CN111987452B - Transmission/reflection switchable and amplitude-adjustable metamaterial - Google Patents
Transmission/reflection switchable and amplitude-adjustable metamaterial Download PDFInfo
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- CN111987452B CN111987452B CN202010901591.5A CN202010901591A CN111987452B CN 111987452 B CN111987452 B CN 111987452B CN 202010901591 A CN202010901591 A CN 202010901591A CN 111987452 B CN111987452 B CN 111987452B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q1/00—Details of, or arrangements associated with, antennas
- H01Q1/42—Housings not intimately mechanically associated with radiating elements, e.g. radome
- H01Q1/422—Housings not intimately mechanically associated with radiating elements, e.g. radome comprising two or more layers of dielectric material
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
- H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
- H01Q15/0013—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective
- H01Q15/002—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices said selective devices working as frequency-selective reflecting surfaces, e.g. FSS, dichroic plates, surfaces being partly transmissive and reflective said selective devices being reconfigurable or tunable, e.g. using switches or diodes
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Abstract
The invention discloses a transmission/reflection switchable and amplitude-adjustable metamaterial, which is of a layered structure and sequentially comprises the following components from bottom to top: the device comprises an active frequency selection surface, a microwave dielectric layer and a graphene capacitor layer. The active frequency selective surface is composed of a medium substrate and periodic metal microstructure patterns printed on two sides of the medium substrate, and PIN diodes are loaded in the metal microstructures. The microwave dielectric layer is a wave-transparent material commonly used in a microwave band, and the graphene capacitor layer is composed of a high sheet resistance film layer, an insulating dielectric layer soaked in ionic liquid and a PET substrate single-layer graphene layer. The invention has the advantages that: by controlling the on-off of the PIN diode, the dynamic switching between the transmission mode and the reflection mode can be realized, the Fermi level of the graphene is further adjusted through external bias voltage to change the sheet resistance of the graphene, and the dynamic tuning of the transmission amplitude and the reflection amplitude can also be realized. The metamaterial has the advantages of complete polarization response characteristic, integration of various electromagnetic regulation and control functions, simple structure and easy realization.
Description
Technical Field
The invention relates to the field of a metamaterial antenna housing, in particular to a metamaterial with switchable transmission/reflection and adjustable amplitude.
Background
The frequency selective surface is widely used in the fields of antenna housing, electromagnetic absorption, electromagnetic protection, etc. due to its excellent electromagnetic properties. The traditional frequency selection surface mostly adopts a passive structure, once the frequency selection surface is designed, the electromagnetic property is solidified, the dynamic regulation and control cannot be realized, and the dual requirements of the current and future equipment window materials on electromagnetic communication/detection and low scattering characteristics are difficult to meet. Therefore, it is necessary to develop a novel intelligent electromagnetic control material, and simultaneously realize high-efficiency wave-transmitting and low-electromagnetic scattering properties.
The appearance of the metamaterial opens an effective way for constructing an intelligent electromagnetic window. By introducing active devices or adopting tunable materials into the microstructure units, the electromagnetic response of the microstructure units can be dynamically regulated, and integration of multiple electromagnetic functions is realized. At present, two approaches are mainly used for realizing dynamically controllable metamaterial, one is to load lumped elements such as PIN diodes, variable capacitance diodes and the like in a metamaterial surface, and dynamically regulate and control electromagnetic characteristics by changing bias voltages of the lumped elements. Another approach is to use tunable materials such as liquid crystals, graphene, etc. Graphene is a two-dimensional carbon nanomaterial, the Fermi level of graphene is regulated and controlled by external bias voltage, the surface impedance of graphene can be changed, and a dynamically tunable absorber can be constructed. Various dynamically tunable metamaterial in the prior public reports usually focus on dynamic regulation and control of single electromagnetic characteristics (frequency, amplitude, direction and the like), and have single functions; even though some multifunctional dynamic metamaterials are available, most of the materials can only work in a single polarization state and cannot meet the application requirements of complex electromagnetic environments.
Disclosure of Invention
In order to solve the technical problems, the invention provides a transmission/reflection switchable and amplitude-adjustable metamaterial. The metamaterial mainly comprises an active frequency selective surface and a graphene capacitor layer. By controlling the on-off of the PIN diode, the dynamic switching between the transmission mode and the reflection mode can be realized, the Fermi level of the graphene is further adjusted through external bias voltage to change the sheet resistance of the graphene, and the dynamic tuning of the transmission amplitude and the reflection amplitude can also be realized.
