Echo intensifier based on cylindrical conformal metasurface structure and design method thereof

Abstract

The invention provides an echo intensifier based on a cylindrical conformal metasurface structure and a design method of the echo intensifier. The echo intensifier comprises a metal cylinder and a plurality of metasurface units, wherein the metasurface units are periodically arranged on the side face of the metal cylinder, and the metasurface units are used for regulating and controlling the electromagnetic scattering characteristic of the metal cylinder. According to the scheme, when the structure design of the echo intensifier is carried out, cylindrical conformal array design is carried out on the metasurface unit on the side face of the metal cylinder by combining a geometric partitioning method and a phase gradient theory, and meanwhile, the size parameters of the metal patches in the metasurface unit are optimized by utilizing an optimization algorithm; and the optimized metal patches with different sizes form an array and are arranged on the side surface of the metal cylinder so as to meet electromagnetic regulation and control. Therefore, backward echo enhancement can be effectively realized on the cylindrical curved surface carrier, and a solution is provided for echo enhancement of a curved surface structure in a certain angular domain.

Description

Technical Field

[0001] The present invention relates to the technical field of signal feature control, and in particular to an echo enhancer based on a cylindrical conformal metasurface structure and a design method thereof. Background Art

[0002] Radar echo enhancer is a device used to enhance radar echo signals. It can be divided into active echo enhancer and passive echo enhancer according to the excitation method. The passive echo enhancer itself does not contain a radiation source, and only passively generates echoes by its own structure. Its structure is relatively simple, low in production cost, stable and practical, short in response time, and good in mobility. Metal cylinders are a typical electromagnetic scatterer. When electromagnetic waves are irradiated onto the cylinder surface, the energy is distributed in all directions, and the backscattering is weak.

[0003] Therefore, there is an urgent need to provide an echo enhancer based on a cylindrical conformal metasurface structure and a design method thereof. Summary of the invention

[0004] The embodiment of the present invention provides an echo enhancer based on a cylindrical conformal metasurface structure and a design method thereof, which can effectively enhance the backscattering of a cylindrical scatterer.

[0005] In the first aspect, an embodiment of the present invention provides an echo enhancer based on a cylindrical conformal metasurface structure, comprising a metal cylinder and a plurality of metasurface units; wherein the metasurface units are periodically arranged on the side of the metal cylinder, and the metasurface units are used to regulate the electromagnetic scattering characteristics of the metal cylinder.

[0006] In a possible design, each of the metasurface units includes a metal base plate, a dielectric layer, and a metal patch arranged in sequence from bottom to top;

[0007] The metal patch includes a cross-shaped patch and four arc patches respectively located at the open ends of the cross-shaped patch, and each arc patch is symmetrical to each other along the center of the cross-shaped patch, so that the metal patch presents a Jerusalem-like structure.

[0008] In a possible design, in two symmetrical curved surfaces with an axial surface of the metal cylinder as the symmetry axis, the metal patches in the metasurface unit all conform to the following rules:

[0009] At least two rows of supersurface units are included along the axial direction of the metal cylinder, and the size parameters of the metal patches in each row of supersurface units are the same;

[0010] Along the radial direction of the metal cylinder, at least two columns of periodically arranged metasurface units are included, and the size parameters of the metal patches in each group of metasurface units are different, so that an electromagnetic reflection phase gradient is formed between the metasurface units in two adjacent columns.

[0011] In a possible design, the size parameters of the metal patch include the thickness and length of the cross-shaped patch, the thickness, radius and center angle of the arc patch; wherein the radius of the arc patch is half of the length of the cross-shaped patch.

[0012] In one possible design, the size parameters of the metal patch are controlled by the center angle corresponding to the arc patch and the radius of the arc patch; wherein the arc length of the arc patch varies with the radius and center angle of the arc patch, and the width of the arc patch and the width of the cross patch are both constants.

