CN113193381A

CN113193381A - Multi-band adjustable wave absorber based on silicon and vanadium dioxide all-dielectric metamaterial

Info

Publication number: CN113193381A
Application number: CN202110497432.8A
Authority: CN
Inventors: 肖丙刚; 刘金荣
Original assignee: China Jiliang University
Current assignee: China Jiliang University
Priority date: 2021-05-07
Filing date: 2021-05-07
Publication date: 2021-07-30

Abstract

The invention discloses a multiband adjustable wave absorber based on a silicon and vanadium dioxide all-dielectric metamaterial, and belongs to the field of electromagnetic wave absorbing metamaterials. In order to be used for electromagnetic shielding and radar stealth and overcome the inherent problems of a metal wave absorber, the invention provides an all-dielectric metamaterial multi-band adjustable wave absorber based on silicon and vanadium dioxide, which can generate 7S waves in an X wave band (8-12GHz)₁₁Absorption peaks with parameters below-10 dB (industry standard). The lowest peak value reaches-35 dB, and the electromagnetic wave absorption rate is more than 99 percent. The vanadium dioxide layer designed at the bottom can adjust the wave absorption size and frequency through the change of temperature.

Description

Multi-band adjustable wave absorber based on silicon and vanadium dioxide all-dielectric metamaterial

Technical Field

The invention relates to the field of electromagnetic metamaterials, in particular to an all-dielectric metamaterial wave-absorbing device. In practical application, the electromagnetic wave absorbing material has the capability of absorbing electromagnetic waves at multiple frequency band points in an X-band (8GHz-12 GHz).

Background

With the increasingly widespread use of electromagnetic waves in society, people increasingly attach importance to the damage to people under excessive electromagnetic radiation. In military, electromagnetic stealth of radar is also strived for development in various countries. These inventions do not depart from the high efficiency wave absorber.

The traditional metamaterial wave absorber is generally in a sandwich structure, namely the metamaterial wave absorber is composed of metal patches with periodic surfaces, a middle dielectric layer and a metal layer on the bottom surface. However, the metal structure makes the wave absorber heavy and small, and the metal is easy to break, high in heat conductivity and high in ohmic loss, and is often accompanied with loss and temperature rise in the using process, so that the adaptability to the environment is poor. When the frequency reaches the resonance frequency, surface plasmons are excited and saturate the magnetic response, making the metal-based metamaterial useless at higher frequencies.

Disclosure of Invention

In order to be used for electromagnetic shielding and radar stealth and overcome the inherent problems of a metal wave absorber, the invention provides an all-dielectric metamaterial multi-band adjustable wave absorber based on silicon and vanadium dioxide, which can generate 7S waves in an X wave band (8-12GHz)₁₁Absorption peaks with parameters below-10 dB (industry standard). The lowest peak value reaches-35 dB, and the electromagnetic wave absorption rate is more than 99 percent.

In order to achieve the above purpose, the invention adopts a technical scheme that: by designing the large and small structures of the silicon structural unit under specific frequency, the structural array and electromagnetic waves are subjected to coupling resonance to achieve a wave absorbing effect. And the vanadium dioxide layer is designed at the bottom, so that the wave absorption size and frequency can be adjusted through temperature change. It is characterized by comprising:

a three-dimensional silicon structure array on the top and a bottom vanadium dioxide temperature sensitive adjustable reflecting layer.

The three-dimensional silicon structural unit at the top is a cube with a length and width p of 12mm and a height h of 12mm minus two diagonal cylindrical notches, wherein the radius r of the cylindrical notch is 5mm, and the height h is 12mm, as shown in the figure I.

The structural unit of the bottom vanadium dioxide temperature-sensitive adjustable reflecting layer is a cuboid layer with the length and width of 12mm and the height of 0.5mm and is attached under a silicon structure as shown in the figure I.

Through the change of the structural shape of the metamaterial unit size, different structures can excite different resonance modes, double negative characteristics of dielectric constant and magnetic permeability can occur at resonance points under the condition of sub-wavelength, and double negative materials are difficult to match in free space impedance, so that band elimination is realized.

The invention has the beneficial effects that:

(1) the defects that a traditional metal wave absorber is easy to break, high in heat conductivity, high in ohmic loss, poor in adaptability to the environment and the like are overcome through the structural design of the all-dielectric metamaterial, and the all-dielectric metamaterial wave absorber is small in size, low in cost and easy to prepare in a large scale and at low cost;

(2) 7 absorption peaks lower than-10 dB (industrial standard) are realized at 8GHZ-12GHZ, the strongest absorption peak reaches-35 dB, and the wave absorbing effect is more than 99%.

(3) The amplitude and frequency of wave absorption can be adjusted through temperature change through the vanadium dioxide layer at the bottom.