The technical scheme adopted by the invention for solving the technical problems is as follows: a transmission/reflection switchable and amplitude-adjustable metamaterial comprises an active frequency selection surface, a microwave dielectric layer and a graphene capacitor layer from bottom to top in sequence. The active frequency selection surface is composed of a medium substrate and metal patterns printed on periodic microstructures on two sides of the medium substrate, and PIN diodes are loaded on the periodic microstructures on two sides. The microwave dielectric layer is a wave-transparent material commonly used in a microwave band, and the graphene capacitor layer is composed of a high sheet resistance film layer, an insulating dielectric layer soaked in ionic liquid and a PET substrate single-layer graphene layer. The dynamic switching between the transmission mode and the reflection mode can be realized by controlling the on-off of the PIN diode on the active frequency selection surface, the sheet resistance of the graphene can be changed by further controlling the external bias voltage of the graphene capacitor layer to adjust the Fermi energy level of the graphene, and the dynamic tuning of the transmission amplitude and the reflection amplitude can also be realized.
Wherein, the period of the bottom layer active frequency selective surface is P, and the corresponding value range is lambda0/10≤P≤λ0/2，λ0The center wavelength. The metal patterns distributed on the upper side and the lower side of the dielectric substrate are respectively placed in a 90-degree mode through a pair of T-shaped metal patches, the line width of each T-shaped metal patch is W, the value range of W is more than or equal to P/30 and less than or equal to P/2, the gap between the two T-shaped metal patches is g, and the value range of P/40 and less than or equal to g and less than or equal to P/10. The thickness of the dielectric substrate is t and the value range is lambda0/400<t<λ0/20，λ0The center wavelength. It is betweenElectric constant of epsilonsThe corresponding value range is 2-epsilons≤5。
Wherein the microwave dielectric layer is a low dielectric constant dielectric with a dielectric constant less than 4, a thickness of h and a value range of lambda0/20≤h≤λ0/2，λ0For the center wavelength, polymethacrylimide is preferred.
The graphene capacitor layer is formed by transferring a single-layer graphene layer on a PET substrate, the insulating medium is a commercial Celgard PE diaphragm, and the soaking liquid is ionic liquid, preferably DEETFSI. The sheet resistance of the high sheet resistance film layer is larger than that of a single-layer graphene layer of a PET substrate, and the value range of the sheet resistance is 3000 omega/sq-10000 omega/sq.
The invention has the beneficial effects that: the tunable metamaterial provided by the invention combines the graphene capacitor layer with the active frequency selective surface, so that not only can the dynamic switching of the two modes of wave transmission and reflection be realized, but also the dynamic regulation and control of the wave transmission amplitude and the reflection amplitude under the two modes can be realized. In addition, compared with the prior art, the metamaterial provided by the invention only adopts a small number of lumped components, is low in cost and simple to manufacture, has full-polarization electromagnetic response characteristics and angle stability, and can meet the application requirements under a complex electromagnetic environment.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic diagram of an active frequency selective surface layer structure;
fig. 3 is a S-parameter curve corresponding to the PIN diode being on and off without the graphene capacitor layer:
FIG. 4 is an S-parameter curve of a PIN diode in two states of ON and OFF
Fig. 5 is an S-parameter curve corresponding to different graphene sheet resistances in the reflection mode:
fig. 6 is an S-parameter curve corresponding to different sheet resistances of graphene in the transmission mode.
In the figure, 1 is an active frequency selective surface, 2 is a microwave dielectric layer, 3 is a high sheet resistance thin film layer, 4 is a soaking ionic liquid insulating dielectric layer, and 5 is a single-layer graphene layer of a PET substrate.
Detailed Description
The present invention will be described in detail with reference to the drawings and the detailed description, but the scope of the present invention is not limited to the following embodiments, and the present invention shall include the entire contents of the claims. And those skilled in the art will realize the full scope of the claims from a single embodiment described below.
As shown in fig. 1, a metamaterial with switchable transmission/reflection and adjustable amplitude includes an active frequency selective surface 1, a microwave dielectric layer 2 and a graphene capacitor layer from bottom to top. The graphene capacitor layer is composed of a high sheet resistance film layer 3, an insulating medium layer 4 soaked with ionic liquid and a PET substrate single-layer graphene layer 5, wherein the sheet resistance of the high sheet resistance film layer is larger than that of the substrate single-layer graphene layer, the value range of the sheet resistance is 3000 omega/sq-10000 omega/sq, the soaking liquid is ionic liquid, preferably DEETFSI, and the insulating medium is a commercial Celgard PE diaphragm. The thickness of the dielectric substrate of the active frequency selective surface is t, and the value range is lambda0/400<t<λ0/20，λ0Has a central wavelength and a dielectric constant of epsilonsThe corresponding value range is 2-epsilonsLess than or equal to 5. The microwave medium layer 2 is a low dielectric constant medium (dielectric constant less than 4), has a thickness of h and a value range of lambda0/20≤h≤λ0/2，λ0For the center wavelength, polymethacrylimide is preferred.
