Antenna unit, antenna array and array antenna based on polarization conversion metasurface

Abstract

The application discloses an antenna unit based on a polarization conversion metasurface, an antenna array and an array antenna, and the antenna unit comprises a unit carrier assembly, a unit function structure and a unit metal grounding surface, wherein the unit carrier assembly adopts a structure of mutual lamination of a flexible dielectric substrate and an aramid honeycomb paper core, which can realize the feature of conforming to the shape of the carrier and has the surface load bearing property of the carrier; the unit function structure comprises a unit microstrip feed line, a unit polarization conversion metasurface, a unit coupling slot and a unit coaxial feed head; the multi-layer base frame and the configuration of multiple groups of unit polarization conversion metasurfaces in different states are used to expand the function of the multifunctional polarization metasurface. The array antenna adopts a modular design idea, has the characteristics of a low profile, light weight and simple structure in the structure, has the electromagnetic stealth and electromagnetic wave transmitting and receiving dual electromagnetic functions in the function, can be conformal to the surface of a complex carrier and has the surface load bearing function, and has the integration of structure and function.

Description

Technical Field

[0001] The present invention relates to antenna technology in the field of wireless communication technology, and in particular to an antenna unit, an antenna array and an array antenna based on a polarization conversion metasurface. Background Art

[0002] A metasurface is a two-dimensional metamaterial array with subwavelength dimensions. By designing the structure and arrangement of its units, it can control the polarization of electromagnetic waves. Therefore, it is of great significance in the fields of microwave antennas, stealth, and communications.

[0003] Polarization-converting metasurfaces utilize the anisotropic properties of metasurfaces to achieve polarization conversion of incident electromagnetic waves by manipulating the structural parameters of their cells. Compared to other electromagnetic wave manipulation methods, polarization-converting metasurfaces can freely control the electromagnetic wave state by adjusting the structural parameters of their cells and their array arrangement, thereby achieving electromagnetic stealth. Traditional metasurfaces generally have a single function, significantly limiting their universal applicability in practical applications. Incorporating multiple complex functions, such as flexible conformality, structural support, antenna transmission and reception, and electromagnetic wave polarization control, into metasurface designs can significantly enhance their application prospects. On the one hand, flexible conformality and structural support effectively support the aerodynamic and aerodynamic layout of the carrier, resulting in better stealth performance than flat surfaces. Furthermore, metasurfaces are typically installed beneath the carrier's outer skin. Considering the distortion and deformation caused by external pressure, structural support effectively addresses the issue of electrical stability. Furthermore, as electromagnetic devices, multifunctional integration and lightweighting are key research and development goals. Combining the metasurface's control of incident electromagnetic waves with the antenna's electromagnetic wave transmission and reception can effectively address issues such as equipment occupying internal space and heat dissipation. Therefore, to meet the demand for multifunctional stealth conformal antennas, combining flexible materials with polarization-converting metasurfaces to reduce the antenna's RCS (radar cross section) is one of the new approaches currently available for achieving wide-band conformal stealth antennas. Summary of the Invention

[0004] To address the technical deficiencies of existing metasurfaces in terms of multifunctional integration and performance, the present invention provides antenna units, antenna arrays, and array antennas based on polarization-converting metasurfaces. These array antennas utilize a modular design approach, enabling large-scale expansion. They feature a low profile, lightweight, and simple structure. They also possess dual electromagnetic capabilities, including electromagnetic stealth and electromagnetic wave transmission and reception. They can conformally attach to complex carrier surfaces and provide surface load-bearing capabilities, achieving structural and functional integration.

[0005] The technical solution of the present invention to solve the technical problem is: designing an antenna unit based on a polarization conversion metasurface, characterized in that the antenna unit includes a unit carrier assembly, a unit functional structure and a unit metal ground plane, wherein the unit carrier assembly includes an upper unit flexible dielectric substrate, a middle unit flexible dielectric substrate, a lower unit flexible dielectric substrate and a unit aramid honeycomb paper core layer, and the unit functional structure includes a unit microstrip feed line, a unit polarization conversion metasurface, a unit coupling slot, and a unit coaxial feed head; wherein, a unit aramid honeycomb paper core layer is respectively provided between the upper unit flexible dielectric substrate and the middle unit flexible dielectric substrate and between the middle unit flexible dielectric substrate and the lower unit flexible dielectric substrate, and the unit metal ground plane is provided on the back side of the lower unit flexible dielectric substrate, and the six layers are assembled by punching holes and installing nylon screws;

[0006] The unit polarization conversion metasurface is printed on the upper surface of the upper unit flexible dielectric substrate; the unit polarization conversion metasurface is a structure composed of sixteen identical corner-cut strip metal patches arranged in four rows and four columns with equal spacing, and is obtained by symmetrically etching two equilateral right-angled triangles of the same size from 16 square metal patches of equal size arranged in a 4×4 pattern in the same direction. The line connecting the two remaining vertices of the square metal patch after etching is the center line of the corresponding corner-cut strip metal patch. The center line of the corner-cut strip metal patch on the same unit polarization conversion metasurface has the same angle with the horizontal direction, which is 45° or 135°.

[0007] A metal unit microstrip feed line is printed on the upper surface of the middle unit flexible dielectric substrate. The unit microstrip feed line consists of two parts: a 50-ohm microstrip feed line and an impedance matching feed line. The two parts are placed horizontally, with the impedance matching feed line connected to the left side of the 50-ohm microstrip feed line. The horizontal symmetry lines of the two coincide with the horizontal center line of the area enclosed by the unit polarization conversion metasurface. The unit coaxial feed head is installed in a through hole that runs through the center of the impedance matching feed line, the middle unit flexible dielectric substrate, the lower unit aramid honeycomb paper core layer, the lower unit flexible dielectric substrate, and the unit metal ground plane.

[0008] The unit coupling slot is a rectangular slot opened on the unit metal ground plane; the rectangular slot is arranged along the front-to-back direction of the unit metal ground plane, and the symmetry line of the rectangular slot in the front-to-back direction and the center line of the front-to-back direction of the area enclosed by the unit polarization conversion metasurface are spatially aligned; the back surface of the lower unit flexible dielectric substrate, except for the unit coupling slot, the through hole for installing the unit coaxial feed head, and the nylon screw hole, is covered by the unit metal ground plane;

[0009] The upper unit flexible dielectric substrate, the middle unit flexible dielectric substrate, and the lower unit flexible dielectric substrate are all of the same size, material, and thickness. Meanwhile, the two unit aramid honeycomb paper core layers used are all of the same size, material, and thickness, and their size can completely cover the upper unit flexible dielectric substrate.

