective metasurface unit on the reflective metasurface 1 is:

[0086] Δφ min (i,j)=|φ x (l x ,l y )-φ x (i,j)|+|φ y (l y ,l x )-φ y (i,j)|

[0087] Where φ x (l x ,l y φ represents the phase compensation achieved by the (i,j)th metasurface unit in the x-direction. y (l y ,l x ) represents the phase compensation achieved by the (i,j)th metasurface unit in the y-direction.

[0088] Furthermore, in some preferred embodiments, the transmissive metasurface 4 comprises at least two dielectric layers;

[0089] On the surfaces of the two dielectric plates that are far apart from each other, there are a number of parallel metal strips spaced apart, and the metal strips on the two surfaces are orthogonally arranged.

[0090] Reference Figure 17 Specifically, the dielectric substrate is configured as two layers, and the metal open ring structure of the transmissive metasurface unit 5 is printed between the two dielectric substrate layers. The metal strip is disposed on the side of the two dielectric substrate layers that are far apart from each other. The periodic dimension of the transmissive metasurface unit 5 is 9 mm; the width of the metal strip is 0.9 mm, and the gap width between the metal strips is 0.9 mm.

[0091] Reference Figure 18 The printed transmissive metasurface unit 5 has a metal open-ring structure including:

[0092] The two arc segments are located on the same circumference and are symmetrical about the center. The two arc segments are spaced apart in the circumferential direction to form an opening angle. The arc segments are metal structures.

[0093] A connecting strip connects the midpoints of two arc segments radially, and the connecting strip is a square metal structure.

[0094] Specifically, the inner diameter of the arc segment is 3.2 mm, the outer diameter of the arc segment is 4.3 mm, and the width of the connecting strip is 1.8 mm.

[0095] Based on the above approach, this application provides a specific implementation scheme:

[0096] This specific embodiment discloses a bandwidth-enhanced folded reflective array antenna based on a dual metasurface, such as... Figure 1 As shown, the antenna includes a reflective metasurface 1, several reflective metasurface elements 2, a polarization grating array 3, a transmissive metasurface 4, several transmissive metasurface elements 5, a feed antenna 6, and a support column 7. The support column 7 is preferably made of a plastic material such as polytetrafluoroethylene (PTFE) to reduce reflection of radiated electromagnetic waves; however, the specific material can be selected based on the radiation performance requirements of the folded reflective array antenna.

[0097] The polarization grating array 3 is installed above the reflective metasurface 1 at a position h1 = 67.05 mm, and the transmissive metasurface 4 is installed above the polarization grating array 3 at a position h2 = 2.4 mm. Preferably, four support pillars 7 can be provided, and the polarization grating array 3 is fixed above the reflective metasurface 1 by the support pillars 7, and the transmissive metasurface 4 is also fixed above the polarization grating array 3 by the support pillars 7.

[0098] In this embodiment, the reflective metasurface 1 is composed of multiple reflective metasurface units 2 that have the function of adjusting the reflection phase in orthogonal directions, the feed antenna 6 is embedded in the middle of the reflective metasurface 1, the lower surface of the reflective metasurface 1 is set as a metal base plate to reflect electromagnetic waves, and the transmissive metasurface 4 is composed of multiple transmissive metasurface units 5 that have the function of adjusting the polarization and phase of the transmitted waves.

[0099] The reflective metasurface unit 2 is disposed on a single-layer dielectric substrate 8, preferably formed by printing a Jerusalem cross-shaped metal structure with a loaded square open ring on the single-layer dielectric substrate 8.

[0100] The open ring structure of the transmissive metasurface unit 5 is printed between two dielectric substrates, namely between the first dielectric substrate 9 and the second dielectric substrate 10. Orthogonally arranged metal strips 11 are printed on the upper surface of the first dielectric substrate 9 and the lower surface of the second dielectric substrate 10, respectively. Preferably, it is formed by printing a metal open ring structure arranged diagonally between the two dielectric substrates.

[0101] The present invention can adjust the phase of reflected and transmitted waves by adjusting the size of the reflective metasurface unit and the transmissive polarization conversion unit respectively, without the need for a complex feeding circuit.

