Foldable transmission array antenna based on Kigami structure

Abstract

The invention relates to the technical field of antennas, in particular to a foldable transmission array antenna based on a Kirgami structure, which comprises a dielectric lens array and a Ku wave band standard gain horn antenna positioned on one side of the dielectric lens array, the dielectric lens array is composed of 16 * 16 lens units, each lens unit comprises four dielectric cylinders and four dielectric sheets, and one dielectric sheet is embedded between every two dielectric cylinders; the lens unit is switched between an unfolded state and a folded state; a pure mechanical structure is adopted to achieve the folding function, and the problems caused by fatigue of flexible materials and active devices are avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of antenna, and particularly relates to a foldable transmissive array antenna based on Kirigami structure. BACKGROUND

[0002] With the development of millimeter wave communication, space deployment antenna system and portable radar technology, the demand for high-performance, stowable and lightweight antenna structure is increasing. Especially in the scenes of 5G communication, satellite communication, unmanned aerial load, etc., the antenna is required to have good volume compression ability, environmental adaptability and structural stability while ensuring electromagnetic performance. Under this background, the deployable antenna based on origami or kirigami structure gradually becomes a research hotspot. This kind of antenna relies on the deformable mechanism of the structure, and can greatly reduce the volume in the stowed state, and form a working radiation surface array in the unfolded state, so as to balance portability and performance.

[0003] At present, the foldable or reconfigurable antenna scheme based on origami or kirigami structure shows certain potential in packaging efficiency, multi-functional integration and other aspects, but there are still obvious limitations in actual engineering application. On the one hand, the existing scheme generally uses flexible materials (such as polyimide film, fabric substrate, etc.) to make antenna structure, and this kind of material has great deficiency in structural rigidity and flatness control after unfolding, which is difficult to guarantee the phase consistency of the antenna array, thereby affecting the directivity and gain stability of the transmitted beam. On the other hand, these flexible materials are prone to fatigue or permanent deformation when facing mechanical impact, long-term vibration or temperature cycle, and have limited reliability, especially difficult to meet the occasions with high environmental adaptability requirements such as aerospace, portable communication, etc. In addition, some structural designs introduce active control devices (such as MEMS switch, actuator, etc.), which can realize a certain degree of reconfiguration function, but also bring a series of problems such as electromagnetic performance decline, system complexity improvement, power consumption rise, etc., which is not conducive to the miniaturization and low-cost implementation of the system.

[0004] With the development of 3D printing manufacturing technology, high-precision printing processes such as light curing make it possible to manufacture complex three-dimensional structure antennas. The diversity of 3D printing materials also provides more choices for antenna unit design, making the reconfigurable antenna array with all-dielectric structure a feasible path, especially in terms of lightweight, customization and one-piece molding. In the literature "3D Printed “Kirigami”-Inspired Deployable Bi-focal Beam-scanning Dielectric Reflectarray Antenna for mm-Wave Applications" (IEEE Transactions on Antennas and Propagation, 2022, 70(9): 7683-7690), researchers proposed an advanced 3D printed deployable dielectric reflectarray antenna based on Kirigami structure, which has one-time deployment capability and bidirectional beam scanning function within ±30° range. The antenna structure adopts a two-stage buckle type Kirigami-inspired unit design, which can achieve a compression ratio of about 66% in the storage state, significantly saving space. Its prototype is manufactured by stereolithography 3D printing process (Formlabs Flexible 80A material), taking into account the flexibility of the structure and the feasibility of processing. In terms of electromagnetic performance design, the scheme uses a dual-focus phase distribution optimization method to achieve beam control in the 10° to 30° and -10° to -30° directions, suitable for 5G communication and satellite communication applications in the millimeter wave frequency band. Although this design has certain advantages in folding capacity and electromagnetic performance, it still has the following shortcomings: (1) its structure is reflective and cannot be directly used for wavefront control of transmissive arrays; (2) due to the dependence on flexible photopolymer as a connecting unit, repeated folding or long-term use can cause fatigue damage, affecting the service life of the structure and the flatness of the array surface; (3) in extreme environments such as high temperature and high vibration, flexible materials are prone to permanent deformation or performance degradation, making it difficult to meet the usage requirements of aerospace or high-reliability scenarios. SUMMARY

[0005] To solve the above problems, the present application provides a foldable transmissive array antenna based on Kirigami structure, which includes a dielectric lens array and a Ku-band standard gain horn antenna on one side of the dielectric lens array; the dielectric lens array is composed of 16x16 lens units, and each lens unit includes 4 dielectric columns and 4 dielectric sheets, with one dielectric sheet inserted between every two dielectric columns; the lens unit switches between the unfolded and folded states.

