A folded transmissive array antenna

Abstract

The application belongs to the technical field of antennas and discloses a folding transmission array antenna, which comprises a linear polarization to circular polarization super surface, a transmission super surface and a feed antenna array, the linear polarization to circular polarization super surface is located directly above the transmission super surface, and the feed antenna array is integrated on the upper surface of the transmission super surface; the linear polarization to circular polarization super surface comprises a plurality of linear polarization to circular polarization units connected with each other, each linear polarization to circular polarization unit converts input linear polarization waves into circular polarization waves; the transmission super surface comprises a plurality of transmission units connected with each other, each transmission unit regulates and controls the propagation direction of electromagnetic waves; and the feed antenna array comprises a plurality of microstrip array antennas connected with each other, each microstrip array antenna provides an excitation signal for the folding transmission array antenna. By adjusting the geometric characteristics of each metal structure in the linear polarization to circular polarization super surface and the transmission super surface, the efficiency of linear polarization to circular polarization conversion is effectively improved, and high gain is realized under the condition of low surface.

Description

Technical Field

[0001] This invention belongs to the field of antenna technology, and in particular relates to a folded transmission array antenna. Background Technology

[0002] With the continuous development of wireless communication technology, the millimeter-wave band has attracted much attention due to its abundant spectrum resources, and it has broad application prospects in many fields such as 77GHz millimeter-wave radar systems. In radar systems, antenna performance plays a crucial role in the overall system performance. However, traditional antennas often fail to meet the miniaturization and high-performance requirements of modern radar systems in terms of gain and profile characteristics. For example, conventional antennas have low gain, resulting in insufficient signal strength in long-range detection or high-precision positioning scenarios, affecting the radar system's range and detection accuracy. At the same time, a high profile height is not conducive to the integrated design of radar systems, increasing the overall size and weight of the radar system. In addition, traditional antennas have poor flexibility in polarization control, making it difficult to adapt to complex and changing electromagnetic environments and diverse signal transmission needs.

[0003] Therefore, how to provide a high-gain folded transmission array antenna is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] This invention provides a folded transmission array antenna to solve the technical problem of low gain in existing antennas. The folded transmission array antenna includes: a linear polarization-to-circular polarization metasurface, a transmission metasurface, and a feed antenna array. The linear polarization-to-circular polarization metasurface is located directly above the transmission metasurface, and the feed antenna array is integrated on the upper surface of the transmission metasurface.

[0005] The linear-to-circular polarization metasurface includes several interconnected linear-to-circular polarization units, each of which is used to convert an input linearly polarized wave into a circularly polarized wave; the transmissive metasurface includes several interconnected transmissive units, each of which is used to control the propagation direction of electromagnetic waves.

[0006] The feed antenna array includes several interconnected microstrip array antennas, each of which is used to provide an excitation signal to the folded transmission array antenna.

[0007] Furthermore, the linear-to-circular polarization metasurface includes 25×25 linear-to-circular polarization units, the transmissive metasurface includes 25×25 transmissive units, and the feed antenna array includes a 2×2 microstrip array antenna.

[0008] Furthermore, the linear polarization to circular polarization unit includes a metal reflection surface, a first dielectric layer, and a first metal structure. The metal reflection surface is located on the upper surface of the first dielectric layer, and the first metal structure is located on the lower surface of the first dielectric layer.

[0009] Furthermore, the first metal structure is a first "cross" - shaped ring rotated by 45°. The long branch of the first "cross" - shaped ring is 0.95 mm, the short branch of the first "cross" - shaped ring is 0.55 mm, and the groove width of the first "cross" - shaped ring is 0.1 mm.

[0010] Furthermore, the transmission unit includes a second metal structure, a second dielectric layer, and a third metal structure. The second metal structure is located on the upper surface of the second dielectric layer, and the third metal structure is located on the lower surface of the second dielectric layer.

[0011] Furthermore, the second metal structure and the third metal structure have the same shape. The second metal structure and the third metal structure are both two "king" - shaped rings arranged perpendicular to each other, and the groove width of each "king" - shaped ring is 0.1 mm.

[0012] Each "king" - shaped ring includes a second "cross" - shaped ring and arc branches connected to both ends of the long branch of the second "cross" - shaped ring, and the arc branches are arc branches with variable lengths.

