Circularly polarized folded transmission array antenna

Abstract

The invention discloses a circularly polarized folded transmission array antenna which comprises a multifunctional polarization converter, a polarization torsion sub-reflecting surface and a linear polarization feed source. The multifunctional polarization converter comprises a plurality of multifunctional polarization conversion units, the polarization torsion subreflector is formed by periodically arranging polarization torsion reflection units, and the linear polarization feed source of SIW feed can emit linear polarization electromagnetic waves. The multifunctional polarization conversion unit provided by the invention has polarization selection and polarization conversion characteristics, and can reflect incident y-polarized electromagnetic waves and convert and transmit incident x-polarized electromagnetic waves into right-handed circularly polarized electromagnetic waves; and the polarized torsion sub-reflecting surface can be used for reflecting incident y-polarized electromagnetic waves into x-polarized electromagnetic waves in a torsion manner and is applied to a folded transmission array, so that the profile of the antenna is reduced to one third.

Description

Technical Field

[0001] This invention relates to a communication antenna, specifically to a circularly polarized folded transmission array antenna. Background Technology

[0002] With the widespread deployment of 5G and the rapid evolution of 6G technology, high efficiency, wide bandwidth, high gain, and low profile have become important development trends for modern millimeter-wave antennas. However, traditional phased array antennas face problems such as high cost, high loss, and complex feeding networks in the millimeter-wave band, making it difficult to meet the engineering application requirements of low cost and high integration. Against this backdrop, folded transmission array antennas, as a new type of high-performance antenna, combine the advantages of reflective and transmission arrays, while also possessing characteristics such as low profile, lightweight, and easy conformal design, and have become a research hotspot in recent years. Meanwhile, traditional linearly polarized antennas are susceptible to multipath interference and polarization mismatch in complex electromagnetic environments, resulting in limited stability and transmission efficiency of communication systems. In contrast, circularly polarized antennas, with their insensitivity to polarization mismatch and outstanding resistance to multipath fading, have become a highly advantageous polarization scheme choice in modern wireless communication systems.

[0003] To achieve the circular polarization radiation characteristics of the antenna, current research often uses circular polarization feeds. A circular polarization feed itself needs to simultaneously satisfy impedance matching and a 90° phase difference (i.e., low axial ratio) over a wide frequency band, which is extremely difficult to design. Summary of the Invention

[0004] Purpose of the invention: In view of the above-mentioned prior art, a circularly polarized folded transmission array antenna is proposed. This antenna adopts linear polarization feeding to achieve circular polarization function, and through the polarization selection of the elements and polarization torsion characteristics, the antenna profile is reduced to one-third.

[0005] Technical solution: A circularly polarized folded transmission array antenna includes a multifunctional polarization converter and a polarization torsion sub-reflector arranged opposite each other, and a linear polarization feed is provided at the center of the polarization torsion sub-reflector.

[0006] The multifunctional polarization converter is composed of periodically arranged multifunctional polarization conversion units, and the polarization torsion sub-reflector is composed of periodically arranged polarization torsion reflection units.

[0007] The multifunctional polarization conversion unit has both polarization selection and polarization conversion characteristics. Its lower metal patch layer reflects y-polarized electromagnetic waves and transmits x-polarized electromagnetic waves, while the upper metal patch layer converts x-polarized electromagnetic waves into right-hand circularly polarized electromagnetic waves. The upper metal patch layer of the polarization torsion reflection unit has polarization torsion characteristics, which can torsion y-polarized electromagnetic waves into x-polarized electromagnetic waves.

[0008] The y-polarized electromagnetic wave output from the linearly polarized feed source is reflected by the lower metal patch layer of the multifunctional polarization conversion unit, twisted by the polarization torsion reflection unit, and then reflected back to the lower metal patch layer of the multifunctional polarization conversion unit and transmitted. It is then converted into a right-hand circularly polarized electromagnetic wave by the upper layer. After phase compensation, the right-hand circularly polarized electromagnetic wave forms a high-gain beam coverage in the far-field region.