[0006] Further, two ends of each medium column respectively protrude outwardly with two cylinders, two ends of each medium sheet respectively protrude outwardly to the same side with a baffle, and two circular through holes are arranged on each baffle.

[0007] Further, the included angle between every two adjacent medium columns is 90° when the lens unit is in the unfolded state, and the four medium sheets are opposite to each other and do not contact each other; when the lens unit is in the unfolded state, the two opposite medium sheets are compressed along the x-axis direction, and the remaining two opposite medium sheets are compressed along the y-axis direction; when the lens unit is in the folded state, the two opposite medium sheets are attached to each other, and the remaining two medium sheets are located on both sides of the two attached medium sheets, and the four medium columns remain horizontal.

[0008] Further, the radius of the cylinder is r2, and the radius of the circular through hole is r1, and r1 = r2 + 0.15 mm.

[0009] Further, the transmission phase of the lens unit changes with the cylinder radius r2, and in the range of 0.5 mm to 1.1 mm of the cylinder radius r2, a complete 0 to 2π phase shift range is realized.

[0010] Further, the medium lens array adopts a 3D printable material PREPERM™ low-loss dielectric thermoplastic plastic.

[0011] Further, the lens unit is divided into two types according to the material characteristics, the first type of lens unit adopts a 3D printable material PREPERM™ low-loss dielectric thermoplastic plastic with a relative dielectric constant of 3.5 and a loss tangent of 0.0042, and the second type of lens unit adopts a 3D printable material PREPERM™ low-loss dielectric thermoplastic plastic with a relative dielectric constant of 6.5 and a loss tangent of 0.0034.

[0012] The beneficial effects of the present application are as follows:

[0013] The present application realizes the folding function by using a pure mechanical structure, avoids the problems caused by flexible material fatigue and active devices. The structure is manufactured by 3D printing, which simplifies the manufacturing process and improves the assembly precision and structural stability. The antenna is composed of two low-loss materials with different dielectric constants, which has good transmission performance and mechanical support ability. In the structural design, the Kirigami hinge mechanism with two-dimensional folding ability is introduced, so that the antenna can be greatly compressed in the non-working state, and after unfolding, a flat array surface is formed, which is convenient for realizing stable beam control. This design takes into account the electromagnetic performance and mechanical reliability, and is also suitable for application scenarios that require storage and lightness, such as portable devices, small platforms and space deployment systems. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a schematic diagram of a foldable transmissive array antenna based on Kirigami structure according to some embodiments of the present application;

[0015] Figure 2 is a front view of a foldable transmissive array antenna based on Kirigami structure according to some embodiments of the present application;

[0016] Figure 3 is a schematic diagram of a lens unit according to some embodiments of the present application;

[0017] Figure 4 is a schematic diagram of different state structures of a lens unit according to some embodiments of the present application;

[0018] Figure 5 is a phase response curve of a lens unit according to some embodiments of the present application;

[0019] Figure 6 is an amplitude response curve of a lens unit according to some embodiments of the present application;

[0020] Figure 7 is a schematic diagram of a phase distribution of a dielectric lens array according to some embodiments of the present application;

[0021] Figure 8 is a r2 size distribution diagram of a dielectric lens array according to some embodiments of the present application;

[0022] Figure 9 is a diagram of different dielectric constants of a dielectric lens array according to some embodiments of the present application;

[0023] Figure 10 is a phase error distribution diagram of a dielectric lens array according to some embodiments of the present application;

[0024] Figure 11 is a reflection coefficient and gain curve diagram of a feed according to some embodiments of the present application;

[0025] Figure 12 is a radiation pattern of a foldable transmissive array antenna according to some embodiments of the present application; (a) 13 GHz, (b) 15 GHz;

[0026] Figure 13 is a gain and aperture efficiency curve diagram of a foldable transmissive array antenna according to some embodiments of the present application. DETAILED DESCRIPTION

[0027] Clearly, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present application.

