Polarization conversion structure and antenna

Abstract

A polarization conversion structure and an antenna. In a direction perpendicular to a plane in which the polarization conversion structure is located, the polarization conversion structure comprises a grounding structure layer (11), a first dielectric substrate (21), and a radiation structure layer (300) that are stacked. The radiation structure layer (300) comprises at least one radiation unit (30), and the radiation unit (30) comprises a radiation structure (31). The radiation structure (31) is symmetrically arranged relative to a first center line, and in a plane parallel to the polarization conversion structure, the first center line is a center line of the radiation structure (31) extending in a fourth direction. The orthographic projections of the radiation unit (30) and the grounding structure layer (11) on the first dielectric substrate (21) at least partially overlap.

Description

Polarization conversion structure and antenna Technical Field

[0001] The embodiments of the present disclosure relate to, but are not limited to, the field of communication technology, and in particular to a polarization conversion structure and an antenna. Background Art

[0002] With the development of the Internet of Things (IoT) and 5G mobile communications, wireless communication technologies and wireless smart devices are constantly evolving, dramatically improving people's quality of life. Polarization, the direction of electric field oscillation in a plane orthogonal to the direction of electromagnetic wave propagation, is a key parameter for electromagnetic wave manipulation. Manipulating the polarization properties of electromagnetic waves is essential for many polarization-sensitive applications and devices, such as communications, navigation, and radar recognition.

[0003] Summary of the Invention

[0004] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0005] The embodiment of the present disclosure provides a polarization conversion structure, which includes a stacked ground structure layer, a first dielectric substrate, and a radiation structure layer in a direction perpendicular to the plane where the polarization conversion structure is located;

[0006] The radiation structure layer includes at least one radiation unit, the radiation unit includes a radiation structure, the radiation structure is symmetrical with respect to a first center line, and on a plane parallel to the polarization conversion structure, the first center line is the center line of the radiation structure extending along a fourth direction; the orthographic projections of the radiation unit and the ground structure layer on the first dielectric substrate at least partially overlap.

[0007] In an exemplary embodiment, the radiation unit further includes a resonance structure spaced apart from the radiation structure. The resonance structure is located around the radiation structure to form a ring structure. The resonance structure includes a resonance opening.

[0008] In an exemplary embodiment, the outer contour of the resonant structure is in the shape of a square, and the resonant opening is located at at least one set of opposite corners of the square, or the resonant opening is located at at least one set of opposite sides of the square; on a plane parallel to the polarization conversion structure, one set of opposite sides of the resonant structure extends along a first direction, and the other set of opposite sides extends along a second direction, and the resonant structure is symmetrical with respect to a third center line and a fourth center line, the third center line is the center line of the resonant structure extending along the first direction, and the fourth center line is the center line of the resonant structure extending along the second direction, and the first direction, the second direction, and the fourth direction intersect.

[0009] In an exemplary embodiment, in a structure in which the resonant opening is located at least one set of diagonal corners or two sets of opposite sides of the square, the resonant structure is symmetrical with respect to a fifth center line and a sixth center line. On a plane parallel to the polarization conversion structure, the fifth center line is the center line of the resonant structure extending along the fourth direction, the sixth center line is the center line of the resonant structure extending along the third direction, the fifth center line coincides with the first center line, and the third direction intersects with the first direction, the second direction, and the fourth direction.

[0010] In an exemplary embodiment, the radiating structure is also symmetrical with respect to a second center line. On a plane parallel to the polarization conversion structure, the second center line is the center line of the radiating structure extending along a third direction, and the third direction intersects with the first direction, the second direction, and the fourth direction.

[0011] In an exemplary embodiment, the radiating structure is a polygonal structure, and the first center line coincides with a diagonal line of the polygonal structure extending along the fourth direction.

[0012] In an exemplary embodiment, the radiation structure has a hexagonal shape, the hexagon including a first group of opposite sides, a second group of opposite sides, and a third group of opposite sides, two sides in each group of opposite sides are parallel to each other, the first group of opposite sides extends along the first direction, the second group of opposite sides extends along the second direction, and the third group of opposite sides extends along the fourth direction.

[0013] In an exemplary embodiment, the line width of the ring structure is 0.1 mm to 0.4 mm;

[0014] The size of the radiation structure along the first direction is equal to the size along the second direction, both being 5 mm to 7 mm;

[0015] The lengths of two sides in the first set of opposite sides are equal to the lengths of two sides in the second set of opposite sides, both being 2 mm to 6 mm.

[0016] In an exemplary embodiment, the shape of the radiating structure is a double-arrow shape, which includes two isosceles right triangles and a rectangle. The rectangle connects the two isosceles right triangles into one, and a set of opposite sides of the rectangle are respectively connected to the bases of the two isosceles right triangles. The midline of the rectangle extending along the fourth direction and the angle bisectors of the two right angles in the two isosceles right triangles coincide with the first midline.

[0017] In an exemplary embodiment, the radiating structure has a rhombus shape, one diagonal line of the rhombus coincides with the third center line, and another diagonal line of the rhombus coincides with the fourth center line.

[0018] In an exemplary embodiment, the radiation patch with a square radiation structure is provided with concave arc-shaped notches at a set of diagonal positions on both sides of the first center line; or, the radiation patch with a circular radiation structure is provided with concave arc-shaped notches at opposite positions on both sides of the first center line; or, the radiation patch with a circular radiation structure is provided with fan-shaped notches at opposite positions on both sides of the first center line.

[0019] In an exemplary embodiment, there are a plurality of radiation units, and the plurality of radiation units are arranged in an array.

[0020] In an exemplary embodiment, the plurality of radiation structures in the plurality of radiation units are arranged in a consistent manner.

[0021] In an exemplary embodiment, the polarization conversion structure is a square. On a plane parallel to the polarization conversion structure, one group of opposite sides of the polarization conversion structure extends along the first direction, and another group of opposite sides extends along the second direction. The multiple radiation units are symmetrically arranged relative to a seventh center line and an eighth center line. The seventh center line is the center line of the polarization conversion structure extending along the third direction, and the eighth center line is the center line of the polarization conversion structure extending along the fourth direction.

[0022] In an exemplary embodiment, the polarization conversion structure is square, and includes a first subarray to a fourth subarray defined by a ninth center line and a tenth center line. The arrangement of the multiple radiating structures in the first subarray is consistent with the arrangement of the multiple radiating structures in the third subarray, and the arrangement of the multiple radiating structures in the second subarray is consistent with the arrangement of the multiple radiating structures in the fourth subarray. On a plane parallel to the polarization conversion structure, one set of opposite sides of the polarization conversion structure extends along the first direction, and another set of opposite sides extends along the second direction. The ninth center line is the center line of the polarization conversion structure extending along the first direction, and the tenth center line is the center line of the polarization conversion structure extending along the second direction. The first direction, the second direction, the third direction, and the fourth direction intersect.

