1-bit broadband RCS reduction intelligent metasurface

Abstract

The utility model relates to a 1-bit broadband RCS reduction intelligent metasurface, which comprises a metal pattern layer, two dielectric substrate layers and a metal grounding layer which are arranged from top to bottom, the two dielectric substrate layers and the metal grounding layer are connected through a connecting glue layer, the metal pattern layer is composed of metal pattern units which are periodically arranged at equal intervals, and the metal pattern units are connected through a connecting glue layer. Each metal pattern unit is composed of two symmetrically-arranged bowl-shaped patches, a long rectangular feeder line is arranged on the adjacent side of the two patches, and the two feeder lines are connected with a PIN diode. The antenna of the utility model has the advantage that RCS reduction can be realized in a wider frequency band.

Description

Technical Field

[0001] The utility model belongs to the technical field of novel artificial electromagnetic metasurfaces, and particularly relates to a 1-bit broadband RCS reduction intelligent metasurface. Background Art

[0002] With the continuous development of radar detection technology, the demand for electromagnetic stealth technology by various electromagnetic devices, especially military devices, is getting higher and higher. In the increasingly complex battlefield electromagnetic environment, the survivability and combat effectiveness of devices such as aircraft and ships with low radar cross section (RCS) characteristics in a wide frequency band will be significantly improved. Magnetic metamaterials are novel artificial electromagnetic materials with electromagnetic properties beyond those of traditional materials. Their main body is composed of periodic or regularly arranged artificial electromagnetic elements, which can be equivalently regarded as artificial "atoms" and "molecules". When these elements are combined together, unique electromagnetic properties can be exhibited macroscopically. These properties can be used to design a variety of novel electromagnetic devices, such as negative refraction, inverse Cherenkov radiation, negative Goos-Hänchen shift, filters, polarization regulation, and so on. The initial metamaterials were all three-dimensional materials with a large thickness, and their applications were long restricted to academic research fields and were not convenient for practical applications and equipment.

[0003] In September 2011, the CAPASSO research group at Harvard University in the United States designed a two-dimensional planar electromagnetic metamaterial, namely an electromagnetic metasurface (also translated as a metasurface, a metasurface, etc.), and published it in the journal "Science". The electromagnetic metasurface is designed based on the ideas of phase mutation and polarization control and obeys the generalized Snell's law of refraction / reflection. Its thickness is generally less than the operating wavelength. This two-dimensional metamaterial has the advantages of thin size, precise processing, and easy conformal shaping, greatly enhancing its application prospects, especially in the fields of radomes and stealth skins. Compared with traditional RCS reduction technologies, the metasurface has become a research hotspot in the field of stealth technology due to its low profile, easy conformal shaping, and flexible design. Loading the RCS reduction metasurface on the outside of devices such as aircraft and ships can effectively improve their stealth performance. The reconfigurable characteristics of the electromagnetic metasurface are also very important. By introducing tunable devices into the metasurface, its electromagnetic response can be adjusted in real time according to the application scenario. In the existing research on reconfigurable stealth metasurfaces, 1-bit phase reconfigurable metasurfaces and frequency-tunable electromagnetic absorbers are the most common. How to achieve RCS reduction in a wider frequency band is still an urgent problem to be solved. Therefore, designing a reconfigurable metasurface with broadband regulation characteristics is of great significance for metasurface stealth technology. Summary of the Utility Model

[0004] The purpose of the utility model is to overcome the deficiencies of the prior art and provide a 1-bit broadband RCS reduction intelligent metasurface capable of achieving RCS reduction in a wider frequency band.

[0005] The technical solution of the utility model is as follows:

[0006] A 1-bit broadband RCS reduction smart metasurface comprises a metal pattern layer, two dielectric substrate layers and a metal grounding layer arranged from top to bottom, wherein the two dielectric substrate layers and the metal grounding layer are connected by a connecting glue layer, the metal pattern layer is composed of metal pattern units arranged periodically and evenly, the metal pattern unit is composed of two symmetrically arranged bowl-shaped patches, and a long rectangular feeder is arranged on one side adjacent to the two patches, and the two feeders are connected to a PIN diode.

[0007] Furthermore, the material of the metal pattern layer is metal.

[0008] Furthermore, the material of the dielectric substrate layer is a wave absorbing material.

[0009] Compared with the prior art, the beneficial effects of the utility model are:

[0010] 1. The utility model uses the common switch control of the diodes to provide phase changes of 0° and 180°, thereby realizing digital coding to realize dynamic control of the state of the artificial atoms inside;

[0011] 2. The utility model can adjust the resonant peak reflectivity by changing the external excitation of the PIN diode, thereby achieving a certain wave absorbing effect while realizing a reconfigurable intelligent metasurface;

[0012] 3. The utility model can achieve broadband absorption in the range of 7.3 GHz to 12.7 GHz, reduce RCS by more than 10 dB, and achieve absorption performance with a relative bandwidth of 54%.