[0013] In a second aspect, an embodiment of the present invention further provides a method for designing an echo enhancer based on a cylindrical conformal metasurface structure as described in any one of the first aspects above, comprising:

[0014] (1) Based on the determined target frequency of the echo enhancer, the period length of the metasurface unit, the structural parameters of the metal bottom layer and the dielectric layer, and the size parameters of the metal patch are designed to determine the reflection phase coverage range of each metasurface unit within a preset incident angle range;

[0015] (2) dividing the side area of ​​the metal cylinder along the axial direction of the metal cylinder according to the period length of the metasurface unit and the size of the metal cylinder to obtain a plurality of array-arranged areas;

[0016] (3) using the generalized reflection law as a guide to calculate the electromagnetic reflection phase gradient of each patch area to determine the structural parameters of the metal patch in the metasurface unit in each patch area;

[0017] (4) optimizing the size parameters of the metal patches in the metasurface unit using a trust region framework algorithm according to the variation range of the structural parameters and size parameters of the metal patches, so as to determine the size parameters of the metal patches in each patch area;

[0018] (5) Based on the determined size parameters and structural parameters of the metal patch in each patch area, the metasurface unit is adhered to the surface of each patch area to obtain the echo enhancer based on the cylindrical conformal metasurface structure.

[0019] In one possible design, the structural parameters of each layer in the metasurface unit include the material and thickness of the metal bottom layer, the material, thickness, dielectric constant and loss tangent value of the dielectric layer.

[0020] In a possible design, the structural parameters of the metal patch include the size type and size variation rule of the metal patch.

[0021] In one possible design, the electromagnetic reflection phase gradient in each patch area is determined by the following formula:

[0022]

[0023] Where f0 is the target frequency, c is the speed of light, θ im is the incident angle of the electromagnetic wave, and Ф is the electromagnetic reflection phase gradient.

[0024] In a possible design, the reflection phase coverage range of the echo enhancer within a preset incident angle range of 0-60° exceeds 360°.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] In the present invention, the echo enhancer is designed as a metal cylinder, and a periodically arranged metasurface unit is attached to the side of the metal cylinder to perform electromagnetic scattering control; when designing the structure of the echo enhancer, the surface of the metal cylinder is approximated into several planes in combination with the idea of ​​geometric partitioning, and a cylindrical conformal array is designed for the side of the metal cylinder in combination with the phase gradient theory, and the size parameters of the metal patch in the metasurface unit are optimized by an optimization algorithm, and the optimized metal patches of different sizes are arranged in an array on the side of the metal cylinder to meet the electromagnetic scattering control. In this way, the back echo enhancement can be effectively realized on the cylindrical curved surface carrier, and a solution is provided for the echo enhancement of the curved surface structure in a certain angular domain. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 1 is a schematic diagram of the overall structure of an echo enhancer based on a cylindrical conformal metasurface structure provided by an embodiment of the present invention;

[0029] Figure 2 is a side view of an echo enhancer and a top view of a metal patch metasurface unit provided by an embodiment of the present invention;

[0030] Figure 3 is a schematic diagram of a partial array of a metal patch metasurface unit provided by an embodiment of the present invention;

[0031] Figure 4is a design flow chart of an echo enhancer based on a cylindrical conformal metasurface structure provided by an embodiment of the present invention;

[0032] Figure 5 It is a reflection phase diagram of a metal patch metasurface unit as the arc patch center angle α changes, provided by an embodiment of the present invention;

[0033] Figure 6 It is a reflection phase diagram of a metal patch metasurface unit as the arc patch radius R changes, provided by an embodiment of the present invention;

[0034] Figure 7 It is a schematic diagram of geometric partitioning of a dielectric layer cylinder provided by an embodiment of the present invention;

[0035] Figure 8 It is a theoretical reflection phase diagram of 30 metal patch metasurface units provided by an embodiment of the present invention;

[0036] Fig. 9 The present invention provides a dual-station RCS (azimuth) of a metal cylinder loaded with a metal patch metasurface unit before and after. );

[0037] Fig.10 The present invention provides a dual-station RCS (azimuth) of a metal cylinder loaded with a metal patch metasurface unit before and after. );

[0038] In the figure: 100-metal cylinder; 200-super surface unit. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions 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, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0040] As mentioned above, the backscattering of the metal cylindrical electromagnetic scatterer is weak, and considering that the electromagnetic metasurface has a strong electromagnetic control capability, and it has the advantages of small size, low profile, conformability, and easy processing, etc. Therefore, in the embodiment of the present invention, it is considered to load a conformal metasurface on the surface of the metal cylinder to improve its backscattering intensity in a specific angular domain and change its electromagnetic scattering characteristics.

