Folding transmission array antenna

Abstract

The invention belongs to the technical field of antennas, and discloses a folding transmission array antenna. The antenna comprises a linear polarization-to-circular polarization metasurface, a transmission metasurface and a feed source antenna array, the linear polarization-to-circular polarization metasurface is located right above the transmission metasurface, and the feed source antenna array is integrated on the upper surface of the transmission metasurface; the linear polarization-to-circular polarization metasurface comprises a plurality of linear polarization-to-circular polarization units which are connected with one another, and each linear polarization-to-circular polarization unit converts an input linear polarization wave into a circular polarization wave; the transmission metasurface comprises a plurality of mutually connected transmission units, and each transmission unit regulates and controls the propagation direction of electromagnetic waves; the feed source antenna array comprises a plurality of micro-strip array antennas which are connected with one another, and each micro-strip array antenna provides excitation signals for the folding transmission array antenna. According to the invention, by adjusting the geometrical characteristics of each metal structure in the linear polarization-to-circular polarization metasurface and the transmission metasurface, the efficiency of converting a linear polarization wave into a circular polarization wave is effectively improved, and high gain is realized under the condition of a low planed surface.

Description

Technical Field

[0001] The invention belongs to the technical field of antennas, and in particular relates to a folded transmission array antenna. Background Art

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

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

[0004] The present invention provides a folded transmission array antenna to solve the technical problem of low antenna gain in the existing antenna. The folded transmission array antenna comprises: 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 polarization-to-circular polarization metasurface includes a plurality of interconnected linear polarization-to-circular polarization units, each of which is used to convert an input linear polarization wave into a circular polarization wave; the transmission metasurface includes a plurality of interconnected transmission units, each of which is used to adjust the propagation direction of the electromagnetic wave;

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

[0007] Furthermore, the linear polarization-to-circular polarization metasurface includes 25×25 linear polarization-to-circular polarization units, the transmission metasurface includes 25×25 transmission 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 reflective surface, a first dielectric layer and a first metal structure, the metal reflective 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 ring rotated 45°; the long branch of the first cross ring is 0.95 mm, the short branch of the first cross ring is 0.55 mm, and the groove width of the first cross 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 an upper surface of the second dielectric layer, and the third metal structure is located on a lower surface of the second dielectric layer.

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

[0012] Each of the "W"-shaped rings includes a second "X"-shaped ring and arc branches connected to both ends of the long branches of the second "X"-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 the square patches, a metal ground and a signal input port;

[0017] Each of the square patches 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 a central symmetrical position of the one-to-four power divider, and the signal input port is electrically connected to the coaxial line through the second dielectric layer;

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

[0020] Furthermore, a support column is arranged between the circularly polarized metasurface and the transmission metasurface; a plurality of first through holes are arranged on the first dielectric layer, and a plurality of second through holes are arranged on the second dielectric layer, and the support column passes through the first through holes and the second through holes to connect the circularly polarized metasurface and the transmission metasurface.

[0021] Compared with the prior art, the folded transmission 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 linearly polarized to circularly polarized metasurface and the metal structures in the transmission metasurface, and the folded transmission array antenna achieves high gain under low planarization conditions. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0023] Figure 2 A top view of a linear polarization-to-circular polarization metasurface provided in an embodiment of the present invention;

[0024] Figure 3 A bottom view of a linear polarization-to-circular polarization metasurface provided in an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of the structure of a first "cross" shaped ring provided in an embodiment of the present invention;

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

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

[0028] Figure 7 A schematic diagram of the structure of a "W"-shaped ring provided in an embodiment of the present invention;

[0029] Figure 8 A gain diagram of a folded transmission array antenna provided by an embodiment of the present invention;

[0030] Fig. 9 A diagram showing the variation of the array axis ratio with frequency of a folded transmission array antenna provided in an embodiment of the present invention.

[0031] Among them, 10 is a linear polarization-to-circular polarization metasurface, 11 is a linear polarization-to-circular polarization unit, 111 is a metal reflective surface, 112 is a first dielectric layer, 1121 is a first through hole, 113 is a first metal structure, 114 is a first "cross" ring, 20 is a transmission metasurface, 21 is a transmission 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 "W"-shaped ring, 2141 is a second "cross"-shaped ring, 2142 is an arc branch, 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 supporting column. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with 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 disclosed content more detailed and complete, the following is an illustrative description of the implementation mode and specific examples of the present invention; however, this is not the only form of implementing or applying the specific embodiments of the present invention. The implementation mode covers the features of multiple specific embodiments and the method steps and their sequence for constructing and operating these specific embodiments. However, other specific embodiments can also be used to achieve the same or equal functions and step sequences. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0034] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein.