[0009] Furthermore, the multifunctional polarization conversion unit includes a first upper metal patch layer, an upper dielectric substrate layer, an intermediate metal ground layer, a first adhesive layer, a lower dielectric substrate layer, and a lower metal patch layer stacked sequentially from top to bottom, and also includes a metal through-hole connecting the first upper metal patch layer and the lower metal patch layer.

[0010] Furthermore, the multifunctional polarization conversion unit has a square structure in the plane; the circular metal patch of the first upper metal patch layer is offset in the plane relative to the center of the metal through hole; a circular gap is etched in the center of the middle metal ground layer, and the metal through hole passes through the circular gap.

[0011] Furthermore, the circular metal patch of the first upper metal patch layer has symmetrical stepped rectangular grooves diagonally formed; the circular metal patch of the lower metal patch layer has an open rectangular groove, and the left and right sides of the open rectangular groove have symmetrical outward protruding teeth; the middle metal grounding layer has a square structure.

[0012] Furthermore, the polarization torsional reflection unit includes a second upper metal patch layer, an intermediate dielectric substrate layer, and a lower metal ground layer stacked sequentially from top to bottom; the intermediate dielectric substrate layer is a square substrate.

[0013] Furthermore, the second upper metal patch layer is composed of two symmetrical chamfered triangular patches, which are symmetrically distributed about a diagonal of the intermediate dielectric substrate layer, and the hypotenuses of the two chamfered triangular patches are arranged opposite each other.

[0014] Furthermore, the linearly polarized feed includes a 4×4 metasurface unit, an upper SIW dielectric substrate layer, an upper SIW metal wall, a second adhesive layer, a lower SIW dielectric substrate layer, and a lower SIW metal wall stacked sequentially from top to bottom, and the lower SIW dielectric substrate layer is provided with SIW sidewall metal pillars.

[0015] Furthermore, the SIW structure of the linearly polarized feed consists of a narrow rectangular section open at one end, a wide rectangular section closed at one end, and a transition section connecting the narrow rectangular section and the wide rectangular section; a rectangular slot along the x-direction is provided on the upper dielectric substrate layer of the SIW, directly opposite the 4×4 metasurface unit; a pair of trapezoidal slots symmetrical about the y-direction centerline of the lower metal wall of the SIW are provided on the lower metal wall of the SIW, located inside the side wall of the SIW, and each trapezoidal slot is connected to a slot strip at its bottom, the slot strips extending to the opening of the SIW structure as a feed port.

[0016] Furthermore, the first upper metal patch layer introduces a perturbation unit through diagonally opened stepped rectangular slots to form a 90° phase difference, thereby realizing the conversion of x-polarized electromagnetic waves into right-hand circularly polarized electromagnetic waves; the multifunctional polarization conversion unit controls phase compensation by rotating the first upper metal patch layer, achieving 360° phase coverage without changing the transmission amplitude.

[0017] Beneficial effects: 1. The multifunctional polarization conversion unit proposed in this invention utilizes the polarization selection characteristics of the lower metal layer and the polarization conversion characteristics of the upper metal layer to achieve linear polarization to circular polarization. Compared with linearly polarized antennas, circularly polarized antennas have outstanding advantages such as resistance to polarization mismatch, resistance to multipath fading, and adaptability to misaligned mobile scenarios.

[0018] 2. The polarization torsion reflection unit proposed in this invention utilizes the polarization torsion characteristics of the upper metal layer and combines them with the polarization selection characteristics of the lower metal layer of the multifunctional polarization conversion unit to reduce the antenna profile to one-third.

[0019] 3. Simulation results show that the multifunctional polarization conversion unit proposed in this invention achieves an impedance bandwidth of 20.2% and an axial ratio bandwidth of 17%.