[0010] Furthermore, the present invention designs an antenna array based on a polarization conversion metasurface, characterized in that the array antenna is based on the antenna unit described above, and the antenna array includes an array carrier assembly, an array functional structure, and an array metal ground plane, wherein the array carrier assembly includes an upper array flexible dielectric substrate, a middle array flexible dielectric substrate, a lower array flexible dielectric substrate, and an array aramid honeycomb paper core layer, wherein an array aramid honeycomb paper core layer is respectively provided between the upper array flexible dielectric substrate and the middle array flexible dielectric substrate and between the middle array flexible dielectric substrate and the lower array flexible dielectric substrate, and the array metal ground plane is provided on the back side of the lower array flexible dielectric substrate, and the six layers are assembled by punching holes and installing nylon screws;

[0011] The array functional structure includes four groups of unit functional structures of the antenna units described above, and the four groups of unit functional structures are arranged at equal intervals of 2×2. Four unit polarization conversion metasurfaces are arranged on the upper surface of the upper array flexible dielectric substrate, and four unit microstrip feeders are arranged on the upper surface of the middle array flexible dielectric substrate; the four unit coupling slots are rectangular slots opened on the metal ground surface of the array; the relative positions of the unit microstrip feeders, unit polarization conversion metasurfaces, unit coupling slots, and unit coaxial feed heads in each group of unit functional structures are the same as those in the antenna units; wherein the two unit polarization conversion metasurfaces on the upper left and lower right are The angle between the center line of the cut-angle strip metal patch and the horizontal direction is 45°, and the angle between the center line of the cut-angle strip metal patch of the two unit polarization conversion metasurfaces on the lower left and upper right is 135°. The unit coaxial feed head is installed in the center of the corresponding impedance matching feed line that runs through the unit microstrip feed line, the middle array flexible dielectric substrate, the lower array aramid honeycomb paper core layer, the lower array flexible dielectric substrate, and the through hole of the array metal ground plane. The back of the lower array flexible dielectric substrate is covered by the array metal ground plane except for the unit coupling gap, the through hole for installing the unit coaxial feed head, and the nylon screw hole.

[0012] The upper array flexible dielectric substrate, the middle array flexible dielectric substrate, and the lower array flexible dielectric substrate are all of the same size, material, and thickness. Furthermore, the two array aramid honeycomb paper core layers used are all of the same size, material, and thickness, and their size can completely cover the upper array flexible dielectric substrate.

[0013] Furthermore, the present invention designs an array antenna based on a polarization conversion metasurface, characterized in that the array antenna is based on the antenna array described above, and includes an antenna carrier assembly, an antenna functional structure, and an antenna metal ground plane, wherein the antenna carrier assembly includes an upper antenna flexible dielectric substrate, a middle antenna flexible dielectric substrate, a lower antenna flexible dielectric substrate, and an antenna aramid honeycomb paper core layer, wherein an antenna aramid honeycomb paper core layer is respectively provided between the upper antenna flexible dielectric substrate and the middle antenna flexible dielectric substrate and between the middle antenna flexible dielectric substrate and the lower antenna flexible dielectric substrate, and the antenna metal ground plane is provided on the back side of the lower antenna flexible dielectric substrate, and the six layers are assembled by punching holes and installing nylon screws;

[0014] The antenna functional structure includes four array functional structures of the antenna array as described above, and the four array functional structures are arranged at equal intervals of 2×2; the four unit polarization conversion metasurfaces of each array functional structure are arranged on the upper surface of the upper antenna flexible dielectric substrate, and its four unit microstrip feed lines are arranged on the upper surface of the middle antenna flexible dielectric substrate, and its four unit coupling slots are rectangular slots opened on the antenna metal ground surface. The configuration of each array functional structure is the same as that in the antenna array; each unit coaxial feed head in each array functional structure is installed in the center of the corresponding impedance matching feed line running through the unit microstrip feed line, the middle antenna flexible dielectric substrate, the lower antenna aramid honeycomb paper core layer, the lower antenna flexible dielectric substrate, and the antenna metal ground surface; the back of the lower antenna flexible dielectric substrate is covered by the antenna metal ground surface except for the unit coupling slots, the through holes for installing the unit coaxial feed heads, and the nylon screw holes;

[0015] The upper antenna flexible dielectric substrate, the middle antenna flexible dielectric substrate, and the lower antenna flexible dielectric substrate are all of the same size, material, and thickness. Furthermore, the two antenna aramid honeycomb paper core layers are all of the same size, material, and thickness, and their size can completely cover the upper antenna flexible dielectric substrate.

[0016] Compared with the prior art, the array antenna designed in the application adopts the structure of the flexible dielectric substrate and the aramid honeycomb paper core being stacked with each other, which can realize the conformal feature with the carrier shape, has the carrier surface bearing property, and realizes the integration of structure and function; through the configuration of the multi-layer base frame and the multiple groups of unit polarization conversion super surfaces in different states, the multifunctional polarization conversion super surface function is expanded. On one hand, the multi-layer base frame realizes the improvement of the polarization converter in the polarization conversion bandwidth, so that the wide-band RCS is reduced through the placement of the multiple groups of unit polarization conversion super surfaces in different states; on the other hand, through the multi-layer stacked configuration, the feeding structure of the antenna is introduced, the super surface and the coupled slot are in the resonant state through the excitation of the feeding structure, the electromagnetic wave transmission function of the antenna is realized, and based on the electromagnetic coupling, the super surface and the coupled slot are excited together, so that the working bandwidth of the antenna is greatly widened; the array antenna with the RCS reduction wide-band conformal function adopts the modular design idea, and the large-scale expansion can be realized through the antenna array. The antenna array has the characteristics of low profile, light weight and simple structure in structure, has the electromagnetic stealth and electromagnetic wave transmitting and receiving dual electromagnetic functions in function, can be conformal on the complex carrier surface and has the surface bearing function, has the characteristics of the integration of structure and function. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is an assembly schematic diagram of an embodiment of an antenna unit based on a polarization conversion super surface.

[0018] Figure 2 is a front structure schematic diagram of an upper unit flexible dielectric substrate of an embodiment of an antenna unit based on a polarization conversion super surface.

[0019] Figure 3 is a front structure schematic diagram of a middle unit flexible dielectric substrate of an embodiment of an antenna unit based on a polarization conversion super surface.

[0020] Figure 4 is a unit metal ground plane structure schematic diagram of an embodiment of an antenna unit based on a polarization conversion super surface.

[0021] Figure 5 is an assembly schematic diagram of an embodiment of an antenna array based on a polarization conversion super surface.

[0022] Figure 6 is a front structure schematic diagram of an upper array flexible dielectric substrate of an embodiment of an antenna array based on a polarization conversion super surface.

[0023] Figure 7This is a front structural schematic diagram of a middle array flexible dielectric substrate of an embodiment of an antenna array based on a polarization conversion metasurface of the present invention.

[0024] Figure 8 This is a schematic diagram of the array metal ground plane structure of an embodiment of an antenna array based on a polarization conversion metasurface of the present invention.

[0025] Figure 9 This is an assembly diagram of an embodiment of an array antenna based on a polarization conversion metasurface of the present invention.

[0026] Figure 10 This is a schematic diagram of the front structure of the upper antenna flexible dielectric substrate of an embodiment of an array antenna based on a polarization conversion metasurface of the present invention.

[0027] Figure 11 This is a schematic diagram of the front structure of a flexible dielectric substrate of a middle antenna of an embodiment of an array antenna based on a polarization conversion metasurface of the present invention.

[0028] Figure 12 This is a schematic diagram of the antenna metal ground plane structure of an embodiment of an array antenna based on a polarization conversion metasurface of the present invention.