[0013] In summary, the utility model has the advantage of achieving RCS reduction in a wider frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a metal pattern unit diagram of the utility model;

[0015] Figure 2 It is a schematic diagram of the overall structure of the utility model;

[0016] Figure 3 It is a schematic diagram of reflection values ​​in the fully cut-off, fully conductive and half conductive states of the present invention;

[0017] Figure 4 It is a phase diagram of the utility model in the fully cut-off and fully conducting state;

[0018] Figure 5 This is a schematic diagram showing the reduction of the scattering pattern of the present utility model's metamaterial compared to a metal floor at 10 GHz.

[0019] In the figure, 1 is a patch, 2 is a feeder, 3 is a dielectric substrate layer, 4 is a metal grounding layer, and 5 is an adhesive layer. Specific embodiments

[0020] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present utility model.

[0021] As Figures 1-5 shown, a 1-bit broadband RCS reduction intelligent metamaterial includes a metal pattern layer, two dielectric substrate layers 3, and a metal grounding layer 4 arranged from top to bottom. The two dielectric substrate layers 3 and the metal grounding layer 4 are connected by an adhesive layer 5. The metal pattern layer is composed of periodically equally spaced metal pattern units. Each metal pattern unit is composed of two symmetrically arranged bowl-shaped patches 1, and a long rectangular feeder 2 is arranged on one adjacent side of the two patches 1. The two feeders 2 are connected to a PIN diode;

[0022] The material of the metal pattern layer is metal, such as gold, silver, copper, or aluminum.

[0023] The material of the dielectric substrate layer 3 is an absorbing material, such as non-metallic materials like quartz glass, glass fiber, ceramic, SH260 board, foam board, PI film, Rogers RO4350B, etc.

[0024] In this embodiment, the metal pattern layer is arranged on the surface of the dielectric substrate layer 3 through a process;

[0025] When the material of the dielectric substrate layer 3 is quartz glass, the Cu Mesh process is adopted. First, the metal pattern layer is printed on a transparent flexible material such as PET material, and then the metal pattern layer is adhered to the surface of the dielectric substrate layer 3 through an adhesion process;

[0026] When the dielectric substrate is glass fiber, processes such as vacuum coating method, vapor deposition method, and hot dipping method can be used to coat the metal pattern layer on it;

[0027] If the dielectric substrate layer 3 is ceramic, various ceramic metallization processes such as the molybdenum-manganese method, gold plating method, copper plating method, tin plating method, nickel plating method, LAP method (laser post-metal plating), etc. can be used to firmly adhere a metal thin film on the ceramic surface, so as to realize the welding between the dielectric substrate layer 3 of the ceramic and the metal pattern layer;

[0028] If the dielectric substrate layer 3 is SH260 board, the metal pattern layer is etched on the surface of the dielectric substrate layer 3 by using the conventional lead-free reflow soldering process, etc.;

[0029] In this embodiment, the bowl-shaped structure of the patch 1 is formed by removing an arc section from a fan-shaped metal sheet to form a bowl-shaped structure;

[0030] The purpose of such a design is that firstly, the circular sector has a wider bandwidth and is more prone to resonance than a pure rectangular pattern. Secondly, when the parameters are changed by cutting the fan shape, as the radius of the sector increases, it is more difficult for the periodic structure to coincide with adjacent sectors, which will not cause feed interference. Cutting off a section of the sector will not have too much impact on the amplitude and phase regulation of the experimental results, etc.;

[0031] Secondly, by loading two long rectangular feed lines 2, such a design can enable the metal pattern unit to form a series circuit on the surface, which is easy to feed and realize. A PIN diode is loaded between the two feed lines 2, and by controlling the different current states of the diode, the function of amplitude and phase regulation of the unit can be realized;

[0032] Firstly, when the PIN diode is in two states of full conduction and full cut-off, experiments have found that within the broadband frequency range of 7.3 GHz - 12.7 GHz, the amplitude is less than 3 dB, and the phase difference basically remains around 180°. The phase regulation function can be well realized and can be used as a digital metasurface and a programmable metasurface in more applications;

[0033] When the diode current states are 5 μA, 10 μA, 20 μA, 50 μA..., the effect of amplitude regulation of the PIN diode on the metal pattern unit can be realized, and the amplitude can be realized to float up and down around -10 dB. In the amplitude regulation, when the amplitude < 10 dB, the unit can become a kind of absorbing material, which can be used for full-angle absorption in military and other fields. A broadband metasurface unit with adjustable amplitude and phase within a frequency band greater than the X-band (i.e., short-range fire control radar) is designed, thus realizing many advantages such as multi-path multifunctional bandwidth of the metal pattern unit and easy realization as a single-polarization unit;

[0034] In this embodiment, the metal pattern layer is formed by arranging metal pattern units at equal intervals with a specific unit period. The equal interval arrangement period T of the metal pattern layer is 0.1 - 0.5 air wavelengths at the center frequency point of the incident wave, and it satisfies the formula T = 133.3 / (-1.5d + δ) (where T is the metal pattern period, Er is the dielectric constant of the material, d is the material thickness, δ is the correction factor, and the range of δ is between ±0.1 air wavelengths at the center frequency point. δ is adjusted according to actual situations such as different material thicknesses, and all parameter units are mm).