[0035] In the description of the embodiments of the present invention, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two, and other quantifiers are similar. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention, and the embodiments of the present application and the features in the embodiments may be combined with each other without conflict.

[0036] In order to solve the technical problem of low antenna gain in the prior art, the present invention provides a folded transmission array antenna. Figure 1 , Figure 1 A structural schematic diagram of a folded transmission array antenna provided in an embodiment of the present invention, the folded transmission array antenna includes a linear polarization-to-circular polarization metasurface 10, a transmission metasurface 20 and a feed antenna array 30, wherein the linear polarization-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 polarization-to-circular polarization metasurface 10 includes a plurality of interconnected linear polarization-to-circular polarization units 11, each of which is used to convert an input linear polarization 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 the electromagnetic wave; 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. The present invention effectively improves the efficiency of converting linearly polarized waves into circularly polarized waves, realizes the high gain of the folded transmission array antenna, and meets the requirements of the 77GHz millimeter wave radar system for high antenna gain, low profile, good polarization characteristics, etc.

[0037] Specifically, in an embodiment of the present invention, the linear polarization-to-circular polarization metasurface 10 includes a plurality of interconnected linear polarization-to-circular polarization units 11, which can effectively convert the input linear polarization wave into a circular polarization wave. The circular polarization wave has better anti-interference ability and more stable transmission performance, especially in a complex electromagnetic environment, which can significantly improve the stability of the signal. The transmission metasurface 20 includes a plurality of interconnected transmission units 21, which can accurately control the consistency of the emission direction of the electromagnetic wave, thereby achieving gain improvement. The feed antenna array 30 is integrated on the upper surface of the transmission metasurface 20, which effectively reduces the overall height and volume of the antenna, which is conducive to the integration and miniaturization of the vehicle-mounted millimeter-wave radar system, and the microstrip array antenna 31 can provide an efficient excitation signal to ensure that the antenna has high gain within the working frequency band.

[0038] As a further preferred embodiment, the linear polarization-to-circular polarization metasurface 10 includes 25×25 linear polarization-to-circular polarization units 11, the transmission metasurface 20 includes 25×25 transmission units 21, and the feed antenna array 30 includes 2×2 microstrip array antennas 31. Specifically, in the embodiment of the present invention, the linear polarization-to-circular polarization metasurface 10 is configured with 25×25 linear polarization-to-circular polarization units 11, which can ensure the uniformity of the polarization conversion process and effectively improve the overall polarization conversion efficiency of the antenna; the transmission metasurface 20 is configured with 25×25 transmission units 21, each transmission unit 21 can independently adjust the propagation direction of the electromagnetic wave according to the incident electromagnetic wave angle of each transmission unit, so that the electromagnetic wave emission direction is consistent to obtain high gain; the feed antenna array is composed of 4 microstrip array antennas, which is a moderate number, which not only ensures that an efficient excitation signal can be provided, ensures that the antenna has high gain in the working frequency band, but also maintains the compact design of the antenna, which is convenient for integration into the 77GHz vehicle-mounted millimeter wave radar.