[0029] Figure 13 Schematic diagram of the bending deformation of the antenna unit, antenna array and array antenna in Example 1 of the present invention.

[0030] Figure 14 This is a data diagram of the polarization conversion rate of a unit polarization conversion metasurface in Example 1 of the present invention, in which the angle between the center line of the cut-angle strip metal patch and the horizontal direction is 45°.

[0031] Figure 15 It is the comparison data of the reflection coefficient of the antenna unit in Example 1 of the present invention before and after the unit polarization conversion metasurface is loaded (wherein, unit 1 is an antenna unit loaded with a unit polarization conversion metasurface in which the angle between the center line of the cut-angle strip metal patch and the horizontal direction is 45°, unit 2 is an antenna unit loaded with a unit polarization conversion metasurface in which the angle between the center line of the cut-angle strip metal patch and the horizontal direction is 135°, and no metasurface loading is an antenna unit in which the unit polarization conversion metasurface, the upper unit flexible dielectric substrate, and the upper unit aramid honeycomb paper core layer are removed).

[0032] Figure 16 The antenna units of the two polarization conversion metasurfaces in the embodiment 1 of the present invention (i.e. Figure 15 The E-plane (electric field) and H-plane (magnetic field) radiation patterns of unit 1 and unit 2 in the figure at the center frequency of 7.14 GHz.

[0033] Figure 17 It is a reflection coefficient diagram of an antenna unit in embodiment 1 of the present invention (the angle between the center line of the cut-angle strip metal patch of the unit polarization conversion metasurface and the horizontal direction is 45°) in different states (wherein, planar is a planar state, θ1 is a bending state of the xoz surface of the antenna unit along the center of the antenna unit toward the negative z-axis at 60° and 120°, and θ2 is a bending state of the yoz surface of the antenna unit along the center of the antenna unit toward the negative z-axis at 60° and 120°).

[0034] Figure 18 This is a comparison diagram of the single-station RCS of the antenna array in Example 1 of the present invention under different deformations in the plane and along the negative z-axis with that of a metal plate of equal area for x-polarized incident waves.

[0035] Figure 19 This is a comparison diagram of the single-station RCS of the antenna array in Example 1 of the present invention under different deformations in the plane and along the negative z-axis with that of a metal plate of equal area for y-polarized incident waves.

[0036] Figure 20 It is the xoz plane radiation gain pattern of the antenna array in Example 1 of the present invention under different deformations in the plane and along the negative z-axis.

[0037] Figure 21 yoz plane radiation gain pattern of the antenna array in Example 1 of the present invention under different deformations in the plane and along the negative z-axis.

[0038] Figure 22 This is a comparison diagram of the single-station RCS of the array antenna in Example 1 of the present invention under different deformations in the plane and along the negative z-axis with that of a metal plate of equal area for x-polarized incident waves.

[0039] Figure 23 3 is a comparison diagram of the single-station RCS of the array antenna in Example 1 of the present invention under different deformations in the plane and along the negative z-axis with that of a metal plate of equal area for y-polarized incident waves. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0041] The present invention proposes an antenna unit based on a polarization-conversion metasurface (hereinafter referred to as the antenna unit), characterized in that the antenna unit includes a unit carrier assembly, a unit functional structure, and a unit metal ground plane. The unit carrier assembly includes an upper unit flexible dielectric substrate, a middle unit flexible dielectric substrate, a lower unit flexible dielectric substrate, and a unit aramid honeycomb paper core layer. The unit functional structure includes a unit microstrip feeder, a unit polarization-conversion metasurface, a unit coupling slot, and a unit coaxial feed head. A unit aramid honeycomb paper core layer is provided between the upper unit flexible dielectric substrate and the middle unit flexible dielectric substrate, and between the middle unit flexible dielectric substrate and the lower unit flexible dielectric substrate. The unit metal ground plane is provided on the back of the lower unit flexible dielectric substrate. The six layers are assembled by punching holes and installing nylon screws.

[0042] The unit polarization conversion metasurface is printed on the upper surface of the upper unit flexible dielectric substrate; the unit polarization conversion metasurface is a structure composed of sixteen identical corner-cut strip metal patches arranged in four rows and four columns with equal spacing, and is obtained by symmetrically etching two equilateral right-angled triangles of the same size in the same direction from 16 square metal patches of equal size arranged in a 4×4 interval. The line connecting the two remaining vertices of the square metal patch after corrosion is the center line of the corresponding corner-cut strip metal patch. The center line of the corner-cut strip metal patch on the same unit polarization conversion metasurface has the same angle with the horizontal direction, which is 45° or 135°.

[0043] A metal unit microstrip feeder is printed on the upper surface of the central unit flexible dielectric substrate. The unit microstrip feeder consists of two parts: a 50-ohm microstrip feeder and an impedance-matching feeder. The two parts are arranged horizontally, with the impedance-matching feeder connected to the left side of the 50-ohm microstrip feeder. The horizontal symmetry lines of the two coincide with the horizontal centerline of the area enclosed by the unit polarization conversion metasurface in space (z-axis direction). The unit coaxial feed head is installed in a through-hole that runs through the center of the impedance-matching feeder, the central unit flexible dielectric substrate, the lower unit aramid honeycomb paper core layer, the lower unit flexible dielectric substrate, and the unit metal ground plane.

[0044] The unit coupling slot is a rectangular slot cut into the unit metal ground plane; it runs along the front-to-back direction of the unit metal ground plane, with the front-to-back symmetry line of the rectangular slot coinciding with the front-to-back midline of the region enclosed by the unit polarization-conversion metasurface in space (the z-axis). The backside of the lower unit flexible dielectric substrate, with the exception of the unit coupling slot, the through-hole for mounting the unit coaxial feed head, and the nylon screw hole, is covered by the unit metal ground plane.

[0045] The upper unit flexible dielectric substrate, the middle unit flexible dielectric substrate, and the lower unit flexible dielectric substrate are all of the same size, material, and thickness. Meanwhile, the two unit aramid honeycomb paper core layers used are all of the same size, material, and thickness, and their size can completely cover the upper unit flexible dielectric substrate.

[0046] The working principle of the antenna unit is as follows: the unit coaxial feed head passes through the impedance matching feed line, the middle unit flexible dielectric substrate, the lower unit aramid honeycomb paper core layer, the lower unit flexible dielectric substrate and the unit metal ground plane from top to bottom. The unit polarization conversion metasurface arranged on the upper unit flexible dielectric substrate and the unit metal ground plane arranged on the lower unit flexible dielectric substrate constitute a unit polarization converter, which has the function of polarization conversion of the incident electromagnetic wave; secondly, the unit microstrip feed line and the unit coupling gap constitute the excitation source, and the electrical signal is fed into the micro-unit strip feed line through the coaxial bottom feeding method. The unit polarization conversion metasurface and the unit coupling gap resonate, thereby realizing the electromagnetic wave transmission function of the antenna unit;

[0047] Furthermore, in order to achieve a reduction in the RCS (antenna radar cross-section) size, the present invention provides an antenna array based on a polarization conversion metasurface (hereinafter referred to as the antenna array), characterized in that the antenna array includes an array carrier assembly, an array functional structure, and an array metal ground plane, wherein the array carrier assembly includes an upper array flexible dielectric substrate, a middle array flexible dielectric substrate, a lower array flexible dielectric substrate, and an array aramid honeycomb paper core layer, wherein an array aramid honeycomb paper core layer is respectively arranged between the upper array flexible dielectric substrate and the middle array flexible dielectric substrate and between the middle array flexible dielectric substrate and the lower array flexible dielectric substrate, and the array metal ground plane is arranged on the back side of the lower array flexible dielectric substrate, and the six layers are assembled by punching holes and installing nylon screws.