[0020] 4. Simulation verification shows that the circularly polarized folded transmission array antenna based on a novel chamfered patch proposed in this invention can achieve a gain bandwidth of 15.4% and an axial ratio bandwidth of 23.9% while ensuring a low profile. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the three-dimensional structure of the antenna according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the folding function of the antenna in an embodiment of the present invention;

[0023] Figure 3 This is a top view schematic diagram of the multifunctional polarization conversion surface structure of the antenna according to an embodiment of the present invention;

[0024] Figure 4 This is a top view schematic diagram of the linearly polarized feed and polarized torsional sub-reflector structure of the antenna according to an embodiment of the present invention;

[0025] Figure 5 This is a three-dimensional structural diagram of the multifunctional polarization conversion unit of the antenna according to an embodiment of the present invention;

[0026] Figure 6 This is a top view of the metal structure layers of the multi-functional polarization conversion unit of the antenna in an embodiment of the present invention, wherein (a) is the upper metal patch layer, (b) is the middle metal ground layer, and (c) is the lower metal patch layer.

[0027] Figure 7 This is a three-dimensional structural diagram of the polarization torsion reflection unit of the antenna according to an embodiment of the present invention;

[0028] Figure 8 This is a top view schematic diagram of the upper metal patch layer of the polarization torsion reflection unit of the antenna in an embodiment of the present invention;

[0029] Figure 9 This is a three-dimensional structural diagram of the linearly polarized feed source of the antenna according to an embodiment of the present invention;

[0030] Figure 10 This is a top view of the antenna line polarization feed according to an embodiment of the present invention, wherein (a) is a 4×4 metasurface single surface, (b) is the upper metal wall of the SIW, and (c) is the lower metal wall of the SIW.

[0031] Figure 11 These are the performance simulation results of the multifunctional polarization conversion unit of the antenna in this embodiment of the invention, where (a) represents the t of the incident y-polarized electromagnetic wave. xy t yy Transmission coefficient and r xy r yy Reflection coefficient performance diagram, (b) is the incident t of x-polarized electromagnetic wave xx t yx Transmission coefficient and r xx r yx Reflection coefficient performance diagram, (c) is ∠t yx 、∠t xx Transmission phase and ∠t yx -∠t xx Phase difference performance diagram;

[0032] Figure 12 This is a graph showing the axial ratio of the multifunctional polarization conversion unit of the antenna in an embodiment of the present invention as a function of frequency;

[0033] Figure 13 This is a diagram showing the reflection coefficient and phase response performance of the polarization torsional reflection element of the antenna in an embodiment of the present invention;

[0034] Figure 14 These are the E-plane and H-plane radiation patterns of the linearly polarized feed of the antenna in this embodiment of the invention at the center frequency;

[0035] Figure 15 The S-polarization feed of the antenna in this embodiment of the invention is 11 Reflectance coefficient performance diagram;

[0036] Figure 16 This is a graph showing the gain and axial ratio of the antenna in an embodiment of the present invention as a function of frequency.

[0037] Figure 17 The beam radiation pattern of the antenna in this embodiment of the invention;

[0038] In the attached figures, 1-Multifunctional polarization conversion unit; 2-Polarization torsional reflection unit; 3-Linear polarization feed; 4-First upper metal patch layer; 5-Upper dielectric substrate layer; 6-Intermediate metal ground layer; 7-First adhesive layer; 8-Lower dielectric substrate layer; 9-Lower metal patch layer; 10-Metal via; 11-Second upper metal patch layer; 12-Intermediate dielectric substrate layer; 13-Lower metal ground layer; 14-4×4 metasurface unit; 15-SIW upper dielectric substrate layer; 16-SIW upper metal wall; 17-Second adhesive layer; 18-SIW lower dielectric substrate layer; 19-SIW sidewall metal pillar; 20-SIW lower metal wall. Detailed Implementation

[0039] The invention will now be further explained with reference to the accompanying drawings.

[0040] like Figure 1 As shown, a circularly polarized folded transmission array antenna includes a multifunctional polarization converter and a polarization torsion sub-reflector arranged vertically. A SIW-fed linearly polarized feed 3 is arranged at the center of the polarization torsion sub-reflector.