As shown in fig. 2, the period of the active frequency selective surface is P, and the corresponding value range is λ0/10≤P≤λ0/2，λ0The center wavelength. The metal patterns distributed on the upper side and the lower side of the dielectric substrate are respectively placed in a 90-degree mode through a pair of T-shaped metal patches, the line width of each T-shaped metal patch is W, the value range of W is more than or equal to P/30 and less than or equal to P/2, the gap between the two T-shaped metal patches is g, and the value range of P/40 and less than or equal to g and less than or equal to P/10.
Under the condition of normal incidence of electromagnetic waves, the switching between the transmission mode and the reflection mode can be realized by controlling the on-off of the PIN diode; the external bias voltage of the graphene capacitor is further adjusted to change the graphene Fermi level (the microwave frequency band shows the change of the graphene equivalent sheet resistance), and dynamic regulation and control of wave transmission and reflection amplitude in two working modes can be realized. The following is set forth in connection with specific embodiments.
Example 1
The invention designs a transmission/reflection switchable and amplitude-adjustable metamaterial. As shown in fig. 1, the structure comprises from bottom to top: the device comprises an active frequency selection surface 1, a microwave dielectric layer 2, a high sheet resistance film layer 3, an ion liquid soaking insulating dielectric layer 4 and a PET substrate single-layer graphene layer 5. As shown in fig. 2, the active frequency selective surface period is P ═ 6mm, the width of the "T" type metal patch is w ═ 0.5mm, the gap between the metal structures is g ═ 0.3mm, the selected medium is F4B, the thickness T is 0.254mm, and the corresponding dielectric constant is 2.65; the microwave dielectric layer adopts polymethacrylimide foam, and the thickness h is 10.2 mm. The insulating medium is a commercial Celgard PE diaphragm, and the infiltration liquid is ionic liquid DEMETFSI; the sheet resistance of the high sheet resistance film is 5000 omega/sq.
In order to clarify the switchable and amplitude-adjustable transmission/reflection characteristics of the metamaterial, the wave transmission and reflection coefficients of the structural material under the normal incidence condition of electromagnetic waves are simulated by using electromagnetic simulation software. In the simulation, the unit structure of the metamaterial is placed in an XY plane, boundaries are parallel to X and Y axes respectively, and electromagnetic waves propagate along a linear polarization plane of the X axis along the direction of an electric field along the + z direction. In order to reduce the amount of computation, the present invention sets periodic boundary conditions in the X and Y directions instead of full mode computation, and monitors the transmission and reflection characteristics of the electromagnetic wave using two waveguide ports. When the PIN diode is in a conducting state, the small resistor R can be equivalently formeds3 Ω and an inductor Ls0.6nH in series; when the PIN diode is in an off state, the PIN diode is equivalent to a capacitor COFF0.05pF and an inductance Ls0.6nH in series.
Fig. 3 shows S-parameter curves of the whole metamaterial when the PIN diode is in two states of on and off when the graphene electronic control layer is not loaded. As can be seen from the figure, when the PIN diode is in a conducting state, the whole material is in a total reflection state within the frequency range of 3-10 GHz; when the PIN diode is in the off state, the whole material generates a transmission peak between 6 and 7GHz, and the insertion loss is only 0.4 dB. The above structure fully illustrates the function of the underlying active frequency selective surface with the inter-switching of transmission and reflection.
Fig. 4 shows the S-parameter curve of the whole metamaterial with the PIN diode in both on and off states. As can be seen from the figure, when the PIN diode is in a conducting state and the sheet resistance of the graphene is 400 omega/sq, the metamaterial shows a strong wave-absorbing characteristic, and the whole material is almost free of reflection and transmission within a frequency band of 4.2-8.4 GHz and is completely in a full wave-absorbing state. At the central frequency point of 6.4GHz, the reflected energy and the transmitted energy are respectively about 0.05% and 2%, and nearly 97.5% of energy is absorbed by the graphene structure. When the PIN diode is in an off state and the sheet resistance of the graphene is 1600 omega/sq, a transmission peak with insertion loss of only 0.95dB appears between 6GHz and 7GHz in the whole material.
