Mechanically reconfigurable frequency selective surface based on rotational rigid body structure tuning

Abstract

The application discloses a mechanical reconfigurable frequency selective surface based on a rotating rigid body structure tuning, comprising N frequency selective surface units arranged in a periodic shape array; the frequency selective surface unit comprises four frequency selective surface subunits; the frequency selective surface subunit comprises a dielectric substrate and a circular ring conductive layer; the circular ring conductive layer is arranged on the surface of the dielectric substrate; the four frequency selective surface subunits are connected through an included angle of a degrees, 180-a degrees, a degrees and 180-a degrees between adjacent frequency selective surface subunits; since the rotating rigid body structure is selected as the dielectric substrate, mechanical deformation only occurs in the horizontal plane during the tuning process, and the complexity of mechanical tuning is reduced; the application has the advantages of a large frequency tuning range, strong polarization stability, good tuning continuity and the like, and has great application potential in the fields of wearable devices and antenna covers.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electromagnetic metamaterials, and relates to a mechanically reconfigurable frequency selective surface based on rotation rigid body structure tuning. BACKGROUND

[0002] A frequency selective surface (FSS) is a two-dimensional material with a periodic structure that can selectively reflect, transmit or absorb electromagnetic waves within a specific frequency range. FSSs are widely used in wireless communication, electromagnetic shielding, radar stealth, and other fields. In the context of rapidly changing modern communication technologies, the demand for FSSs with higher flexibility and adaptability is increasingly prominent.

[0003] Passive FSSs are usually designed as static structures and cannot be adjusted according to changes in operating environment or requirements. Once designed, their electromagnetic properties remain fixed, limiting their adaptability in complex electromagnetic environments. To overcome the shortcomings of passive FSSs, reconfigurable frequency selective surfaces (RFSSs) have attracted widespread attention from scholars. Literature [1-3] By introducing active elements, the resonance frequency of the frequency selective surface is tuned. Literature [4-6] Using a medium material with variable electromagnetic properties, the resonance frequency of the frequency selective surface is tuned by changing the electromagnetic properties of the medium material. Literature [7-10] By mechanically deforming the FSS unit structure or array arrangement, the resonance frequency of the frequency selective surface is tuned. The above RFSSs can realize real-time regulation of electromagnetic properties according to requirements, thereby better adapting to complex external electromagnetic environments.

[0004] Among the many design concepts of RFSSs, the mechanical tuning method of changing the shape of the flexible RFSS substrate has the advantages of low loss, simple structure, no need for biasing network, and good tuning continuity, and has gradually attracted attention.

[0005] Some mechanically reconfigurable frequency selective surfaces (MRFSSs) based on changing the shape of the flexible RFSS substrate have been proposed. Literature [11-14] An Origami substrate-based RFSS is designed, which realizes tuning by changing the folding angle of the RFSS unit substrate. Literature

[15] ,

[16] FSS units are loaded onto a flexible substrate, and tuning is achieved by stretching the flexible substrate. With the development of materials science, Literature

[17] ,

[18] The mechanical metamaterial is applied to the design of electromagnetic metamaterial. Although the MRFSS structure can realize the tuning of the resonant frequency, the tuning range is limited, the polarization stability is poor, and continuous tuning cannot be realized. SUMMARY

[0006] To solve the above problems, the technical scheme adopted by the present application is: a mechanical reconfigurable frequency selective surface based on rotation rigid body structure tuning, comprising N frequency selective surface units, the N frequency selective surface units are arranged in a periodic shape array;

[0007] The frequency selective surface unit comprises four frequency selective surface subunits.

[0008] The frequency selective surface subunit comprises a dielectric substrate and a circular ring conductive layer.

[0009] The circular ring conductive layer is arranged on the surface of the dielectric substrate.

[0010] The four frequency selective surface subunits are connected by an included angle of a degrees, 180-a degrees, a degrees and 180-a degrees between adjacent frequency selective surface subunits.

[0011] Further, the periodic shape array arrangement comprises a matrix arrangement.

[0012] Further, the dielectric substrate adopts a rotation rigid body structure.

[0013] Further, the dielectric substrate adopts a square shape.

[0014] Further, the center of the circular ring conductive layer coincides with the center of the dielectric substrate.

[0015] Further, 0°≤a≤90°.

[0016] Further, the distance d1 from the outer edge of the circular ring conductive layer to the edge of the dielectric substrate is greater than 0.