[0023] In an exemplary embodiment, the multiple radiation units are symmetrically arranged with respect to the ninth, tenth, seventh and eighth center lines. On a plane parallel to the polarization conversion structure, the seventh center line is the center line of the polarization conversion structure extending along the third direction, and the eighth center line is the center line of the polarization conversion structure extending along the fourth direction.

[0024] In an exemplary embodiment, the period length of the radiation unit along the arrangement direction is: p=a+2*d+2*w;

[0025] Wherein, p is the length of the radiation unit along the arrangement direction, w is the line width of the resonant structure, a is the length of the radiation structure along the arrangement direction, and d is the distance between the resonant structure and the corresponding opposite side surface of the radiation structure.

[0026] In an exemplary embodiment, the length a of the radiation structure along the arrangement direction is 5 mm to 7 mm, the line width w of the resonant structure is 0.1 mm to 0.4 mm, the distance d between the opposite side surfaces of two adjacent radiation units is 0.1 mm to 0.4 mm, the length of the radiation unit along the arrangement direction is 5.2 mm to 8.6 mm, and the distance between two adjacent radiation units is half an operating wavelength.

[0027] An embodiment of the present disclosure further provides an antenna, comprising at least one polarization conversion structure described in any of the above embodiments.

[0028] In an exemplary embodiment, the antenna also includes a feed source. In a direction perpendicular to the plane where the polarization conversion structure is located, the polarization conversion structure includes a stacked ground structure layer, a first dielectric substrate, and a radiation structure layer. The feed source is arranged on a side of the radiation structure layer away from the first dielectric substrate. The polarization conversion structure is configured to receive electromagnetic waves from the feed source and perform polarization conversion on the received electromagnetic waves.

[0029] In an exemplary embodiment, the antenna further includes a second dielectric substrate and a feed structure layer. In a direction perpendicular to the plane of the antenna, the polarization conversion structure includes a stacked ground structure layer, a first dielectric substrate, and a radiation structure layer. The second dielectric substrate and the feed structure layer are located between the ground structure layer and the first dielectric substrate, and the feed structure layer is located on a side of the second dielectric substrate away from the ground structure layer.

[0030] In an exemplary embodiment, the antenna further includes at least one coaxial conductive structure, the radiation structure layer includes at least one radiation element, the feed structure layer includes at least one feed structure, and the at least one feed structure is electrically connected to the ground structure layer through the at least one coaxial conductive structure;

[0031] The at least one feeding structure corresponds to the at least one radiating structure, and an orthographic projection of the feeding structure on the first dielectric substrate at least partially overlaps with an orthographic projection of the corresponding radiating structure on the first dielectric substrate.

[0032] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are intended to provide a further understanding of the technical solutions of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the technical solutions of the present disclosure and do not constitute a limitation of the technical solutions of the present disclosure. The shapes and sizes of each component in the drawings do not reflect the actual scale and are intended only to illustrate the contents of the present disclosure.

[0034] FIG1 is a schematic diagram of a planar structure of a polarization conversion structure provided by an embodiment of the present disclosure;

[0035] FIG2 is a schematic diagram of the cross-sectional structure at the L1-L1 position in FIG1a;

[0036] FIG3 a is a schematic diagram showing a planar structure of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0037] FIG3 b is a schematic diagram showing a planar structure of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0038] FIG3 c is a schematic diagram showing a planar structure of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0039] FIG3 d is a schematic planar structural diagram of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0040] FIG3e is a schematic diagram of a planar structure of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0041] FIG4 is a schematic diagram of a planar structure of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0042] FIG5 is a schematic diagram of a planar structure of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0043] FIG6 is a schematic diagram showing a planar structure of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0044] FIG7 is a schematic diagram showing a planar structure of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0045] FIG8 is a schematic diagram of a planar structure of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0046] FIG9 is a schematic diagram showing a planar structure of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0047] FIG10 is a schematic diagram showing a planar structure of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0048] FIG11a is a reflection coefficient simulation curve diagram of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0049] FIG11 b is a simulation curve diagram of polarization conversion efficiency of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0050] FIG11c is a phase angle simulation curve diagram of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0051] FIG12 is a simulation curve diagram of polarization conversion efficiency of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0052] FIG13 is a simulation curve diagram of polarization conversion efficiency of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0053] FIG14 is a simulation curve diagram of polarization conversion efficiency of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0054] FIG15 is a simulation curve diagram of polarization conversion efficiency of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0055] FIG16 is a simulation curve diagram of polarization conversion efficiency of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0056] FIG17 is a simulation curve diagram of polarization conversion efficiency of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0057] FIG18 is a simulation curve diagram of polarization conversion efficiency of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0058] FIG19 is a simulation curve diagram of polarization conversion efficiency of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0059] FIG20 is a schematic diagram showing the polarization conversion principle of a polarization conversion structure provided by an exemplary embodiment of the present disclosure;

[0060] FIG21 is a schematic diagram of an antenna structure provided by an exemplary embodiment of the present disclosure;

[0061] FIG22 is a schematic diagram showing a cross-sectional structure of an antenna provided by an exemplary embodiment of the present disclosure;

[0062] FIG23 is a schematic diagram showing a planar structure of a feeding structure layer in an antenna provided by an exemplary embodiment of the present disclosure;

[0063] FIG24 is a schematic diagram showing a planar structure of a ground structure layer in an antenna provided by an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0064] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. The embodiments can be implemented in a number of different forms. A person of ordinary skill in the art can easily understand the fact that the methods and contents can be transformed into various forms without departing from the purpose and scope of the present disclosure. Therefore, the present disclosure should not be interpreted as being limited to the contents described in the following embodiments. Unless there is a conflict, the embodiments in the present disclosure and the features in the embodiments can be arbitrarily combined with each other. In order to keep the following description of the embodiments of the present disclosure clear and concise, the present disclosure omits detailed descriptions of some known functions and known components. The drawings of the embodiments of the present disclosure only involve structures related to the embodiments of the present disclosure. Other structures can refer to the general design

[0065] The scales of the figures in this disclosure are intended to serve as a reference for actual processes, but are not intended to be limiting. For example, the thickness and spacing of each film layer, and the width and spacing of each signal line, can be adjusted based on actual conditions. The figures described in this disclosure are merely schematic diagrams of the structures, and one embodiment of this disclosure is not limited to the shapes or values ​​shown in the figures.

[0066] In this specification, ordinal numbers such as “first”, “second” and “third” are provided to avoid confusion among constituent elements, and are not intended to limit the number.

[0067] In this specification, for convenience, words and phrases indicating orientation or positional relationships, such as "middle," "upper," "lower," "front," "back," "vertical," "horizontal," "top," "bottom," "inside," and "outside," are used to illustrate the positional relationships of constituent elements with reference to the accompanying drawings. This is merely for the purpose of facilitating the description of this specification and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present disclosure. The positional relationships of constituent elements may be appropriately changed depending on the direction in which each constituent element is described. Therefore, the present disclosure is not limited to the words and phrases described in the specification and may be appropriately replaced depending on the circumstances.

