A three-dimensional space circuit for an electromagnetic stealth cloak, an electromagnetic stealth cloak, and a processing method thereof

Abstract

The present invention discloses a three-dimensional space circuit for an electromagnetic stealth cloak, an electromagnetic stealth cloak and a processing method thereof. The receiving end receives electromagnetic waves and transmits them to the feedback end through a cascaded first-stage transmission circuit, a second-stage transmission circuit and a third-stage transmission circuit respectively for feedback, so that the propagation of the electromagnetic waves is not affected by the shielding of an object and is not changed. The present invention can reduce the space occupied by the electromagnetic stealth cloak and achieve better stealth effect, and improve the signal reception efficiency; only different sizes are required for different antennas to achieve stealth, improving the versatility; for antenna components of different lengths, the structure can be assembled in multiple cycles to achieve electromagnetic stealth, greatly reducing the processing and assembly difficulty.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic stealth cloaks, and particularly relates to a three-dimensional space circuit for an electromagnetic stealth cloak, an electromagnetic stealth cloak, and a processing method thereof. Background Art

[0002] With the rapid development of radar and antenna technologies, electromagnetic stealth technology has been increasingly applied to the military field and daily life.

[0003] Electromagnetic stealth refers to the ability to make an object in an electromagnetic wave invisible and not be detected. An electromagnetic stealth cloak is a substance wrapped on the surface of an object. By reducing the reflection and scattering of electromagnetic waves, the propagation of electromagnetic waves is not affected by the object and is changed, so that it cannot be detected by detection devices. Therefore, electromagnetic stealth cloaks have wide applications in the military field, medical imaging, and communication fields.

[0004] Traditional electromagnetic stealth cloaks include:

[0005] 1. Realized based on metamaterials through an optical transformation method. By wrapping an object with metamaterials, electromagnetic waves propagate near the metamaterials, avoiding the interaction between the object and electromagnetic waves, and achieving the stealth effect. This requires thick and anisotropic inhomogeneous artificial metamaterials. Therefore, this cloak not only has a large thickness, a single stealth frequency, but also has a high material cost.

[0006] 2. A plasma cloak realized by using dielectric scattering cancellation. By introducing a dielectric to generate overall cancellation interference on the scattered electromagnetic waves, the scattering is significantly reduced, thereby achieving the effect of electromagnetic stealth. This method effectively reduces the thickness, but can only achieve stealth in a very narrow frequency band, and it is required that the object material and the thin metasurface material constituting the cloak are completely reciprocal.

[0007] In the Chinese patent with the publication number CN117786983A, a design method for a double-layer structured static magnetic field stealth cloak is mentioned. The electromagnetic stealth cloak is obtained through the following steps: 1) Solve the Laplace equation to obtain the size and permeability relationship between the layers of the static magnetic stealth cloak; 2) Determine the size parameters and material properties of the ideal static magnetic stealth cloak; 3) Determine the discretization degree and discretize the circular cloak into unit cells; 4) Use the S-parameter inversion method to obtain the relationship between the unit cell configuration and the equivalent permeability; 5) Assemble the unit cells with the equivalent permeability equal to the required permeability of the ideal cloak into a complete static magnetic stealth cloak. This invention obtains the size and property requirements of the stealth cloak by solving the Laplace equation under the stealth boundary conditions, getting rid of the strict property requirements of the transformation optics design theory.

[0008] The existing research methods of electromagnetic stealth cloaks are relatively complex and are basically analyzed and designed from the perspective of electromagnetic fields. After the structure of the electromagnetic cloak is known and analyzed, when a fixed electromagnetic stealth cloak is designed according to this method, it is impossible to flexibly adjust the electromagnetic stealth effect when the stealth object changes. Therefore, compared with the previous analysis of electromagnetic fields, the three-dimensional space circuit of the electromagnetic stealth cloak analyzes its electromagnetic stealth effect from the circuit perspective. By changing the circuit elements and then changing its specific structure to achieve stealth has greater advantages. When receiving an antenna signal, due to the shielding of electromagnetic waves by metal components, the quality of the received signal is weakened, affecting the communication efficiency. Therefore, it is necessary to stealth the metal components to improve the antenna reception efficiency. Summary of the Invention