[0048] The array functional structure comprises four groups of unit functional structures, arranged in a 2×2 pattern with equal spacing. Four unit polarization-conversion metasurfaces are positioned on the upper surface of the upper array flexible dielectric substrate, and four unit microstrip feeds are positioned on the upper surface of the middle array flexible dielectric substrate. Four unit coupling slots are rectangular slots cut into the array's metal ground plane. The relative positions of the unit microstrip feeds, unit polarization-conversion metasurfaces, unit coupling slots, and unit coaxial feed heads in each group of unit functional structures are identical to those in the antenna units. The centerlines of the chamfered strip metal patches of the upper left and lower right unit polarization-conversion metasurfaces are angled 45° to the horizontal, while the centerlines of the chamfered strip metal patches of the lower left and upper right unit polarization-conversion metasurfaces are angled 135° to the horizontal. The unit coaxial feed heads are installed in the center of the impedance matching feed lines that pass through the corresponding unit microstrip feed lines, the middle array flexible dielectric substrate, the lower array aramid honeycomb paper core layer, the lower array flexible dielectric substrate, and the array metal ground plane. The back side of the lower array flexible dielectric substrate is covered by the array metal ground plane except for the unit coupling gap, the through hole for installing the unit coaxial feed head, and the nylon screw hole.

[0049] The upper array flexible dielectric substrate, the middle array flexible dielectric substrate, and the lower array flexible dielectric substrate are all of the same size, material, and thickness. Furthermore, the two array aramid honeycomb paper core layers used are all of the same size, material, and thickness, and their size can completely cover the upper array flexible dielectric substrate.

[0050] The working principle of this antenna array is as follows: the four unit polarization conversion metasurfaces of the array functional structure of the antenna array are set in different states. The center line of the cut-angle strip metal patches of the two unit polarization conversion metasurfaces on the upper left and lower right is at an angle of 45° to the horizontal direction, and the center line of the cut-angle strip metal patches of the two unit polarization conversion metasurfaces on the lower left and upper right is at an angle of 135° to the horizontal direction. Because the unit polarization conversion metasurface has a polarization modulation effect on the incident wave, the polarization direction of the reflected wave differs by 90° from the polarization direction of the incident wave. Therefore, based on the principle of phase cancellation, the phase of the reflected waves in different parts can be made to differ by 180°, thereby reducing the amplitude of the reflected wave and reducing the RCS. The antenna array achieves effective RCS reduction by configuring the unit polarization conversion metasurfaces in different states.

[0051] Specifically, in the case of antenna array radiation, each group of unit functional structures and the corresponding metal ground plane part constitute a basic radiation unit, and its radiation polarization direction is determined by its physical arrangement; the total radiation field of the antenna array is Expressed as:

[0052]

[0053] Where, is the radiation field of a radiating unit, and AF is the array factor. Therefore, it can be combined with the arrangement of radiating units and further expressed as:

[0054]

[0055] Where, Contains the phase and amplitude of the radiation, d and are the radiation unit spacing and phase respectively. The total radiation field of the antenna array can be determined by the amplitude and phase of each radiating element. Therefore, when all radiating elements have the same radiation field, that is, the same amplitude and phase, the radiation field of the antenna can be expressed as:

[0056]

[0057] Among them, AF rad The array factor represents a uniform array with identical radiating element arrangements and equal spacing.

[0058] For the scattering case, the canonical minimum scattering antenna is defined as a prerequisite when the terminal is open-circuited. Therefore, the open-circuit metasurface antenna unit can be further considered from the perspective of the metasurface. The metasurface antenna unit mentioned here is a total reflection type. When the electromagnetic wave is vertically incident on the antenna array with a unit polarization conversion metasurface, the electric field vector of the reflected electromagnetic wave of the radiation unit of the unit polarization conversion metasurface in two different states can be expressed as:

[0059]

[0060] Where, represents the electric field of the reflected wave, Represents the reflection phase of the two radiating elements. When the incident wave is incident vertically, Equation (3.4) can be further expressed as:

[0061]

[0062] Therefore, when The reflected electric field is 0, that is, the adjacent radiating elements use the phase difference to achieve phase cancellation, thereby canceling the electric field. However, it is usually difficult to maintain the ideal phase difference of the reflected wave at 180 degrees in a wide frequency band. In order to measure the RCS reduction effect, we use a metal plate of equal size as a reference. According to the above process, the total reflected field amplitude of the metal plate can be Once the reflected wave amplitudes of the antenna array and the metal plate satisfy the following relationship, it means that the reflected energy remains at a low level.

[0063]

[0064]

[0065]

[0066] It can be seen from equations (6)-(8) that for vertically incident electromagnetic waves, if the phase difference of the reflected waves of adjacent radiating elements satisfies 180°±37°, the RCS of the antenna array can be reduced by more than 10 dB compared with the RCS of a metal plate of the same size.

[0067] Furthermore, in order to verify that the above-mentioned antenna subarray is not general, the present invention provides an array antenna based on a polarization conversion metasurface (hereinafter referred to as array antenna), characterized in that the array antenna includes an antenna carrier assembly, an antenna functional structure and an antenna metal ground plane, wherein the antenna carrier assembly includes an upper antenna flexible dielectric substrate, a middle antenna flexible dielectric substrate, a lower antenna flexible dielectric substrate, and an antenna aramid honeycomb paper core layer, wherein an antenna aramid honeycomb paper core layer is respectively arranged between the upper antenna flexible dielectric substrate and the middle antenna flexible dielectric substrate and between the middle antenna flexible dielectric substrate and the lower antenna flexible dielectric substrate, and the antenna metal ground plane is arranged on the back of the lower antenna flexible dielectric substrate, and the six layers are assembled by punching and installing nylon screws.

[0068] The antenna functional structure includes four array functional structures, arranged in a 2×2 pattern with equal spacing. Each array functional structure's four polarization-conversion metasurfaces are located on the upper surface of the upper antenna flexible dielectric substrate. Its four unit microstrip feed lines are located on the upper surface of the middle antenna flexible dielectric substrate. Its four unit coupling slots are rectangular slots in the antenna's metal ground plane. The configuration of each array functional structure is identical to that of the antenna array. Each unit coaxial feed head in each array functional structure is mounted within a through-hole located in the center of the corresponding impedance-matching feed line that passes through the unit microstrip feed line, the middle antenna flexible dielectric substrate, the lower antenna aramid honeycomb paper core layer, the lower antenna flexible dielectric substrate, and the antenna's metal ground plane. The backside of the lower antenna flexible dielectric substrate, except for the unit coupling slots, the through-holes for mounting the unit coaxial feed heads, and the nylon screw holes, is covered by the antenna's metal ground plane.