[0068] In this specification, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they can refer to fixed, removable, or integral connections; mechanical or electrical connections; direct connections, indirect connections through intermediaries, or internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure.

[0069] In this specification, "electrically connected" includes components connected together via an element having some electrical function. There are no particular limitations on the "element having some electrical function" as long as it enables the transfer of electrical signals between the connected components. Examples of "element having some electrical function" include not only electrodes and wiring but also switching elements such as transistors, resistors, inductors, capacitors, and other components with one or more functions.

[0070] In this specification, "parallel" refers to a state where the angle formed by two straight lines is greater than -10° and less than 10°, and thus includes a state where the angle is greater than -5° and less than 5°. Furthermore, "perpendicular" refers to a state where the angle formed by two straight lines is greater than 80° and less than 100°, and thus includes a state where the angle is greater than 85° and less than 95°.

[0071] In this specification, the terms "film" and "layer" may be interchanged. For example, "conductive layer" may be replaced with "conductive film." Similarly, "insulating film" may be replaced with "insulating layer."

[0072] The triangles, rectangles, trapezoids, pentagons or hexagons in this specification are not in the strict sense, but may be approximate triangles, rectangles, trapezoids, pentagons or hexagons, etc. There may be some small deformations caused by tolerances, and there may be chamfers, arc edges and deformations.

[0073] The term "about" in the present disclosure refers to a numerical value that is not strictly defined and allows for process and measurement errors.

[0074] The "thickness" in this disclosure refers to the dimension of the film layer in the direction perpendicular to the substrate.

[0075] Traditional polarization converters have disadvantages such as narrow bandwidth, large size, and difficult processing, and cannot meet the needs of practical use.

[0076] The embodiment of the present disclosure provides a polarization conversion structure, which may include a stacked ground structure layer, a first dielectric substrate, and a radiation structure layer in a direction perpendicular to the plane where the polarization conversion structure is located;

[0077] The radiation structure layer may include at least one radiation unit, and the radiation unit may include a radiation structure, the radiation structure is symmetrical with respect to a first center line, and on a plane parallel to the polarization conversion structure, the first center line is the center line of the radiation structure extending along a fourth direction; the orthographic projections of the radiation unit and the ground structure layer on the first dielectric substrate at least partially overlap.

[0078] The polarization conversion structure provided in the embodiment of the present disclosure has a radiation unit and a ground structure layer respectively arranged on both sides of the first dielectric layer, and the radiation structure in the radiation unit is symmetrically arranged relative to the first center line. While having a high conversion efficiency, it has the characteristics of simple structure, easy processing, low profile and small size.

[0079] In practical applications, designing a polarization conversion structure with simple structure, compact size and good performance has great engineering significance.

[0080] In an exemplary embodiment, the polarization conversion structure provided in the embodiment of the present disclosure is a polarization conversion metasurface (PCM) structure based on a metasurface, which has the characteristics of low profile, flexible design, low loss, and easy processing. It has obvious advantages in engineering applications and can improve the gain of the antenna, reduce crosstalk, and reduce the radar cross section (full name in English: radar cross section, abbreviated as RCS).

[0081] As shown in Figures 1 and 2, a schematic planar structure diagram of a polarization conversion structure provided in an embodiment of the present disclosure is shown. Figure 2 shows a cross-sectional view taken along line L1-L1 in Figure 1. In a direction Z perpendicular to the plane of the polarization conversion structure, the polarization conversion structure may include a stacked ground structure layer 11, a first dielectric substrate 21, and a radiation structure layer 300.

[0082] The radiation structure layer 300 may include at least one radiation unit 30, and the radiation unit 30 may include a radiation structure 31. The radiation structure 31 may be symmetrical with respect to a first center line Q1-Q1. On a plane parallel to the polarization conversion structure, the first center line Q1-Q1 is a center line of the radiation structure 31 extending along the fourth direction V. The orthographic projections of the radiation unit 30 and the ground structure layer 11 on the first dielectric substrate 21 at least partially overlap.

[0083] In an exemplary embodiment, as shown in Figure 2 , the thickness h of the first dielectric substrate 21 is 1 mm to 2 mm, the thickness t1 of the ground structure layer 11 is 0.01 mm to 0.05 mm, and the thickness t2 of the radiating structure layer 300 is 0.01 mm to 0.05 mm. It can be understood that, in a direction Z perpendicular to the plane of the polarization conversion structure, the dimension h of the first dielectric substrate 21 is 1 mm to 2 mm, the dimension t1 of the ground structure layer 11 is 0.01 mm to 0.05 mm, and the dimension t2 of the radiating structure layer 300 is 0.01 mm to 0.05 mm. For example, the thickness h of the first dielectric substrate 21 is 1.6 mm, the thickness t1 of the ground structure layer 11 is 0.035 mm, and the thickness t2 of the radiating structure layer is 0.035 mm.

[0084] In an exemplary embodiment, as shown in FIG1 , the radiation unit 30 may further include a resonant structure 32 spaced apart from the radiation structure 31 . The resonant structure 32 is located around the radiation structure 31 to form a ring structure. The resonant structure 32 may include a resonant opening 33 , and the ring structure is disconnected at the position of the resonant opening 33 .

[0085] In an exemplary embodiment, the outer contour of the resonant structure 32 may be in the shape of a square, as shown in Figures 1, 3a, and 3b, and the resonant opening 33 may be located at least one set of opposite sides of the square, or, as shown in Figures 3c to 3e, the resonant opening 33 may be located at at least one set of opposite corners of the square; in the structures shown in Figures 1, 3a to 3e, on a plane parallel to the polarization conversion structure, one set of opposite sides of the resonant structure 31 extends along the first direction X, and the other set of opposite sides extends along the second direction Y, and the resonant structure 32 is symmetrical with respect to the third center line Q3-Q3 and the fourth center line Q4-Q4, the third center line Q3-Q3 is the center line of the resonant structure 32 extending along the first direction X, and the fourth center line Q4-Q4 is the center line of the resonant structure 32 extending along the second direction Y, and the first direction X, the second direction Y, and the fourth direction V intersect.

[0086] In an exemplary embodiment, as shown in FIG1 and FIG3c through FIG3e , in a structure where the resonant opening 33 is located at at least one set of diagonal corners or two sets of opposite sides of a square (the shape of the outer contour of the resonant structure 32), the resonant structure 32 may further be symmetrical about a fifth centerline Q5-Q5 and a sixth centerline Q6-Q6. The fifth centerline Q5-Q5 is the centerline of the resonant structure 32 extending along the fourth direction V, and the sixth centerline Q6-Q6 is the centerline of the resonant structure 32 extending along the third direction U. The third direction U intersects the first direction X, the second direction Y, and the fourth direction V. In an exemplary embodiment, the fifth centerline Q5-Q5 coincides with the first centerline Q1-Q1.

