Three-dimensional space circuit for electromagnetic invisible cloak, electromagnetic invisible cloak and processing method of electromagnetic invisible cloak

Abstract

The invention discloses a three-dimensional space circuit for an electromagnetic invisible cloak, the electromagnetic invisible cloak and a processing method of the electromagnetic invisible cloak. A receiving end receives electromagnetic waves, and the electromagnetic waves are transmitted to a feedback end through a first-stage transmission circuit, a second-stage transmission circuit and a third-stage transmission circuit which are cascaded to be fed back; the propagation of the electromagnetic wave is not changed by the shielding effect of an object. According to the invention, the space occupation of the electromagnetic stealth cloak can be reduced, the stealth effect is good, and the signal receiving efficiency is improved; stealth can be realized only by different sizes in different antennas, so that the universality is improved; and for antenna components with different lengths, the structure can be assembled in multiple periods to realize electromagnetic stealth, so that the processing and assembling difficulty is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic stealth cloaks, and in particular 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 technology, electromagnetic stealth technology is increasingly used in military fields and daily life.

[0003] Electromagnetic stealth refers to the ability to create a stealth effect on an object in an electromagnetic wave without being detected. An electromagnetic stealth cloak is a material wrapped around 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 not detected by detection equipment. Therefore, electromagnetic stealth cloaks have a wide range of applications in the military, medical imaging and communications fields.

[0004] Traditional electromagnetic invisibility cloaks include: 1. Based on metamaterials, it is achieved through optical transformation. By wrapping the object with metamaterials, electromagnetic waves propagate near the metamaterials, avoiding the interaction between the object and the electromagnetic waves, and achieving the stealth effect. This requires thicker and anisotropic non-uniform artificial metamaterials. Therefore, the cloak not only has a larger thickness and a single stealth frequency, but also has a higher material cost.

[0005] 2. Plasma cloaks that use dielectric scattering to achieve destructive interference. By introducing a medium to produce overall destructive 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 within a very narrow frequency band, and requires that the object material and the thin metasurface material that constitutes the cloak are completely reciprocal.

[0006] In the Chinese patent with publication number CN117786983A, a design method for a double-layer structured static magnetic field stealth cloak is mentioned. The method obtains an electromagnetic stealth cloak through the following steps: 1) Solving the Laplace equation to obtain the size and permeability relationship between the layers of the static magnetic stealth cloak; 2) Determining the size parameters and material properties of the ideal static magnetic stealth cloak; 3) Determining the degree of discretization, discretizing the circular cloak into unit cells; 4) Using the S parameter inversion method to obtain the relationship between the unit cell configuration and the equivalent permeability; 5) Assembling the unit cells whose equivalent permeability is equal to the permeability required by 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, thus getting rid of the strict property requirements of the transformation optical design theory.

[0007] The existing research methods of electromagnetic stealth cloaks are relatively complicated, and are basically analyzed and designed from the perspective of electromagnetic fields. After the structure of the electromagnetic cloak is known, it is analyzed. After a fixed electromagnetic stealth cloak is designed according to this method, when the invisible object changes, the electromagnetic stealth effect cannot be flexibly adjusted. Therefore, compared with the previous analysis of the electromagnetic field, the three-dimensional space circuit of the electromagnetic stealth cloak analyzes its electromagnetic stealth effect from the perspective of the circuit, and has greater advantages in achieving stealth by changing the circuit elements and then changing its specific structure. When the antenna signal is received, the shielding of the electromagnetic wave by the metal parts causes the weakening of the received signal quality, which affects the communication efficiency. Therefore, it is necessary to make the metal parts invisible to improve the antenna reception efficiency. Summary of the invention

[0008] The purpose of the present invention is to propose a three-dimensional space circuit for an electromagnetic stealth cloak, an electromagnetic stealth cloak and a processing method thereof. Based on its ultra-thin and wide-band characteristics, the space occupied in the antenna component is reduced and the stealth effect is better, thereby improving the efficiency of signal reception. The structure can achieve different stealth effects by simply changing the size parameters, so only different sizes are required in different antennas to achieve stealth, thereby improving versatility. In addition, for antenna components of different lengths, the structure can be assembled in multiple cycles to achieve electromagnetic stealth, thereby greatly reducing the difficulty of processing and assembly.