[0041] like Figure 1As shown, an embodiment of the present invention provides an echo enhancer based on a cylindrical conformal metasurface structure, comprising a metal cylinder 100 and a plurality of metasurface units 200; wherein the metasurface units 200 are periodically arranged on the side of the metal cylinder 100, and the metasurface units 200 are used to regulate the electromagnetic scattering characteristics of the metal cylinder 100.

[0042] The cylinder is a developable curved surface, which is convenient for the fitting of metasurface units. Therefore, in the embodiment of the present invention, the echo enhancer is designed as a metal cylinder. Combined with the idea of ​​replacing curves with straight lines, the side surfaces of the metal cylinder are approximated as several planes. After geometrically partitioning the cylinder, the metasurface conformal units and their arrangement structure are first designed, so that the metasurface units are arranged in a periodic array on the side surfaces of the metal cylinder. By designing the size and regularity of the metal patch metasurface units, the echo enhancement can be effectively achieved on the cylinder, thereby realizing the electromagnetic characteristic simulation of the curved surface structure.

[0043] In some embodiments, Figure 2 As shown, each of the metasurface units includes a metal base plate, a dielectric layer and a metal patch arranged in sequence from bottom to top; the metal patch includes a cross-shaped patch and four arc patches respectively located at the open ends of the cross-shaped patch, and each arc patch is symmetrical to each other along the center of the cross-shaped patch, so that the metal patch presents a Jerusalem-like structure.

[0044] In some embodiments, the size parameters of the metal patch include the thickness and length of the cross-shaped patch, the thickness, radius and center angle of the arc patch; wherein the radius of the arc patch is half of the length of the cross-shaped patch.

[0045] In some embodiments, the size parameters of the metal patch are controlled by the center angle corresponding to the arc patch and the radius of the arc patch; wherein the arc length of the arc patch varies with the radius and center angle of the arc patch, and the width of the arc patch and the width of the cross patch are both constants.

[0046] like Figure 2 As shown in, in the embodiment of the present invention, by designing each metal patch in the metasurface unit as the above structure, the cylindrical surface can have good reflection characteristics in a wide incident angle domain. In this embodiment, the resonance characteristics of the metasurface unit can be changed by adjusting the width d of the arc patch and the cross patch in the metal patch in the metasurface unit, the radius R of the arc patch, and the arc length L of the arc patch. Since the width d of the arc patch and the cross patch has a weak effect on the performance of the metasurface unit, the width d of the arc patch and the cross patch is set to a fixed value;

[0047] Assuming that the central angle of the arc patch is 2α, the arc length L of the arc patch and the radius R of the arc patch have the following relationship:

[0048]

[0049] From the above formula, we know that L is related to R and α, and the range of α is 0-45°. Therefore, the size change of the metal patch in the metasurface unit can be reflected in R and α.

[0050] In some embodiments, when incident in the -z direction, with an axial plane as the axis of symmetry, the two curved surfaces on both sides of the cylinder are symmetrical to each other, and the electromagnetic wave incident angles of the bilaterally symmetrical curved surfaces are the same. Therefore, in the embodiment of the present invention, the metasurface units of the bilaterally symmetrical curved surfaces are designed to be symmetrical to each other along the axis of symmetry, so that the metasurface units in each symmetrical curved surface have:

[0051] like Figure 3 As shown, along the axial direction of the metal cylinder, there are at least two rows of metasurface units, and the size parameters of the metal patches in each row of metasurface units are the same; along the radial direction of the metal cylinder, there are at least two columns of periodically arranged metasurface units, and the size parameters of the metal patches in each group of metasurface units are different, so that an electromagnetic reflection phase gradient is formed between the metasurface units in two adjacent columns.