[0087] In an exemplary embodiment, as shown in Figures 1 and 3a to 3e, the radiation structure 31 can also be symmetrical with respect to the second center line Q2-Q2. On a plane parallel to the polarization conversion structure, the second center line Q2-Q2 can be the center line of the radiation structure 31 extending along the third direction U, and the third direction U intersects with the first direction X, the second direction Y, and the fourth direction V.

[0088] In an exemplary embodiment, the second center line Q2-Q2 may coincide with the sixth center line Q6-Q6. In an exemplary embodiment, the first center line Q1-Q1 and the fifth center line Q5-Q5 may coincide with a diagonal line of the square (the shape of the outer contour of the resonant structure 32) extending along the fourth direction V, and the second center line Q2-Q2 and the sixth center line Q6-Q6 may coincide with a diagonal line of the square (the shape of the outer contour of the resonant structure 32) extending along the third direction U.

[0089] In an exemplary embodiment, as shown in FIG. 1 and FIG. 3 a to FIG. 4 , the radiation structure 31 may be a polygonal structure, and the first center line Q1 - Q1 coincides with a diagonal line of the polygonal structure extending along the fourth direction.

[0090] In an exemplary embodiment, as shown in Figures 1 and 3a to 3e, the radiating structure 31 may be hexagonal, including a first set of opposite sides (D11 and D12), a second set of opposite sides (D21 and D22), and a third set of opposite sides (D31 and D32). Two sides in each set of opposite sides are parallel to each other. The first set of opposite sides extends along a first direction X, the second set of opposite sides extends along a second direction Y, and the third set of opposite sides extends along a fourth direction V. In an exemplary embodiment, the radiating structure 31 may be formed by cutting off a set of opposite corners from a square radiating patch. In an exemplary embodiment, the first set of sides (D11 and D12) is parallel to one set of opposite sides of the resonant structure 32, the second set of opposite sides (D21 and D22) is parallel to another set of opposite sides of the resonant structure 32, and the third set of opposite sides (D31 and D32) is parallel to the first centerline Q1-Q1.

[0091] In an exemplary embodiment, the linewidth w of the ring-shaped resonant structure 32 can be 0.1 mm to 0.4 mm. As shown in Figures 1 and 3a to 3e, the dimension a1 of the radiating structure 31 along the first direction X is equal to the dimension a2 along the second direction, both being 5 mm to 7 mm. The side lengths b1 of two sides in the first set of opposite sides (D11 and D12) and b2 of two sides in the second set of opposite sides (D21 and D22) are equal, both being 2 mm to 6 mm. For example, a1 = a2 = 6 mm, and the dimensions of b1 and b2 can be 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, or 5.5 mm. In an exemplary embodiment, as shown in Figures 1 and 3a, the dimension g of the resonant opening 33 is approximately half an operating wavelength, which can be the wavelength of the electromagnetic wave received by the polarization conversion structure.

[0092] In an exemplary embodiment, as shown in Figure 4, the shape of the radiating structure 31 can be a double-arrow shape, which can include two isosceles right triangles (T1 and T2) and a rectangle (T3), where the rectangle T3 connects the two isosceles right triangles (T1 and T2) into one, and a set of opposite sides (T31 and T32) of the rectangle T3 are respectively connected to the bases of the two isosceles right triangles (T11 and T21), and the midline of the rectangle T3 extending along the fourth direction V, the angle bisectors of the two right angles in the two isosceles right triangles (T1 and T2) coincide with the first midline Q1-Q1.

[0093] In an exemplary embodiment, as shown in FIG5 , the radiation structure 31 may be in the shape of a rhombus, one diagonal line of the rhombus coincides with the third center line Q3 - Q3 , and the other diagonal line of the rhombus coincides with the fourth center line Q4 - Q4 .

[0094] In an exemplary embodiment, as shown in FIG6 , the radiation structure 31 may be a square radiation patch with concave arc-shaped notches K1 provided at a set of diagonal positions on both sides of the first center line Q1-Q1. For example, the radiation structure 31 may be formed by rounding off a square radiation patch at a set of diagonal positions. Alternatively, as shown in FIG7 , the radiation structure 31 may be a circular radiation patch with concave arc-shaped notches K2 provided at opposite positions on both sides of the first center line Q1-Q1. For example, the radiation structure 31 may be formed by cutting off arcs from a circular radiation patch at opposite positions on both sides of the first center line Q1-Q1. Alternatively, as shown in FIG8 , the radiation structure 31 may be a circular radiation patch with fan-shaped notches K3 provided at opposite positions on both sides of the first center line Q1-Q1. The radiation structure 31 may be formed by cutting off a fan-shaped circular radiation patch at opposite positions on both sides of the first center line Q1-Q1.

[0095] In an exemplary embodiment, as shown in Figures 9 and 10, there are multiple radiation units 30, which are arranged in an array. In an exemplary embodiment, the array arrangement of multiple radiation units 30 can meet the requirements of high bandwidth and high gain.

[0096] In an exemplary embodiment, as shown in FIG9 , the plurality of radiation structures 31 in the plurality of radiation units 30 are arranged in a consistent manner.

[0097] In an exemplary embodiment, as shown in Figure 9, the polarization conversion structure can be a square. On a plane parallel to the polarization conversion structure, one group of pairs of sides of the polarization conversion structure extend along the first direction X, and another group of pairs of sides extend along the second direction Y. The multiple radiation units 30 can be symmetrically arranged relative to the seventh center line Q7-Q7 and the eighth center line Q8-Q8. The seventh center line Q7-Q7 is the center line of the polarization conversion structure extending along the third direction U, and the eighth center line Q8-Q8 is the center line of the polarization conversion structure extending along the fourth direction V.

[0098] In an exemplary embodiment, as shown in FIG10 , the polarization conversion structure is square and includes first to fourth subarrays 301 to 304 defined by a ninth center line Q9-Q9 and a tenth center line Q10-Q10. The arrangement of the multiple radiating structures 31 in the first subarray 301 is consistent with the arrangement of the multiple radiating structures 31 in the third subarray 303. The arrangement of the multiple radiating structures 31 in the second subarray 302 is consistent with the arrangement of the multiple radiating structures 31 in the fourth subarray 304. In a plane parallel to the polarization conversion structure, one set of paired edges of the polarization conversion structure extends along a first direction X, and another set of paired edges extends along a second direction Y. The ninth center line Q9-Q9 is the center line of the polarization conversion structure extending along the first direction X, and the tenth center line Q10-Q10 is the center line of the polarization conversion structure extending along the second direction Y. The ninth center line Q9-Q9 intersects with the tenth center line Q10-Q10.