[0041] like Figure 3 , Figure 5 As shown, the multi-functional polarization converter includes a periodically arranged multi-functional polarization conversion unit 1. The multi-functional polarization conversion unit 1 includes a first upper metal patch layer 4, an upper dielectric substrate layer 5, an intermediate metal ground layer 6, a first adhesive layer 7, a lower dielectric substrate layer 8, a lower metal patch layer 9, and a metal through-hole 10 connecting the upper metal patch layer 4 and the lower metal patch layer 9, which are stacked sequentially from top to bottom.

[0042] like Figure 5As shown, the upper dielectric substrate layer 5 and the lower dielectric substrate layer 8 of the multifunctional polarization conversion unit 1 are both made of the same material, with a relative permittivity εr of [2.2, 6.2], a loss tangent tanδ of 0.0027, and a height h1 of [0.02λ, 0.1λ]. The metal via 10 is made of PEC. The adhesive layer 7 has a relative permittivity of 3.5, a loss tangent tanδ of 0.004, and a height h2 of [0.006λ, 0.01λ], where λ is the free space wavelength.

[0043] like Figure 6 As shown, the xoy plane of the multifunctional polarization conversion unit 1 has a square structure with a side length p of [0.2λ, λ]. Figure 6 As shown in (a), the circular metal patch of the first upper metal patch layer 4 has symmetrical stepped rectangular grooves on its diagonal. The radius r1 of the circular metal patch is [0.1λ, 0.5λ], the outer groove length a1 of the stepped rectangular groove is [0.06λ, 0.1λ], the width b1 is [0.01λ, 0.05λ], and the inner groove length a2 of the stepped rectangular groove is [0.02λ, 0.1λ], the width b2 is [0.01λ, 0.05λ].

[0044] like Figure 6 As shown in (c), the circular metal patch of the lower metal patch layer 9 has an open rectangular groove. The outer length a3 of the open rectangular groove is [0.1λ, 0.2λ], the inner length a4 is [0.06λ, 0.15λ], the outer width b3 is [0.06λ, 0.15λ], and the inner width b4 is [0.06λ, 0.1λ]. The groove width b5 of the side where the opening is located is [0.01λ, 0.05λ], and the opening length a5 is [0.02λ, 0.06λ]. Symmetrical outward protruding external teeth are provided on the left and right sides, the width b6 of the external teeth is [0.006λ, 0.02λ], and the length a6 of the external teeth is [0.02λ, 0.06λ].

[0045] like Figure 6 As shown in (b), the intermediate metal grounding layer 6 is a square structure with a side length of p. A circular slit is etched at the center of its surface. The metal via 10 passes through the circular slit, and the circular metal patch of the first upper metal patch layer 4 is offset by a distance s in the xoy direction relative to the metal via 10. Where s is [0.01λ, 0.1λ], the diameter d2 of the circular slit is [0.06λ, 0.1λ], and the diameter d1 of the metal via 10 is [0.03λ, 0.06λ].

[0046] like Figure 4 , Figure 7As shown, the polarization torsion sub-reflector surface includes periodically arranged polarization torsion reflection units 2. The polarization torsion reflection unit 2 includes a second upper metal patch layer 11, an intermediate dielectric substrate layer 12, and a lower metal ground layer 13, which are stacked sequentially from top to bottom. Among them, the intermediate dielectric substrate layer 12 is a square substrate with a side length rep1 of [0.2λ, λ], a relative permittivity εr of [2.2, 6.2], and a loss tangent tanδ of 0.0027.

[0047] like Figure 8 As shown, the second upper metal patch layer 11 is composed of two symmetrical chamfered triangular patches. The two chamfered triangles are symmetrically distributed about a diagonal of the intermediate dielectric substrate layer 12, and the hypotenuses of the two chamfered triangles are arranged opposite each other. The right-angle side length rea1 of the triangular patch is [0.1λ, 0.4λ], and the corner side reb1 of the chamfered triangle is [0.06λ, 0.1λ].

