Electromagnetic wave stealth device and preparation method thereof

Abstract

The present invention provides an electromagnetic wave stealth device and a preparation method, which relate to the field of electromagnetic wave stealth technology. The device includes a lossy metasurface, a gain metasurface and a three-dimensional photonic crystal. The three-dimensional photonic crystal is in the form of a cuboid. The lossy metasurface and the gain metasurface are arranged on two surfaces of the three-dimensional photonic crystal relative to each other. The surface admittances of the lossy metasurface and the gain metasurface satisfy an inverse relationship. The energy band edge of the three-dimensional photonic crystal is within the electromagnetic wave frequency range. The stealth effect of the device of the present invention is unidirectional, that is, it has stealth characteristics only for electromagnetic waves incident from one side of the lossy metasurface. The stealth electromagnetic wave frequency of the device of the present invention is tunable and can adapt to changes in different environments and needs. The frequency of the stealth electromagnetic wave can be changed by changing the structural size of the three-dimensional photonic crystal.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic wave stealth, and in particular to an electromagnetic wave stealth device and a preparation method thereof. Background Art

[0002] Electromagnetic stealth technology has always been a hot topic in military and civilian research. Its core goal is to reduce the detectability of the stealthed object, thereby avoiding enemy detection equipment or improving the confidentiality of civilian equipment. With the continuous development of science and technology, electromagnetic stealth technology has also gone through multiple stages of evolution, but there are still many challenges and limitations.

[0003] Traditional electromagnetic wave stealth methods mainly include wave absorption or directional scattering stealth, making objects transparent to the observer, and mimicry stealth. Although these methods can achieve stealth effects to a certain extent, each has obvious shortcomings. Wave absorption or directional scattering stealth technology reduces the scattered energy received by the detector by absorbing electromagnetic waves or adjusting the radar scattering cross section of the object. When there is no background field in space or the background field is not ignored as a measurement object, this method has a certain effect, but in a complex background, the stealth effect may be greatly reduced, and may even be accelerated due to the interference of background information.

[0004] The invisibility method that makes an object transparent to the observer is to suppress the scattering of the object so that the detection wave is neither scattered nor absorbed in any direction. Although this perfect invisibility in the physical sense is very attractive, it has extremely stringent requirements on the electromagnetic parameters of the material, is extremely difficult to achieve in practice, and is difficult to be widely used in reality.

[0005] Mimicry stealth is achieved by adjusting the scattered light of an object to make it similar to the background environment, so that it blends into the background and becomes invisible. However, the stealth effect of this method is heavily dependent on the specific background environment. Once the background environment changes, the stealth effect will be greatly reduced, so its application scenarios are relatively limited.

[0006] In summary, although the development of electromagnetic wave stealth technology has achieved certain results, it still faces many challenges, especially the limitations in achieving unidirectional electromagnetic wave stealth and tunability. Therefore, it is necessary to propose a new electromagnetic wave stealth device. Summary of the invention

[0007] To this end, an embodiment of the present invention provides an electromagnetic wave stealth device and a preparation method, which are used to solve the problem that the prior art cannot achieve unidirectional electromagnetic wave stealth, that is, stealth for electromagnetic waves incident in a specific direction, and generally has no tunability.

[0008] In order to solve the above problems, an embodiment of the present invention provides an electromagnetic wave cloaking device, which includes a lossy metasurface, a gain metasurface and a three-dimensional photonic crystal, wherein the three-dimensional photonic crystal is a rectangular parallelepiped, and the lossy metasurface and the gain metasurface are arranged on two surfaces of the three-dimensional photonic crystal opposite to each other;

[0009] The surface admittances of the loss metasurface and the gain metasurface satisfy an inverse relationship;

[0010] The energy band edge of the three-dimensional photonic crystal is located within the frequency range of electromagnetic waves.

[0011] In one embodiment of the present invention, the three-dimensional photonic crystal is composed of a plurality of dielectric spheres arranged in a cubic lattice.

[0012] In one embodiment of the present invention, the radius r of the dielectric sphere ranges from 0.01a to 0.5a, where a is the lattice constant of the cubic lattice.

[0013] In one embodiment of the present invention, the lattice constant a of the cubic lattice has a value range of 0.01 mm-1 m.

[0014] In one embodiment of the present invention, the relative dielectric constant ε of the dielectric sphere is r The value range is 2–50.