[0099] In an exemplary embodiment, as shown in Figure 10, multiple radiation units 30 can be symmetrically arranged relative to the ninth center line Q9-Q9, the tenth center line Q10-Q10, the seventh center line Q7-Q7 and the eighth center line Q8-Q8. On a plane parallel to the polarization conversion structure, the seventh center line Q7-Q7 is the center line of the polarization conversion structure extending along the third direction U, and the eighth center line Q8-Q8 is the center line of the polarization conversion structure extending along the fourth direction V.

[0100] In the exemplary embodiment, in the structures shown in Figures 9 and 10, the straight line connecting the centers of one set of opposite sides of the polarization conversion structure overlaps with the orthographic projection of the ninth center line Q9-Q9 on the first dielectric substrate 21, and the straight line connecting the centers of another set of opposite sides of the polarization conversion structure overlaps with the orthographic projection of the tenth center line Q10-Q10 on the first dielectric substrate 21; and the two diagonal lines of the polarization conversion structure overlap with the orthographic projections of the seventh center line Q7-Q7 and the eighth center line Q8-Q8 on the first dielectric substrate 21, respectively.

[0101] In an exemplary embodiment, as shown in FIG9 and FIG10 , the length of the radiation unit 30 along the arrangement direction is: p=a+2*d+2*w;

[0102] Where p is the length of the radiating element 30 along the arrangement direction, d is the distance between the opposite side surfaces of two adjacent radiating elements 30, w is the linewidth of the resonant structure 32, and a is the length of the radiating structure 31 along the arrangement direction. The linewidth w of the resonant structure 32 can be marked with reference to Figures 3b and 4.

[0103] In an exemplary embodiment, as shown in FIG. 9 and FIG. 10 , the radiation units 30 may be arranged in a first direction X and a second direction Y. As shown in FIG.

[0104] In an exemplary embodiment, the length a of the radiating structure 31 along the arrangement direction may be 5 mm to 7 mm, the line width w of the resonant structure 32 may be 0.1 mm to 0.4 mm, the distance d between the resonant structure 32 and the corresponding opposite side surface of the radiating structure 31 may be 0.1 mm to 0.4 mm, and the length p of the radiating element 30 along the arrangement direction may be 5.2 mm to 8.6 mm. For example, the length a of the radiating structure 31 along the arrangement direction may be 6 mm, and the length p of the radiating element 30 along the arrangement direction may be 7 mm.

[0105] In an exemplary embodiment, the distance f between two adjacent radiation units 30 (ie, the distance between opposite side surfaces of two adjacent radiation units 30) may be about half an operating wavelength. In an exemplary embodiment, the operating wavelength may be the wavelength of the electromagnetic wave received by the polarization conversion structure.

[0106] In an exemplary embodiment, in the process of designing the polarization conversion structure, the period length p of the radiation unit 30 along the arrangement direction can be determined first, and then the length a of the radiation structure 31 along the arrangement direction can be determined. Then, the line width w of the resonant structure 32 can be optimized according to the simulation results, thereby determining the value of the line width w of the resonant structure 32. Finally, according to the formula p=a+2*d+2*w, the value of the distance d between the opposite side surfaces of the final resonant structure 32 and the corresponding radiation structure 31 can be obtained.

[0107] In an exemplary embodiment, in the polarization conversion structure shown in Figures 1, 3a to 9, the polarization angle of a linearly polarized electromagnetic wave can be converted, or the polarization angle of a circularly polarized electromagnetic wave can be converted; in the polarization conversion structure shown in Figure 10, synthesis and decomposition between linear polarization and circular polarization can be achieved, that is, a linearly polarized electromagnetic wave can be converted into a circularly polarized electromagnetic wave, or a circularly polarized electromagnetic wave can be converted into a linearly polarized electromagnetic wave.

[0108] In an exemplary embodiment, as shown in the polarization conversion structure in Figures 1 and 3a to 8, under the premise of realizing the polarization conversion function, the radiation unit 30 has a simple design structure with the characteristics of low profile, flexible design, low loss, and easy processing. It has obvious advantages in engineering applications and can improve the gain of the antenna, reduce crosstalk, and reduce the radar cross section (full name in English: radar cross section, abbreviated as RCS).

[0109] In an exemplary embodiment, the radiation unit 30 shown in FIG. 1 and FIG. 3 a to FIG. 8 can be used alone as a polarization conversion structure, or a plurality of radiation units 30 can be arrayed to obtain the polarization conversion structure shown in FIG. 9 or FIG. 10 .

[0110] In an exemplary embodiment, as shown in FIG. 1 , FIG. 3 a to FIG. 3 e , and FIG. 5 , the radiation unit 30 (which can be used alone as a polarization conversion structure) and the radiation structure 31 are simple in design, which greatly reduces the difficulty of the processing technology.

[0111] In an exemplary embodiment, as shown in FIG4 , the radiation unit 30 (which can be used alone as a polarization conversion structure) and the radiation structure 31 are configured in a double-arrow shape to achieve polarization conversion in multiple frequency bands. By optimizing the parameters, the bandwidth characteristics and conversion efficiency of different frequency bands can be improved, thereby achieving the polarization conversion function of two or more working frequency bands by one radiation unit.

[0112] In an exemplary embodiment, as shown in the radiation unit 30 in Figure 6 (which can be used as a polarization conversion structure alone), the radiation structure 31 can be formed by a square radiation patch with rounded corners cut off at a set of diagonal positions. The radiation structure 31 forms a concave arc M1 at the edge of the cut-off rounded corner position. The bandwidth is affected by the edge shape of the arc M1 in the radiation structure 31. The bandwidth of the polarization conversion structure can be flexibly set by changing the arc length of the arc M1 at the cut-off rounded corner position and the radius of the circle where the arc M1 is located. After optimized design, a polarization conversion structure with narrow bandwidth and high directivity can be obtained, and it has the advantage of low processing difficulty.

[0113] In an exemplary embodiment, as shown in the radiation unit 30 of FIG7 (which can be used alone as a polarization conversion structure), the radiation structure 31 is formed by cutting out circular arcs from a circular radiation patch at positions opposite to each other on both sides of the first center line Q1-Q1. The radiation structure 31 has a concave first arc edge M21 and a convex second arc edge M22. Since the curvature change between the concave first arc edge M21 and the convex second arc edge M22 is relatively obvious, the current flowing through the edge of the radiation structure 31 changes rapidly, resulting in a relatively narrow frequency bandwidth near the center frequency point, which can achieve an ultra-narrow bandwidth and strong directivity polarization conversion function.

[0114] In an exemplary embodiment, as shown in the radiation unit 30 of FIG8 (which can be used alone as a polarization conversion structure), the radiation structure 31 is formed by cutting out a circular radiation patch into a sector shape at opposite positions on both sides of the first center line Q1-Q1, so that the current flowing through the edge of the radiation structure 31 changes relatively slowly, which is beneficial to improving the gain and directivity on the basis of appropriate expansion of the bandwidth.