[0048] like Figure 4 , Figure 9 As shown, the linearly polarized feed 3 for SIW power supply includes, from top to bottom, a 4×4 metasurface unit 14, an upper SIW dielectric substrate layer 15, an upper SIW metal wall 16, a second adhesive layer 17, a lower SIW dielectric substrate layer 18 with internal SIW sidewall metal pillars 19, and a lower SIW metal wall 20. The SIW structure consists of a narrow rectangular section open at one end, a wide rectangular section closed at one end, and a transition section connecting the narrow and wide sections. A rectangular slot along the x-direction is provided on the upper SIW dielectric substrate layer 15 opposite the 4×4 metasurface unit 14. On the lower SIW metal wall 20, a pair of trapezoidal slots are provided on the inner side of the SIW sidewall. These trapezoidal slots are symmetrical about the y-direction centerline of the lower SIW metal wall 20. The bottom of each trapezoidal slot connects to a slot strip extending to the opening of the SIW structure at one end of the lower SIW metal wall, serving as a power supply port.

[0049] The SIW upper dielectric substrate layer 15 and SIW lower dielectric substrate layer 18 of the linearly polarized feed 3 are made of the same material and have the same size. Their dielectric constant εr is [2.2, 6.2] and their loss tangent tanδ is 0.0027.

[0050] like Figure 10 As shown in (a), the side length sub_a of the out-of-specification surface element is [0.1λ, 0.2λ], and the spacing sub_b between the out-of-specification surface elements is [0.004λ, 0.01λ]. Figure 10 As shown in (b), the width f of the rectangular slit x The length f of the rectangular slit is [0.2λ, 0.6λ]. yThe radius rr of the SIW sidewall metal column is [0.04λ, 0.1λ], the width siw_w of the wide section of the SIW structure is [0.3λ, 0.5λ], and the distance f between the center of the rectangular gap and the closed end of the wide section of the SIW structure is [0.04λ, 0.1λ]. m [0.06λ, 0.15λ]. For example... Figure 10 As shown in (c), the height tapl_1 of the trapezoidal groove is [0.2λ, 0.4λ], the length of the lower base tapw_1 of the trapezoidal groove is [0.01λ, 0.05λ], the length of the upper base tapw_2 of the SIW trapezoidal groove is [0.1λ, 0.2λ], the length of the slit strip tapl_2 is [0.5λ, λ], the width g of the slit strip is [0.004λ, 0.01λ], and the distance wg between the two slit strips is [0.04λ, 0.1λ].

[0051] like Figure 2 As shown, the SIW-fed linearly polarized feed 3 outputs a y-polarized electromagnetic wave, which is incident on the lower metal patch layer 9 of the multi-functional polarization converter. Due to its polarization selectivity, the y-polarized wave is reflected to the second upper metal patch layer 11 of the polarized torsional sub-reflector. After being torn into an x-polarized electromagnetic wave, it is reflected back to the lower metal patch layer 9 of the multi-functional polarization converter. After being received by the converter, it is transmitted through the metal via 10 to the first upper metal patch layer 4, where it is converted into a right-hand circularly polarized electromagnetic wave. After obtaining the corresponding phase compensation, a high-gain beam coverage is formed in the far-field region.

[0052] Among them, the second upper metal layer 11 of the polarization torsion reflection unit 2 has polarization torsion characteristics, which can torsion the y-polarized wave reflected by the lower metal patch layer 9 of the multifunctional polarization conversion unit 1 into an x-polarized wave, and then reflect it back to the lower metal patch layer 9 of the multifunctional polarization conversion unit 1. After two reflections, the antenna profile is reduced to one-third.

[0053] The multifunctional polarization conversion unit 1 has polarization selection and polarization conversion characteristics. The lower metal patch layer 9 of the multifunctional polarization conversion unit 1 has polarization selection characteristics, reflecting y-polarized waves and transmitting x-polarized waves; the first upper metal patch layer 4 has polarization conversion characteristics, which can convert x-polarized waves into right-hand circularly polarized waves.