[0013] Furthermore, the thickness of the first dielectric layer is 0.5 mm, the thickness of the second dielectric layer is 0.554 mm, and the materials of the first dielectric layer and the second dielectric layer are both F4B materials.

[0014] Furthermore, the dielectric constant of the first dielectric layer and the second dielectric layer is 2.2, and the loss tangent of the first dielectric layer and the second dielectric layer is 0.001.

[0015] Furthermore, the dielectric constant of the first dielectric layer and the second dielectric layer is 2.2, and the loss tangent of the first dielectric layer and the second dielectric layer is 0.001.

[0016] Furthermore, the microstrip array antenna includes a plurality of square patches, a one - to - four power divider connecting each square patch, a metal ground, and a signal input port.

[0017] Each square patch and the one - to - four power divider are located on the upper surface of the second dielectric layer, and the metal ground is located on the lower surface of the second dielectric layer.

[0018] The signal input port is located at the centrosymmetric position of the one - to - four power divider, and the signal input port passes through the second dielectric layer and is electrically connected to the coaxial line.

[0019] A circular isolation gap is provided at the center of the metal ground to isolate the metal ground and the input signal port.

[0020] Furthermore, support columns are provided between the circularly polarized metasurface and the transmissive metasurface; a plurality of first through-holes are provided on the first dielectric layer, and a plurality of second through-holes are provided on the second dielectric layer. The support columns pass through the first through-holes and the second through-holes to connect the circularly polarized metasurface and the transmissive metasurface.

[0021] Compared with the prior art, a folded transmissive array antenna provided by the present invention effectively improves the efficiency of converting linearly polarized waves into circularly polarized waves by adjusting the geometric characteristics of the metal structures in the linearly polarized to circularly polarized metasurface and the transmissive metasurface, and the folded transmissive array antenna achieves high gain under low-profile conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of a folded transmissive array antenna provided by an embodiment of the present invention;

[0023] Figure 2 It is a top view of a linearly polarized to circularly polarized metasurface provided by an embodiment of the present invention;

[0024] Figure 3 It is a bottom view of a linearly polarized to circularly polarized metasurface provided by an embodiment of the present invention;

[0025] Figure 4 It is a schematic structural diagram of a first "cross" ring provided by an embodiment of the present invention;

[0026] Figure 5 It is a top view of a transmissive metasurface provided by an embodiment of the present invention;

[0027] Figure 6 It is a bottom view of a transmissive metasurface provided by an embodiment of the present invention;

[0028] Figure 7 It is a schematic structural diagram of a "king" ring provided by an embodiment of the present invention;

[0029] Figure 8 It is a gain graph of a folded transmissive array antenna provided by an embodiment of the present invention; [[ID=4​​​​Among them, 10 is a linear polarization to circular polarization metasurface, 11 is a linear polarization to circular polarization unit, 111 is a metal reflector, 112 is a first dielectric layer, 1121 is a first through hole, 113 is a first metal structure, 114 is a first "plus" shaped ring, 20 is a transmissive metasurface, 21 is a transmissive unit, 211 is a second metal structure, 212 is a second dielectric layer, 2121 is a second through hole, 213 is a third metal structure, 214 is a "king" shaped ring, 2141 is a second "plus" shaped ring, 2142 is an arc stub, 30 is a feed antenna array, 31 is a microstrip array antenna, 311 is a square patch, 312 is a power divider, 313 is a metal ground, 314 is a signal input port, 315 is a circular isolation gap, and 40 is a support column. Detailed implementation manners

[0032] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] In order to make the description of the present disclosure more detailed and complete, the following provides an illustrative description of the implementation manners and specific embodiments of the present invention; however, this is not the only form for implementing or applying the specific embodiments of the present invention. The implementation manners cover the features of multiple specific embodiments and the method steps and their sequences for constructing and operating these specific embodiments. However, other specific embodiments can also be used to achieve the same or equivalent functions and step sequences. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

[0034] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here.

[0035] In the description of the embodiments of the present invention, unless otherwise stated, " / " means "or". For example, A / B can mean A or B. The word "and / or" in the text is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more. Other quantifiers should be understood similarly. The preferred embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention. Furthermore, the embodiments and features in the embodiments of this application can be combined with each other without conflict.