[0017] Further, the center distance d2 of the circular ring conductive layer of adjacent frequency selective surface subunits is greater than 0.

[0018] Further, the adjacent frequency selective surface subunits are connected by a hinge structure.

[0019] Further, the circular ring conductive layer adopts a high electrical conductivity material.

[0020] The application provides a mechanical reconfigurable frequency selective surface based on a rotating rigid body structure tuning, and the tuning of the resonant frequency of the frequency selective surface is realized by changing the included angle of the rotating rigid body structure medium base; since the rotating rigid body structure is selected as the medium base, only mechanical deformation occurs in the horizontal plane during the tuning, and the complexity of mechanical tuning is reduced; the application has the advantages of a large frequency tuning range, strong polarization stability, good tuning continuity and the like, and has great application potential in the fields of wearable devices and antenna covers and the like.

[0021] (1) The application changes the electromagnetic coupling relationship between the conductive circular rings by changing the rotation angle of the rotating rigid body structure unit, so as to achieve the purpose of tuning; the change of the period shape of each unit of the MRFSS structure can be realized by applying a simple external force to the rotating rigid body structure, and the difficulty of mechanical tuning is reduced.

[0022] (2) The application uses the rotating rigid body structure as the medium base of the MRFSS, so as to realize the frequency tuning of the MRFSS; the rotating rigid body structure has rich topological structures and arrangement modes, so that the design of the FSS is more flexible.

[0023] (3) The application has a band-stop type frequency response, and the stopband resonance point can realize continuous and large-range frequency tuning; the experimental results are consistent with the simulation results.

[0024] (4) The application has symmetry in structure, and therefore has strong polarization stability.

[0025] (5) The structure of the application is simple, easy to process, and has low requirements on processing precision.

[0026] (6) The application can be manufactured by 3D printing technology, which greatly simplifies the manufacturing steps and reduces the manufacturing time while wasting less manufacturing materials. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0028] Figure 1 is a frequency selective surface subunit structure schematic diagram, wherein (a) is a frequency selective surface subunit structure schematic Figure 3 D structure, (b) a top view of the frequency selective surface subunit structure, (c) a side view of the frequency selective surface subunit structure, and (d) a bottom view of the frequency selective surface subunit structure.

[0029] Figure 2 are schematic diagrams of different viewing angles of the frequency selective surface subunit, (a) is a top view of the frequency selective surface subunit in a square grid included angle a = 90° state, (b) is a top view of the frequency selective surface subunit in a square grid included angle a = 45° state, (c) is a top view of the frequency selective surface subunit in a square grid included angle a = 0° state;

[0030] Figure 3 Simulation transmission coefficient of MRFSS structure in different square grid included angle states;

[0031] Figure 4 (a) is a schematic diagram of the overall structure of the MRFSS sample, wherein (a) is a schematic diagram of the overall structure of the MRFSS sample in a square grid included angle a = 90° state, (b) is a schematic diagram of the overall structure of the MRFSS sample in a square grid included angle a = 60° state, (c) is a schematic diagram of the overall structure of the MRFSS sample in a square grid included angle a = 90° state, and (d) is a schematic diagram of the overall structure of the MRFSS sample in a square grid included angle a = 0° state;

[0032] Figure 5 Schematic diagram of experimental device;

[0033] Figure 6 (a) is the test transmission coefficient of the MRFSS sample in different square grid included angle states, and (b) is a comparison diagram of the test and simulation of the resonance frequency.

[0034] The drawings show that: 1, dielectric substrate, 2, circular conductive layer. DETAILED DESCRIPTION

[0035] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict, and the present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0036] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0037] A mechanical reconfigurable frequency selective surface based on rotating rigid body structure tuning, comprising N frequency selective surface units, the N frequency selective surface units are arranged in a periodic shape array; N≥0;

[0038] The frequency selective surface unit comprises four frequency selective surface subunits;

[0039] The frequency selective surface subunit comprises a dielectric substrate 1 and a circular ring conductive layer 2;

[0040] The circular ring conductive layer 2 is arranged on the surface of the dielectric substrate 1;

[0041] The four frequency selective surface subunits are connected by being connected at an angle of a degrees, 180-a degrees, a degrees, and 180-a degrees between adjacent frequency selective surface subunits, and the frequency tuning is realized by changing the included angle of the dielectric substrate 1 unit square of the rotating rigid body structure and further changing the electromagnetic coupling relationship between the conductive circular rings.