[0009] In order to achieve the above technical objectives, the technical solution adopted by the present invention is: In a first aspect, the present invention discloses a three-dimensional space circuit of an electromagnetic invisibility cloak, wherein 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 electromagnetic waves, transmits them to the feedback end through the cascaded first-stage transmission circuit, the second-stage transmission circuit, and the third-stage transmission circuit, and feeds them back, so that the propagation of the electromagnetic waves is not affected by the shielding effect of the object.

[0010] Furthermore, the equivalent input impedance of the first-stage transmission circuit is: ; In the formula, is the capacitance of the first capacitor C1, is the angular frequency.

[0011] Furthermore, the equivalent input impedance of the second-stage transmission circuit is: ; in , , The first transmission line impedance The transmission length, is the relative dielectric constant of the material, is the wavelength of electromagnetic waves, is the electromagnetic wave frequency, is the characteristic impedance of air.

[0012] Furthermore, the equivalent input impedance of the third-stage transmission circuit is: ; in, , is the characteristic impedance of air, is the slot line equivalent characteristic impedance, is the load impedance of the first-stage transmission loop.

[0013] Furthermore, the equivalent input impedance of the three-dimensional space circuit is: ; 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.

[0014] Furthermore, the electromagnetic cloak adjusts the reflection coefficient by changing the circuit element parameters. : ; In the formula, is the voltage reflection coefficient.

[0015] In a second aspect, the present invention discloses an electromagnetic stealth cloak based on the aforementioned three-dimensional space circuit, wherein 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.

[0016] In a third aspect, the present invention discloses a method for manufacturing an electromagnetic invisible cloak, the method comprising the following steps: Separate all structural parts of the electromagnetic stealth cloak into electroplated copper units and non-electroplated copper units, 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.

[0017] Compared with the prior art, the present invention has the following beneficial effects: First, the three-dimensional space circuit for electromagnetic stealth cloak, electromagnetic stealth cloak and its processing method of the present invention are transformed from the traditional electromagnetic field perspective to the circuit perspective. Due to the complex properties of the electromagnetic field itself, the study of the electromagnetic field is often more complicated, while the analysis of the simplified circuit model is relatively simple, which greatly reduces the complexity of the design of the electromagnetic stealth cloak. In addition, in specific applications, due to different requirements for stealth in different scenarios, the effect of the cloak needs to change. At this time, the reflection coefficient of the microwave circuit can be changed by simply 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 can be changed to achieve the adjustment of stealth. Thereby, it can adapt to different scenarios and needs, and improve the scope of application of the cloak.

[0018] Second, the three-dimensional space circuit for electromagnetic stealth cloak, electromagnetic stealth cloak and processing method thereof of the present invention not only reduce the difficulty of realizing the stealth cloak, but also, compared with the method of realizing stealth by traditional materials, the structure only realizes stealth through its own geometric structure, making the processing and realization of the cloak simpler and more efficient, and compared with the high cost of metamaterials, the cost of this structure is low, which provides the necessary conditions for mass production and use. In addition, the thickness of the metal cloak in this structure is greatly reduced, which improves the flexibility and adaptability of the cloak in practical applications, and also reduces the weight of the cloak, providing the possibility of stealth for some objects that need to be invisible under special conditions. In addition, the stealth bandwidth realized by this structure is large, which can cover electromagnetic waves of more frequency bands, improve the stealth effect, and enhance the anti-interference ability of signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of a three-dimensional space circuit for an electromagnetic invisible cloak of the present invention; Figure 2 for Figure 1 A simplified microwave circuit schematic diagram of the three-dimensional space circuit shown; Figure 3 This is a schematic diagram of the structure of an electromagnetic invisible cloak based on a three-dimensional space circuit; Figure 4 This is a cross-sectional diagram of the structure of the electromagnetic invisibility cloak; Figure 5 It is a cross-sectional view of the processed structural part 1 of the electromagnetic stealth cloak; Figure 6 This is a cross-sectional view of the processed structural part 2 of the electromagnetic stealth cloak. DETAILED DESCRIPTION