[0036] To address the issue of low gain in existing antennas, this invention provides a folded transmission array antenna. Please refer to [reference needed]. Figure 1 , Figure 1 This is a schematic diagram of a folded transmission array antenna according to an embodiment of the present invention. The folded transmission array antenna includes a linear-to-circular-polarization metasurface 10, a transmission metasurface 20, and a feed antenna array 30. The linear-to-circular-polarization metasurface 10 is located directly above the transmission metasurface 20, and the feed antenna array 30 is integrated on the upper surface of the transmission metasurface 20. The linear-to-circular-polarization metasurface 10 includes a plurality of interconnected linear-to-circular-polarization units 11, each of which is used to convert an input linearly polarized wave into a circularly polarized wave. The transmission metasurface 20 includes a plurality of interconnected transmission units 21, each of which is used to control the propagation direction of electromagnetic waves. The feed antenna array 30 includes a plurality of interconnected microstrip array antennas 31, each of which is used to provide an excitation signal to the folded transmission array antenna. This invention effectively improves the efficiency of converting linearly polarized waves to circularly polarized waves, achieves high gain for folded transmission array antennas, and meets the requirements of 77GHz millimeter-wave radar systems for high antenna gain, low profile, and good polarization characteristics.

[0037] Specifically, in this embodiment of the invention, the linear-to-circular polarization metasurface 10 includes several interconnected linear-to-circular polarization units 11. These units effectively convert the input linearly polarized wave into a circularly polarized wave. Circularly polarized waves have better anti-interference capabilities and more stable transmission performance, especially in complex electromagnetic environments, significantly improving signal stability. The transmissive metasurface 20 includes several interconnected transmissive units 21. These units precisely control the consistency of the electromagnetic wave's emission direction, thereby improving gain. The feed antenna array 30 is integrated on the upper surface of the transmissive metasurface 20, effectively reducing the overall height and volume of the antenna, which is beneficial for the integration and miniaturization of the vehicle-mounted millimeter-wave radar system. The microstrip array antenna 31 provides a highly efficient excitation signal, ensuring high gain within the operating frequency band.

[0038] As a further preferred embodiment, the linear-to-circular polarization metasurface 10 includes 25×25 linear-to-circular polarization units 11, the transmissive metasurface 20 includes 25×25 transmissive units 21, and the feed antenna array 30 includes 2×2 microstrip array antennas 31. Specifically, in this embodiment, the linear-to-circular polarization metasurface 10 is configured with 25×25 linear-to-circular polarization units 11, which ensures the uniformity of the polarization conversion process and effectively improves the overall polarization conversion efficiency of the antenna; the transmissive metasurface 20 is configured with 25×25 transmissive units 21, and each transmissive unit 21 can independently adjust the propagation direction of the electromagnetic wave according to the incident electromagnetic wave angle of each transmissive unit, so that the electromagnetic wave emission direction is consistent to obtain high gain; the feed antenna array consists of 4 microstrip array antennas, which is a moderate number, ensuring that it can provide efficient excitation signals and ensure that the antenna has high gain in the operating frequency band, while maintaining the compact design of the antenna, which is convenient for integration into a 77GHz vehicle-mounted millimeter-wave radar.

[0039] As a further preferred option, please refer to Figures 2-3 , Figure 2 This is a top view of a linearly polarized to circularly polarized metasurface provided in an embodiment of the present invention. Figure 3 This is a bottom view of a linear-to-circular-polarization metasurface provided in an embodiment of the present invention. The linear-to-circular-polarization unit 11 includes a metal reflective surface 111, a first dielectric layer 112, and a first metal structure 113. The metal reflective surface 111 is located on the upper surface of the first dielectric layer 112, and the first metal structure 113 is located on the lower surface of the first dielectric layer 112. Specifically, in this embodiment, the metal reflective surface 111, located on the upper surface of the first dielectric layer 112, can reflect incident linearly polarized waves, ensuring that most of the energy is effectively utilized. The first metal structure 113, located on the lower surface of the first dielectric layer 112, can convert the reflected linearly polarized waves into circularly polarized waves through specific geometric shape and size design. The first dielectric layer 112, disposed between the metal reflective surface 111 and the first metal structure 113, can have good impedance matching, effectively reducing energy loss and improving the overall efficiency of the antenna.

