Frequency-adjustable electromagnetic metamaterial wave absorber based on radial shrinkage

Abstract

The invention provides a frequency-adjustable electromagnetic metamaterial wave absorber based on radial shrinkage. The wave absorber comprises a plurality of wave absorbing units which are distributed in an array mode. Each wave absorbing unit comprises a unit substrate, a reflecting layer, a resonance device and a driving mechanism; the reflecting layer is arranged on one surface of the unit substrate, a mounting groove is formed in the other surface of the unit substrate, and the resonant device is movably arranged in the mounting groove; the driving mechanism is used for driving the resonance device to move in the installation groove in the radial direction. According to the invention, by adjusting the radial displacement of the resonance device, the dynamic adjustment of the pattern shape of the metamaterial unit is realized, the optimized wave absorption can be realized for different polarization threats, and the reflection coefficient S11 can be below-10dB. The complementary polarization design enables the device to have a multi-polarization coping capability in a wide frequency band. The problem that a traditional fixed-frequency wave absorber is poor in adaptability is solved, and a new technical scheme is provided for radar wave absorption and electromagnetic compatibility application.

Description

Technical Field

[0001] This invention belongs to the field of metamaterial electromagnetic control technology, specifically relating to an adjustable frequency electromagnetic metamaterial absorber based on radial contraction. Background Technology

[0002] In modern warfare and electronic communication environments, the requirements for stealth performance and electromagnetic compatibility (EMC) of weapons and equipment are constantly increasing. Traditional radar absorbing materials have limitations in meeting the performance indicators of "thin, light, wide, and strong". In contrast, metamaterial absorbers based on periodic subwavelength structures have attracted widespread attention due to their simple structure, thin thickness, high absorption rate, and flexible control of electromagnetic response. Metamaterial absorbers dissipate the energy of incident electromagnetic waves within the material through special design, thereby reducing reflection and transmission and achieving efficient absorption. To broaden the absorption bandwidth and achieve dynamic tunability, researchers have proposed various tunable techniques. For example, the resonant frequency can be dynamically controlled by loading active adjustment elements such as varactor diodes, PIN diodes, phase change materials, graphene, or liquid crystals, or tuning can be achieved through mechanical means of structural geometric deformation. Existing research shows that these approaches each have their advantages and disadvantages. For example, patent CN105140654A uses a structure with loaded varactor diodes and passive components to achieve frequency tunability, but this solution requires an external bias circuit, has high system integration complexity, and its disclosed absorption bandwidth is mainly concentrated in the 8~14 GHz band; another mechanically adjustable design (such as the stretchable structure realized by Zhang et al. on an all-dielectric substrate) can significantly change the cell period to expand the operating bandwidth, but its manufacturing process is complex and difficult to integrate with microwave devices.

[0003] In summary, to meet the demands of modern applications for wideband absorption and dynamic tuning, there is an urgent need for a new type of adjustable frequency absorber that possesses both broadband and high-efficiency absorption performance and is easy to manufacture. Summary of the Invention

[0004] This invention addresses the problems of existing technologies by providing a radially contracting adjustable frequency electromagnetic metamaterial absorber. By generating an adjustable displacement in the radial direction through a resonant device, the geometric structure and resonant characteristics of the unit pattern are changed to achieve dynamic adjustment of the absorption frequency. This solves the problems of narrow bandwidth and complex manufacturing of existing absorbers.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a radially contracting adjustable frequency electromagnetic metamaterial absorber, the absorber comprising a plurality of absorber units arranged in an array; each absorber unit comprises a unit substrate, a reflective layer, a resonant device, and a driving mechanism; the reflective layer is disposed on one side of the unit substrate, and a mounting groove is formed on the other side of the unit substrate, the resonant device being movably disposed within the mounting groove; the driving mechanism is used to drive the resonant device to move radially within the mounting groove.

[0006] Furthermore, the driving mechanism includes a rotating disk disposed in the mounting groove of the unit substrate, the rotating disk being rotatable relative to the unit substrate, and the rotating disk having a plurality of arc-shaped grooves; the bottom surface of the mounting groove of the unit substrate having a number of straight grooves matching the number of arc-shaped grooves, the straight grooves being radially distributed along the rotating disk; the resonant device having an upper slider and a lower slider, the upper slider being slidably disposed in the arc-shaped groove, and the lower slider being slidably disposed in the straight groove.

[0007] Furthermore, the driving mechanism also includes a motor, which is fixed on the side of the reflective layer facing away from the unit substrate; both the reflective layer and the unit substrate are provided with through holes for the motor output shaft to pass through, and the motor output shaft passes through the reflective layer and the unit substrate in sequence to drive the rotating disk.