[0020] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0021] The present invention discloses a three-dimensional space circuit for an electromagnetic stealth cloak, wherein 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 grounding 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, the third transmission line impedance Z2, the second capacitor C2, and the 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 electromagnetic waves, transmits them to the feedback end through the cascaded first-stage transmission circuit, the second-stage transmission circuit, and the third-stage transmission circuit, and feeds them back, so that the propagation of the electromagnetic waves is not affected by the shielding effect of the object.

[0022] See also Figure 1 In the application, the electromagnetic cloak is divided into two ports: receiving electromagnetic waves and feeding back electromagnetic waves. Its three-dimensional space circuit has two ports: port 1 (receiving end) and port 2 (feedback end). Because the receiving and output need to be consistent, a symmetrical structure is adopted. , . In a specific application, the electromagnetic wave is input from port 1, transmitted to port 2 through three transmission loops in cascade and fed back; the first is grounded through the first capacitor C1 to form a first-level transmission circuit 11 loop; the second is grounded through the second-level transmission circuit 12 loop formed by the first transmission line impedance Z1; the third is grounded through the third-level transmission circuit 13 loop, wherein the load impedance of the third-level transmission circuit 13 is completely symmetrical with the load impedance of the first-level transmission circuit 11. Through the cascade of the three-level transmission loop, the electromagnetic wave is finally fed back through port 2, so that the propagation of the electromagnetic wave is not affected by the shielding effect of the object through the action of the circuit.

[0023] After designing the specific structure of the circuit, the specific parameters of the components are calculated according to the specific frequency band and effect required for stealth based on the transmission line theory. After designing the first-level transmission circuit 11, the second-level transmission circuit 12, and the third-level transmission circuit 13, the circuit structure is further simplified as follows Figure 2 , the equivalent input impedance can be obtained by three , , The total equivalent input impedance is formed by parallel connection First, the first-stage transmission circuit 11 is only composed of the first capacitor composition, so Secondly, according to the transmission line principle, the second-stage transmission circuit 12 is composed of the first transmission line impedance The equivalent input impedance of the short-circuited transmission line is ,in , ; The first transmission line impedance The transmission length of this embodiment is: It is also the thickness of the cloak; is the relative dielectric constant of the structural material of this part. Finally, the third-level transmission circuit 13 is relatively complex, and its equivalent input impedance ,in, According to the above calculation, the input impedance of the simplified circuit can be obtained ,use The voltage reflection coefficient is used to measure the stealth effect of the electromagnetic cloak. To characterize ,Right now Therefore, cloaks with different effects can be obtained by simply changing the parameters of circuit components.

[0024] The three-dimensional microwave circuit of the electromagnetic invisibility cloak is obtained from the above analysis. Figure 3 and Figure 4 The structure realizes the specific function of the invisible cloak. Specifically, the three-dimensional microwave circuit can realize its specific structure through the equivalent circuit method. Due to the symmetry of the three-dimensional space circuit, the realized cloak structure is also symmetrical, and the upper part that receives the electromagnetic wave and the lower part that feeds back the electromagnetic wave are completely symmetrical. The circuit is divided into three transmission routes: the first capacitor part in the first transmission loop is equivalent to the gap capacitor 34a between the upper surfaces 33a of the adjacent metal cloaks (electromagnetic wave receiving surfaces); the first transmission line Z1 in the second transmission loop is equivalent to the medium 32 filled between the upper surface 33a of the cloak and the invisible object 31; the second transmission line impedance Z in the third transmission loop s is equivalent to the slot line 34b between the side surfaces 33b of the metal cloak. The second capacitor C2 of the loaded terminal part of the transmission line is equivalent to the gap capacitor 34c between the adjacent cloak lower surfaces 33a (electromagnetic wave feedback surface), the third transmission line impedance Z2 is equivalent to the medium 32 filled between the cloak lower surface 33a and the invisible object 31, and the air characteristic impedance Z0 is equivalent to the free space outside the cloak lower surface 33a. Finally, we get Figure 3 The specific implementation structure of the wide-band ultra-thin electromagnetic stealth cloak is shown.