[0009] The purpose of the present invention is to propose a three-dimensional space circuit for an electromagnetic stealth cloak, an electromagnetic stealth cloak and its processing method. Based on its ultra-thin and wide-band characteristics, it reduces the space occupation in the antenna component and has a good stealth effect, improving the signal reception efficiency; this structure can achieve different stealth effects only by changing the size parameters. Therefore, different sizes are only needed in different antennas to achieve stealth, improving the versatility; in addition, for antenna components of different lengths, this structure can be assembled in multiple cycles to achieve electromagnetic stealth, greatly reducing the processing and assembly difficulty.

[0010] To achieve the above technical objectives, the technical solutions adopted by the present invention are as follows:

[0011] In the first aspect, the present invention discloses a three-dimensional space circuit of an electromagnetic stealth cloak. The three-dimensional space circuit is a two-wire two-port transmission line network. The two ports are a receiving end and a feedback end respectively, and the two wires are a transmission line and a ground wire respectively; a first-stage transmission circuit, a second-stage transmission circuit and a third-stage transmission circuit are sequentially arranged between the receiving end and the feedback end;

[0012] The first-stage transmission circuit includes a first capacitor C1 between the transmission line and the ground wire;

[0013] The second-stage transmission circuit includes a first transmission line impedance Z1 connected in series and a short-circuit load between the transmission line and the ground wire;

[0014] The third-stage transmission circuit includes a second transmission line impedance Z s , a third transmission line impedance Z2, a second capacitor C2, and an air characteristic impedance Z0. Among them, the third transmission line impedance Z2 and the second capacitor C2 are both connected between the feedback end and the ground, and are symmetrically structured with the first transmission line impedance Z1 and the first capacitor C1; the second transmission line impedance Z sConnected between the receiving end and the feedback end, the air characteristic impedance Z0 is connected between the transmission line and the ground wire and is adjacent to the feedback end; the load composed of the third transmission line impedance Z2, the second capacitor C2, and the air characteristic impedance Z0 forms a terminally loaded transmission line.

[0015] The receiving end receives electromagnetic waves and transmits them to the feedback end through the cascaded first-stage transmission circuit, second-stage transmission circuit, and third-stage transmission circuit respectively, so that the propagation of electromagnetic waves is not affected by the shielding of objects.

[0016] Further, the equivalent input impedance of the first-stage transmission circuit is:

[0017] ;

[0018] In the formula, is the capacitance value of the first capacitor C1, is the angular frequency.

[0019] Further, the equivalent input impedance of the second-stage transmission circuit is:

[0020] ;

[0021] Where , , is the first transmission line impedance is the transmission length, is the relative dielectric constant of the material, is the electromagnetic wave wavelength, is the electromagnetic wave frequency, is the air characteristic impedance.

[0022] Further, the equivalent input impedance of the third-stage transmission circuit is:

[0023] ;

[0024] Where, , is the air characteristic impedance, is the equivalent characteristic impedance of the slot line, is the load impedance of the first-stage transmission loop.

[0025] Further, the equivalent input impedance of the three-dimensional space circuit is:

[0026] ;

[0027] In the formula, , and They are the equivalent input impedances of the first-stage transmission circuit, the second-stage transmission circuit, and the third-stage transmission circuit, respectively.

[0028] Furthermore, the electromagnetic stealth cloak adjusts the reflection coefficient by changing the circuit element parameters :

[0029] ;

[0030] In the formula, is the voltage reflection coefficient.