[0040] As a further preferred option, please refer to Figure 4 , Figure 4This is a schematic diagram of a first cross-shaped ring provided in an embodiment of the present invention. The first metal structure 113 is a first cross-shaped ring 114 rotated at 45°. The long stub of the first cross-shaped ring 114 is 0.95 mm long, the short stub of the first cross-shaped ring 114 is 0.55 mm long, and the groove width of the first cross-shaped ring is 0.1 mm. Specifically, in this embodiment of the present invention, the first metal structure 113 is a first cross-shaped ring 114 rotated at 45°. This structure can effectively convert linearly polarized waves into circularly polarized waves, and the 45° rotation angle helps to balance the phase difference between the two orthogonal components, thereby achieving high-quality circularly polarized wave output. In addition, setting the long stub of the first cross-shaped ring 114 to 0.95 mm and the short stub length to 0.55 mm can optimize the phase and amplitude of the electromagnetic wave, further improving the polarization conversion performance.

[0041] As a further preferred option, please refer to Figures 5-6 , Figure 5 A top view of a transmissive metasurface provided in this embodiment of the invention. Figure 6 This invention provides a bottom view of a transmissive metasurface. The transmissive unit 21 includes a second metal structure 211, a second dielectric layer 212, and a third metal structure 213. The second metal structure 211 is located on the upper surface of the second dielectric layer 212, and the third metal structure 213 is located on the lower surface of the second dielectric layer 212. Specifically, in this invention, by adjusting the geometry and size of the second metal structure 211 and the third metal structure 213, the phase and amplitude of the electromagnetic wave can be precisely controlled. The second dielectric layer 212 is disposed between the second metal structure 211 and the third metal structure 213, which can reduce the reflection of electromagnetic waves at the interface and effectively improve the transmission efficiency.

[0042] As a further preferred option, please refer to Figure 7 , Figure 7Schematic diagram of the structure of a "king" - shaped ring provided by an embodiment of the present invention. The shapes of the second metal structure 211 and the third metal structure 213 are the same. Both the second metal structure 211 and the third metal structure 213 are composed of 2 "king" - shaped rings 214 arranged perpendicular to each other, and the groove width of each "king" - shaped ring 214 is 0.1 mm. Each "king" - shaped ring 214 includes a second "cross" - shaped ring 2141 and arc branches 2142 connected to both ends of the long branches of the second "cross" - shaped ring 2141, and the arc branches 2142 are arc branches with variable lengths. Specifically, in the embodiment of the present invention, both the second metal structure 211 and the third metal structure 213 are composed of 2 "king" - shaped rings 214 arranged perpendicular to each other. This geometric shape can effectively control the transmission characteristics of electromagnetic waves and ensure efficient transmission of electromagnetic waves when passing through the transmission unit. In addition, through the design of the second "cross" - shaped ring 2141, the phase and amplitude of electromagnetic waves can be precisely controlled. Arc branches 2142 are connected to both ends of the long branches of the second "cross" - shaped ring 2141, and the length of the arc branches 2142 is variable and can be adjusted according to specific application requirements to further improve the antenna gain.

[0043] As a further preference, the thickness of the first dielectric layer 112 is 0.5 mm, the thickness of the second dielectric layer 212 is 0.554 mm, and the materials of both the first dielectric layer 112 and the second dielectric layer 212 are F4B materials. Specifically, in the embodiment of the present invention, by setting the thickness of the first dielectric layer 112 to 0.5 mm and the thickness of the second dielectric layer 212 to 0.554 mm, the best transmission and reflection performance can be achieved. The materials of both the first dielectric layer 112 and the second dielectric layer 212 are set to F4B materials, which can effectively reduce the energy loss during signal transmission and improve the transmission efficiency of electromagnetic waves.

[0044] As a further preference, the dielectric constants of the first dielectric layer 112 and the second dielectric layer 212 are 2.2, and the loss tangents of the first dielectric layer 112 and the second dielectric layer 212 are 0.001. Specifically, in the embodiment of the present invention, the lower dielectric constant of the dielectric layer enables the electromagnetic waves to propagate faster in the dielectric layer with a smaller phase delay. In addition, the lower loss tangent of the dielectric layer means that the dielectric layer absorbs very little electromagnetic waves and has extremely low energy loss, effectively reducing signal attenuation and ensuring the integrity of signal transmission.