[0069] The upper antenna flexible dielectric substrate, the middle antenna flexible dielectric substrate, and the lower antenna flexible dielectric substrate are all of the same size, material, and thickness. Furthermore, the two antenna aramid honeycomb paper core layers are all of the same size, material, and thickness, and their size can completely cover the upper antenna flexible dielectric substrate.

[0070] The antenna unit, antenna array and array antenna all adopt a structure in which three layers of flexible dielectric substrate and two layers of aramid honeycomb paper core are stacked on each other. The good bending and ductility characteristics of the flexible dielectric substrate enable the antenna to achieve good conformality with the carrier, and the addition of the aramid honeycomb paper core layer enables the antenna to have surface load-bearing characteristics while being conformal. The polarized metasurface can effectively achieve RCS reduction in a wide frequency band based on the reasonable design, sequential mirror configuration and periodic configuration of the unit. At the same time, the coupling slots opened on the ground surface and the excitation generated by the microstrip line can cause the upper metasurface to resonate. By reasonably adjusting the impedance matching and coupling slots of the microstrip feed line, the metasurface can generate multiple resonance points, effectively broadening the working frequency band of the antenna.

[0071] Example 1

[0072] This embodiment provides an antenna unit based on a polarization conversion metasurface (hereinafter referred to as antenna unit, see Figure 1 ), characterized in that the antenna unit comprises a unit carrier assembly, a unit functional structure, and a unit metal ground plane 108. The unit carrier assembly comprises an upper unit flexible dielectric substrate 101, a middle unit flexible dielectric substrate 102, a lower unit flexible dielectric substrate 103, and a unit aramid honeycomb paper core layer 104. The unit functional structure comprises a unit microstrip feed line 106, a unit polarization conversion metasurface 105, a unit coupling slot 107, and a unit coaxial feed head. A unit aramid honeycomb paper core layer 104 is disposed between the upper unit flexible dielectric substrate 101 and the middle unit flexible dielectric substrate 102, and between the middle unit flexible dielectric substrate 102 and the lower unit flexible dielectric substrate 103. The unit metal ground plane 108 is disposed on the back of the lower unit flexible dielectric substrate 103. The six layers are assembled by punching holes and installing nylon screws.

[0073] The unit polarization conversion metasurface 105 is printed on the upper surface of the upper unit flexible dielectric substrate 101; the unit polarization conversion metasurface 105 is a structure composed of sixteen identical corner-cut strip metal patches arranged in four rows and four columns with equal spacing. The structure is obtained by symmetrically etching two equilateral right-angled triangles of the same size from 16 square metal patches of equal size arranged in a 4×4 spacing in the same direction. The line connecting the two remaining vertices of the square metal patch after corrosion is the center line of the corresponding corner-cut strip metal patch. The center line of the corner-cut strip metal patch on the same unit polarization conversion metasurface 105 has the same angle with the horizontal direction, which is 45° or 135°.

[0074] The upper surface of the middle unit flexible dielectric substrate 102 is printed with a unit microstrip feed line 106 made of metal, which includes two parts: a 50-ohm microstrip feed line and an impedance matching feed line, both of which are placed horizontally, with the impedance matching feed line connected to the left side of the 50-ohm microstrip feed line, and the horizontal symmetry line of the two coincides with the horizontal center line of the area surrounded by the unit polarization conversion metasurface 105 in space (z-axis direction). The unit coaxial feed head is installed in the through hole that penetrates through the center of the impedance matching feed line, the middle unit flexible dielectric substrate 102, the lower unit aramid honeycomb paper core layer, the lower unit flexible dielectric substrate 103, and the unit metal ground plane 108.

[0075] The unit coupling slot 107 is a rectangular groove opened on the unit metal ground plane 108; the rectangular groove is arranged in the front-back direction of the unit metal ground plane 108, and the front-back symmetry line of the rectangular groove coincides with the front-back center line of the area surrounded by the unit polarization conversion metasurface 105 in space (z-axis direction). The back surface of the lower unit flexible dielectric substrate 103 is covered by the unit metal ground plane 108 except for the unit coupling slot 107, the through hole for installing the unit coaxial feed head, and the nylon screw hole.

[0076] The size, material, and thickness of the upper unit flexible dielectric substrate 101, the middle unit flexible dielectric substrate 102, and the lower unit flexible dielectric substrate 103 are the same, and the size, material, and thickness of the two unit aramid honeycomb paper core layers 104 are also the same, and the size can completely cover the upper unit flexible dielectric substrate 101.

[0077] In this embodiment, the material of the unit flexible dielectric substrate of the antenna unit is a polyimide glass cloth laminate with a dielectric constant of 4.1, a loss tangent of 0.0067, and a thickness of 0.3 mm, and the size of the unit flexible dielectric substrate is 38 mm x 38 mm x 0.3 mm; the material of the unit aramid honeycomb paper core layer is aramid paper with a dielectric constant of 4 and a thickness of 2.0 mm, and each honeycomb is a regular hexagon with a side length of 1.83 mm.

[0078] The unit polarization conversion metasurface 105 is a structure arranged by sixteen identical cut-angle strip-shaped metal patches in four rows and four columns at equal intervals, which is obtained by etching away two isosceles right triangles with a side length of 8 mm from each of the sixteen square metal patches with a size of 9 mm x 9 mm arranged in a 4 x 4 array at an interval of 0.5 mm in the same direction. The center-to-center distance between two adjacent square metal patches is 9.5 mm, and the distance between the left and right or the top and bottom adjacent square metal patches is 0.5 mm.

[0079] The distance between the polarization conversion metasurface 105 and the upper, lower, left and right edges of the upper unit flexible dielectric substrate is 0.25 mm. The width of the 50-ohm microstrip feed line of the unit microstrip feed line 106 is 0.65 mm. The distance between its left end and the center of the middle unit flexible dielectric substrate 102 (in this embodiment, the center coincides with the center of the unit polarization conversion metasurface in space) is 3.5 mm. The distance between its right end and the center of the middle unit flexible dielectric substrate 102 is 5 mm. The length and width of the impedance matching feed line segment are: 8 mm × 2.4 mm. There is a A circular through-hole with a diameter of 0.8 mm is used to connect the feeding probe of the coaxial bottom feed. The through-hole passes through the unit microstrip feed line 106, the middle unit flexible dielectric substrate 102, the lower unit aramid honeycomb paper core layer 104, the lower unit flexible dielectric substrate 103, and the unit metal ground plane 108 from top to bottom. The size of the metal ground plane 108 is the same as that of the lower unit flexible dielectric substrate 103, with a length and width of 38 mm × 38 mm. The coupling gap 107 is a rectangular groove opened in the center of the metal ground plane 108, with a length and width of 2.5 mm × 18.5 mm.

[0080] Figure 14 This is a data graph of the polarization conversion rate of the unit polarization conversion metasurface 105 in this embodiment, in which the angle between the center line of the cut-angle strip metal patch and the horizontal direction is 45°. It can be seen from the figure that the polarization conversion rate of the unit polarization conversion metasurface in the frequency bands of 5.6-20.67GHz and 26.04-26.23GHz is greater than 90%. Since the structure is at 45° to the horizontal direction, its polarization conversion rate is the same under x-polarized incident waves and y-polarized incident waves.