[0115] The following describes simulation results of the polarization conversion structure (including a radiating unit 30) shown in FIG1 . When other dimensions of the polarization conversion structure remain unchanged and the length b of the short side of the radiating structure 31 (i.e., the length of the side of the radiating structure 31 extending along the second direction Y) is changed, the simulation results of the polarization conversion structure are as follows:

[0116] The thickness h of the first dielectric substrate 21 is 1.6 mm, the thickness t1 of the ground structure layer 11 is 0.035 mm, the thickness t2 of the radiation structure 31 is 0.035 mm, the side length p of the square radiation unit 30 is 7 mm, and the length a of the radiation structure 31 in the first direction X and the second direction Y is 6.4 mm.

[0117] In an exemplary embodiment, the dielectric constant of the first dielectric substrate 21 may be taken into consideration during the simulation process, and an effective wavelength may be used. The effective wavelength = operating wavelength / dielectric constant. The operating wavelength is the wavelength of electromagnetic waves that can be received.

[0118] Figures 11a to 11c show simulation results for a short side length b of the radiating structure 31 in Figure 1 (the side length of the radiating structure 31 extending along the second direction Y) of 3.2 mm. Figure 11a shows the simulation results for the normalized reflection coefficient, Figure 11b shows the simulation results for the polarization conversion efficiency, and Figure 11c shows the simulation results for the phase angle. Figure 11a shows that within the 6-10 GHz frequency band, the magnitude of the cross-polarization reflection coefficient (Rxy) exceeds 0.95, while the main polarization reflection coefficient (Ryy) is less than 0.3. Figure 11b shows that the polarization conversion efficiency (PCR) within the 6-10 GHz frequency band is greater than 0.9. As shown in Figure 11c, simulation of the phase difference (ΔФ) shows that the phase difference ranges from -154° to 294° across the entire frequency band, but this does not affect the polarization conversion efficiency (because Rxy is much greater than Ryy). In Figure 11c, at one of the determined frequencies, △Ф=Ф(Rxy)-Ф(Ryy), where △Ф is the phase difference, Ф(Ryy) is the phase angle of the main polarization reflection coefficient when the polarization direction of the incident wave is the second direction Y; Ф(Rxy) is the phase angle of the cross-polarization reflection coefficient when the polarization direction of the incident wave is the second direction Y.

[0119] Figure 12 is a schematic diagram of the simulation results of the polarization conversion efficiency when the length b of the short side of the radiation structure 31 in Figure 1 (the length of the side of the radiation structure 31 extending along the second direction Y) is 2 mm. Figure 13 is a schematic diagram of the simulation results of the polarization conversion efficiency when the length b of the short side of the radiation structure 31 in Figure 1 (the length of the side of the radiation structure 31 extending along the second direction Y) is 3 mm. Figure 14 is a schematic diagram of the simulation results of the polarization conversion efficiency when the length b of the short side of the radiation structure 31 in Figure 1 (the length of the side of the radiation structure 31 extending along the second direction Y) is 3.5 mm. As can be seen from Figures 12 and 13, a comparison reveals that the structure with a short side length b of 3 mm for the radiating structure 31 exhibits a larger Rxy reflection coefficient amplitude (exceeding 0.98 in the 6.5-9.1 GHz band and 1 in the 7-9 GHz band) and the lowest Ryy reflection coefficient amplitude (less than 0.1 in the 6.5-9.1 GHz band). This indicates that a b value of 3 mm achieves better polarization conversion efficiency. As shown in Figure 14, a structure with a short side length b of 3.5 mm for the radiating structure 31 (the length of the side extending along the second direction Y of the radiating structure 31) achieves a wider operating bandwidth (with a reflection coefficient Rxy exceeding 0.95 in the 6-10.2 GHz band) while maintaining a significant reduction in reflection coefficient and conversion efficiency.

[0120] Figures 15 to 19 are schematic diagrams of simulation results of polarization conversion efficiency for a structure in which the side length b of the short side of the radiation structure 31 in Figure 1 (the side length of the radiation structure 31 extending along the second direction Y) is 4 mm to 6 mm, wherein Figure 15 shows a schematic diagram of simulation results of polarization conversion efficiency when the side length b of the short side of the radiation structure 31 in Figure 1 (the side length of the radiation structure 31 extending along the second direction Y) is 4 mm; Figure 16 shows a schematic diagram of simulation results of polarization conversion efficiency when the side length b of the short side of the radiation structure 31 in Figure 1 (the side length of the radiation structure 31 extending along the second direction Y) is 4.5 mm. Figure 17 shows a schematic diagram of the simulation results of the polarization conversion efficiency when the side length b of the short side of the radiating structure 31 in Figure 1 (the side length of the radiating structure 31 extending along the second direction Y) is 5 mm; Figure 18 shows a schematic diagram of the simulation results of the polarization conversion efficiency when the side length b of the short side of the radiating structure 31 in Figure 1 (the side length of the radiating structure 31 extending along the second direction Y) is 5.5 mm; and Figure 19 shows a schematic diagram of the simulation results of the polarization conversion efficiency when the side length b of the short side of the radiating structure 31 in Figure 1 (the side length of the radiating structure 31 extending along the second direction Y) is 6 mm. As can be seen from Figures 13 to 19, good polarization conversion performance is achieved when the side length b of the short side of the radiating structure 31 is within the range of 3 mm to 6 mm. As the side length b of the short side of the radiating structure 31 (the side length of the radiating structure 31 extending along the second direction Y) changes from 4 mm to 6 mm, the polarization conversion efficiency gradually decreases in structures with gradually increasing b values ​​within the range of 4 mm to 6 mm, and the performance shows a trend of gradually deteriorating.

[0121] In an exemplary embodiment, when the line width w of the resonant structure 32 changes, the frequency band of polarization conversion and the intensity of the reflection coefficient will fluctuate. The reflection coefficient and the frequency bandwidth can be adjusted by adjusting the line width w of the resonant structure 32 .

[0122] In the exemplary embodiment, as described above and shown in FIG. 11 a to FIG. 19 , the performance of the polarization conversion structure can be evaluated using the polarization conversion efficiency (PCR) and the reflection coefficient. If the incident wave is polarized along the Y axis, the polarization conversion efficiency PCR and the reflection coefficient are calculated as follows:

[0123] Where PCR is the polarization conversion efficiency, R xy =|E rx | / |E iy |, R yy =|E ry | / |E iy|, Rxy and Ryy are the reflection coefficients for cross polarization and main polarization, respectively, Erx is the reflected electric field along the X-axis, Eiy is the incident electric field along the Y-axis, and Ery is the reflected electric field along the Y-axis. In the exemplary embodiment, as can be seen from the polarization conversion efficiency calculation formula, the polarization conversion efficiency PCR is used to evaluate the efficiency of converting the incident electric field along the Y-axis into the reflected electric field along the X-axis.