[0052] like Figure 4 As shown, an embodiment of the present invention further provides a design method of an echo enhancer based on a cylindrical conformal metasurface structure as described in any one of the above, comprising:

[0053] (1) Based on the determined target frequency of the echo enhancer, the period length of the metasurface unit, the structural parameters of the metal bottom layer and the dielectric layer, and the size parameters of the metal patch are designed to determine the reflection phase range of each metasurface unit within a preset incident angle range;

[0054] (2) dividing the side area of ​​the metal cylinder along the axial direction of the metal cylinder according to the period length of the metasurface unit and the size of the metal cylinder to obtain a plurality of array-arranged patch areas;

[0055] (3) using the generalized reflection law as a guide to calculate the electromagnetic reflection phase gradient of each patch area to determine the structural parameters of the metal patch in the metasurface unit in each patch area;

[0056] (4) optimizing the size parameters of the metal patches in the metasurface unit using a trust region framework algorithm according to the variation range of the structural parameters and size parameters of the metal patches, so as to determine the size parameters of the metal patches in each patch area;

[0057] (5) Based on the determined size parameters and structural parameters of the metal patch in each patch area, the metasurface unit is adhered to the surface of each patch area to obtain the echo enhancer based on the cylindrical conformal metasurface structure.

[0058] In the embodiment of the present invention, the echo enhancer is designed as a metal cylinder, and the side of the metal cylinder is fitted with periodically arranged metasurface units to perform electromagnetic scattering control; when designing the structure of the echo enhancer, the surface of the metal cylinder is approximated into several planes in combination with the idea of ​​geometric partitioning, and the side of the metal cylinder is designed with a cylindrical conformal array in combination with the phase gradient theory, and the size parameters of the metal patch in the metasurface unit are optimized by an optimization algorithm, and the optimized metal patches of different sizes are arranged in an array on the side of the metal cylinder to meet the electromagnetic scattering control. In this way, the back echo enhancement can be effectively realized on the cylindrical curved surface carrier, and a solution is provided for the echo enhancement of the curved surface structure in a certain angular domain.

[0059] In some embodiments, the structural parameters of each layer in the metasurface unit include the material and thickness of the metal base layer, the material, thickness, dielectric constant and loss tangent value of the dielectric layer.

[0060] In some embodiments, the structural parameters of the metal patch include the size type and size variation rule of the metal patch.

[0061] The following is an example of each step in the above design method:

[0062] Step (1): In the embodiment of the present invention, the target frequency of the target echo enhancer is designed to be 10 GHz, and the unit period length p=5 mm, which is 1 / 6 of the design wavelength. According to the target frequency and unit period, metal copper is selected as a metal cylinder with a height of 150 mm. The structure of the metasurface unit is as follows: Figure 2 As shown, it presents a Jerusalem-like structure. The metal base plate and the metal patch are both copper, with a thickness of 0.01 mm. The thickness of the dielectric layer is 1.6 mm. The material is Rogers RT6006, with a dielectric constant of 6.45 and a loss tangent of 0.0027. The width d of the arc patch and the cross patch in the metal patch are both 0.2 mm. The radius R of the arc patch is the distance from the center of the cross patch to the arc patch, and the range of variation is 0-2.5 mm.

[0063] like Figure 6 As shown in the figure, when the electromagnetic wave shines on the metal cylindrical surface, the incident angle is the same as the angle between the center of two metasurface units in the metal cylindrical patch area and the center of the metal cylinder, and the variation range is large. Therefore, the metasurface unit needs to have good reflection characteristics in a wide incident angle range, that is, a wide adjustable reflection phase range and a high reflection amplitude.

[0064] For the incident angle domain, this design is in the range of 0-60°. Through simulation in the embodiment of the present invention, it is found that the reaction phase of the metasurface unit can be controlled by changing the size parameters of the metal patch in the metasurface unit. Given the conditions that the incident angle is 30° and R is 2mm, the reflection phase changes from 5° to 40° as shown in Figure 5 As shown, under the given conditions of incident angle 30° and α of 25°, the reflection phase changes from R 0.5mm to 2.5mm as shown in Figure 6 As shown. Figure 5 and Figure 6 It can be seen that when other size parameters are fixed, the reflection phase decreases monotonically as α increases, and the two are negatively correlated; the reflection phase decreases monotonically as R increases, and the two are also negatively correlated. Therefore, the extreme values ​​of the reflection phase of the metasurface unit at different incident angles can be calculated by simulation, thereby calculating the coverage range of the metasurface unit phase.