[0081] Figure 15is the reflection coefficient of the antenna unit in this embodiment before and after the unit polarization conversion metasurface is loaded, wherein unit 1 is an antenna unit loaded with a unit polarization conversion metasurface in which the angle between the center line of the cut-angle strip metal patch and the horizontal direction is 45°, unit 2 is an antenna unit loaded with a unit polarization conversion metasurface in which the angle between the center line of the cut-angle strip metal patch and the horizontal direction is 135°, and no metasurface loading is an antenna unit in which the unit polarization conversion metasurface, the upper unit flexible dielectric substrate, and the upper unit aramid honeycomb paper core layer are removed. Under the loading of the unit polarization conversion metasurface, the operating frequency band of the antenna unit (reflection coefficient lower than -10dB) is effectively broadened. Without the loading of the unit polarization conversion metasurface, the operating frequency band of the antenna unit is 5.51-5.98GHz and 6.65-8.57GHz, with a relative bandwidth of 33%. Under the loading of the unit polarization conversion metasurface, its operating frequency band is 5.2-12.2GHz, with a relative bandwidth of 98%. At the same time, it can be seen from the data results that the antenna units in the two unit polarization conversion metasurface setting states have the same operating frequency band.

[0082] Figure 16 The E-plane (electric field) and H-plane (magnetic field) radiation patterns of the antenna units (i.e., unit 1 and unit 2) in the two unit polarization conversion metasurface settings in this embodiment at the center frequency of 7.14 GHz. As can be seen from the figure, the H-plane radiation patterns of the antenna units in the two unit polarization conversion metasurface settings are consistent, and the E-plane radiation patterns are very different. It can be concluded that the antenna units in the two unit polarization conversion metasurface settings have consistent patterns.

[0083] Figure 17: is a reflection coefficient diagram of an antenna unit in this embodiment, including planar state, and 60° and 120° bending data of the xoz and yoz planes along the center of the antenna unit toward the negative z-axis. In the flat state, the antenna unit's center operating frequency is 7.14 GHz, and the operating frequency band is 5.2-12.2 GHz. When the xoz plane is bent at 60°, the operating frequency bands are 5.2-9.61 GHz and 10.56-11.65 GHz. When the xoz plane is bent at 120°, the operating frequency bands are 5.07-9.24 GHz and 10.1-11.35 GHz. When the yoz plane is bent at 60°, the operating frequency bands are 5.27-12.36 GHz. When the yoz plane is bent at 120°, the operating frequency bands are 5.26-10.5 GHz and 11.18-12.21 GHz. In the flat state, the relative operating bandwidth of the antenna unit (center operating frequency is 7.14 GHz) is 98%, and in the deformed state, the relative operating bandwidth is greater than 84%. This shows that the antenna unit's operating frequency band remains stable when bent.

[0084] Furthermore, in order to achieve RCS reduction, this embodiment provides an antenna array based on a polarization conversion metasurface (hereinafter referred to as antenna array, see Figure 5-8 )), characterized in that the antenna array includes an array carrier component, an array functional structure and an array metal grounding surface 208, wherein the array carrier component includes an upper array flexible dielectric substrate 201, a middle array flexible dielectric substrate 202, a lower array flexible dielectric substrate 203, and an array aramid honeycomb paper core layer 204, wherein an array aramid honeycomb paper core layer 204 is respectively arranged between the upper array flexible dielectric substrate 201 and the middle array flexible dielectric substrate 202 and between the middle array flexible dielectric substrate 202 and the lower array flexible dielectric substrate 203, and the array metal grounding surface 208 is arranged on the back side of the lower array flexible dielectric substrate 203, and the six layers are assembled by punching holes and installing nylon screws.

[0085] The array functional structure includes four groups of unit functional structures, which are arranged at equal intervals of 2×2. Four unit polarization conversion metasurfaces 105 are arranged on the upper surface of the upper array flexible dielectric substrate 201, and four unit microstrip feed lines 106 are arranged on the upper surface of the middle array flexible dielectric substrate 202; the four unit coupling slots 107 are rectangular slots opened on the array metal ground surface 208; the relative positions of the unit microstrip feed lines 106, the unit polarization conversion metasurfaces 105, the unit coupling slots 107, and the unit coaxial feed heads in each group of unit functional structures are the same as those in the antenna unit; wherein, the center lines of the cut-angle strip metal patches of the two unit polarization conversion metasurfaces 105 on the upper left and lower right are at an angle of 45° to the horizontal direction, and the center lines of the cut-angle strip metal patches of the two unit polarization conversion metasurfaces 105 on the lower left and upper right are at an angle of 135° to the horizontal direction. The unit coaxial feed head is installed in the center of the corresponding impedance matching feed line running through the unit microstrip feed line 106, the middle array flexible dielectric substrate 202, the lower array aramid honeycomb paper core layer 204, the lower array flexible dielectric substrate 203, and the through hole of the array metal ground plane 208.

[0086] The backside of the lower array flexible dielectric substrate 203, except for the unit coupling slots 107, the through holes for installing the unit coaxial feed heads, and the nylon screw holes, is covered by an array metal ground plane 208. The upper array flexible dielectric substrate 201, the middle array flexible dielectric substrate 202, and the lower array flexible dielectric substrate 203 are all identical in size, material, and thickness. Furthermore, the two arrays of aramid honeycomb paper core layers 204 are all identical in size, material, and thickness, and are sized to completely cover the upper array flexible dielectric substrate 201.

[0087] The four groups of unit functional structures are arranged at equal intervals of 2×2 with a distance of 0.5 mm between the edges of the four unit polarization conversion metasurfaces 105. Correspondingly, the center distance between two unit polarization conversion metasurfaces 105 is 38 mm.

[0088] In this embodiment, the material used for the arrayed flexible dielectric substrates 201-203 is polyimide glass fiber cloth laminate, with a dielectric constant of 4.1, a loss tangent of 0.0067, and a thickness of 0.3 mm. The length, width, and height dimensions of the arrayed flexible dielectric substrate are: 76 mm × 76 mm × 0.3 mm. The material used for the arrayed aramid honeycomb paper core layer 204 is aramid honeycomb paper, with a dielectric constant of 4 and a thickness of 2.0 mm. A single honeycomb is a regular hexagon with a side length of 1.83 mm. The arrayed aramid honeycomb paper core layer can completely cover the arrayed flexible dielectric substrate.

[0089] To more intuitively verify the RCS reduction effect of the antenna array, plane waves are incident along the -z axis, including x-polarized and y-polarized plane waves. The scattering of metal plates of equal size and antenna arrays in the plane and under different deformations is observed. Due to the symmetry of the upper unit polarization conversion metasurface, the deformation of the antenna array only needs to consider the deformation under the xoz plane. Figure 18 and Figure 19 The figures show a comparison of the RCS data of the antenna array in this embodiment in the planar state and the deformed state under x-polarized incident waves and y-polarized incident waves, respectively, with those of a metal plate of equal area. As can be seen from the figures, the antenna has the same reduction effect in the planar state under x-polarized incident waves and y-polarized incident waves, and can achieve effective RCS reduction compared to the metal plate in the range of 5-30 GHz, with the maximum reduction at 16 GHz. At the same time, the RCS reduction effect of the antenna array in the deformed state is better than that of the planar metal plate, indicating that the antenna array in the conformal state has better stealth performance.