[0028] Figure 1 is a schematic diagram of a foldable transmissive array antenna based on a Kirigami structure according to some embodiments of the present application. Figure 2 is a front view of a foldable transmissive array antenna based on a Kirigami structure according to some embodiments of the present application.

[0029] Some embodiments of the present application provide a foldable transmissive array antenna based on a Kirigami structure, as shown in Figures 1-2 includes one standard gain horn antenna and one dielectric lens array; the standard gain horn antenna is located on one side of the bottom surface of the dielectric lens array and faces the geometric center of the dielectric lens array. Among them, the standard gain horn antenna is used as a feed source to generate a spherical wave signal; the dielectric lens array is used to focus the spherical wave and convert it into a plane wave to realize the high-gain beam radiation function.

[0030] The dielectric lens array adopts an array design and is composed of a plurality of regularly arranged lens units. The plurality of lens units are distributed in an array and form a square as a whole. The lens unit of the present application has high transmittance, and the dielectric lens array has excellent gain performance, wideband coverage and low production cost.

[0031] Figure 3 is a schematic diagram of a lens unit according to some embodiments of the present application.

[0032] In some embodiments, the lens unit is a cuboid as a whole, as shown in Figure 3 includes four dielectric columns and four dielectric sheets, and one dielectric sheet is embedded between every two dielectric columns. Each dielectric column has two cylindrical protrusions at both ends, and the positions of the cylindrical protrusions at both ends correspond to each other; each dielectric sheet has a baffle protruding to the same side at both ends, and each baffle has two circular through holes, and the positions of the circular through holes at both ends correspond to each other. The circular through holes of each dielectric sheet in a lens unit are respectively embedded with the cylindrical protrusions of two dielectric columns to form a mechanical hinge structure, and the hinge positions are distributed around the lens unit, so that the lens unit can be folded in two mutually orthogonal directions in the plane, and the dielectric columns and the dielectric sheets can be closely stored after folding.

[0033] Figure 4are schematic diagrams of different states of the lens unit according to some embodiments of the present application, wherein (a) is a structural perspective view and a top view of the lens unit in an unfolded state, and (b) is a structural perspective view and a top view of the lens unit in a folded state.

[0034] In some embodiments, the lens unit is switched between the unfolded and folded states.

[0035] When the lens unit is in the unfolded state, the included angle between every two adjacent dielectric columns is 90°, and the four dielectric sheets are opposite to each other and do not contact each other; as shown in (a). Figure 4

[0036] When the lens unit is in the unfolded state, the two opposite dielectric sheets are compressed along the x-axis direction, and the remaining two opposite dielectric sheets are compressed along the y-axis direction; when the lens unit is in the folded state, the two opposite dielectric sheets are attached to each other, and the remaining two dielectric sheets are located on both sides of the two attached dielectric sheets, and the four dielectric columns remain horizontal; as shown in (b). It should be noted that there is a gap between the two ends of the dielectric column and the baffle of the dielectric sheet, and the length of the gap is the same as the thickness of the baffle. Figure 4

[0037] The entire dielectric lens array can also be unfolded and folded for storage. The thickness of the dielectric lens array in the folded state is compressed to about 50% of the unfolded state, which is suitable for occasions sensitive to space, such as satellite communication, portable radar, etc.

[0038] In some embodiments, in order to make the dielectric lens array a planar structure, a 3D printable material PREPERM™ low-loss dielectric thermoplastic plastic is used. Since a single material unit cannot achieve a complete 0-2π phase change, embodiments of the present application achieve a complete 0-2π phase change through size changes (r2 changes) of two different material units. Specifically, the lens unit is divided into two categories according to the material characteristics, the first type of lens unit uses a 3D printable material PREPERM™ low-loss dielectric thermoplastic plastic with a relative dielectric constant of 3.5 and a loss tangent of 0.0042, and the second type of lens unit uses a 3D printable material PREPERM™ low-loss dielectric thermoplastic plastic with a relative dielectric constant of 6.5 and a loss tangent of 0.0034, so that the dielectric lens array has good dielectric properties and low loss characteristics in the designed frequency band.