[0039] As a further preferred option, please refer to Figure 2-Figure 3 , Figure 2 A top view of a linear polarization-to-circular polarization metasurface provided in an embodiment of the present invention, Figure 3 A bottom view of a linear polarization-to-circular polarization metasurface provided in an embodiment of the present invention; the linear polarization-to-circular polarization unit 11 includes a metal reflective surface 111, a first dielectric layer 112, and a first metal structure 113, wherein 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 an embodiment of the present invention, the metal reflective surface 111 is located on the upper surface of the first dielectric layer 112, and can reflect incident linear polarization waves to ensure that most of the energy is effectively utilized. The first metal structure 113 is located on the lower surface of the first dielectric layer 112, and can convert reflected linear polarization waves into circular polarization waves through a specific geometric shape and size design. The first dielectric layer 112 is disposed between the metal reflective surface 111 and the first metal structure 113, and 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 4A schematic diagram of the structure of a first cross ring provided in an embodiment of the present invention, wherein the first metal structure 113 is a first cross ring 114 rotated at 45°; the long branch of the first cross ring 114 is 0.95 mm, the short branch of the first cross ring 114 is 0.55 mm, and the groove width of the first cross ring is 0.1 mm. Specifically, in an embodiment of the present invention, the first metal structure 113 is a first cross ring 114 rotated at 45°, and the use of this structure can effectively convert linear polarization waves into circular polarization waves, and the 45° rotation angle helps to balance the phase difference between the two orthogonal components, thereby achieving high-quality circular polarization wave output. In addition, setting the long branch of the first cross ring 114 to 0.95 mm and the short branch length to 0.55 mm can optimize the phase and amplitude of the electromagnetic wave and further improve the performance of polarization conversion.

[0041] As a further preferred option, please refer to Figure 5-Figure 6 , Figure 5 A top view of a transmissive metasurface provided by an embodiment of the present invention, Figure 6 A bottom view of a transmission metasurface provided in an embodiment of the present invention. The transmission unit 21 includes a second metal structure 211, a second dielectric layer 212 and a third metal structure 213, wherein 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 an embodiment of the present invention, the phase and amplitude of the electromagnetic wave can be precisely controlled by adjusting the geometric shape and size of the second metal structure 211 and the third metal structure 213. 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 the electromagnetic wave at the interface and effectively improve the transmission efficiency.

[0042] As a further preferred option, please refer to Figure 7 , Figure 7A schematic diagram of the structure of a "W"-shaped ring provided in an embodiment of the present invention, wherein the second metal structure 211 and the third metal structure 213 have the same shape, and both the second metal structure 211 and the third metal structure 213 are two "W"-shaped rings 214 arranged perpendicularly to each other, and the groove width of each "W"-shaped ring 214 is 0.1 mm; each "W"-shaped ring 214 includes a second "cross"-shaped ring 2141, and arc branches 2142 connected to the two ends of the long branches of the second "cross"-shaped ring 2141, and the arc branches 2142 are arc branches of variable length. Specifically, in the embodiment of the present invention, the second metal structure 211 and the third metal structure 213 are two "W"-shaped rings 214 arranged perpendicularly to each other, and this geometric shape can effectively control the transmission characteristics of electromagnetic waves, and ensure the efficient transmission of electromagnetic waves when passing through the transmission unit. In addition, through the design of the second "cross" ring 2141, the phase and amplitude of the electromagnetic wave can be accurately controlled. The two ends of the long branch of the second "cross" ring 2141 are connected with arc branches 2142. The length of the arc branch 2142 is variable and can be adjusted according to specific application requirements to further improve the antenna gain.

[0043] As a further preferred embodiment, 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. 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 the first dielectric layer 112 and the second dielectric layer 212 are both set to F4B materials, which can effectively reduce the energy loss in the signal transmission process and improve the transmission efficiency of electromagnetic waves.

[0044] As a further preferred embodiment, 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. Specifically, in the embodiment of the present invention, the dielectric constant of the dielectric layer is low, which can make the propagation speed of electromagnetic waves in the dielectric layer faster and the phase delay smaller. In addition, the loss tangent of the dielectric layer is also low, which can make the dielectric layer absorb very little electromagnetic waves and have very low energy loss, effectively reducing signal attenuation and ensuring the integrity of signal transmission.

[0045] As a further preference, please refer to Figure 5, the microstrip array antenna 31 includes a plurality of square patches 311, a power divider 312 connecting the square patches 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, the signal input port 314 is located at a central symmetrical position of the one-to-four power divider 312, and the signal input port 314 is electrically connected to the coaxial line through the second dielectric layer 312; 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 the embodiment of the present invention, the number of the square patches 311 can be 4, and the four square patches 311 form an arrangement. The one-to-four power divider 312 is used to distribute the input signal power, amplitude, and phase to each square patch 311, and can efficiently radiate linearly polarized electromagnetic waves.