[0124] In an exemplary embodiment, FIG20 is a schematic diagram showing the polarization conversion principle, wherein Ei (i.e., E iy ) is the electric field incident along the Y-axis direction, and Er (i.e., Erx) is the electric field reflected along the X-axis direction.

[0125] An embodiment of the present disclosure further provides an antenna, comprising the polarization conversion structure described in any of the above embodiments.

[0126] In an exemplary embodiment, as shown in FIG21 , the antenna may further include a feed 400. In a direction perpendicular to the plane of the polarization conversion structure, the polarization conversion structure may include a stacked ground structure layer 11, a first dielectric substrate 21, and a radiating structure layer 300. The feed 400 is disposed on a side of the radiating structure layer away from the first dielectric substrate 21. The polarization conversion structure is configured to receive electromagnetic waves (which can be understood as incident waves) from the feed 400, perform polarization conversion on the electromagnetic waves, and reflect the polarization-converted electromagnetic waves. This is a reflection operating mode. In this application state, the polarization conversion can be applied to the electromagnetic wave signals from the feed 400. The electromagnetic waves emitted by the feed 400 may be emitted by other antennas, or the feed 400 may be a separate antenna structure, and the polarization conversion structure performs polarization conversion on the electromagnetic waves emitted by another antenna structure serving as the feed 400. In the antenna structure shown in FIG21 , the polarization conversion structure may be the same as the polarization conversion structure described in any of the above embodiments.

[0127] In an exemplary embodiment, as shown in FIG22 , the antenna may further include a second dielectric substrate 500 and a feed structure layer 600. In a direction perpendicular to the plane of the antenna, the polarization conversion structure may include a stacked ground structure layer 11, a first dielectric substrate 21, and a radiation structure layer 300. The second dielectric substrate 500 and the feed structure layer 600 are located between the ground structure layer 11 and the first dielectric substrate 21, and the feed structure layer 600 is located on a side of the second dielectric substrate 500 away from the ground structure layer 11.

[0128] In an exemplary embodiment, as shown in FIG22 , the antenna may further include at least one coaxial conductive structure 602 , the radiation structure layer 300 may include at least one radiation unit 30 , the feed structure layer 600 may include at least one feed structure 601 , and the at least one feed structure 601 may be electrically connected to the ground structure layer 11 via the at least one coaxial conductive structure 602 ;

[0129] At least one feeding structure 601 corresponds to at least one radiating element 30 , and an orthographic projection of the feeding structure 601 on the first dielectric substrate 21 at least partially overlaps with an orthographic projection of the corresponding radiating element 30 on the first dielectric substrate 21 .

[0130] In an exemplary embodiment, FIG22 shows a polarization conversion structure comprising one radiating element 30, corresponding to a feed structure 601 and a coaxial conductive structure 602. In a structure where the polarization conversion structure includes multiple arrays of radiating elements 30, there are correspondingly multiple arrays of feed structures 601 and multiple coaxial conductive structures 602. FIG23 is a schematic planar structural diagram of a feed structure layer 600 corresponding to the polarization conversion structure in FIG9 , and FIG24 is a schematic planar structural diagram of a ground structure layer 11 corresponding to the feed structure layer 600 in FIG23 . In an exemplary embodiment, the coaxial conductive structure 602 may be a coaxial feed probe or a coaxial conductive post. In an exemplary embodiment, one end of the coaxial conductive structure 602 is connected to the feed structure layer 600, and the other end extends to a side of the ground structure layer 11 away from the second dielectric substrate 500. The coaxial conductive structure 602 is configured to receive electromagnetic waves and transmit the received electromagnetic waves to the corresponding feed structure 601 in the feed structure layer 600. The feed structure 601 then feeds the electromagnetic waves into the corresponding radiating element 30 in the radiating structure layer 300. In an exemplary embodiment, the polarization conversion structure can be any of the polarization conversion structures described in any of the above embodiments.

[0131] In an exemplary embodiment, the working mode of the antenna shown in Figure 22 can adopt a transmission working mode (obtaining the electromagnetic waves received by the coaxial conductive structure 602 by transmission and performing polarization conversion on the electromagnetic waves), and the working mode of the antenna shown in Figure 21 can adopt a reflection working mode (obtaining the electromagnetic waves emitted by the feed source 400 by reflection and performing polarization conversion on the electromagnetic waves).

[0132] The polarization conversion structure provided in the embodiment of the present disclosure has a radiation unit and a ground structure layer respectively arranged on both sides of the first dielectric layer, and the radiation structure in the radiation unit is symmetrically arranged relative to the first center line. While having a high conversion efficiency, it has the characteristics of simple structure, easy processing, low profile and small size.

[0133] The drawings of the embodiments of the present disclosure only involve the structures involved in the embodiments of the present disclosure, and other structures may refer to general designs.

[0134] In the absence of conflict, the embodiments of the present disclosure, i.e., features in the embodiments, can be combined with each other to form new embodiments.

[0135] Although the embodiments disclosed in the present disclosure are as described above, the contents described are only embodiments adopted to facilitate understanding of the embodiments of the present disclosure and are not intended to limit the embodiments of the present disclosure. Any person skilled in the art in the field to which the embodiments of the present disclosure belong may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the embodiments of the present disclosure, but the scope of patent protection of the embodiments of the present disclosure shall still be based on the scope defined by the attached claims.

Claims

1. A polarization conversion structure, in a direction perpendicular to the plane where the polarization conversion structure is located, includes a stacked ground structure layer, a first dielectric substrate, and a radiation structure layer; The radiation structure layer includes at least one radiation unit, the radiation unit includes a radiation structure, the radiation structure is symmetric with respect to a first midline, and in a plane parallel to the polarization conversion structure, the first midline is the midline of the radiation structure extending along a fourth direction; the radiation unit and the ground structure layer have at least partial overlap in the orthographic projection on the first dielectric substrate.

2. The polarization conversion structure according to claim 1, wherein, The radiation unit further includes a resonant structure spaced apart from the radiation structure, the resonant structure is located around the radiation structure to form an annular structure, the resonant structure includes a resonant opening, and the annular structure is disconnected at the position of the resonant opening.

3. The polarization conversion structure according to claim 2, wherein, The shape of the outer contour of the resonant structure is a square, the resonant opening is located at at least one set of diagonals of the square, or the resonant opening is located at at least one set of opposite sides of the square; In a plane parallel to the polarization conversion structure, a set of opposite sides of the resonant structure extends along a first direction, and the other set of opposite sides extends along a second direction, the resonant structure is symmetric with respect to a third midline and a fourth midline, the third midline is the midline of the resonant structure extending along the first direction, the fourth midline is the midline of the resonant structure extending along the second direction, and the first direction, the second direction, and the fourth direction intersect.