[0031] In a second aspect, the present invention discloses an electromagnetic stealth cloak based on the aforementioned three-dimensional space circuit. The electromagnetic stealth cloak includes a first wrapping medium, a second wrapping medium, and a plurality of metal cloaks;

[0032] The plurality of metal cloaks are sequentially sleeved outside the stealth object, and there is a cloak gap between adjacent metal cloaks;

[0033] The upper surface of the metal cloak serves as the receiving end, and the gap capacitance between the upper surfaces of adjacent metal cloaks is equivalent to the first capacitor; the lower surface of the metal cloak serves as the feedback end, and the gap capacitance between the lower surfaces of adjacent metal cloaks is equivalent to the second capacitor; the slot line between the sides of adjacent metal cloaks is equivalent to the second transmission line impedance Z s ;

[0034] The first wrapping medium is filled between the upper surface of the metal cloak and the stealth object, and is equivalent to the first transmission line impedance Z1; the second wrapping medium is filled between the lower surface of the metal cloak and the stealth object, and is equivalent to the third transmission line Z2; the free space outside the lower surface of the metal cloak is equivalent to the air characteristic impedance Z0.

[0035] In a third aspect, the present invention discloses a processing method for an electromagnetic stealth cloak. The processing method includes the following steps:

[0036] Split all the structural components of the electromagnetic stealth cloak into electroplated copper units and units without electroplated copper, and perform overall electroplating on the electroplated copper units;

[0037] Use a CNC machine to process the first wrapping medium and the second wrapping medium;

[0038] Stack all the structural components in an alternating manner, and apply external pressure to fully compress them to obtain the electromagnetic stealth cloak.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] First, the three-dimensional space circuit for an electromagnetic stealth cloak, the electromagnetic stealth cloak, and its manufacturing method according to the present invention change from the perspective of traditional electromagnetic fields to the perspective of circuits. Due to the complex nature of electromagnetic fields themselves, the research on electromagnetic fields is often relatively complex, while the analysis of a simplified circuit model is much simpler, which greatly reduces the complexity of the design of the electromagnetic stealth cloak. In addition, in specific applications, since the requirements for stealth are different in different scenarios and the effect of the cloak needs to be changed, the reflection coefficient of the microwave circuit can be changed only by adjusting the parameters of the circuit components, thereby changing the stealth effect. The specific three-dimensional space structure of the circuit is realized by the equivalent circuit method. When changing the parameters, only the structural size parameters of the electromagnetic stealth cloak need to be changed to achieve the adjustment of stealth. Thus, it can adapt to different scenarios and requirements, and improve the applicable range of the cloak.

[0041] Second, the three-dimensional space circuit for an electromagnetic stealth cloak, the electromagnetic stealth cloak, and its manufacturing method according to the present invention not only reduce the difficulty of realizing the stealth cloak, but also, compared with the method of realizing stealth with traditional materials, this structure realizes stealth only through its own geometric structure, making the processing and realization of this cloak simpler and more efficient. Moreover, compared with the high cost of metamaterials, this structure has a low cost, providing the necessary conditions for mass production and use. In addition, the thickness of the metal cloak in this structure is greatly reduced, improving the flexibility and adaptability of the cloak in practical applications, while also reducing the weight of the cloak, providing the possibility of stealth for some objects that need to be stealthy under special conditions. In addition, the stealth bandwidth achieved by this structure is relatively large, capable of covering electromagnetic waves in a relatively wide frequency band, improving the stealth effect and enhancing the anti-interference ability of signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the three-dimensional space circuit for an electromagnetic stealth cloak according to the present invention;

[0043] Figure 2 is Figure 1 Schematic diagram of the simplified microwave circuit of the three-dimensional space circuit shown;

[0044] Figure 3 Schematic diagram of the structure of an electromagnetic stealth cloak based on a three-dimensional space circuit;

[0045] Figure 4 Cross-sectional view of the structure of the electromagnetic stealth cloak;

[0046] Figure 5 Cross-sectional view of part 1 of the processing structure of the electromagnetic stealth cloak;

[0047] Figure 6 Cross-sectional view of part 2 of the processing structure of the electromagnetic stealth cloak. DETAILED DESCRIPTION OF THE INVENTION

[0048] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0049] The present invention discloses a three-dimensional space circuit for an electromagnetic stealth cloak. The three-dimensional space circuit is a two-wire and two-port transmission line network. The two ports are a receiving end and a feedback end respectively, and the two wires are a transmission line and a ground wire respectively. A first-stage transmission circuit, a second-stage transmission circuit, and a third-stage transmission circuit are sequentially arranged between the receiving end and the feedback end.