[0015] In one embodiment of the present invention, the thickness of the loss metasurface and the gain metasurface are both less than one percent of the operating wavelength, where the operating wavelength refers to the wavelength of the incident electromagnetic wave.

[0016] In one embodiment of the present invention, the absolute value of the surface admittance of the loss metasurface and the gain metasurface is 0.9Y0-Y0, where Y0 is the vacuum admittance, Y0=0.00265S, and S is the unit of admittance, Siemens.

[0017] The embodiment of the present invention also provides a method for preparing an electromagnetic wave stealth device, the method comprising:

[0018] Constructing a three-dimensional photonic crystal so that the energy band edge of the three-dimensional photonic crystal is within the frequency range of electromagnetic waves, wherein the three-dimensional photonic crystal is in the shape of a cuboid;

[0019] Manufacturing a loss metasurface and a gain metasurface so that the surface admittances of the loss metasurface and the gain metasurface satisfy an inverse relationship;

[0020] The manufactured loss metasurface and gain metasurface are arranged opposite to each other on two surfaces of the three-dimensional photonic crystal to complete the preparation of the electromagnetic wave stealth device.

[0021] In one embodiment of the present invention, the method of constructing a three-dimensional photonic crystal so that the energy band edge of the three-dimensional photonic crystal is within the frequency range of electromagnetic waves, wherein the three-dimensional photonic crystal is in the shape of a cuboid, is:

[0022] Arrange multiple dielectric spheres in a cubic lattice to obtain a three-dimensional photonic crystal in the form of a rectangular parallelepiped, and make the energy band edge of the three-dimensional photonic crystal be within the frequency range of electromagnetic waves, the radius r of the dielectric sphere ranges from 0.01a to 0.5a, and the relative dielectric constant ε of the dielectric sphere is r The value range is 2–50, where a is the lattice constant of the cubic lattice and the value range is 0.01mm-1m.

[0023] In one embodiment of the present invention, the method of manufacturing the loss metasurface and the gain metasurface so that the surface admittances of the loss metasurface and the gain metasurface satisfy an inverse relationship is:

[0024] A loss metasurface and a gain metasurface are manufactured so that the surface admittances of the loss metasurface and the gain metasurface satisfy an inverse relationship, and the thicknesses of the loss metasurface and the gain metasurface are both less than one percent of an operating wavelength, wherein the operating wavelength refers to the wavelength of an incident electromagnetic wave, and the absolute value of the surface admittances of the loss metasurface and the gain metasurface is 0.9Y0-Y0, wherein Y0 is a vacuum admittance, Y0=0.00265S, and S is the unit of admittance, Siemens.

[0025] It can be seen from the above technical solutions that the present invention has the following beneficial effects:

[0026] The embodiment of the present invention provides an electromagnetic wave stealth device and a preparation method. The device of the present invention can achieve electromagnetic wave stealth for an object placed in the center of a three-dimensional photonic crystal, and the stealth effect is independent of the material of the stealthed object. The stealth effect of the device of the present invention is unidirectional, that is, it only has stealth characteristics for electromagnetic waves incident from one side of the lossy metasurface. At this time, the electromagnetic wave reflection is about 0, the transmittance is close to 1, and the outgoing wave maintains a straight wavefront. The stealth electromagnetic wave frequency of the device of the present invention is tunable and can adapt to changes in different environments and needs. The frequency of the stealth electromagnetic wave can be changed by changing the structural size of the three-dimensional photonic crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the implementation cases of the present invention or the technical solutions in the prior art, the following is a brief description of the drawings required for use in the embodiments. By referring to the drawings, the features and advantages of the present invention will be more clearly understood. The drawings are schematic and should not be understood as limiting the present invention in any way. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0028] Figure 1 A schematic diagram of the structure of an electromagnetic wave stealth device provided in an embodiment;

[0029] Figure 2 The three-dimensional photonic crystal band diagram in the embodiment;

[0030] Figure 3 This is a simulation diagram of the electromagnetic wave stealth effect when the cloaked object is a metal block at the center in the embodiment;

[0031] Figure 4 This is a simulation diagram of the electromagnetic wave stealth effect when the dielectric block is centered on the cloaked object in the embodiment;

[0032] Figure 5 This is a flow chart of a method for preparing an electromagnetic wave stealth device provided in an embodiment.