[0090] Figure 20 and Figure 21 The radiation gain patterns for the xoz and yoz planes of the antenna array in this embodiment, in both planar and deformed states, at the center operating frequency of 7.14 GHz, are shown. The four antenna elements are fed with equal amplitude and in-phase currents. The figures show that the antenna array maintains a stable radiation pattern even in the deformed state, with maximum radiation along the positive z-axis and a stable gain of 11.2 dBi.

[0091] Furthermore, based on the antenna array designed above, this embodiment provides an array antenna based on a polarization conversion metasurface (hereinafter referred to as array antenna, see Figure 9-12 ), characterized in that the array antenna includes an antenna carrier component, an antenna functional structure and an antenna metal ground plane 308, wherein the antenna carrier component includes an upper antenna flexible dielectric substrate 301, a middle antenna flexible dielectric substrate 302, a lower antenna flexible dielectric substrate 303, and an antenna aramid honeycomb paper core layer 304, wherein an antenna aramid honeycomb paper core layer 304 is respectively arranged between the upper antenna flexible dielectric substrate 301 and the middle antenna flexible dielectric substrate 302 and between the middle antenna flexible dielectric substrate 302 and the lower antenna flexible dielectric substrate 303, and the antenna metal ground plane 308 is arranged on the back of the lower antenna flexible dielectric substrate 303, and the six layers are assembled by punching and installing nylon screws.

[0092] The antenna functional structure includes four array functional structures arranged at equal intervals in 2x2; the four unit polarization conversion metasurfaces 105 of each array functional structure are arranged on the upper surface of the upper antenna flexible dielectric substrate, the four unit microstrip feed lines 106 are arranged on the upper surface of the middle antenna flexible dielectric substrate 302, and the four unit coupling slots 107 are rectangular slots opened on the antenna metal ground plane 308; each array functional structure is arranged in the same manner as in the antenna array. The coaxial feed head of each unit in each array functional structure is installed in the through hole of the center of the impedance matching feed line corresponding to the unit microstrip feed line 107, the middle antenna flexible dielectric substrate 302, the lower antenna aramid honeycomb paper core layer 304, the lower antenna flexible dielectric substrate 303, and the antenna metal ground plane 308. The back of the lower antenna flexible dielectric substrate 303 is covered by the antenna metal ground plane 308 except for the unit coupling slots 107, the through holes for installing the unit coaxial feed head, and the nylon screw holes.

[0093] The four array functional structures are arranged at equal intervals in 2x2 with a distance of 0.5mm between the edges of the four groups of unit polarization conversion metasurfaces 105 (one group of unit polarization conversion metasurfaces 105 is four unit polarization conversion metasurfaces 105 arranged in the array antenna), and correspondingly, the center distance between the two groups of unit polarization conversion metasurfaces 105 is 76mm.

[0094] The material of the antenna flexible dielectric substrate in the embodiment is a polyimide glass cloth laminated board, the dielectric constant is 4.1, the loss tangent is 0.0067, and the thickness is 0.3mm; the length, width and height of the antenna flexible dielectric substrate are 152mmx152mmx0.3mm; the material of the antenna aramid honeycomb paper core layer is aramid honeycomb paper, the dielectric constant of the aramid paper is 4, the thickness is 2.0mm, and the single honeycomb is a regular hexagon with a side length of 1.83mm; the antenna aramid honeycomb paper core layer can completely cover the antenna flexible dielectric substrate.

[0095] Figure 22 and Figure 23 respectively, are the single station RCS data diagrams of the array antenna in the embodiment under different deformations under x-polarized incident waves and y-polarized incident waves. It can be seen from the diagrams that based on the expansion of the antenna array, the single station RCS reduction performance is stable, and the number of antenna arrays can continue to expand. In the array antenna, each antenna unit is independently fed, and such a feeding method does not increase the complexity of array expansion. The above data shows that the array antenna has stable electromagnetic radiation characteristics in the flat and deformed states, has the functions of carrier conforming and surface bearing, and has good stealth effect on the single station RCS.

[0096] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art may make various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions shall be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

[0097] Any matters not described in the present invention are applicable to the prior art.

Claims

1. An antenna unit based on a polarization conversion metasurface, characterized in that: The antenna unit includes a unit carrier assembly, a unit functional structure, and a unit metal ground plane, wherein the unit carrier assembly includes an upper unit flexible dielectric substrate, a middle unit flexible dielectric substrate, a lower unit flexible dielectric substrate, and a unit aramid honeycomb paper core layer, and the unit functional structure includes a unit microstrip feeder, a unit polarization conversion metasurface, a unit coupling slot, and a unit coaxial feed head; wherein, a unit aramid honeycomb paper core layer is respectively provided between the upper unit flexible dielectric substrate and the middle unit flexible dielectric substrate, and between the middle unit flexible dielectric substrate and the lower unit flexible dielectric substrate, and the unit metal ground plane is provided on the back side of the lower unit flexible dielectric substrate, and the six layers of the upper unit flexible dielectric substrate, the unit aramid honeycomb paper core layer, the middle unit flexible dielectric substrate, the unit aramid honeycomb paper core layer, the lower unit flexible dielectric substrate, and the unit metal ground plane are assembled and formed by punching holes and installing nylon screws; The unit polarization conversion metasurface is printed on the upper surface of the upper unit flexible dielectric substrate; the unit polarization conversion metasurface is a structure composed of sixteen identical corner-cut strip metal patches arranged in four rows and four columns with equal spacing, and is obtained by symmetrically etching two equilateral right-angled triangles of the same size from 16 square metal patches of equal size arranged in a 4×4 pattern in the same direction. The line connecting the two remaining vertices of the square metal patch after etching is the center line of the corresponding corner-cut strip metal patch. The center line of the corner-cut strip metal patch on the same unit polarization conversion metasurface has the same angle with the horizontal direction, which is 45° or 135°. A metal unit microstrip feed line is printed on the upper surface of the middle unit flexible dielectric substrate. The unit microstrip feed line consists of two parts: a 50-ohm microstrip feed line and an impedance matching feed line. The two parts are placed horizontally, with the impedance matching feed line connected to the left side of the 50-ohm microstrip feed line. The horizontal symmetry lines of the two coincide with the horizontal center line of the area enclosed by the unit polarization conversion metasurface. The unit coaxial feed head is installed in a through hole that runs through the center of the impedance matching feed line, the middle unit flexible dielectric substrate, the lower unit aramid honeycomb paper core layer, the lower unit flexible dielectric substrate, and the unit metal ground plane. The unit coupling slot is a rectangular slot opened on the unit metal ground plane; the rectangular slot is arranged along the front-to-back direction of the unit metal ground plane, and the symmetry line of the rectangular slot in the front-to-back direction and the center line of the front-to-back direction of the area enclosed by the unit polarization conversion metasurface are spatially aligned; the back surface of the lower unit flexible dielectric substrate, except for the unit coupling slot, the through hole for installing the unit coaxial feed head, and the nylon screw hole, is covered by the unit metal ground plane; The upper unit flexible dielectric substrate, the middle unit flexible dielectric substrate, and the lower unit flexible dielectric substrate are all of the same size, material, and thickness. Meanwhile, the two unit aramid honeycomb paper core layers used are all of the same size, material, and thickness, and their size can completely cover the upper unit flexible dielectric substrate.