[0045] As a further preference, please refer to Figure 5The microstrip array antenna 31 includes several square patches 311, a power divider 312 connecting each square patch 311, a second dielectric layer 212, a metal ground 313, and a signal input port 314. The square patches 311 and the power divider 312 are located on the upper surface of the second dielectric layer 212, the metal ground 313 is located on the lower surface of the second dielectric layer 212, and the signal input port 314 is located symmetrically at the center of the 1-to-4 power divider 312, and the signal input port 314 passes through the second dielectric layer 312 and is electrically connected to a coaxial line. A circular isolation gap 315 is provided at the center of the metal ground 313 to isolate the metal ground 313 and the input signal port 314. Specifically, in this embodiment of the invention, the number of square patches 311 can be four, and the four square patches 311 are arranged in an array. The 1-to-4 power divider 312 is used to distribute the input signal power to each square patch 311 with equal amplitude and phase, which can efficiently radiate linearly polarized electromagnetic waves.

[0046] As a further preferred embodiment, a support post 40 is disposed between the circularly polarized metasurface 10 and the transmissive metasurface 20. A plurality of first through holes 1121 are disposed on the first dielectric layer 112, and a plurality of second through holes 2121 are disposed on the second dielectric layer 212. The support post 40 passes through the first through holes 1121 and the second through holes 2121 to connect the circularly polarized metasurface 10 and the transmissive metasurface 20. Specifically, in this embodiment of the invention, the support post 40 ensures the physical connection between the circularly polarized metasurface 10 and the transmissive metasurface 20, enhances the structural stability of the entire antenna system, and guarantees the normal operation of the antenna in various environments.

[0047] For further details, please refer to Figure 8 , Figure 8 The gain diagram of a folded transmission array antenna provided in this embodiment of the invention is as follows: Figure 8 As can be seen, the folded transmission array antenna achieves a high gain of 27.2 dBi at a center frequency of 77 GHz, indicating that the folded transmission array antenna provided by this invention can concentrate most of the energy in the desired direction, effectively improving the signal transmission distance and coverage. It should be noted that 77 GHz is an important frequency point in the millimeter-wave band, widely used in automotive radar, wireless communication, and other fields. Achieving high gain at the 77 GHz millimeter-wave band demonstrates the effectiveness and practicality of the folded transmission array antenna in the high-frequency millimeter-wave band.

[0048] For further details, please refer to Figure 9 , Figure 9 The axial ratio of a folded transmission array antenna provided in this embodiment of the invention varies with frequency. It should be noted that the 3dB axial ratio bandwidth of the antenna refers to the bandwidth covered by the antenna within a frequency range where the axial ratio does not exceed 3dB. Figure 9 As can be seen from the data, the 3dB axial ratio bandwidth of the folded transmission array antenna reaches 5GHz, indicating that the folded transmission array antenna proposed in this invention can maintain good circular polarization characteristics over a wide frequency range.

[0049] This invention proposes a folded transmission array antenna, comprising a linear-to-circular-polarization metasurface, a transmission metasurface, and a feed antenna array. The linear-to-circular-polarization metasurface is located directly above the transmission metasurface, and the feed antenna array is integrated on the upper surface of the transmission metasurface. The linear-to-circular-polarization metasurface includes several interconnected linear-to-circular-polarization units, each used to convert an input linearly polarized wave into a circularly polarized wave. The transmission metasurface includes several interconnected transmission units, each used to control the propagation direction of the electromagnetic wave. The feed antenna array includes several interconnected microstrip array antennas, each used to provide an excitation signal to the folded transmission array antenna. This invention effectively improves the efficiency of converting linearly polarized waves to circularly polarized waves by adjusting the geometric characteristics of the metal structures in the linear-to-circular-polarization metasurface and the transmission metasurface, thus achieving high gain for the folded transmission array antenna.

[0050] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0051] The above embodiments merely illustrate preferred implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims.