[0039] For example, Figure 1 ​​For the 16x16 medium lens array constructed by two different material units, the red part is the first type of lens unit, which uses PREPERM™ low-loss dielectric thermoplastic material with a relative permittivity of 3.5 and a loss tangent of 0.0042 that can be 3D printed; the blue part is the second type of lens unit, which uses PREPERM™ low-loss dielectric thermoplastic material with a relative permittivity of 6.5 and a loss tangent of 0.0034 that can be 3D printed. The structure of the first type of lens unit is completely consistent with that of the second type of lens unit, except that different materials are used for fabrication. By changing the cylindrical radius r2 of the lens unit, a phase change of 0-2π can be achieved.

[0040] In some embodiments, to verify the electromagnetic performance of the lens unit, modeling and optimization are performed using the full-wave simulation tool ANSYS HFSS. In the simulation, the lens units are arranged periodically in the x and y directions, and are excited using Floquet ports to simulate the condition of an infinite periodic array. By setting periodic boundary conditions, each lens unit is equivalent to a part of an infinite homogeneous array, thereby more accurately reflecting the electromagnetic response of the actual lens unit in operation. Through optimization analysis, the parameter settings of the lens unit are as follows:

[0041] For the baffle of the dielectric sheet, the width lx=0.8mm, the length ly=6mm, and the thickness s=1mm; the thickness of the dielectric sheet tx=0.8mm; in the unfolded state, the distance p between the outer edges of the two opposite dielectric sheets is 14.67mm, and the center distance l between the two cylinders of the same end of a dielectric column is 5mm. Let the radius of the cylinder be r2 and the radius of the circular hole be r1, r1 and r2 are variable, r1 = r2+0.15mm; by changing the size of r2, the lens unit can achieve a phase change of 360°.

[0042] Figure 5 The phase response curve of the medium lens unit at 13GHz is shown; Figure 6 The amplitude response curve of the medium lens unit at 13GHz is shown, S21 / dB represents the insertion loss of the lens unit, Figure 5 The abscissa represents the transmission phase of the lens unit, Figure 6 The ordinate represents the transmission amplitude value of the lens unit. The black dotted line represents the lens unit with a dielectric constant of 6.5, and the red curve represents the lens unit with a dielectric constant of 3.5 during simulation verification. The simulation results show that at a frequency of 13GHz:

[0043] The transmission coefficient is better than -0.7dB, proving that electromagnetic energy can penetrate the structure well and be effectively radiated;

[0044] The transmission phase of the lens unit varies with the cylindrical radius r2, and a complete 0-2π phase shift range is achieved when the cylindrical radius r2 is in the range of 0.5mm to 1.1mm.

[0045] In some embodiments, the phase distribution on the medium lens array is determined by the distance between the focal point and each lens unit. The transmission phase of the lens unit The calculation formula is:

[0046]

[0047] wherein, represents the phase shift amount required to be achieved by the lens unit in the medium lens array, represents the coordinates of the lens unit, represents the coordinates of the lens unit on the x-axis, represents the coordinates of the lens unit on the y-axis, is the free wave number in vacuum, represents the distance from the phase center of the feed source to the i-th lens unit, represents the main beam pointing direction, wherein represents the elevation angle of the beam, represents the azimuth angle of the beam.

[0048] The standard gain horn antenna emits a spherical wave, which is incident on the top of each lens unit. The variation of the dielectric column parameters r1 and r2 in the lens unit changes the corresponding transmission phase (complete 0-2π range) of the lens unit. The transmission phase is shown in Figure 5 , and the insertion loss is shown in Figure 6 . The circumferentially varying r2 values are arranged in a predetermined distribution in the entire array to achieve beamforming.