[0033] Figure numerals in the specification: 1. three-dimensional photonic crystal; 11. dielectric sphere; 2. loss metasurface; 3. gain metasurface; 4. invisible object. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Embodiment 1

[0036] In order to solve the problem that the existing technology cannot achieve unidirectional electromagnetic wave stealth, that is, stealth for electromagnetic waves incident from a specific direction, and generally has no tunability. Figure 1 As shown, an embodiment of the present invention provides an electromagnetic wave stealth device, which includes a lossy metasurface 2, a gain metasurface 3, and a three-dimensional photonic crystal 1. The three-dimensional photonic crystal 1 is a rectangular parallelepiped, and the lossy metasurface 2 and the gain metasurface 3 are relatively arranged on two surfaces of the three-dimensional photonic crystal 1;

[0037] The surface admittances of the loss metasurface 2 and the gain metasurface 3 satisfy an inverse relationship;

[0038] The energy band edge of the three-dimensional photonic crystal 1 is located within the frequency range of electromagnetic waves.

[0039] It can be seen from the above technical scheme that the present invention proposes an electromagnetic wave stealth device, including a lossy metasurface, a gain metasurface and a three-dimensional photonic crystal, wherein the lossy metasurface and the gain metasurface are relatively arranged on the two sides of the three-dimensional photonic crystal, and the surface admittances of the lossy metasurface and the gain metasurface satisfy an inverse relationship, and the energy band edge of the three-dimensional photonic crystal is within the electromagnetic wave frequency range. The device of the present invention can achieve electromagnetic wave stealth for an object placed in the center of the three-dimensional photonic crystal, and the stealth effect has nothing to do with the material of the stealthed object. The stealth effect of the device of the present invention is unidirectional, that is, it only has stealth characteristics for electromagnetic waves incident from one side of the lossy metasurface. At this time, the electromagnetic wave reflection is about 0, the transmittance is close to 1, and the outgoing wave maintains a straight wavefront. The stealth electromagnetic wave frequency of the device of the present invention is tunable and can adapt to changes in different environments and needs. The frequency of the stealth electromagnetic wave can be changed by changing the structural size of the three-dimensional photonic crystal.

[0040] In this embodiment, the present invention designs an electromagnetic wave stealth device that combines a loss surface 2, a gain metasurface 3 and a three-dimensional photonic crystal 1, such as Figure 1 The loss metasurface 2 and the gain metasurface 3 are arranged on two sides of the three-dimensional photonic crystal 1, that is, attached to the left and right sides of the three-dimensional photonic crystal 1 respectively.

[0041] Specifically, the thickness of the lossy metasurface 2 and the gain metasurface 3 are both less than one percent of the working wavelength, where the working wavelength refers to the wavelength of the incident electromagnetic wave. In addition, the surface admittance of the lossy metasurface 2 is Y s , the surface admittance of the gain metasurface 3 is its opposite, i.e. -Y s .

[0042] Furthermore, the absolute value of the surface admittance of the loss metasurface 2 and the gain metasurface 3 is 0.9Y0-Y0, where Y0 is the vacuum admittance, Y0=0.00265S, and S is the unit of admittance, Siemens.

[0043] In this embodiment, the three-dimensional photonic crystal 1 is composed of a plurality of dielectric spheres 11 arranged in a cubic lattice.

[0044] Specifically, the radius r of the dielectric sphere 11 ranges from 0.01a to 0.5a, where a is the lattice constant of the cubic lattice and ranges from 0.01mm to 1m. The relative dielectric constant ε of the dielectric sphere 11 is r The value range is 2–50.

[0045] Placing the invisible object 4 at the center of the three-dimensional photonic crystal 1 can achieve electromagnetic wave invisibility, and the invisibility effect is independent of the material of the invisible object 4 .

[0046] Without the metasurfaces (loss metasurface 2 and gain metasurface 3) and the three-dimensional photonic crystal 1, the central cloaked object 4 will strongly scatter the incident electromagnetic waves, making them easily detected. Under appropriate parameters, the device can achieve one-way cloaking of electromagnetic waves, that is, electromagnetic waves incident from the left can pass through the entire device without reflection and maintain a complete flat wave front without being affected by the central PEC object.

[0047] In summary, the surface admittance Y of the metasurface is s The parameter requirements are: slightly less than Y0, that is, 0.9Y0-Y0; and the requirement for the three-dimensional photonic crystal 1 is that the band edge of its energy band is located at the electromagnetic wave frequency, by changing the radius r of the dielectric sphere 11 in the three-dimensional photonic crystal 1, the relative dielectric constant ε r , the lattice constant a of the cubic lattice can satisfy this condition.