[0102] For a reflective metasurface 1, there are i×j reflective metasurface units 2 arranged at equal intervals on a single-layer dielectric substrate 8. In order to achieve orthogonal polarization conversion, the phase compensation required for each reflective metasurface unit 2 on the reflective metasurface 1 in the orthogonal direction is as follows:

[0103]

[0104] Where k is the wavenumber at the operating frequency, and d(i,j) is the distance from the phase center of the feed antenna to the geometric center of the (i,j)th metasurface element. Let (x(i,j), y(i,j)) represent the radiation direction of the beam, and (x(i,j), y(i,j)) represent the coordinates of the geometric center of the (i,j)th metasurface unit. In this design, the antenna's radiation direction is designed as follows:

[0105] Since the metasurface elements on the reflective metasurface 1 aperture are mutually coupled in the orthogonal directions, in order to further improve the aperture efficiency of the designed folded reflective array antenna, it is necessary to minimize the phase compensation error in the orthogonal directions. The objective function for minimizing the phase compensation error in the orthogonal directions can be defined as follows:

[0106] Δφ min (i,j)=|φ x (l x ,l y )-φ x (i,j)|+|φ y (l y ,l x )-φ x (i,j)| (2)

[0107] Where φ x (l x ,l y φ represents the phase compensation achieved by the (i,j)th metasurface unit in the x-direction. y (l y ,l x) represents the phase compensation achieved by the (i,j)th metasurface unit in the y-direction.

[0108] For the transmissive metasurface 4, m×n transmissive anisotropic metasurface units 2 are arranged at equal intervals between the first dielectric plate 9 and the second dielectric plate 10. To achieve broadband directional radiation by secondary modulation of the electromagnetic waves transmitted from the polarization grating array 3, the phase compensation required for the (m,n)th metasurface unit on the transmissive metasurface 4 at the i-th frequency point can be obtained by conjugating the near-field electric field phase calculated using the finite-time integration method, as shown in the following equation:

[0109]

[0110] in Let represent the near-field electric field phase calculated using the finite-time integration method at the i-th frequency point on the transmissive metasurface 4(x,y). Since the radiation performance of the air-fed planar array antenna is determined by the relative phase of each element on the metasurface, the reference phase is chosen as the optimization variable for design, and equation (3) needs to be modified as follows:

[0111]

[0112] in Let represent the reference phase at the i-th frequency. To ensure the phase compensation at each frequency is as accurate as possible, a weighted phase optimization function based on the illumination factor is constructed, as shown below:

[0113]

[0114] Where s (i) w represents the correction weight related to the electrical size of the metasurface aperture at the i-th frequency point. (i) (x,y) represents the illumination weight of the metasurface unit at (x,y), w (i) (x,y) is generally taken as the normalized transmission electric field modulus at (x,y) calculated by the finite-time integration method, φ realized(i) (x,y) represents the phase compensation achieved by the metasurface element at (x,y). Finally, the global optimization objective function for a transmissive metasurface 4 with m×n elements can be expressed as:

[0115]

[0116] In this embodiment, a reflective metasurface with a size of D1 = 225 mm and a transmissive metasurface 4 with a size of D2 = 225 mm are optimized. By employing a global particle swarm optimization algorithm to optimize equations (2) and (6), a folded reflective array antenna with a 1-dB gain bandwidth of 20.8% is designed. For the reflective metasurface, the phase compensation required in the orthogonal direction at the center frequency of 12 GHz is as follows: Figure 2 and 3 As shown. Through optimized design, the phase compensation error in the orthogonal direction is as follows. Figure 4 As shown in the figure, the maximum phase compensation error of the reflective metasurface in the orthogonal direction is only about 2.5°. Based on the above analysis, it can be seen that by achieving ideal polarization conversion and accurate phase compensation, the aperture efficiency of the bandwidth-enhanced folded reflective array antenna is expected to improve. For the transmissive metasurface 4, the transmission phase at frequencies of 11 GHz, 11.5 GHz, 12 GHz, 12.5 GHz, and 13 GHz was optimized. Considering that the electrical size of the antenna aperture gradually increases with frequency, the correction weights at the above five frequency points were set to 0.3, 0.25, 0.2, 0.15, and 0.1, respectively. Finally, the optimized reference phases at each frequency point are as follows: The phase compensation, normalized illumination weight, and phase compensation error required for the four apertures of the transmissive metasurface at 11 GHz, 12 GHz, and 13 GHz are as follows: Figures 5-13 As shown in the figure, after optimization, relatively accurate phase compensation can be achieved at all frequency points. It exhibits the characteristic of small phase compensation error in areas with high illumination weight. This also indicates that good radiation gain can be achieved at all frequency points, which will be highly beneficial for the realization of broadband folded reflective array antennas. Finally, the optimized transmissive metasurface 4 has the following structure: Figure 14 As shown.