4. The polarization conversion structure according to claim 3, wherein In the structure where the resonant opening is located at at least one set of diagonals or two sets of opposite sides of the square, the resonant structure is symmetric with respect to a fifth midline and a sixth midline, in a plane parallel to the polarization conversion structure, the fifth midline is the midline of the resonant structure extending along the fourth direction, the sixth midline is the midline of the resonant structure extending along a third direction, the fifth midline coincides with the first midline, and the third direction intersects with the first direction, the second direction, and the fourth direction.

5. The polarization conversion structure according to claim 3, wherein, The radiation structure is also symmetric with respect to a second midline, in a plane parallel to the polarization conversion structure, the second midline is the midline of the radiation structure extending along a third direction, and the third direction intersects with the first direction, the second direction, and the fourth direction.

6. The polarization conversion structure according to claim 5, wherein, The radiation structure is a polygonal structure, and the first midline coincides with the diagonal of the polygonal structure extending along the fourth direction.

7. The polarization conversion structure according to claim 6, wherein, The shape of the radiation structure is a hexagon, the hexagon includes a first set of opposite sides, a second set of opposite sides, and a third set of opposite sides, the two sides in each set of opposite sides are parallel to each other, the first set of opposite sides extends along the first direction, the second set of opposite sides extends along the second direction, and the third set of opposite sides extends along the fourth direction.

8. The polarization conversion structure according to claim 7, wherein, The line width of the annular structure is 0.1 mm to 0.4 mm; The dimension of the radiation structure along the first direction is equal to the dimension along the second direction, both are 5 mm to 7 mm; The side lengths of the two sides in the first set of opposite sides are equal to the side lengths of the two sides in the second set of opposite sides, both are 2 mm to 6 mm.

9. The polarization conversion structure according to claim 6, wherein, The shape of the radiation structure is a double-arrow shape, and the double-arrow shape includes two isosceles right triangles and a rectangle. The rectangle connects the two isosceles right triangles into one body. One pair of opposite sides of the rectangle is respectively connected to the bases of the two isosceles right triangles. The median line of the rectangle extending along the fourth direction, the angle bisectors of the two right angles in the two isosceles right triangles coincide with the first median line.

10. The polarization conversion structure according to claim 5, wherein, The shape of the radiation structure is a rhombus. One diagonal of the rhombus coincides with the third median line, and the other diagonal of the rhombus coincides with the fourth median line.

11. The polarization conversion structure according to claim 5, wherein, The radiation structure is a square radiation patch with concave arc-shaped notches provided at a set of diagonal positions on both sides of the first median line; Alternatively, the radiation structure is a circular radiation patch with concave arc-shaped notches provided at opposite positions on both sides of the first median line; or the radiation structure is a circular radiation patch with sector-shaped notches provided at opposite positions on both sides of the first median line.

12. The polarization conversion structure according to any one of claims 3 to 11, wherein, The number of the radiation units is multiple, and the multiple radiation units are arranged in an array.

13. The polarization conversion structure according to claim 12, wherein, The arrangement modes of the multiple radiation structures in the multiple radiation units are the same.

14. The polarization conversion structure according to claim 13, wherein, The polarization conversion structure is a square. In a plane parallel to the polarization conversion structure, one pair of opposite sides of the polarization conversion structure extends along the first direction, and the other pair of opposite sides extends along the second direction. The multiple radiation units are symmetrically arranged with respect to the seventh median line and the eighth median line. The seventh median line is the median line of the polarization conversion structure extending along the third direction, and the eighth median line is the median line of the polarization conversion structure extending along the fourth direction.

15. The polarization conversion structure according to claim 12, wherein, The polarization conversion structure is a square. The polarization conversion structure includes a first sub-array to a fourth sub-array defined by a ninth median line and a tenth median line. The arrangement mode of the multiple radiation structures located in the first sub-array is the same as the arrangement mode of the multiple radiation structures located in the third sub-array. The arrangement mode of the multiple radiation structures located in the second sub-array is the same as the arrangement mode of the multiple radiation structures located in the fourth sub-array. In a plane parallel to the polarization conversion structure, one pair of opposite sides of the polarization conversion structure extends along the first direction, and the other pair of opposite sides extends along the second direction. The ninth median line is the median line of the polarization conversion structure extending along the first direction, and the tenth median line is the median line of the polarization conversion structure extending along the second direction. The first direction, the second direction, the third direction and the fourth direction intersect.

16. The polarization conversion structure according to claim 15, wherein, The multiple radiation units are symmetrically arranged with respect to the ninth median line, the tenth median line, the seventh median line and the eighth median line. In a plane parallel to the polarization conversion structure, the seventh median line is the median line of the polarization conversion structure extending along the third direction, and the eighth median line is the median line of the polarization conversion structure extending along the fourth direction.

17. The polarization conversion structure according to claim 12, wherein, The length of the radiation unit along the arrangement direction is: p = a + 2*d + 2*w; Among them, p is the length of the radiation unit along the arrangement direction, w is the line width of the resonant structure, a is the length of the radiation structure along the arrangement direction, and d is the distance between the resonant structure and the opposite side surface of the corresponding radiation structure.

18. The polarization conversion structure according to claim 17, wherein, The length a of the radiation structure along the arrangement direction is 5 mm to 7 mm, the line width w of the resonant structure is 0.1 mm to 0.4 mm, the distance d between the opposite side surfaces of two adjacent radiation units is 0.1 mm to 0.4 mm, the length of the radiation unit along the arrangement direction is 5.2 mm to 8.6 mm, and the distance between two adjacent radiation units is half of the operating wavelength.

19. An antenna comprising at least one polarization conversion structure according to any one of claims 1 to 18.

20. The antenna according to claim 19, further comprising a feed source. In a direction perpendicular to the plane where the polarization conversion structure is located, the polarization conversion structure includes a stacked ground structure layer, a first dielectric substrate, and a radiation structure layer. The feed source is disposed on a side of the radiation structure layer away from the first dielectric substrate, and the polarization conversion structure is configured to receive an electromagnetic wave from the feed source and perform polarization conversion on the received electromagnetic wave.

21. The antenna according to claim 19, further comprising a second dielectric substrate and a feed structure layer. In a direction perpendicular to the plane where the antenna is located, the polarization conversion structure includes a stacked ground structure layer, a first dielectric substrate, and a radiation structure layer; the second dielectric substrate and the feed structure layer are located between the ground structure layer and the first dielectric substrate, and the feed structure layer is located on a side of the second dielectric substrate away from the ground structure layer.

22. The antenna according to claim 21, further comprising at least one coaxial conductive structure. The radiation structure layer includes at least one radiation unit, and the feed structure layer includes at least one feed structure. The at least one feed structure is electrically connected to the ground structure layer through the at least one coaxial conductive structure; The at least one feed structure corresponds to the at least one radiation structure, and the orthographic projection of the feed structure on the first dielectric substrate at least partially overlaps with the orthographic projection of the corresponding radiation structure on the first dielectric substrate.

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