[0050] The first-stage transmission circuit includes a first capacitor C1 between the transmission line and the ground wire.

[0051] The second-stage transmission circuit includes a series-connected first transmission line impedance Z1 and a short-circuit load between the transmission line and the ground wire.

[0052] The third-stage transmission circuit includes a second transmission line impedance Z s , a third transmission line impedance Z2, a second capacitor C2, and an air characteristic impedance Z0. Among them, the third line transmission impedance Z2 and the second capacitor C2 are both connected between the feedback end and the ground, and are in a symmetric structure with the first transmission line impedance Z1 and the first capacitor C1. The second transmission line impedance Z s is connected between the receiving end and the feedback end, and the air characteristic impedance Z0 is connected between the transmission line and the ground wire and is adjacent to the feedback end. The load composed of the third transmission line impedance Z2, the second capacitor C2, and the air characteristic impedance Z0 forms a terminated transmission line.

[0053] The receiving end receives electromagnetic waves and transmits them to the feedback end through the cascaded first-stage transmission circuit, second-stage transmission circuit, and third-stage transmission circuit respectively for feedback, so that the propagation of the electromagnetic waves is not changed by the shielding effect of an object.

[0054] Refer to Figure 1 , in the application of the electromagnetic stealth cloak, it is divided into two ports for receiving electromagnetic waves and feedbacking electromagnetic waves. Its three-dimensional space circuit has two ports: port 1 (receiving end) and port 2 (feedback end). Because the reception and output need to be consistent, a symmetric structure is adopted. , . In a specific application, electromagnetic waves are input from port 1 and transmitted to port 2 for feedback through the cascaded transmission of three transmission loops. The first is through the first capacitor C1 grounded to form the first-stage transmission circuit 11 loop; the second is through the second-stage transmission circuit 12 loop formed by the first transmission line impedance Z1 grounded; the third is through the third-stage transmission circuit 13 loop grounded, where the load impedance of the third-stage transmission circuit 13 and the load impedance of the first-stage transmission circuit 11 are completely symmetric. Through the cascading of the three-stage transmission loops, finally the electromagnetic waves are feedback out through port 2, so that the propagation of the electromagnetic waves is not changed by the shielding effect of an object through the action of the circuit.

[0055] After designing the specific structure of the circuit, according to the specific frequency band and effect to be cloaked, the specific parameters of the components are calculated based on the transmission line theory. After designing the first-stage transmission circuit 11, the second-stage transmission circuit 12, and the third-stage transmission circuit 13, the circuit structure is further simplified as Figure 2 , and the total equivalent input impedance can be obtained by the parallel connection of three equivalent input impedances 、 、 . First, the first-stage transmission circuit 11 is only composed of the first capacitor . Therefore . Secondly, according to the transmission line principle, the second-stage transmission circuit 12 consists of a terminally shorted transmission line composed of the first transmission line impedance , and its equivalent input impedance , where , , ; is the transmission length of the first transmission line impedance . In the structure of this embodiment, is also the thickness of the cloak at the same time; is the relative dielectric constant of the material of this part of the structure. Finally, the third-stage transmission circuit 13 is more complex, and its equivalent input impedance , where, . According to the above calculations, the input impedance of the simplified circuit can be obtained . The parameter, that is, the reflection coefficient, is used to measure the stealth effect of the electromagnetic cloak. In this three-dimensional space circuit, the voltage reflection coefficient is used to characterize , that is . Therefore, by simply changing the parameters of the circuit components, cloaks with different effects can be obtained.