[0049] Figure 7 The array phase distribution diagram of the medium lens array in the embodiment of the application is obtained by simulation calculation. Figure 7 In the figure, the abscissa represents the x-coordinate of the medium lens array, the ordinate represents the y-coordinate of the medium lens array, and the numbers 0-350 represent the transmission phase achieved.

[0050] Referring to Figure 7 , the transmission phase of the lens unit is calculated according to the calculation formula , and the phase distribution diagram required at the position of each lens unit is obtained, and then the r2 of the lens unit is adjusted to the corresponding size, and the lens unit is placed at the corresponding position. In this way, a plurality of lens units are distributed in an array according to a predetermined rule, and form a transmission array as a whole, and after 3D printing, a medium lens array is obtained.

[0051] Figure 8A r2 size distribution diagram of each lens unit in the medium lens array of the embodiment of the present application is obtained through simulation calculation. Figure 8 In the diagram, the abscissa represents the x coordinate of the medium lens array, the ordinate represents the y coordinate of the medium lens array, and the numbers 0.6-1.1 represent the r2 size distribution of the lens units. Since two materials with different dielectric constants are used, Figure 9 The distribution of the two materials with different dielectric constants in the medium lens array is shown in the diagram, in which the abscissa represents the x coordinate of the medium lens array, the ordinate represents the y coordinate of the medium lens array, and the numbers 0-1 are used to distinguish the distribution of the materials with different dielectric constants on the lens array. In the diagram, the black part represents the material with a dielectric constant of 6.5, and the white part represents the material with a dielectric constant of 3.5.

[0052] In combination with the phase distribution curve of the lens unit, the lens units are arranged in sequence according to the r2 size distribution diagram obtained through calculation, as shown in Figure 8 and Figure 9 In an ideal case, each lens unit should be optimized to achieve a continuously variable phase shift value in the range of 0°-360° to achieve the best radiation performance.

[0053] Figure 10 A lens surface phase error distribution diagram of the medium lens array of the embodiment of the present application is obtained through simulation calculation. Figure 10 In the diagram, the abscissa represents the x coordinate of the medium lens array, the ordinate represents the y coordinate of the medium lens array, and the numbers -10-8 represent the error value of the phase of the actual lens unit at the position and the phase calculated at the position.

[0054] As shown in Figure 7 , 9 The medium lens of the embodiment of the present application can well cover the phase of 0-360°, and the phase error is within ±10°.

[0055] In some embodiments, the directional diagram of the feed source should have good axial symmetry performance, the side lobe and back lobe should be as small as possible, the main lobe should have a small irradiation level on the edge of the array, and the radiation level outside the irradiation angle should be small. Secondly, within the irradiation angle range, the feed source should have a clear phase center and a small phase fluctuation to ensure that the Cassegrain antenna array can obtain an accurate phase distribution. As a feed source, the reflection coefficient bandwidth should be greater than the working bandwidth of the Cassegrain antenna array unit, and the beam width should remain stable within the working frequency band. The horn antenna is one of the most commonly used feed sources of the medium lens antenna. The embodiment of the present application selects a standard gain horn antenna in the Ku band as the feed source, and the working frequency is 12GHz to 18GHz. Figure 11The selected standard gain horn antenna is shown in the reflection coefficient curve and gain variation in the 12-18GHz frequency band. It can be seen that the horn has stable reflection characteristics and good gain performance in the design frequency band, which can meet the requirements of the lens antenna feed.

[0056] To verify the performance of the foldable transmissive array antenna proposed in the application, full-wave simulation software is used to model and analyze the antenna structure. Figure 12 The far-field radiation patterns of the embodiment at 13GHz and 15GHz operating frequencies are shown. In the simulation, the E-plane is defined as the plane (xoz) in which the electric field and the maximum radiation direction are located, and the H-plane is the plane (yoz) in which the magnetic field and the maximum radiation direction are located. As can be seen from the figure, the E-plane and H-plane patterns both exhibit good symmetry, clear main lobe and concentrated beam, indicating that the dielectric lens array achieves good wavefront conversion effect.