[0048] In order to further illustrate the advantages of the present invention, Figures 2 to 4 To elaborate.

[0049] First, the three-dimensional photonic crystal 1 is designed, the lattice constant a is 12.8 mm, the radius r of the dielectric sphere 11 is 0.3a, and the dielectric constant ε r is 30. Figure 2 The energy band diagram of the three-dimensional photonic crystal along the ΓX direction is given. It can be seen that at the Γ point, the third energy band in the diagram (the topmost in the diagram) is located at a frequency of 9.915 GHz. At this time, the three-dimensional photonic crystal 1 can be regarded as an equivalent dielectric constant near-zero material, that is, its equivalent dielectric constant is close to zero.

[0050] Secondly, the super surface is optimized according to the electromagnetic parameters of the three-dimensional photonic crystal 1, and the thickness of the super surface is taken as the wavelength of the electromagnetic wave. The absolute value of the surface admittance Ys is 0.968Y0. At this time, the surface admittance of the loss metasurface 2 on the left is 0.968Y0, while the surface admittance of the gain metasurface 3 on the right is -0.968Y0.

[0051] Figure 3 The simulation results using numerical software Comsol Multiphysics are given. A plane electromagnetic wave with a frequency of 9.915 GHz is incident from the air end on the left. The three-dimensional photonic crystal 1 in the middle area is composed of 3×3 dielectric spheres 11, with a loss metasurface 2 on the left and a gain metasurface 3 on the right. The center is a metal cube as the cloaked object 4. The simulation results show that the reflectivity of the electromagnetic wave is about 0, the transmittance is close to 1, and the outgoing electromagnetic wave maintains a flat wavefront, which indicates that the device has good electromagnetic wave cloaking properties.

[0052] It should be pointed out that the stealth effect of the device has nothing to do with the material of the central invisible object, that is, electromagnetic wave stealth can be achieved for any object. Figure 4 Another example is given, where the central cloaked object 4 is a dielectric block (relative dielectric constant is 30). The results show that the device still has a very good electromagnetic wave cloaking effect.

[0053] Embodiment 2

[0054] like Figure 5 As shown, the present invention provides a method for preparing an electromagnetic wave cloaking device, the system is used to prepare the electromagnetic wave cloaking device of the above-mentioned embodiment 1, specifically comprising:

[0055] Constructing a three-dimensional photonic crystal so that the energy band edge of the three-dimensional photonic crystal is within the frequency range of electromagnetic waves, wherein the three-dimensional photonic crystal is in the shape of a cuboid;

[0056] Manufacturing a loss metasurface and a gain metasurface so that the surface admittances of the loss metasurface and the gain metasurface satisfy an inverse relationship;

[0057] The manufactured loss metasurface and gain metasurface are arranged opposite to each other on two surfaces of the three-dimensional photonic crystal to complete the preparation of the electromagnetic wave stealth device.

[0058] In this embodiment, a method for constructing a three-dimensional photonic crystal 1 such that the energy band edge of the three-dimensional photonic crystal 1 is within the frequency range of electromagnetic waves, wherein the three-dimensional photonic crystal 1 is a rectangular parallelepiped is as follows:

[0059] Arrange multiple dielectric spheres 11 in a cubic lattice to obtain a three-dimensional photonic crystal 1 in the form of a rectangular parallelepiped, and make the energy band edge of the three-dimensional photonic crystal 1 within the frequency range of electromagnetic waves. The radius r of the dielectric sphere 11 ranges from 0.01a to 0.5a, and the relative dielectric constant ε of the dielectric sphere 11 is r The value range is 2–50, where a is the lattice constant of the cubic lattice and the value range is 0.01mm-1m.

[0060] In this embodiment, the method for making the loss metasurface 2 and the gain metasurface 3 so that the surface admittances of the loss metasurface 2 and the gain metasurface 3 satisfy the inverse relationship is:

[0061] A loss metasurface 2 and a gain metasurface 3 are manufactured so that the surface admittances of the loss metasurface 2 and the gain metasurface 3 satisfy an inverse relationship, and the thicknesses of the loss metasurface 2 and the gain metasurface 3 are both less than one percent of an operating wavelength, where the operating wavelength refers to the wavelength of an incident electromagnetic wave. The absolute value of the surface admittances of the loss metasurface 2 and the gain metasurface 3 is 0.9Y0-Y0, where Y0 is the vacuum admittance, Y0=0.00265S, and S is the unit of admittance, Siemens.