[0025] Examples In this example, first, according to Figure 1 The three-dimensional space circuit shown in the figure builds a three-level cascade circuit, and the implementation structure and parameters of the three-dimensional space microwave circuit are obtained through the equivalent method. Among them; The first-stage transmission circuit 11 uses a gap capacitance C1 = 0.474 pF, which is equivalently formed by the gap 34a (spacing w = 2.4 mm) between the upper surfaces 33a of adjacent metal cloaks.

[0026] Second-stage transmission circuit 12: transmission line Z1=277.8 Ω, terminal short-circuited.

[0027] The third level transmission circuit 13: transmission line Z s =753.8 Ω, terminal loading capacitance C2=0.474 pF (gap 34c spacing w=2.4 mm).

[0028] The structural materials are selected as follows: Stealth object 31: is made of metal aluminum material.

[0029] Wrapping medium 32: ABS material (dielectric constant εᵣ=3.3) is selected, length a=24.4mm, height b=38.4mm, width c=19.6mm, thickness t=2.7 mm.

[0030] Metal cloak 33: Copper foil (thickness t=0.035 mm) is plated on the surface of the wrapping medium 32 by using a copper electroplating process.

[0031] The cloak of this thickness can only be achieved by electroplating. Since the electroplating process is for the entire object, it is difficult to process the gap capacitors 34a, 34c and the slot line 34b between adjacent cloaks. Therefore, we use a new manufacturing method to achieve this. As a whole, the structure is divided into units containing electroplated copper (32a, 33a and 33b) and units not containing electroplated copper (32b, 34a, 34b and 34c), such as Figure 5 and Figure 6 As shown, the medium part 32 is realized by CNC machining. Finally, the two parts are overlapped and pressed together by external pressure to obtain the final Figure 3 The structure shown.

[0032] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0033] 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 equivalents, 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 electromagnetic waves, transmits them to the feedback end through the cascaded first-stage transmission circuit, the second-stage transmission circuit, and the third-stage transmission circuit, and feeds them back, so that the propagation of the electromagnetic waves is not affected by the shielding effect of the object.

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: ； In the formula, is the capacitance of the first capacitor C1, 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: ； in , , The first transmission line impedance The transmission length, is the relative dielectric constant of the material, is the wavelength of electromagnetic waves, is the electromagnetic wave frequency, is the characteristic impedance of air.

4. The three-dimensional space circuit for electromagnetic stealth cloak according to claim 1, characterized in that: The equivalent input impedance of the third-level transmission circuit is: ； in, , is the characteristic impedance of air, is the slot line equivalent characteristic impedance, is the load impedance of the first-stage transmission loop.

5. The three-dimensional space circuit for electromagnetic stealth cloak according to claim 1, characterized in that: The equivalent input impedance of the three-dimensional space circuit is: ； 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.

6. The three-dimensional space circuit for electromagnetic stealth cloak according to claim 1, characterized in that: The electromagnetic cloak adjusts the reflection coefficient by changing the parameters of the circuit elements : ； In the formula, is the voltage reflection coefficient.

7. An electromagnetic invisible cloak based on the three-dimensional space circuit described in any one of claims 1 to 6, 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.

8. A method for processing the electromagnetic invisible cloak according to claim 7, characterized in that: The processing method comprises the following steps: Separate all structural parts of the electromagnetic stealth cloak into electroplated copper units and non-electroplated copper units, 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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