[0008] Furthermore, the resonant device includes an arc-shaped component and a connecting rod; the upper slider and the lower slider are respectively fixed on the upper and lower surfaces of the connecting rod, and the outer end of the connecting rod is fixedly connected to the arc-shaped component.

[0009] Furthermore, the arc of the resonant device is the same as the arc of the rotating disk, and the arc can fit against the outer ring of the rotating disk; the thickness of the arc of the resonant device is the same as the depth of the mounting groove.

[0010] Furthermore, the mounting groove is a circular groove, and the rotating disk is distributed in the center of the mounting groove, with the upper surface of the rotating disk flush with the upper surface of the unit substrate.

[0011] Furthermore, the rotating disk and the unit substrate are made of polylactic acid.

[0012] Furthermore, the reflective layer is a copper foil sheet; or the reflective layer is obtained by bonding the copper foil sheet to a polymer plate with an adhesive.

[0013] Furthermore, the material of the resonant device is copper.

[0014] The beneficial effects of this invention are: (1) By adjusting the radial displacement of the resonant device, the present invention can change the geometric structure and resonant characteristics of the unit pattern in real time, realize the dynamic adjustment of the shape of the metamaterial unit pattern, and thus can dynamically adjust the absorption frequency according to the needs, which is widely applicable; (2) The present invention provides a driving mechanism for driving the resonant device to move radially in the mounting slot. The rotating disk is driven by a motor to rotate, thereby driving the upper and lower sliders of the resonant device to move along the arc-shaped slide and the straight slide respectively. The resonant device is constrained to move in the radial direction, so that it can move radially along the straight slide. The operation is simple and flexible. (3) By adjusting the radial displacement, this invention can optimize radar absorption for different polarization threats, achieving a reflection coefficient below -10dB. This complementary polarization design enables the device to cope with multiple polarizations over a wide frequency band. This invention solves the problem of poor adaptability of traditional fixed-frequency radar absorbers and provides a new technical solution for radar absorption and electromagnetic compatibility applications. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the adjustable frequency electromagnetic metamaterial absorber based on radial contraction of the present invention; Figure 2 This is a schematic diagram of the wave-absorbing unit of the present invention, wherein (a) is an overall schematic diagram of the unit structure, (b) is a top view of the unit structure, and (c) is a side view of the unit structure; Figure 3 This is an exploded view of the microwave absorbing unit structure of the present invention; Figure 4 This describes the absorption performance and unit pattern under a radial displacement of 1.9 mm according to Embodiment 1 of the present invention. Figure 5 This describes the absorption performance and unit pattern under a radial displacement of 0.9 mm according to an embodiment of the present invention. Figure 6 This is a graph showing the variation trend of the reflection coefficient of the absorber in the embodiment of the present invention under a radial displacement of 0~1.9mm; Figure 7 This refers to the radial shift range of the absorber frequency performance in this embodiment of the invention, which is less than -10dB. The labels in the attached diagram are: 1. Unit substrate; 2. Reflective layer; 3. Rotating disk; 4. Resonant device; 5. Motor. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1 like Figures 1-3As shown, this embodiment provides a radially contracting adjustable frequency electromagnetic metamaterial absorber. The absorber includes multiple absorber units distributed in an array. The center distance between two adjacent absorber units is 20 mm. They are repeatedly arranged in the X and Y orthogonal directions to form a 10×10 two-dimensional periodic array.

[0018] Each absorbing unit includes a unit substrate 1, a reflective layer 2, a resonant device 4, and a driving mechanism. The reflective layer 2 is disposed on one side of the unit substrate 1, and a circular mounting groove is formed on the other side of the unit substrate 1. The resonant device 4 is movably disposed within the mounting groove and includes an arc-shaped component and a connecting rod, the end of which is fixedly connected to the arc-shaped component. The driving mechanism is used to drive the resonant device 4 to move radially within the mounting groove, thereby generating an adjustable displacement of the resonant device 4 in the radial direction, thus changing the geometric structure and resonant characteristics of the unit pattern to dynamically adjust the absorption frequency.