[0054] The multifunctional polarization conversion unit 1 introduces a perturbation unit by creating a 90° phase difference through diagonally opened stepped rectangular slots on the circular metal patch of the first upper metal patch layer 4, thereby achieving circular polarization. The multifunctional polarization conversion unit 1 receives x-polarized waves by opening U-shaped slots on the circular metal patch of the lower metal patch layer 9. The multifunctional polarization conversion unit 1 controls phase compensation by rotating the first upper metal patch layer 4, achieving 360° phase coverage without changing the transmission amplitude.

[0055] The antenna parameters for this embodiment are shown in the table below:

[0056]

[0057] like Figure 11 As shown in (a), when a y-polarized electromagnetic wave is incident on the lower metal patch 9, the receiving patch completely reflects the y-polarized wave. Figure 11 As shown in (b), when the x-polarized wave is incident on the lower metal patch 9, it is received by the patch and transmitted to the upper metal patch 4 through the metal via 10. The upper metal patch 4 decomposes the electric field of the incident wave into two orthogonal components t. xx and t yx Furthermore, within the 24.9 GHz ~ 30.5 GHz frequency band, these two components acquire equal amplitudes (t) during transmission. xx =t yx =-3 dB). Meanwhile, such as Figure 11 As shown in (c), the two orthogonal components t of the decomposition xx and t yx They have a phase difference of 90°±10°. In summary, the two orthogonal components combine into a rotating RHCP wave in the transmission space.

[0058] like Figure 12 As shown, the multifunctional polarization conversion unit 1 has an AR of less than 3 dB in the range of 25.7 GHz to 31.6 GHz and a relative bandwidth of 20.6%.

[0059] like Figure 13 As shown, in the range of 23.3 GHz to 32 GHz, the cross-polarization r xy Above -0.5 dB, the main polarization r yy Below -10 dB. Furthermore, at the resonant frequencies of 24.5 GHz and 30 GHz, the dominant polarization r... yy The amplitude reaches its lowest point, indicating that the incident y-polarized wave has been completely converted into an x-polarized wave.

[0060] like Figure 14 As shown, when theta = 0º, the E-plane and H-plane main lobe shapes of the linearly polarized feed are highly coincident, with a peak gain of 6.5 dBi and a -10 dB beamwidth of ±45º.

[0061] like Figure 15 As shown, in the frequency range of 24 GHz to 32 GHz, the S of the linearly polarized feed... 11 Keep below -10 dB.

[0062] like Figure 16As shown, the antenna exhibits a 15.4% gain bandwidth of 3 dB within the frequency range of 25.8 GHz to 30.1 GHz. Furthermore, within the frequency range of 24 GHz to 30.5 GHz, the measured axial ratio of the antenna is consistently below 3 dB, indicating that the antenna achieves good circular polarization characteristics within the frequency band.

[0063] like Figure 17 As shown, the circularly polarized folded transmission array antenna has a peak gain of 20.6 dBi at a center frequency of 28 GHz and cross-polarization below -20 dB.

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A circularly polarized folded transmission array antenna, characterized in that, It includes a multi-functional polarization converter and a polarization torsion pair reflector arranged opposite each other, and a linear polarization feed is provided at the center of the polarization torsion pair reflector (3). The multifunctional polarization converter is composed of periodically arranged multifunctional polarization conversion units (1), and the polarization torsion sub-reflector is composed of periodically arranged polarization torsion reflection units (2). The multifunctional polarization conversion unit (1) has both polarization selection and polarization conversion characteristics. Its lower metal patch layer (9) reflects y-polarized electromagnetic waves and transmits x-polarized electromagnetic waves, while the upper metal patch layer converts x-polarized electromagnetic waves into right-hand circularly polarized electromagnetic waves. The upper metal patch layer of the polarization torsion reflection unit (2) has polarization torsion characteristics and can torsion y-polarized electromagnetic waves into x-polarized electromagnetic waves. The y-polarized electromagnetic wave output by the linearly polarized feed (3) is reflected by the lower metal patch layer (9) of the multifunctional polarization conversion unit (1), twisted by the polarization torsion reflection unit (2), and reflected back to the lower metal patch layer (9) of the multifunctional polarization conversion unit (1) and transmitted. It is then converted into a right-hand circularly polarized electromagnetic wave by the upper layer. After phase compensation, the right-hand circularly polarized electromagnetic wave forms a high-gain beam coverage in the far field region.