[0117] The structural forms of reflective metasurface units are as follows: Figure 15 and Figure 16 As shown, a Jerusalem cross-shaped metal patch with a square open ring is mounted on a single-layer dielectric substrate 8 with a thickness of h = 3 mm. The period of the reflective metasurface unit is p. r =9mm, which is equivalent to 0.36λ at a center frequency of 12GHz. The arm length of the Jerusalem Cross is l. x , l y a x and a y Their dimensional relationship can be expressed as: a y =l x ×M, a x =l y ×N. The size of the outer square open ring is b.x and b y Its dimensional relationship with the Jerusalem Cross can be expressed as l x =b x , l y =b y The reflective metasurface unit exhibits subwavelength characteristics. The square open ring consists of four metal strips, with a strip width w1 = 0.2 mm, and the distance between the Jerusalem cross and the square open ring is w2 = 0.2 mm. The dimensions of the Jerusalem cross are adjusted individually. x and l y It can achieve independent control of the reflected phase of x-polarized and y-polarized incident waves.

[0118] The structural form of the transmissive metasurface unit 5 is as follows: Figure 17 and Figure 18 As shown, a metal open-ring structure is disposed between the first dielectric plate 9 and the second dielectric plate 10, and metal strips 11 are orthogonally arranged at the top of the first dielectric plate 9 and the bottom of the second dielectric plate 10. The periodic dimension p of the transmissive metasurface unit 5 is... t =9mm, equivalent to 0.36λ at a center frequency of 12GHz, exhibiting significant subwavelength characteristics. The width of the metal strips is w3 = 0.9mm, and the gap width between the metal strips is w4 = 0.9mm. Metal open-end rings are positioned diagonally between the two dielectric layers, with an outer diameter R1 = 4.3mm, an inner diameter R2 = 3.2mm, and a connecting strip width w5 = 1.8mm between the two arms of the metal open-end rings. By changing the opening angle θ of the metal open-end rings, both the phase and polarization of the incident wave can be controlled simultaneously.

[0119] In specific implementation, the single-layer dielectric plate 8 constituting the reflective metasurface 1 and the first dielectric plate 9 and the second dielectric plate 10 constituting the transmissive metasurface 4 are preferably single-layer Rogers 5880 dielectric plates.

[0120] The reflection phase and reflection coefficient of the reflective metasurface unit at different frequencies are as follows: Figure 19 and Figure 20 As shown, by adjusting l x (or l) y The size of the device results in a reflection phase exceeding 490° at a center frequency of 12 GHz under x-polarized incident wave (or y-polarized incident wave) illumination. Furthermore, due to the presence of the metal substrate, the reflection coefficient under x-polarized incident wave (or y-polarized incident wave) illumination is higher than 0.97.

[0121] Reflective metasurface units in different l y And different l x The reflection phase at time such as Figure 21 and Figure 22 As shown, when l y When the phase changes, the maximum phase deviation in the x-direction is 42°. When l x When the phase shifts, the maximum phase deviation in the y-direction is 44°. Therefore, the proposed anisotropic reflective metasurface unit exhibits low mutual coupling in the orthogonal directions.

[0122] Transmission phase and transmission coefficient of a transmissive metasurface unit as a function of frequency, as follows: Figure 23 and Figure 24 As shown, by changing the angle θ of the open ring from 40° to 150°, the transmission phase ∠T xy A 180° transmission phase can be achieved at the center frequency of 12 GHz, and the transmission coefficient is higher than 0.95 in the frequency band from 11 GHz to 13 GHz. In addition, the additional 180° transmission phase can be obtained by mirroring the polarization conversion unit along the y-axis.

[0123] The radiation pattern of the designed bandwidth-enhanced folded reflector array antenna is as follows: Figures 25-28 As shown in the figure, the designed bandwidth-enhanced folded reflector antenna achieves collimated radiation at 10.5 GHz, 11.5 GHz, 12.5 GHz, and 13.5 GHz. The sidelobe levels at 10.5 GHz, 11.5 GHz, 12.5 GHz, and 13.5 GHz are -18.3 dB, -14.4 dB, -14.2 dB, and -11.8 dB, respectively. Furthermore, the cross-polarization within the 10.5 GHz to 13.5 GHz band is below -14 dB, achieving excellent cross-polarization conversion performance.

[0124] The gain and aperture efficiency of the designed bandwidth-enhanced folded reflector antenna as a function of frequency are as follows: Figure 29 and Figure 30 As shown in the figure, the designed wide-enhanced folded reflector array antenna has a 1-dB gain bandwidth of 20.8%, a 3-dB gain bandwidth of 28.3%, and a maximum aperture efficiency of 31.5%.

[0125] Ultimately, the beneficial effects of the folded reflective array antenna based on dual metasurfaces disclosed in this invention are as follows:

[0126] 1) This type of antenna can radiate a high-gain directional beam over a wide frequency band, and can be used in long-distance satellite communication, military radar and information warfare.