2. The antenna unit based on the polarization conversion metasurface according to claim 1, characterized in that: The material used for the upper unit flexible dielectric substrate is polyimide glass fiber cloth laminate with a dielectric constant of 4.1, a loss tangent of 0.0067, and a thickness of 0.3 mm.

3. The antenna unit based on the polarization conversion metasurface according to claim 1, characterized in that: The length, width and height dimensions of the upper unit flexible dielectric substrate are: 38mm×38mm×0.3mm.

4. The antenna unit based on the polarization conversion metasurface according to claim 1, characterized in that: The unit polarization conversion metasurface is composed of 16 square metal patches of 9mm×9mm arranged in a 4×4 array with a spacing of 0.5mm, and two equilateral right triangles with a side length of 8mm are symmetrically corroded in the same direction.

5. The antenna unit based on polarization conversion metasurface according to claim 1, characterized in that: The polarization conversion metasurface is 0.25 mm away from the upper, lower, left, and right edges of the upper unit flexible dielectric substrate. The width of the 50-ohm microstrip feeder of the unit microstrip feeder is 0.65 mm, the distance between its left end and the center of the middle unit flexible dielectric substrate is 3.5 mm, and the distance between its right end and the center of the middle unit flexible dielectric substrate is 5 mm. The length and width of the impedance matching feeder segment are: 8 mm × 2.4 mm. The coupling gap is a rectangular groove opened in the center of the metal ground plane, and the length and width of the rectangular groove are: 2.5 mm × 18.5 mm.

6. An antenna array based on a polarization conversion metasurface, characterized in that: The array antenna is based on the antenna unit according to any one of claims 1 to 5. The antenna array includes an array carrier assembly, an array functional structure, and an array metal ground plane. The array carrier assembly includes an upper array flexible dielectric substrate, a middle array flexible dielectric substrate, a lower array flexible dielectric substrate, and an array aramid honeycomb paper core layer. An array aramid honeycomb paper core layer is provided between the upper array flexible dielectric substrate and the middle array flexible dielectric substrate, and between the middle array flexible dielectric substrate and the lower array flexible dielectric substrate. The array metal ground plane is provided on the back surface of the lower array flexible dielectric substrate. The six layers are assembled by punching holes and installing nylon screws. The array functional structure includes four groups of unit functional structures of the antenna units according to any one of claims 1 to 5, the four groups of unit functional structures are arranged at equal intervals of 2×2, four unit polarization conversion metasurfaces are arranged on the upper surface of the upper array flexible dielectric substrate, and four unit microstrip feed lines are arranged on the upper surface of the middle array flexible dielectric substrate; the four unit coupling gaps are rectangular slots opened on the metal ground surface of the array; the relative positions of the unit microstrip feed lines, unit polarization conversion metasurfaces, unit coupling gaps, and unit coaxial feed heads in each group of unit functional structures are the same as those in the antenna units; wherein the two unit polarization conversion metasurfaces on the upper left and lower right are arranged on the upper surface of the flexible dielectric substrate of the middle array; The centerline of the cut-angle strip metal patch of the metasurface is at an angle of 45° to the horizontal direction, and the centerline of the cut-angle strip metal patch of the two unit polarization conversion metasurfaces on the lower left and upper right is at an angle of 135° to the horizontal direction. The unit coaxial feed head is installed in the center of the corresponding impedance matching feed line that runs through the unit microstrip feed line, the middle array flexible dielectric substrate, the lower array aramid honeycomb paper core layer, the lower array flexible dielectric substrate, and the through hole of the array metal ground plane. The back of the lower array flexible dielectric substrate is covered by the array metal ground plane except for the unit coupling gap, the through hole for installing the unit coaxial feed head, and the nylon screw hole. The upper array flexible dielectric substrate, the middle array flexible dielectric substrate, and the lower array flexible dielectric substrate are all of the same size, material, and thickness. At the same time, the two array aramid honeycomb paper core layers used are all of the same size, material, and thickness, and their size can completely cover the upper array flexible dielectric substrate.

7. The antenna array based on polarization conversion metasurface according to claim 6, characterized in that: The four groups of unit functional structures are arranged at equal intervals of 2×2 with a distance of 0.5 mm between the edges of the four unit polarization conversion metasurfaces.

8. An array antenna based on a polarization conversion metasurface, characterized in that: The array antenna is based on the antenna array according to any one of claims 6 to 7, and includes an antenna carrier assembly, an antenna functional structure, and an antenna metal ground plane. The antenna carrier assembly includes an upper antenna flexible dielectric substrate, a middle antenna flexible dielectric substrate, a lower antenna flexible dielectric substrate, and an antenna aramid honeycomb paper core layer. An antenna aramid honeycomb paper core layer is provided between the upper antenna flexible dielectric substrate and the middle antenna flexible dielectric substrate, and between the middle antenna flexible dielectric substrate and the lower antenna flexible dielectric substrate. The antenna metal ground plane is provided on the back surface of the lower antenna flexible dielectric substrate. The six layers are assembled by punching holes and installing nylon screws. The antenna functional structure includes four array functional structures of the antenna array according to any one of claims 6 to 7, and the four array functional structures are arranged at equal intervals of 2×2; the four unit polarization conversion metasurfaces of each array functional structure are arranged on the upper surface of the upper antenna flexible dielectric substrate, the four unit microstrip feed lines are arranged on the upper surface of the middle antenna flexible dielectric substrate, and the four unit coupling slots are rectangular slots opened on the antenna metal ground surface. The configuration of each array functional structure is the same as that in the antenna array; each unit coaxial feed head in each array functional structure is installed in the center of the corresponding impedance matching feed line running through the unit microstrip feed line, the middle antenna flexible dielectric substrate, the lower antenna aramid honeycomb paper core layer, the lower antenna flexible dielectric substrate, and the antenna metal ground surface; the back of the lower antenna flexible dielectric substrate is covered by the antenna metal ground surface except for the unit coupling slots, the through holes for installing the unit coaxial feed heads, and the nylon screw holes; The upper antenna flexible dielectric substrate, the middle antenna flexible dielectric substrate, and the lower antenna flexible dielectric substrate are all of the same size, material, and thickness. Furthermore, the two antenna aramid honeycomb paper core layers are all of the same size, material, and thickness, and their size can completely cover the upper antenna flexible dielectric substrate.

9. The array antenna based on polarization conversion metasurface according to claim 8, characterized in that: The four array functional structures are arranged at equal intervals of 2×2 with a distance of 0.5 mm between the edges of the four groups of unit polarization conversion metasurfaces.

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