[0019] Specifically, such as Figures 2-3 As shown, the driving mechanism includes a rotating disk 3 and a motor 5. The rotating disk 3 is disposed in the mounting groove of the unit substrate 1 (the central axis of the rotating disk 3 coincides with that of the mounting groove). The rotating disk 3 can rotate relative to the unit substrate 1, and six arc-shaped grooves are provided on the rotating disk 3. The bottom surface of the mounting groove of the unit substrate 1 is provided with straight grooves of the same number as the arc-shaped grooves. The straight grooves are radially distributed along the rotating disk 3, and each straight groove is equidistant. The motor 5 is fixed on the side of the reflective layer 2 facing away from the unit substrate 1. Both the reflective layer 2 and the unit substrate 1 are provided with through holes for the output shaft of the motor 5 to pass through. The output shaft of the motor 5 passes through the reflective layer 2 and the unit substrate 1 in sequence, and is driven and connected to the rotating disk 3 to achieve a rigid transmission connection between the motor and the rotating disk. The connecting rods of the resonant device 4 are distributed between the rotating disk 3 and the mounting groove, and the upper and lower surfaces of the inner ends of the connecting rods are respectively provided with upper sliders and lower sliders. The upper slider is slidably disposed in the arc-shaped groove, and the lower slider is slidably disposed in the straight groove.

[0020] Application principle of the drive mechanism: The motor 5 drives the rotating disk 3 to rotate. The resonant device 4 is constrained by the arc-shaped groove of the rotating disk 3 and the straight groove of the unit substrate 1. The rotation of the rotating disk 3 can drive the upper slider and the lower slider to move along the arc-shaped groove and the straight groove respectively, thereby driving the resonant device 4 to move radially along the straight groove. As a result, the resonant device 4 undergoes centrifugal or centripetal radial movement, changing the shape of the metamaterial unit pattern, so that the absorption frequency of the metamaterial absorber is adjustable.

[0021] In a preferred embodiment of the present invention, the arc of the resonant device 4 is the same as the arc of the rotating disk 3, and the arc can fit against the outer ring of the rotating disk 3. The thickness of the arc of the resonant device 4 is the same as the depth of the mounting groove. The rotating disk 3 is located at the center of the mounting groove, and the upper surface of the rotating disk 3 is flush with the upper surface of the unit substrate 1.

[0022] In this embodiment, the unit substrate 1 is a square polylactic acid dielectric board with a thickness of 4mm, manufactured by 3D printing technology. The circular mounting groove on its surface has a diameter of 16mm and a depth of 1.5mm. A through hole is pre-drilled in the center of the unit substrate 1 for the shaft of the stepper motor 5 to pass through. The length of the straight groove in the mounting groove of the unit substrate 1 is 5mm.

[0023] The rotating disk 3 is made of polylactic acid, with a diameter of 10mm and a thickness of 0.5mm. It has 6 120° arc-shaped grooves (each corresponding to a 60° central angle).

[0024] The resonant device 4 is a copper T-shaped patch. The length × width × thickness of its connecting rod is 3.9mm * 0.5mm * 1.0mm; the width of the arc-shaped part is 1mm, the arc length is 6mm, and the thickness is 1.5mm. Two sets of resonant devices 4 are arranged in a mirror symmetrical manner.

[0025] The reflective layer 2 is a copper foil sheet. The reflective layer of a single absorbing unit has a side length of 20mm and a thickness of 0.2mm. It is integrated with the unit substrate 1 by vacuum hot pressing.

[0026] The assembly process of the radially contracting adjustable frequency electromagnetic metamaterial absorber of this invention includes: S1. A PLA material unit substrate 1 is prepared using 3D printing technology. Six radial straight grooves are opened on one side of the unit substrate 1. Then, the reflective layer 2 (copper foil) is hot-pressed with the other side of the unit substrate 1 at 0.5MPa and 120℃ for 15 minutes to complete the lamination.

[0027] S2. A PLA rotating disk 3 is made using 3D printing technology, and six 120° arc grooves are printed on the surface of the rotating disk 3. The rod of the resonant device 4 is temporarily positioned in the straight groove of the unit substrate 1 using hot melt adhesive.

[0028] S3. After inserting the resonant device 4, cover the rotating disk 3, insert the output screw of the stepper motor 5 and fix it with the internal thread of the rotating disk 3 to ensure that the coaxiality error between the rotating shaft and the rotating disk is ≤0.05mm.

[0029] S4. The assembled absorbing units are bonded together with epoxy adhesive at 20mm intervals to form a 10×10 array plate, thus completing the mechanical forming of the overall absorber.

[0030] Effect test: The absorption performance of the tunable frequency electromagnetic metamaterial absorber prepared in Example 1 was simulated and tested.

[0031] By controlling the rotation angle of the rotating disk with a stepper motor, the resonant device is driven to produce a radial displacement change of 0.0-1.9mm, thereby realizing the dynamic adjustment of the pattern shape of the metamaterial unit.

[0032] In the simulation verification, the present invention uses CST software for model construction and batch simulation. By analyzing the relationship between various structural parameters (displacement of the rotating disk) and the reflection coefficient S11 with frequency, the corresponding law between performance indicators such as -10dB absorption bandwidth and resonant peak frequency and unit deformation is studied.