[0127] 2) The co-aperture optimization method based on multi-frequency near-field phase matching disclosed in this invention can accurately optimize the phase distribution of the transmissive polarization conversion metasurface, thereby achieving the effect of expanding the bandwidth of the folded reflective array antenna.

[0128] 3) The dual-polarization phase matching optimization method disclosed in this invention can optimize the phase design of the orthogonal direction of the reflective anisotropic metasurface, thereby improving the aperture efficiency of the folded reflective array antenna.

[0129] 4) Compared with traditional reflective array antennas, this type of antenna has the advantages of low profile, compact structure and no feed obstruction.

[0130] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0131] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0132] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A folded reflective array antenna based on dual metasurfaces, characterized in that, It includes: Feed antenna; A reflective metasurface, which is connected to the periphery of the feed antenna, includes several equally spaced reflective metasurface units; A polarization grating array is spaced apart on one side of the reflective metasurface, and at least a portion of the polarization grating array forms a first transmission region corresponding to and covering the reflective metasurface; A transmissive metasurface is spaced apart on the side of the polarization grating array away from the reflective metasurface. At least a portion of the transmissive metasurface forms a second transmissive region corresponding to and covering the first transmissive region. The transmissive metasurface includes at least a plurality of equally spaced transmissive metasurface units within the second transmissive region. The phase compensation required for each of the transmissive metasurface units within the second transmission region is obtained by calculating the electric field phase at the center position of the transmissive metasurface unit at multiple frequencies to be optimized, and the reference phase at the corresponding frequencies, using the finite-time integration method; wherein... The second transmission zone is in Required phase compensation: in Indicates the first At each frequency point, in the second transmission region The electric field phase at that point is calculated using the finite-time integration method. Indicates the first Reference phase at each frequency point; Reference phase at each frequency The weighted phase optimization function based on the illumination factor is obtained by optimization; the weighted phase optimization function based on the illumination factor includes: in Indicates the first Correction weights related to the electrical dimensions of the transmissive metasurface aperture at each frequency point. Indicated in the second transmission zone Irradiation weight of transmissive metasurface units, Taken in the second transmission region The normalized transmission electric field modulus was calculated using the finite-time integration method. Indicated in the second transmission zone Phase compensation achieved by a transmissive metasurface unit; The structure of the reflective metasurface unit includes: a Jerusalem cross metal patch with a square open ring loaded on the periphery is set on a single-layer dielectric substrate, and the square open ring is composed of four metal strips; The transmissive metasurface comprises: at least two dielectric layers; On the surfaces of the two dielectric plates that are far apart from each other, there are a number of parallel metal strips spaced apart, and the metal strips on the two surfaces are orthogonally arranged. The dielectric substrate is configured as two layers, the transmissive metasurface unit open ring structure is disposed between the two dielectric substrate layers, and the metal strip is disposed on the side of the two dielectric substrate layers that are far apart from each other; The transmissive metasurface unit is arranged in an open ring structure, including: The two arc segments are located on the same circumference and are symmetrical about the center. The two arc segments are spaced apart in the circumferential direction to form an opening angle. The arc segments are metal structures. A connecting strip connects the midpoints of two arc segments radially, and the connecting strip is a square metal structure.

2. The folded reflective array antenna based on dual metasurfaces as described in claim 1, characterized in that, The overall optimization objective function for each of the transmissive metasurface units arranged in the second transmissive region is: 。 3. The folded reflective array antenna based on dual metasurfaces as described in claim 1, characterized in that, The phase compensation required for each reflective metasurface unit in the orthogonal direction on the reflective metasurface is as follows: in The wave number at the operating frequency. From the phase center of the feed antenna to the first The distance between the geometric centers of each reflective metasurface unit The direction of beam radiation. For the first The coordinates of the geometric center of each reflective metasurface unit; The objective function for minimizing the phase compensation error in the orthogonal directions of each reflective metasurface unit on the reflective metasurface is: in For the first Each metasurface unit in Phase compensation achieved by direction, For the first Each metasurface unit in Phase compensation achieved by the direction.

4. The folded reflective array antenna based on dual metasurfaces as described in claim 1, characterized in that, The periodic dimension of the transmissive metasurface unit is 9 mm; the width of the metal strip is 0.9 mm, and the gap width between the metal strips is 0.9 mm.

5. The folded reflective array antenna based on dual metasurfaces as described in claim 1, characterized in that, The inner diameter of the arc segment is 3.2 mm, and the outer diameter of the arc segment is 4.3 mm; the width of the connecting strip is 1.8 mm.

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