2. The circularly polarized folded transmission array antenna according to claim 1, characterized in that, The multifunctional polarization conversion unit (1) includes a first upper metal patch layer (4), an upper dielectric substrate layer (5), an intermediate metal ground layer (6), a first adhesive layer (7), a lower dielectric substrate layer (8), and a lower metal patch layer (9) stacked sequentially from top to bottom, and also includes a metal through hole (10) connecting the first upper metal patch layer (4) and the lower metal patch layer (9).

3. The circularly polarized folded transmission array antenna according to claim 2, characterized in that, The multifunctional polarization conversion unit (1) has a square structure in the plane; the circular metal patch of the first upper metal patch layer (4) is offset in the plane relative to the center of the metal through hole (10); the center of the middle metal ground layer (6) has a circular gap etched therethrough, and the metal through hole (10) passes through the circular gap.

4. The circularly polarized folded transmission array antenna according to claim 2, characterized in that, The first upper metal patch layer (4) has symmetrical stepped rectangular grooves on the diagonal of the circular metal patch; the lower metal patch layer (9) has an open rectangular groove on the circular metal patch, and the left and right sides of the open rectangular groove have symmetrical outward protruding teeth; the middle metal grounding layer (6) has a square structure.

5. The circularly polarized folded transmission array antenna according to claim 1, characterized in that, The polarization torsional reflection unit (2) includes a second upper metal patch layer (11), an intermediate dielectric substrate layer (12) and a lower metal ground layer (13) stacked sequentially from top to bottom; the intermediate dielectric substrate layer (12) is a square substrate.

6. The circularly polarized folded transmission array antenna according to claim 5, characterized in that, The second upper metal patch layer (11) is composed of two symmetrical chamfered triangular patches. The two chamfered triangular patches are symmetrically distributed about a diagonal of the intermediate dielectric substrate layer (12), and the hypotenuses of the two chamfered triangular patches are arranged opposite each other.

7. The circularly polarized folded transmission array antenna according to claim 1, characterized in that, The linearly polarized feed (3) includes a 4×4 metasurface unit (14), an upper SIW dielectric substrate layer (15), an upper SIW metal wall (16), a second adhesive layer (17), a lower SIW dielectric substrate layer (18), and a lower SIW metal wall (20) stacked sequentially from top to bottom. The lower SIW dielectric substrate layer (18) is provided with SIW sidewall metal pillars (19).

8. The circularly polarized folded transmission array antenna according to claim 7, characterized in that, The SIW structure of the linearly polarized feed (3) consists of a rectangular narrow section open at one end, a rectangular wide section closed at one end, and a transition section connecting the rectangular narrow section and the rectangular wide section; a rectangular slot along the x direction is provided on the upper dielectric substrate layer (15) of the SIW, directly opposite the 4×4 metasurface unit (14); a pair of trapezoidal slots symmetrical about the center line of the y direction of the lower metal wall (20) of the SIW are provided on the inner side of the SIW side wall, and each trapezoidal slot is connected to a slot strip at the bottom, and the slot strip extends to the opening of the SIW structure as a feed port.

9. The circularly polarized folded transmission array antenna according to claim 2, characterized in that, The first upper metal patch layer (4) introduces a micro-perturbation unit through a stepped rectangular groove opened diagonally, forming a 90° phase difference, thereby realizing the conversion of x-polarized electromagnetic waves to right-hand circularly polarized electromagnetic waves; the multifunctional polarization conversion unit (1) controls phase compensation by rotating the first upper metal patch layer (4), thereby achieving 360° phase coverage without changing the transmission amplitude.

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