Claims

1. A folded transmission array antenna, characterized in that, Comprising: A linear polarization to circular polarization metasurface (10), a transmissive metasurface (20), and a feed antenna array (30). The linear polarization to circular polarization metasurface (10) is located directly above the transmissive metasurface (20), and the feed antenna array (30) is integrated on the upper surface of the transmissive metasurface (20); The linear polarization to circular polarization metasurface (10) includes a number of interconnected linear polarization to circular polarization units (11), and each of the linear polarization to circular polarization units is used to convert the input linear polarization wave into a circular polarization wave; the transmissive metasurface (20) includes a number of interconnected transmissive units (21), and each of the transmissive units is used to control the propagation direction of electromagnetic waves; The feed antenna array (30) includes a number of interconnected microstrip array antennas (31), and each of the microstrip array antennas (31) is used to provide an excitation signal to the folded transmissive array antenna; The linear polarization to circular polarization metasurface (10) includes \(25\times25\) linear polarization to circular polarization units (11), the transmissive metasurface (20) includes \(25\times25\) transmissive units (21), and the feed antenna array (30) includes \(2\times2\) microstrip array antennas (3); 2. The folded transmission array antenna according to claim 1, characterized in that, The linear polarization to circular polarization unit (11) includes a metal reflecting surface (111), a first dielectric layer (112), and a first metal structure (113). The metal reflecting surface (111) is located on the upper surface of the first dielectric layer (112), and the first metal structure (113) is located on the lower surface of the first dielectric layer (112).

3. The folded transmission array antenna according to claim 2, characterized in that, The first metal structure (113) is a first "cross" - shaped ring (114) rotated by \(45^{\circ}\); the long branch of the first "cross" - shaped ring (114) is \(0.95\) mm, the short branch of the first "cross" - shaped ring (114) is \(0.55\) mm, and the slot width of the first "cross" - shaped ring (114) is \(0.1\) mm.

4. The folded transmission array antenna according to claim 3, characterized in that, The transmissive unit (21) includes a second metal structure (211), a second dielectric layer (212), and a third metal structure (213). The second metal structure (211) is located on the upper surface of the second dielectric layer (212), and the third metal structure (213) is located on the lower surface of the second dielectric layer (212). The second metal structure (211) and the third metal structure (213) have the same shape. The second metal structure (211) and the third metal structure (213) are both two "king" - shaped rings (214) arranged perpendicular to each other, and the slot width of each "king" - shaped ring (214) is \(0.1\) mm; Each of the "king" - shaped rings (214) includes a second "cross" - shaped ring (2141), and arc branches (2142) connected to both ends of the long branch of the second "cross" - shaped ring (2141), and the arc branches (2142) are arc branches with variable lengths.

5. The folded transmission array antenna according to claim 3, characterized in that, The thickness of the first dielectric layer (112) is 0.5 mm, the thickness of the second dielectric layer (212) is 0.554 mm, and the materials of the first dielectric layer (112) and the second dielectric layer (212) are both F4B materials.

6. The folded transmission array antenna according to claim 5, characterized in that, The dielectric constant of the first dielectric layer (112) and the second dielectric layer (212) is 2.2, and the loss tangent of the first dielectric layer (112) and the second dielectric layer (212) is 0.

001.

7. The folded transmission array antenna according to claim 6, characterized in that, The microstrip array antenna (31) includes several square patches (311), a 1-to-4 power divider (312) connecting each of the square patches (311), a metal ground (313), and a signal input port (314). Each of the square patches (311) and the one-to-four power divider (312) are located on the upper surface of the second dielectric layer (212), and the metal ground (313) is located on the lower surface of the second dielectric layer (212). The signal input port (314) is located at the center symmetrical position of the one-to-four power divider (312), and the signal input port (314) passes through the second dielectric layer (212) and is electrically connected to the coaxial line; A circular isolation gap (315) is provided at the center of the metal ground (313) to isolate the metal ground (313) from the signal input port (314).

8. The folded transmission array antenna according to claim 7, characterized in that, A support post (40) is provided between the circularly polarized metasurface (10) and the transmissive metasurface (20); a plurality of first through holes (1121) are provided on the first dielectric layer (112), and a plurality of second through holes (2121) are provided on the second dielectric layer (212). The support post passes through the first through holes (1121) and the second through holes (2121) to connect the circularly polarized metasurface (10) and the transmissive metasurface (20).

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