[0035] In this embodiment, the dielectric substrate layer 3 is a single-layer or multi-layer structure, and the thickness of each layer and the interval between layers are the actual scenario dimensions. The present invention adjusts the unit structure dimensions of the metal pattern layer according to the specific dimensions of the dielectric substrate layer 3;

[0036] In this embodiment, the bonding layer 5 is a common glue commonly used for inter-layer connection of dielectrics, such as Rogers RO4450F.

[0037] The metal pattern layer is designed based on the principle related to frequency selective surface, and is formed by arranging metal pattern units at equal intervals with a specific unit period. The symmetric bowl-shaped patch 1 is selected as the structural unit of the metasurface, and a PIN diode is loaded in the middle of the bowl-shaped patch 1;

[0038] In addition, this design uses the surface feeding form to provide the required bias for the PIN diode, which also results in a simple circuit that is easy to implement and has wide frequency tuning. Through the control of this PIN diode switch, a phase difference of 180° can be obtained between the on state and the off state. By using this unit to achieve the effect of phase "0" and "1" coding, a smart programmable metasurface can be further realized, which can realize real-time coding, beam control, diffuse scattering and other multi-functional electromagnetic manipulation means on the array surface by controlling the state of the PIN diode through FPGA, and realize digital coding to dynamically control the state of artificial atoms inside;

[0039] The specific implementation steps and results are as follows: in the frequency band range of 7.3 GHz - 12.7 GHz, when all PIN diodes are in the conducting state, the reflection phase of the metal pattern unit is 180°, and when all PIN diodes are in the cut-off state, the reflection phase of the metal pattern unit is 0°. The RCS reduction of the phase modulation type metasurface is based on the principle of dispersing electromagnetic wave energy to other angular domains, and it is impossible to achieve RCS reduction in the whole space. The absorbing type electromagnetic metasurface realizes RCS reduction by absorbing the energy of the incident wave, so it can effectively solve the above problems;

[0040] The electromagnetic response of the unit is regulated by adjusting the PIN diodes on the metal pattern unit. Different from the phase regulation where the PIN diodes operate in two states of full conduction and full disconnection, when regulating the scattering amplitude, the PIN diodes operate in a state from full conduction to slightly conduction, and are characterized by the bias current during their operation. When performing phase regulation, the resonant frequency of the metal pattern unit is adjusted by changing the equivalent impedance of the PIN diodes, thereby achieving phase regulation. The mechanism of amplitude regulation is different. Between the full conduction and slightly conduction states of the PIN diodes, the main parameter that changes is the equivalent resistance value. That is to say, by adjusting its equivalent resistance value, the absorption degree of the incident electromagnetic wave is adjusted, and thus the dynamic regulation of the reflection amplitude of the unit is achieved;

[0041] By switching the current state of the PIN diodes mounted on the surface of patch 1, the amplitude of the unit is controlled, achieving a multifunctional intelligent metasurface with both amplitude and phase adjustable. By changing the relevant equivalent capacitance, equivalent inductance, and equivalent resistance of the equivalent circuit on the surface of patch 1, the resonant point position is controlled according to the resonant frequency point. When all PIN diodes are simultaneously set to a non-fully-conducted state of the conduction current, the PIN diodes exhibit a great resistance, causing the metal pattern unit to exhibit a strong absorption state when excited by a plane wave. In the frequency band range of 7.3 GHz - 12.7 GHz, the reflection amplitude of the unit is less than -10 dB;

[0042] By synchronously switching the current states of all PIN diodes, the metal pattern unit respectively demonstrates a strong wave-absorbing state and a group of 1-bit phase regulation states that satisfy the reflection phase error within ±30° and the reflection amplitude error within 1 dB. At the same time, a feeding network design using a perforated bottom-loaded metal wire for the structure is proposed, which can not only achieve the regulation effect of unit control, but also will not affect the polarization effect of the unit, effectively maintaining the independence of the unit. The wave absorber has excellent performance and a wide wave-absorbing bandwidth, achieving broadband wave absorption in the range of 7.3 GHz - 12.7 GHz and a wave-absorbing performance with a relative bandwidth of 54%;

[0043] Although the present utility model has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A 1-bit broadband RCS reduction smart metasurface, characterized by: It includes a metal pattern layer, two dielectric substrate layers and a metal grounding layer arranged from top to bottom. The two dielectric substrate layers and the metal grounding layer are connected by a connecting glue layer. The metal pattern layer is composed of metal pattern units arranged periodically and evenly. The metal pattern unit is composed of two symmetrically arranged bowl-shaped patches, and a long rectangular feeder is arranged on one side adjacent to the two patches. The two feeders are connected to a PIN diode.

2. The 1-bit broadband RCS reduction smart metasurface according to claim 1, characterized in that: The material of the metal pattern layer is metal.

3. The 1-bit broadband RCS reduction smart metasurface according to claim 1, characterized in that: The material of the dielectric substrate layer is a wave absorbing material.

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