[0056] From the above, the three-dimensional space microwave circuit of the electromagnetic stealth cloak is obtained. After analysis, the specific stealth cloak function is realized through the structures of Figure 3 and Figure 4 . Specifically, the three-dimensional space microwave circuit can realize its specific structure through the equivalent circuit method. Due to the symmetry of the three-dimensional space circuit, the cloak structure realized also has symmetry, and the upper half for receiving electromagnetic waves and the lower half for reflecting electromagnetic waves are completely symmetric. There are three transmission routes in the circuit: in the first transmission loop, the first capacitor part is equivalent to the gap capacitor 34a between the upper surfaces 33a (electromagnetic wave receiving surfaces) of the adjacent metal cloaks; in the second transmission loop, the first transmission line Z1 is equivalent to the dielectric 32 filled between the upper surface 33a of the cloak and the stealth object 31; in the third transmission loop, the second transmission line impedance Z sIt is equivalent to the slot line 34b between the sides 33b of the metal cloak. The second capacitor C2 of the loaded terminal part of the transmission line is equivalent to the gap capacitance 34c between the adjacent lower surfaces 33a of the cloak (the electromagnetic wave feedback surface), the third transmission line impedance Z2 is equivalent to the medium 32 filled between the lower surface 33a of the cloak and the stealth object 31, and the air characteristic impedance Z0 is equivalent to the free space outside the lower surface 33a of the cloak. Finally, we obtain Figure 3 The specific implementation structure of the broadband and ultra-thin electromagnetic stealth cloak shown

[0057] Example

[0058] In this example, first, according to Figure 1 the three-dimensional space circuit shown, a three-stage cascaded circuit is built. Through the equivalent method, the implementation structure and parameters of the three-dimensional space microwave circuit are obtained. Among them;

[0059] The first-stage transmission circuit 11: The gap capacitance C1 = 0.474 pF is adopted, which is equivalently formed by the gap 34a (spacing w = 2.4 mm) between the adjacent upper surfaces 33a of the metal cloak

[0060] The second-stage transmission circuit 12: The transmission line Z1 = 277.8 Ω, and the terminal is short-circuited

[0061] The third-stage transmission circuit 13: The transmission line Z s = 753.8 Ω, and the terminal is loaded with a capacitance C2 = 0.474 pF (the spacing w of the gap 34c is 2.4 mm).

[0062] The structural materials are selected as follows:

[0063] The stealth object 31: It is made of aluminum metal material

[0064] The wrapping medium 32: ABS material (relative permittivity εᵣ = 3.3) is selected, with a length a = 24.4 mm, a height b = 38.4 mm, a width c = 19.6 mm, and a thickness t = 2.7 mm

[0065] The metal cloak 33: Copper foil (thickness t = 0.035 mm) is plated on the surface of the wrapping medium 32 by electroplating copper process

[0066] For the cloak with this thickness, only the electroplating process can be used to achieve it. Since the electroplating process electroplates the whole object, it is difficult to process the gap capacitances 34a, 34c and the slot line 34b between the adjacent cloaks. Therefore, we adopt a new manufacturing method to achieve it. For the whole, this structure is split into a unit containing electroplated copper (composed of 32a, 33a and 33b) and a unit not containing electroplated copper (composed of 32b, 34a, 34b and 34c), as shown in Figure 5 and Figure 6As shown, the medium part 32 is realized by CNC machining. Finally, the two parts are overlapped alternately, and external pressure is applied to press them tightly against each other to obtain the final Figure 3 structure shown.

[0067] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present application.