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

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

[0048] For further information, please refer to Fig. 9 , Fig. 9 A diagram showing a variation of the axial ratio of a folded transmission array antenna with respect to frequency provided in an embodiment of the present invention. It should be noted that the 3 dB axial ratio bandwidth of the antenna refers to the bandwidth covered by the antenna within the frequency range where the axial ratio does not exceed 3 dB. Fig. 9 It can be seen that the 3dB axial ratio bandwidth of the folded transmission array antenna reaches 5GHz, indicating that the folded transmission array antenna proposed in the present invention can maintain good circular polarization characteristics in a wider frequency range.

[0049] The present invention proposes a folded transmission array antenna, the 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; the linear polarization-to-circular polarization metasurface includes a plurality of interconnected linear polarization-to-circular polarization units, each of which is used to convert an input linear polarization wave into a circular polarization wave; the transmission metasurface includes a plurality of interconnected transmission units, each of which is used to control the propagation direction of the electromagnetic wave; the feed antenna array includes a plurality of interconnected microstrip array antennas, each of which is used to provide an excitation signal to the folded transmission array antenna. The present invention effectively improves the efficiency of converting linear polarization waves into circular polarization waves by adjusting the geometric characteristics of each metal structure in the linear polarization-to-circular polarization metasurface and the transmission metasurface, and realizes the high gain of the folded transmission array antenna.

[0050] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, 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 only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A folded transmission array antenna, characterized in that: include: A linear polarization-to-circular polarization metasurface (10), a transmission metasurface (20), and a feed antenna array (30), wherein the linear polarization-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 polarization-to-circular polarization metasurface (10) comprises a plurality of interconnected linear polarization-to-circular polarization units (11), each of which is used to convert an input linear polarization wave into a circular polarization wave; the transmission metasurface (20) comprises a plurality of interconnected transmission units (21), each of which is used to control the propagation direction of the electromagnetic wave; The feed antenna array (30) comprises a plurality of interconnected microstrip array antennas (31), each of the microstrip array antennas (31) being used to provide an excitation signal to the folded transmission array antenna.

2. The folded transmission array antenna according to claim 1, characterized in that: The linear polarization-to-circular polarization metasurface (10) comprises 25×25 linear polarization-to-circular polarization units (11), the transmission metasurface (20) comprises 25×25 transmission units (21), and the feed antenna array (30) comprises 2×2 microstrip array antennas (31).

3. The folded transmission array antenna according to claim 1, characterized in that: The linear polarization-to-circular polarization unit (11) comprises 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).

4. The folded transmission array antenna according to claim 3, characterized in that: The first metal structure (113) is a first cross-shaped ring (114) rotated at 45 degrees; the length of the long branch of the first cross-shaped ring (114) is 0.95 mm, the length of the short branch of the first cross-shaped ring (114) is 0.55 mm, and the groove width of the first cross-shaped ring (114) is 0.1 mm.

5. The folded transmission array antenna according to claim 4, characterized in that: The transmission unit (21) comprises a second metal structure (211), a second dielectric layer (212) and a third metal structure (213), wherein the second metal structure (211) is located on an upper surface of the second dielectric layer (212), and the third metal structure (213) is located on a lower surface of the second dielectric layer (212).

6. The folded transmission array antenna according to claim 5, characterized in that: The second metal structure (211) and the third metal structure (213) have the same shape, and both the second metal structure (211) and the third metal structure (213) are two "W"-shaped rings (214) arranged perpendicular to each other, and the groove width of each "W"-shaped ring (214) is 0.1 mm; Each of the "W"-shaped rings (214) comprises a second "X"-shaped ring (2141), and arc branches (2142) connected to both ends of the long branches of the second "X"-shaped ring (2141), and the arc branches (2142) are arc branches of variable length.

7. The folded transmission array antenna according to claim 5, 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.

8. The folded transmission array antenna according to claim 7, 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.

9. The folded transmission array antenna according to claim 8, characterized in that: The microstrip array antenna (31) comprises a plurality of square patches (311), a one-to-four power divider (312) connecting 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 a central symmetrical position of the one-to-four power divider (312), and the signal input port (314) passes through the second dielectric layer (312) 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 input signal port (314).

10. The folded transmission array antenna according to claim 9, characterized in that: A support column (40) is provided between the circularly polarized metasurface (10) and the transmission 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 column passes through the first through holes (1121) and the second through holes (2121) to connect the circularly polarized metasurface (10) and the transmission metasurface (20).

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