(4) The material adopts a centrosymmetric design and is insensitive to polarization.

Drawings

FIG. 1(a) is a block diagram of a metamaterial unit structure; FIG. 1(b) is a schematic diagram of the complete array structure;

FIG. 2 shows S of the metamaterial in a vanadium dioxide metal state and a medium state₁₁A reflection spectrum;

fig. 3(a) shows the magnetic field distribution of the metamaterial wave absorber in the present invention at the frequency f1 ═ 9.73 GHz; fig. 3(b) shows the magnetic field distribution of the metamaterial wave absorber in the present invention at a frequency f2 of 10.86 GHz; fig. 3(c) shows the magnetic field distribution of the metamaterial wave absorber in the present invention at the frequency f3 ═ 11.41 GHz;

FIG. 4 is a Surface Current (Surface Current) distribution;

Detailed Description

In order to make the method, the purpose and the technical scheme of the present invention clearer, the technical scheme and the performance index of the present invention will be described in more detail with reference to the accompanying drawings.

Fig. 1(a) is a design of the all-dielectric wave absorber unit, and fig. 1(b) is an array composed of the all-dielectric wave absorber unit. We have conducted simulation studies on the electromagnetic performance of the proposed all-dielectric structure using software based on commercial Finite Integration Technology (FIT). Periodic boundary conditions are applied in the fundamental x and y directions, and open boundaries are applied in the z direction. The excitation source is selected to be incident to a plane wave propagating in the-Z direction. Furthermore, due to the rotational symmetry of the structure, the absorber can operate under polarized conditions.

The bottom is made of vanadium dioxide (VO)₂) The layer is covered, vanadium dioxide exists in a metal state and a medium state due to the influence of temperature, and in the metal state, the wave absorber does not transmit (S) due to the blockage of the vanadium dioxide on the back to electromagnetic waves₂₁) Thus, the formula a (ω) 1-R (ω) 1-S₁₁ ²L (where R (ω) is reflectance, S₁₁Is a coefficient of reflection) It can be known that the absorption performance of the wave absorber can be marked by a reflection coefficient S11. And for each absorption peak, when S is₁₁Less than-10 dB, the absorption rate is 90%. As shown in the metallic state curve of FIG. 2, at the frequencies of 8-12GHz, the frequency selector has 7 absorption peaks lower than 10dB at the frequencies of 9.01GHz, 9.73GHz, 9.99GHz, 10.86GHz, 10.97GHz, 11.41GHz and 11.66GHz respectively. In the medium state, as shown in FIG. 2, the medium state curve, S₁₁The wave absorption degree and the absorption frequency can be adjusted and reconstructed by adjusting and controlling the temperature because the wave absorption degree and the absorption frequency are not more than-10 dB all the time.

To understand the physical mechanism of absorption, we calculated the electromagnetic field distribution of three selected peaks, f 1-9.73 GHz, f 2-10.86 GHz, and f 3-11.41 GHz. As can be seen from fig. 3(a), at f1, the electric field is enhanced in the middle region of the dielectric structure. As can be seen from fig. 3(b), at f2, the electric field is enhanced at the cylindrical notch of the dielectric structure in the contact region with other cells, and as can be seen from fig. 3(c), at f3, the electric field is enhanced at the boundary region between the cylindrical notch and the vertex of other cells. This phenomenon can be explained by standing wave theory. A standing wave is generated when two waves of the same amplitude moving in opposite directions on the same line are superimposed on each other.

The Surface Current distribution (fig. 4) gives a more detailed description of the absorption inside the structure. The enhanced electric field and PLD profile confirm that the power loss is mainly due to electrical resonance. It is difficult to introduce strong electric resonance or strong magnetic resonance into a uniform low dielectric constant dielectric plate. However, the design cell forms a dielectric-air interface where resonance phenomena are more likely to occur.

Claims

1. A multiband adjustable wave absorber based on silicon and vanadium dioxide all-dielectric metamaterial is used in the field of electromagnetic wave absorbing metamaterial and is characterized by comprising the following components in parts by weight: the size structure of the silicon structure unit is skillfully designed on the surface, so that the structural array formed by the unit and electromagnetic waves generate coupling resonance to achieve the wave absorbing effect. The vanadium dioxide layer is designed at the bottom, and the wave absorption size and frequency can be adjusted through temperature change.

2. The surface silicon building block size structure of claim 1, wherein: the wave absorbing unit is a cube with the length and width p being 12mm and the height h being 12mm minus two diagonal cylindrical notches, the radius r of the cylindrical notches being 5mm and the height h being 12 mm.

3. The bipolar wireless charging coil of claim 1, wherein: the bottom vanadium dioxide structural unit is a cuboid layer with the length and the width of 12mm and the height of 0.5mm, and is attached below the silicon structure.