[0068] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A three-dimensional space circuit for an electromagnetic invisible cloak, characterized in that: The three-dimensional space circuit is a two-line two-port transmission line network, wherein the two ports are a receiving end and a feedback end, and the two lines are a transmission line and a ground line; a first-level transmission circuit, a second-level transmission circuit and a third-level transmission circuit are sequentially arranged between the receiving end and the feedback end; The first-stage transmission circuit includes a first capacitor C1 between the transmission line and the ground line; The second-stage transmission circuit includes a first transmission line impedance Z1 in series and a short-circuit load between the transmission line and the ground line; The third-stage transmission circuit includes a second transmission line impedance Z s , a third transmission line impedance Z2, a second capacitor C2, and an air characteristic impedance Z0, wherein the third transmission line impedance Z2 and the second capacitor C2 are both connected between the feedback end and the ground, and are symmetrical with the first transmission line impedance Z1 and the first capacitor C1; the second transmission line impedance Z s Connected between the receiving end and the feedback end, the air characteristic impedance Z0 is connected between the transmission line and the ground line, and is close to the feedback end; the load composed of the third transmission line impedance Z2, the second capacitor C2, and the air characteristic impedance Z0 constitutes a terminal loaded transmission line; The receiving end receives the electromagnetic wave, transmits it to the feedback end through the cascaded first-stage transmission circuit, the second-stage transmission circuit, and the third-stage transmission circuit, respectively, and feeds it back out, so that the propagation of the electromagnetic wave is not changed by the shielding effect of the object; The equivalent input impedance of the three-dimensional space circuit is: WITH in =Z in1 ||From in2 ||From in3 ; In the formula, Z in1 , Z in2 and Z in3 are the equivalent input impedances of the first-stage transmission circuit, the second-stage transmission circuit, and the third-stage transmission circuit respectively; The electromagnetic cloak adjusts the reflection coefficient S by changing the parameters of the circuit elements. 11 : Where Γ0 is the voltage reflection coefficient.

2. The three-dimensional space circuit for electromagnetic stealth cloak according to claim 1, characterized in that: The equivalent input impedance of the first-stage transmission circuit is: Wherein, C is the capacitance of the first capacitor C1, and ω is the angular frequency.

3. The three-dimensional space circuit for electromagnetic stealth cloak according to claim 1, characterized in that: The equivalent input impedance of the second-stage transmission circuit is: Where β = 2π / λ, ω = 2πf, h is the transmission length of the first transmission line impedance Z1, ε r is the relative dielectric constant of the material, λ is the wavelength of the electromagnetic wave, f is the frequency of the electromagnetic wave, and Z0 is the characteristic impedance of air.

4. The three-dimensional space circuit for electromagnetic stealth cloak according to claim 3, characterized in that: The equivalent input impedance of the third-level transmission circuit is: in, Z0 is the characteristic impedance of air, Z s is the equivalent characteristic impedance of the slot line.

5. An electromagnetic invisible cloak based on the three-dimensional space circuit described in any one of claims 1 to 4, characterized in that: The electromagnetic stealth cloak comprises a first wrapping medium, a second wrapping medium and a plurality of metal cloaks; A plurality of metal cloaks are sequentially placed on the outside of the invisible object, with cloak gaps between adjacent metal cloaks; The upper surface of the metal cloak is used as a receiving end, and the gap capacitance between the upper surfaces of adjacent metal cloaks is equivalent to the first capacitance; the lower surface of the metal cloak is used as a feedback end, and the gap capacitance between the lower surfaces of adjacent metal cloaks is equivalent to the second capacitance; the slot line between the side surfaces of adjacent metal cloaks is equivalent to the second transmission line impedance Z s ; The first wrapping medium is filled between the upper surface of the metal cloak and the invisible object, which is equivalent to the first transmission line impedance Z1; the second wrapping medium is filled between the lower surface of the metal cloak and the invisible object, which is equivalent to the third transmission line Z2; the free space outside the lower surface of the metal cloak is equivalent to the characteristic impedance Z0 of air.

6. A method for processing the electromagnetic invisible cloak according to claim 5, characterized in that: The processing method comprises the following steps: Separate all structural parts of the electromagnetic cloak into electroplated copper units and units not containing electroplated copper, and perform overall electroplating on the electroplated copper units; A first wrapping medium and a second wrapping medium are obtained by CNC machining; All structural parts are stacked in an interlaced manner and fully compressed by applying external pressure to obtain an electromagnetic stealth cloak.

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