[0042] Figure 1 is a schematic diagram of a frequency selective surface subunit structure, wherein (a) is a schematic diagram of a frequency selective surface subunit structure Figure 3 D structure, (b) is a top view of a frequency selective surface subunit structure, (c) is a side view of a frequency selective surface subunit structure, and (d) is a bottom view of a frequency selective surface subunit structure;

[0043] Figure 2 is a schematic diagram of a frequency selective surface subunit from different perspectives, (a) is a top view of a frequency selective surface subunit in a square included angle a=90° state, (b) is a top view of a frequency selective surface subunit in a square included angle a=45° state, and (c) is a top view of a frequency selective surface subunit in a square included angle a=0° state;

[0044] Further, the periodic shape array arrangement comprises a matrix arrangement.

[0045] Further, the dielectric substrate 1 adopts a rotating rigid body structure.

[0046] Further, the dielectric substrate 1 adopts a square, a rectangle, a triangle, a hexagon, etc.

[0047] Further, the center of the circular ring conductive layer 2 coincides with the center of the dielectric substrate 1.

[0048] Further, 0°≤a≤90°.

[0049] Further, the distance d1 from the outer edge of the circular ring conductive layer 2 to the edge of the dielectric substrate 1 is greater than 0.

[0050] Further, the center distance d2 of the circular ring conductive layer 2 of adjacent frequency selective surface subunits is greater than 0.

[0051] Further, the thickness d of the dielectric substrate 1 ranges from 6mm≥d≥0.

[0052] Further, the adjacent frequency selective surface sub-units are connected by a hinge structure.

[0053] Further, the circular conductive layer 2 adopts high conductivity material. The high conductivity material adopts copper, silver, graphite and other high conductivity materials;

[0054] Embodiment 1: a mechanical reconfigurable frequency selective surface based on rotating rigid body structure tuning, comprising N frequency selective surface units, the N frequency selective surface units are arranged in a periodic shape array;

[0055] The frequency selective surface unit comprises four frequency selective surface sub-units;

[0056] The frequency selective surface sub-unit comprises a dielectric substrate 1 and a circular conductive layer 2; the dielectric substrate 1 adopts a square shape; the side length of the square grid of the dielectric substrate 1 is D=10mm;

[0057] The thickness of the square grid of the rotating rigid body structure dielectric substrate 1 is H=4mm;

[0058] The circular conductive layer 2 is arranged on the surface of the dielectric substrate 1;

[0059] The thickness of the circular conductive layer 2 is t=0.008mm;

[0060] The outer diameter of the circular conductive layer 2 is R2=6mm;

[0061] The inner diameter of the circular conductive layer 2 is R1=4.4mm;

[0062] The four frequency selective surface sub-units are connected by a hinge structure, and the adjacent frequency selective surface sub-units are connected at an angle of a degrees, 180-a degrees, a degrees and 180-a degrees, respectively. By changing the included angle of the square grid of the rotating rigid body structure dielectric substrate 1, the electromagnetic coupling relationship between the conductive circular rings is changed to realize frequency tuning.

[0063] The top view of the proposed MRFSS unit under different dielectric substrate 1 grid angle states is shown in Figure 2 The distance between the centers of the circular conductive patterns is S, which is calculated as follows:

[0064]

[0065] Wherein, D is the side length of the square grid of the dielectric substrate 1, and a is the outer included angle between the adjacent dielectric substrates 1;

[0066] As can be seen from the above formula, by changing the included angle α between the structural dielectric substrates 1, the distance S between the centers of the annular conductive pattern can be changed, thereby changing the electromagnetic coupling relationship between the conductive rings and achieving the purpose of frequency tuning.

[0067] To verify that the MRFSS structure has mechanical tuning capability, CST Studio Suite software was used. Figure 1 Full-wave electromagnetic simulation was performed on the MRFSS structure shown. Floquet ports and periodic boundary conditions were used to simulate the transmission coefficient of the infinite RFSS structure. The grid angle was gradually decreased from 90° to 0°, and simulations were performed every 15°. The full-wave electromagnetic simulation results of the MRFSS structure under different grid angles when the electromagnetic wave is incident perpendicularly are shown below. Figure 3 As shown. From Figure 3 As can be seen, the proposed RFSS has a first-order band-stop frequency response. By rotating the grid, the stopband resonant point achieves continuous frequency tuning from 14.73 GHz to 16.1 GHz, with a tuning range of 1.37 GHz. The –10 dB bandwidth is between 0.732 GHz and 1.826 GHz, and gradually increases as α decreases.