[0065] Table 1 Phase characteristics of metasurface units at multiple incident angles

[0066]

[0067]

[0068] In the embodiment of the present invention, the interval of the incident angle is set to 5°, the first set of parameters is R=0.5mm, α=5°, and the second set of parameters is R=2.49mm, α=44.9°. It can be seen from Table 1 that the reflection phase coverage range of the metasurface unit in this embodiment in the 0-60° incident angle domain exceeds 360°, and has good reflection characteristics.

[0069] Step (2) and step (3): Since the circumference of the metal cylinder is 295 mm, the height is 150 mm, and the period length of the hypersurface unit is p = 5 mm, the side area of ​​the metal cylinder can be divided according to the size of the hypersurface unit and the size of the metal cylinder. At the same time, considering that the curved surfaces on both sides are symmetrical when the axial surface of the cylinder is the symmetry axis, a column of hypersurface units will be reused for the symmetrical curved surfaces on both sides. 30 types of hypersurface units are used, such as Figure 6 As shown, the metal cylinder can be divided into 59 patch areas along the axial direction and 30 patch areas along the radial direction.

[0070] Continue to refer Figure 6 , along the axial direction, the arc angle corresponding to each patch area is small, and each patch area is approximated as an inclined plane. At this time, each patch area has an incident angle θ im ,θ im Equal to ∠AOB, the phase gradient interval is approximately a constant. Combined with the generalized reflection law, the phase gradient can be expressed as:

[0071]

[0072] Where f0 is the target frequency, c is the speed of light, θ im is the incident angle of electromagnetic wave, Ф is the electromagnetic reflection phase gradient;

[0073] The incident angles corresponding to the symmetric surfaces are the same, so we only need to focus on one side. Therefore, in the symmetric surface on one side, the incident angle of the first hypersurface unit is 0°, and the ordinal number of the hypersurface unit is n, then the incident angle θ i It is expressed as:

[0074]

[0075] Where r is the radius of the metal cylinder, H is the total thickness of the metasurface unit, and n is a maximum of 30. It can be concluded that the maximum incident angle of the metasurface unit is 54.8°.

[0076] Then, the six metasurface units are divided into a group, and there are five groups on each side of the symmetrical surface. The central angle of each patch area is 11.3°, and the incident angles of each patch area are 5.7°, 17°, 28.3°, 39.7°, and 51°, respectively. The reflection phases of 30 metasurface units can be calculated (e.g. Figure 7 As shown in the figure, it can be seen that the phase gradient in each patch area is constant, and the phases of two adjacent patch areas will not jump.

[0077] Step (4): Since there are multiple sets of α and R parameter solutions for the phase conditions of each metasurface unit, the optimizer in CST is used for optimization in this embodiment, and the trust region framework algorithm is selected to optimize the specific size parameters of the phase of the metasurface unit in each patch area. Specifically, any set of data is selected from the range of the arc patch radius R (0-2.5mm) of the metal patch in the metasurface unit selected in step (1) and the central angle α (0-45°) corresponding to the arc patch, and it is used as input. The optimization index of the optimizer is set according to Table 2. After solving, the specific size parameters of the metal patch of each metasurface unit in each patch area are obtained.

[0078] Table 2 Optimization indexes of metasurface units

[0079] Unit performance Optimization indicators Reflection Amplitude >0.9 Difference between reflected phase and theoretical value <0.5° The accuracy of α 0.1° Accuracy of R 0.1mm

[0080] Step (5): Finally, in the CST software, the arranged metasurface units are attached to the side of the metal cylinder. The bending shapes in the modeling tool are used to conform the metasurface units layer by layer to the side of the metal cylinder. The far-field results are solved using the time domain solver. When the plane wave is irradiated along the -z direction to the cylindrical conformal echo enhancer, the dual-station radar cross section (RCS) result is as follows: Fig. 9 and Fig.10 As shown in the figure, the RCS comparison of the metal cylinder before and after loading the metasurface unit is given at azimuth angles of 0 and 90°. Figure 8 and 9 It can be seen that after loading the metasurface unit, the RCS of the metal cylinder increased by 9.43dB. The conformal metasurface unit structure greatly improved its backward RCS, achieving echo enhancement.