[0033] Target frequencies of 12 GHz and 16 GHz were selected. Simulations were conducted using radial displacement cases of resonators with diameters of 1.9 mm and 0.9 mm, based on these target absorption frequencies. The results show that absorbing units with radial displacement patterns of 1.9 mm and 0.9 mm exhibit good absorption performance at both 12 GHz and 16 GHz. Figure 4 and Figure 5 As shown.

[0034] Next, simulations were performed on the absorbing unit with a radial displacement pattern of 0-1.9 mm at 2-40 GHz, such as... Figure 6 As shown in the figure. The results show that a continuous absorption bandwidth of 3.078 GHz is achieved in the Y-polarization direction in the X-band (9.9-13.0 GHz), and a continuous absorption bandwidth of 1.9 GHz is achieved in the X-polarization direction in the Ku-band (14.4-17.2 GHz). Dual-polarization absorption can be achieved simultaneously in the 11.6-12.2 GHz and 15.8-16.4 GHz sub-bands.

[0035] Based on the above simulations, this invention achieves a total adjustable absorption bandwidth of 7.182 GHz. It can be specifically adjusted by changing the radial displacement of the resonant device according to the operating frequency band and polarization mode of the target radar, thus significantly improving the absorption performance.

[0036] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A tunable frequency electromagnetic metamaterial absorber based on radial contraction, characterized in that, The absorber comprises an array of several absorbing units; The absorbing unit includes a unit substrate (1), a reflective layer (2), a resonant device (4), and a driving mechanism; The reflective layer (2) is disposed on one side of the unit substrate (1), and a mounting groove is provided on the other side of the unit substrate (1). The resonant device (4) is movably disposed in the mounting groove. The driving mechanism is used to drive the resonant device (4) to move radially in the mounting groove.

2. The tunable frequency electromagnetic metamaterial absorber based on radial contraction according to claim 1, characterized in that, The driving mechanism includes a rotating disk (3), which is disposed in the mounting groove of the unit substrate (1). The rotating disk (3) can rotate relative to the unit substrate (1). The rotating disk (3) is provided with a plurality of arc-shaped sliding grooves. The bottom surface of the mounting groove of the unit substrate (1) is provided with straight sliding grooves that are the same number as the arc-shaped sliding grooves. The straight sliding grooves are radially distributed along the rotating disk (3). The resonant device (4) is provided with an upper slider and a lower slider. The upper slider is slidably disposed in an arc-shaped groove, and the lower slider is slidably disposed in a straight groove.

3. The tunable frequency electromagnetic metamaterial absorber based on radial contraction according to claim 2, characterized in that, The driving mechanism also includes a motor (5), which is fixed on the side of the reflective layer (2) facing away from the unit substrate (1). Both the reflective layer (2) and the unit substrate (1) are provided with through holes for the output shaft of the motor (5) to pass through. The output shaft of the motor (5) passes through the reflective layer (2) and the unit substrate (1) in sequence and is driven to connect with the rotating disk (3).

4. The tunable frequency electromagnetic metamaterial absorber based on radial contraction according to claim 2, characterized in that, The resonant device (4) includes an arc-shaped component and a connecting rod; the upper slider and the lower slider are respectively fixed on the upper and lower surfaces of the connecting rod, and the outer end of the connecting rod is fixedly connected to the arc-shaped component.

5. The tunable frequency electromagnetic metamaterial absorber based on radial contraction according to claim 4, characterized in that, The arc of the resonant device (4) is the same as the arc of the rotating disk (3), and the arc can fit against the outer ring of the rotating disk (3); the thickness of the arc of the resonant device (4) is the same as the depth of the mounting groove.

6. The tunable frequency electromagnetic metamaterial absorber based on radial contraction according to claim 2, characterized in that, The mounting groove is a circular groove, and the rotating disk (3) is distributed in the center of the mounting groove. The upper surface of the rotating disk (3) is flush with the upper surface of the unit substrate (1).

7. The tunable frequency electromagnetic metamaterial absorber based on radial contraction according to claim 2, characterized in that, The rotating disk (3) and the unit substrate (1) are made of polylactic acid.

8. The tunable frequency electromagnetic metamaterial absorber based on radial contraction according to claim 1, characterized in that, The reflective layer (2) is a copper foil sheet; Alternatively, the reflective layer (2) can be obtained by bonding copper foil to a polymer plate with an adhesive.

9. The tunable frequency electromagnetic metamaterial absorber based on radial contraction according to claim 1, characterized in that, The material of the resonant device (4) is copper.

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