[0068] To further verify the effectiveness of the MRFSS structure, an MRFSS prototype was fabricated, such as... Figure 4 This is an overall structural diagram of the MRFSS sample, where (a) is the overall structural diagram of the MRFSS sample with the grid angle α = 90°, (b) is the overall structural diagram of the MRFSS sample with the grid angle α = 60°, (c) is the overall structural diagram of the MRFSS sample with the grid angle α = 90°, and (d) is the overall structural diagram of the MRFSS sample with the grid angle α = 0°; the overall size is 194.2mm * 194.2mm and contains 14 * 14 units;

[0069] First, a rotating rigid body structure medium substrate 1 is manufactured using 3D printing technology. The rotating rigid body structure medium substrate 1 is made of 3D printed flexible filament material (dielectric constant εr=2.7, loss tangent tanδ=0.008).

[0070] Then, the circular conductive pattern is printed on the rotating rigid body structure medium substrate 1 using conductive ink printing technology. The circular conductive pattern uses silver paste conductive ink.

[0071] It is worth noting that, for the sake of simulation, Figure 1The MRFSS shown is an ideal unit structure, the thickness of the connection between the rotating rigid body structure grid is 0, in the sample manufacturing, the thickness of the connection between the rotating rigid body structure grid is set to 0.4mm, through simulation analysis, the slight change of the thickness of the connection between the grid can be ignored.

[0072] The transmission coefficient of the MRFSS sample is measured in a microwave darkroom by using free space measurement method. As shown in Figure 5 The instrument used includes a vector network analyzer (Agilent N5242A), transmitting and receiving antennas (ETS-LINDGREN3117). In order to ensure the far-field condition, the position of the antenna is about 2m away from the sample. In order to reduce the edge effect and improve the test accuracy, the sample is placed in the middle of the tapered wave absorber. The transmission coefficient of the tapered wave absorber without the sample is measured as the normalization coefficient, and the time domain gate technology is used to filter out the influence of the diffraction wave on the measurement results.

[0073] The transmission coefficient results of the sample under the vertical incidence of electromagnetic waves are shown in Figure 6 As shown in (a), the transmission coefficient of the MRFSS sample is tested under different grid angle states, (b) is the comparison chart of the test and simulation of the resonant frequency. With the grid angle decreasing from 90° to 0°, the resonant frequency of the MRFSS decreases from 15.98GHz to 14.84GHz, and the test results are in good agreement with the simulation results. Some slight insertion loss deviation and low frequency fluctuation are caused by manufacturing error, slightly high resistivity of conductive ink, material dielectric deviation and limited size of the sample. It is noted that the tuning range measured in the experiment is slightly smaller than the simulation result, because in the state of a=0°, the existence of a small air gap between the base grids of the MRFSS causes the tuning range to be smaller.

[0074] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

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Claims

1. A mechanically reconfigurable frequency selective surface based on tuning of a rotating rigid body structure, characterized by, The frequency selective surface unit comprises N frequency selective surface subunits arranged in a periodic shape array; The frequency selective surface unit comprises four frequency selective surface subunits; The frequency selective surface subunit comprises a dielectric substrate and a circular ring conductive layer; The circular ring conductive layer is arranged on the surface of the dielectric substrate; The four frequency selective surface subunits are connected by an included angle between adjacent frequency selective surface subunits degrees, 180- degrees, degrees, 180- degrees The dielectric substrate adopts a rotating rigid body structure; The dielectric substrate adopts a square shape; The center of the circular ring conductive layer coincides with the center of the dielectric substrate; 0°≤ ≤90°； The distance d1 from the outer edge of the circular ring conductive layer to the edge of the dielectric substrate is greater than 0; The center distance d2 of the circular ring conductive layers of adjacent frequency selective surface subunits is greater than 0; The adjacent frequency selective surface subunits are connected through a hinge structure.

2. A mechanically reconfigurable frequency selective surface based on a rotating rigid body structure tuning according to claim 1, characterized in that, The periodic shape array arrangement comprises a matrix arrangement.

3. A mechanically reconfigurable frequency selective surface based on a rotating rigid body structure tuning according to claim 1, characterized in that, The circular ring conductive layer adopts a high conductivity material.

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