[0062] The present embodiment provides a method for preparing an electromagnetic wave cloaking device, which is used to prepare the aforementioned electromagnetic wave cloaking device. Therefore, the specific implementation method of the method for preparing the electromagnetic wave cloaking device can be found in the embodiment section of the electromagnetic wave cloaking device in the previous text. In order to avoid redundancy, it will not be repeated here.

[0063] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. An electromagnetic wave stealth device, characterized in that: It includes a loss metasurface, a gain metasurface and a three-dimensional photonic crystal, wherein the three-dimensional photonic crystal is in the form of a cuboid, and the loss metasurface and the gain metasurface are arranged on two surfaces of the three-dimensional photonic crystal opposite to each other; The surface admittances of the loss metasurface and the gain metasurface satisfy an inverse relationship; The energy band edge of the three-dimensional photonic crystal is located within the frequency range of electromagnetic waves.

2. The electromagnetic wave cloaking device according to claim 1, characterized in that: The three-dimensional photonic crystal is composed of a plurality of dielectric spheres arranged in a cubic lattice.

3. The electromagnetic wave cloaking device according to claim 2, characterized in that: The radius r of the dielectric sphere ranges from 0.01a to 0.5a, where a is the lattice constant of the cubic lattice.

4. The electromagnetic wave cloaking device according to claim 3, characterized in that: The lattice constant a of the cubic lattice has a value range of 0.01 mm to 1 m.

5. The electromagnetic wave cloaking device according to claim 2, characterized in that: The relative dielectric constant ε of the dielectric sphere r The value range is 2–50.

6. The electromagnetic wave cloaking device according to claim 1, characterized in that: The thickness of the loss metasurface and the gain metasurface are both less than one percent of the operating wavelength, where the operating wavelength refers to the wavelength of the incident electromagnetic wave.

7. The electromagnetic wave cloaking device according to claim 1, characterized in that: The absolute value of the surface admittance of the loss metasurface and the gain metasurface is 0.9Y0-Y0, where Y0 is the vacuum admittance, Y0=0.00265S, and S is the unit of admittance, Siemens.

8. A method for preparing an electromagnetic wave stealth device, characterized in that: include: Constructing a three-dimensional photonic crystal so that the energy band edge of the three-dimensional photonic crystal is within the frequency range of electromagnetic waves, wherein the three-dimensional photonic crystal is in the shape of a cuboid; Manufacturing a loss metasurface and a gain metasurface so that the surface admittances of the loss metasurface and the gain metasurface satisfy an inverse relationship; The manufactured loss metasurface and gain metasurface are arranged opposite to each other on two surfaces of the three-dimensional photonic crystal to complete the preparation of the electromagnetic wave stealth device.

9. The method for preparing an electromagnetic wave stealth device according to claim 8, characterized in that: The method of constructing a three-dimensional photonic crystal so that the energy band edge of the three-dimensional photonic crystal is within the frequency range of electromagnetic waves, wherein the three-dimensional photonic crystal is in the form of a rectangular parallelepiped, is: Arrange multiple dielectric spheres in a cubic lattice to obtain a three-dimensional photonic crystal in the form of a rectangular parallelepiped, and make the energy band edge of the three-dimensional photonic crystal be within the frequency range of electromagnetic waves, the radius r of the dielectric sphere ranges from 0.01a to 0.5a, and the relative dielectric constant ε of the dielectric sphere is r The value range is 2–50, where a is the lattice constant of the cubic lattice and the value range is 0.01mm-1m.

10. The method for preparing an electromagnetic wave stealth device according to claim 8, characterized in that: The method for manufacturing the loss metasurface and the gain metasurface so that the surface admittances of the loss metasurface and the gain metasurface satisfy an inverse relationship is: A loss metasurface and a gain metasurface are manufactured so that the surface admittances of the loss metasurface and the gain metasurface satisfy an inverse relationship, and the thicknesses of the loss metasurface and the gain metasurface are both less than one percent of an operating wavelength, wherein the operating wavelength refers to the wavelength of an incident electromagnetic wave, and the absolute value of the surface admittances of the loss metasurface and the gain metasurface is 0.9Y0-Y0, wherein Y0 is a vacuum admittance, Y0=0.00265S, and S is the unit of admittance, Siemens.

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