[0057] Figure 13 The gain and aperture efficiency curves of the overall system of the feed horn and the loaded lens at different frequencies are shown. The simulation results show that:

[0058] The gain of the horn feed is 14.09-16.84dBi in the range of 12-17GHz;

[0059] After loading the lens, the gain of the antenna system in the whole frequency band of 12-17GHz is more than 25.74dBi;

[0060] The maximum gain is improved by 12.98dB (13GHz), and the gain reaches 27.61dBi;

[0061] The 1dB gain bandwidth is 24.56%, covering the frequency band of 12.5-16GHz, and the lens antenna realizes 3dB gain bandwidth full coverage in the frequency band of 12-17GHz, with a relative bandwidth of 34.5%, and the peak efficiency is >45%.

[0062] The above simulation results verify that the dielectric lens structure of the application has good transmission efficiency and beam consistency in the working frequency band, and can significantly improve the overall antenna gain performance, and has the feasibility of practical engineering application.

[0063] The foldable transmissive array antenna provided by the application uses a Kirigami hinge structure to replace flexible materials to realize folding, avoids structural fatigue problems, and improves the repeatability and reliability of deployment; based on the method of r2 size control phase, the beamforming structure can be quickly constructed through a regular array; 3D printing is used to realize rapid and low-cost manufacturing, which is suitable for batch application; the overall structure is compact, the wave transmission efficiency is high, and the adaptability is strong, which is suitable for high integration and deployable electromagnetic systems.

[0064] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "setting", "connecting", "fixing", "rotating" and other terms should be understood in a broad sense, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited, the above terms in the present application can be understood according to the specific meaning of the above terms by the person skilled in the art according to the specific circumstances.

[0065] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A foldable transmission array antenna based on the Kirigami structure, characterized in that, It includes a dielectric lens array and a Ku-band standard gain horn antenna located on one side of the dielectric lens array; the dielectric lens array consists of 16×16 lens units, each lens unit including 4 dielectric pillars and 4 dielectric sheets, with 1 dielectric sheet embedded between every two dielectric pillars; the lens units switch between two unfolded and folded states.

2. The foldable transmission array antenna based on the Kirigami structure according to claim 1, characterized in that, Each dielectric column has two cylinders protruding outwards at both ends, and each dielectric sheet has a baffle protruding to the same side at both ends, with two circular through holes on each baffle. The circular through holes of each dielectric sheet are engaged with the cylinders of the two dielectric columns to form a mechanical hinge structure.

3. A foldable transmission array antenna based on a Kirigami structure according to claim 2, characterized in that, The radius of the cylinder is r2, and the radius of the circular through hole is r1, where r1 = r2 + 0.15 mm.

4. A foldable transmission array antenna based on a Kirigami structure according to claim 2, characterized in that, The transmission phase of the lens unit varies with the cylinder radius r2, achieving a complete 0 to 2π phase shift range within the cylinder radius r2, which ranges from 0.5 mm to 1.1 mm.

5. A foldable transmission array antenna based on a Kirigami structure according to claim 1, characterized in that, When the lens unit is in the unfolded state, the angle between any two adjacent dielectric pillars is 90°, and the four dielectric sheets are opposite each other without contact. In the unfolded state, the lens unit compresses two opposing dielectric sheets along the x-axis and the remaining two opposing dielectric sheets along the y-axis. When folded, two opposing dielectric sheets are in contact with each other, and the remaining two dielectric sheets are located on both sides of the two in contact, with the four dielectric pillars remaining horizontal.

6. A foldable transmission array antenna based on a Kirigami structure according to claim 1, characterized in that, The dielectric lens array is made of PREPERM™ low-loss dielectric thermoplastic, a 3D printable material.

7. A foldable transmission array antenna based on a Kirigami structure according to claim 1, characterized in that, The lens units are divided into two categories based on their material characteristics. The first type of lens unit uses PREPERM™ low-loss dielectric thermoplastic, a 3D printable material with a relative permittivity of 3.5 and a loss tangent of 0.0042. The second type of lens unit uses PREPERM™ low-loss dielectric thermoplastic, a 3D printable material with a relative permittivity of 6.5 and a loss tangent of 0.0034.

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