To further illustrate the tunable characteristics of the metamaterial, the wave-transmitting and reflecting characteristics of the metamaterial under different graphene sheet resistance conditions were analyzed. As shown in FIG. 5, in a reflection mode, when the sheet resistance of graphene is 400 Ω/sq, the metamaterial has good wave-absorbing performance, and S11 values are less than-10 dB in the frequency range of 4.2-8.6 GHz. With the gradual increase of the graphene sheet resistance, the S11 value becomes larger gradually, and when the graphene sheet resistance becomes 1600 omega/sq, the S11 value is larger than-5 dB in the frequency range of 3-10 GHz. Therefore, the material has dynamic adjustable performance on the absorption amplitude of the electromagnetic wave. As shown in fig. 6, in the transmission mode, when the sheet resistance of the graphene is gradually reduced from 1600 Ω/sq to 400 Ω/sq, the transmittance of the material is gradually reduced, and the insertion loss is increased from 0.95dB to 4.8dB, so that the dynamic control of the wave-transmitting amplitude in the transmission mode is realized.
Accordingly, while the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-described specific embodiments, which are merely illustrative and not restrictive. Those skilled in the art, having the benefit of this disclosure, may effect numerous modifications thereto without departing from the scope and spirit of the invention as set forth in the claims that follow. The invention has not been described in detail and is part of the common general knowledge of a person skilled in the art.
Claims (3)
1. A transmission/reflection switchable and amplitude tunable metamaterial, characterized by: the super-structure material is of a layered structure and sequentially comprises the following components from bottom to top: the active frequency selective surface consists of a medium substrate and periodic metal microstructure patterns printed on two sides of the medium substrate, PIN diodes are loaded in the metal microstructures, the microwave medium layer is a wave-transmitting material commonly used in a microwave section, the graphene capacitor layer consists of a high sheet resistance film layer, an insulating medium layer soaked with ionic liquid and a single-layer graphene layer of a PET substrate, dynamic switching of transmission and reflection modes can be realized by controlling the on-off of the PIN diodes, the Fermi level of the graphene is further adjusted by external bias to change the sheet resistance of the graphene, and dynamic tuning of transmission amplitude and reflection amplitude can also be realized;
the bottom active frequency selective surface has a period of P and a corresponding value range of lambda0/10≤P≤λ0/2，λ0The metal patterns distributed on the upper side and the lower side of the dielectric substrate are respectively placed by a pair of T-shaped metal patches at 90 degrees as a central wavelength, the line width of the T-shaped metal patches is W, the value range of the W is more than or equal to P/30 and less than or equal to P/2, the gap between the two T-shaped metal patches is g, the value range of the G is more than or equal to P/40 and less than or equal to P/10, the thickness of the dielectric substrate is T, and the value range of the T-shaped metal patches is lambda0/400<t<λ0/20，λ0Has a central wavelength and a dielectric constant of epsilonsThe corresponding value range is 2-epsilons≤5。
2. A transmissive/reflective switchable and amplitude tunable metamaterial as claimed in claim 1, wherein: the microwave dielectric layer is a low dielectric constant dielectric with a dielectric constant less than 4, a thickness of h and a value range of lambda0/20≤h≤λ0/2，λ0Is a central waveLong.
3. A transmissive/reflective switchable and amplitude tunable metamaterial as claimed in claim 1, wherein: the single-layer graphene layer with the PET substrate in the graphene capacitor layer is single-layer graphene transferred to the PET substrate, the insulating medium is a commercial Celgard PE diaphragm, the soaking liquid is ionic liquid, the sheet resistance of the high sheet resistance film layer is larger than that of the single-layer graphene layer with the substrate, and the value range of the sheet resistance film is 3000 omega/sq-10000 omega/sq.
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| CN113300112B (en) * | 2021-05-17 | 2022-05-31 | 广东福顺天际通信有限公司 | Reflecting plate and reflector with switchable working states |
| CN113644453B (en) * | 2021-07-04 | 2024-05-17 | 南京理工大学 | Broadband low-profile reconfigurable absorber for realizing reflection/wave absorption switching in X wave band |
| CN115360528B (en) * | 2022-10-24 | 2022-12-30 | 中国科学院长春光学精密机械与物理研究所 | Radar switch frequency selective surface loaded with polyaniline |
| CN117374604B (en) * | 2023-11-07 | 2024-06-04 | 中南大学 | Active frequency selective surface structure based on PIN diode |
| CN117769237A (en) * | 2023-12-29 | 2024-03-26 | 江苏赛博空间科学技术有限公司 | Electromagnetic shielding structure based on specific function |
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| US7859482B1 (en) * | 2006-09-27 | 2010-12-28 | Rockwell Collins, Inc. | Frequency selective surface waveguide switch |
| KR101161553B1 (en) * | 2009-11-28 | 2012-07-03 | 주식회사 이엠따블유 | Frequency selective surface filter and repeater antenna system for comprising the same |
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