[0081] In summary, in the present invention, a conformal and ultra-low-profile structure is used to achieve efficient backscattering enhancement, the metasurface unit structure is improved and combined with the optimization algorithm to obtain the optimal geometric parameters, and the geometric partitioning method is combined with the gradient phase metasurface for cylindrical conformal array design, thereby achieving cylindrical echo enhancement.

[0082] It should be understood that the above general description and the detailed description below are only exemplary and explanatory and cannot limit the present application. In the present application, the term "multiple" refers to two or more, unless otherwise expressly defined. In the present application, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. Terms such as "installed", "connected", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0083] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An echo enhancer based on a cylindrical conformal metasurface structure, characterized in that: It includes a metal cylinder and a plurality of metasurface units; wherein the metasurface units are periodically arranged on the side of the metal cylinder, and the metasurface units are used to regulate the electromagnetic scattering characteristics of the metal cylinder.

2. The echo enhancer according to claim 1, characterized in that: Each of the metasurface units comprises a metal base plate, a dielectric layer and a metal patch arranged in sequence from bottom to top; The metal patch includes a cross-shaped patch and four arc patches respectively located at the open ends of the cross-shaped patch, and each arc patch is symmetrical to each other along the center of the cross-shaped patch, so that the metal patch presents a Jerusalem-like structure.

3. The echo enhancer according to claim 2, characterized in that: In the two symmetrical curved surfaces with an axial surface of the metal cylinder as the symmetry axis, the metal patches in the metasurface unit all conform to the following rules: At least two rows of supersurface units are included along the axial direction of the metal cylinder, and the size parameters of the metal patches in each row of supersurface units are the same; Along the radial direction of the metal cylinder, at least two columns of periodically arranged metasurface units are included, and the size parameters of the metal patches in each group of metasurface units are different, so that an electromagnetic reflection phase gradient is formed between the metasurface units in two adjacent columns.

4. The echo enhancer according to claim 2 or 3, characterized in that: The size parameters of the metal patch include the thickness and length of the cross-shaped patch, the thickness, radius and center angle of the arc patch; wherein the radius of the arc patch is half of the length of the cross-shaped patch.

5. The echo enhancer according to claim 3, characterized in that: The size parameters of the metal patch are controlled by the center angle of the arc patch and the radius of the arc patch; wherein the arc length of the arc patch varies with the radius and center angle of the arc patch, and the width of the arc patch and the width of the cross patch are both constant values.

6. A design method for an echo enhancer based on a cylindrical conformal metasurface structure according to any one of claims 1 to 5, characterized in that: include: (1) Based on the determined target frequency of the echo enhancer, the period length of the metasurface unit, the structural parameters of the metal bottom layer and the dielectric layer, and the size parameters of the metal patch are designed to determine the reflection phase coverage range of each metasurface unit within a preset incident angle range; (2) dividing the side area of ​​the metal cylinder along the axial direction of the metal cylinder according to the period length of the metasurface unit and the size of the metal cylinder to obtain a plurality of array-arranged patch areas; (3) using the generalized reflection law as a guide to calculate the electromagnetic reflection phase gradient of each patch area to determine the structural parameters of the metal patch in the metasurface unit in each patch area; (4) optimizing the size parameters of the metal patches in the metasurface unit using a trust region framework algorithm according to the variation range of the structural parameters and size parameters of the metal patches, so as to determine the size parameters of the metal patches in each patch area; (5) Based on the determined size parameters and structural parameters of the metal patch in each patch area, the metasurface unit is adhered to the surface of each patch area to obtain the echo enhancer based on the cylindrical conformal metasurface structure.

7. The method according to claim 6, characterized in that The structural parameters of each layer in the metasurface unit include the material and thickness of the metal bottom layer, the material, thickness, dielectric constant and loss tangent value of the dielectric layer.

8. The method according to claim 6, characterized in that The structural parameters of the metal patch include the size type and size variation rule of the metal patch.

9. The method according to claim 6, characterized in that The electromagnetic reflection phase gradient in each patch area is determined by the following formula: Where f0 is the target frequency, c is the speed of light, θ im is the incident angle of the electromagnetic wave, and Ф is the electromagnetic reflection phase gradient.

10. The method according to claim 6, characterized in that The reflection phase coverage range of the echo enhancer within the preset incident angle range of 0-60° exceeds 360°.

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