Low-profile ultra-wideband RCS-reduced polarization conversion metasurface

Abstract

The invention discloses a low-profile ultra-wideband RCS-reduced polarization conversion metasurface, the metasurface is formed by periodically arranging a plurality of metasurface units, and each metasurface unit is sequentially provided with a top layer structure, a middle layer structure and a bottom layer structure from top to bottom; the top layer structure comprises a first dielectric substrate and a first metal pattern patch attached to the upper surface of the first dielectric substrate, and the middle layer structure comprises a second dielectric substrate and a second metal pattern patch attached to the upper surface of the second dielectric substrate. And the bottom layer structure comprises a third dielectric substrate, and a third metal pattern patch and a fourth metal pattern patch which are respectively attached to the upper surface and the lower surface of the third dielectric substrate. The metasurface is formed by periodically arranging the designed metasurface units 0 and metasurface units 1, polarization conversion of electromagnetic waves is achieved, and the ultra-wideband RCS reduction effect is achieved; and meanwhile, the metasurface does not need to integrate other electronic elements, the structure is simple, the profile is very low, and the frequency band for realizing the RCS reduction effect is very wide.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial electromagnetic supersurfaces, and in particular to a low-profile ultra-wideband RCS-reduced polarization conversion supersurface. Background Art

[0002] With the continuous development of radar detection technology, it is crucial to improve the stealth performance of targets in electromagnetic environments. Reducing the RCS (Radar Cross Section) of a target helps reduce the possibility of the target being detected and identified by radar, thereby achieving a stealth effect.

[0003] The existing stealth technology has aerodynamic limitations in terms of shape design technology, and the stealth material coating technology also has shortcomings in terms of cost and maintenance. Therefore, it is of great significance to use artificial electromagnetic metasurfaces to reduce the RCS of the target.

[0004] Polarization conversion metasurface is a metasurface that can modulate the polarization direction of electromagnetic waves. It can rotate the polarization direction of the incident electromagnetic wave within a certain angle range, adjust the amplitude and phase, and maintain its linear polarization properties. Polarization conversion metasurface can effectively control the polarization state of the reflected electromagnetic wave within a certain range, thereby achieving the purpose of reducing RCS by using the cancellation of reflected waves and improving the stealth performance of the target. It has important research significance and wide application value in the military field. However, it is a hot issue worthy of research to fully realize the true application value of polarization conversion metasurface. In current research, there are still design difficulties such as high overall structural profile, wide RCS reduction bandwidth and high requirements for material processing technology. Summary of the invention

[0005] The problem to be solved by the present invention is to provide a low-profile ultra-wideband RCS-reduced polarization conversion metasurface, which is used to solve the problems of high overall structural profile of the polarization conversion metasurface in existing research, narrow metasurface RCS reduction band and high requirements on materials and processing technology.

[0006] The present invention adopts the following technical solution: a low-profile ultra-wideband RCS-reduced polarization conversion metasurface, which is formed by a periodic arrangement of multiple metasurface units, each of which has a top layer structure, a middle layer structure and a bottom layer structure arranged in sequence from top to bottom;

[0007] The top structure includes a first dielectric substrate and a first metal pattern patch attached to the upper surface of the first dielectric substrate;

[0008] The intermediate layer structure includes a second dielectric substrate and a second metal pattern patch attached to the upper surface of the second dielectric substrate;

[0009] The bottom layer structure comprises a third dielectric substrate and a third metal pattern patch and a fourth metal pattern patch respectively attached to the upper surface and the lower surface of the third dielectric substrate.

[0010] Preferably, the arrangement of the plurality of metasurface units is as follows: the metasurface unit is named as unit 0, unit 0 is rotated 90 degrees around the center to obtain unit 1, and unit 0 and unit 1 are periodically arranged to form a metasurface.

[0011] Preferably, the metasurface unit is square.

[0012] Preferably, the first metal pattern patch adopts a first equilateral L-shaped pattern patch and a rectangular pattern patch, and the first equilateral L-shaped pattern patch and the rectangular pattern patch are attached to the diagonal direction of the upper surface of the first dielectric substrate.

[0013] There are two first equilateral L-shaped pattern patches, including a first equilateral L-shaped 1 pattern patch and a second equilateral L-shaped 1 pattern patch; the first equilateral L-shaped 1 pattern patch and the second equilateral L-shaped 1 pattern patch have the same size on both sides; the first equilateral L-shaped 1 pattern patch and the second equilateral L-shaped 1 pattern patch have the same size; the rectangular pattern patch is located in the middle of the first equilateral L-shaped 1 pattern patch and the second equilateral L-shaped 1 pattern patch.

[0014] Preferably, the second metal pattern patch is a double-arrow pattern patch, and the double-arrow pattern patch is attached to the diagonal direction of the upper surface of the second dielectric substrate.

[0015] The double arrow pattern patch includes a first arrow pattern patch, a second arrow pattern patch and a rectangular connecting rod; the first arrow pattern patch and the second arrow pattern patch are of the same size; the vertex of the first arrow pattern patch is connected to one end of the rectangular connecting rod; the other end of the rectangular connecting rod is connected to the vertex of the second arrow pattern patch.

[0016] Preferably, the third metal pattern patch adopts a second equilateral L-shaped pattern patch, and the second equilateral L-shaped pattern patch is attached to the diagonal direction of the upper surface of the third dielectric substrate.

[0017] The second equilateral L-shaped pattern patch includes a first equilateral L-shaped 2-pattern patch and a second equilateral L-shaped 2-pattern patch; the first equilateral L-shaped 2-pattern patch and the second equilateral L-shaped 2-pattern patch have the same size on both sides; the first equilateral L-shaped 2-pattern patch and the second equilateral L-shaped 2-pattern patch have the same size.

[0018] Preferably, the fourth metal pattern patch is a square square ring pattern patch, and the square square ring pattern patch is attached to the lower surface of the third dielectric substrate.

[0019] Preferably, the first metal pattern patch, the second metal pattern patch, the third metal pattern patch and the fourth metal pattern patch are made of copper.

[0020] Preferably, the first dielectric substrate, the second dielectric substrate and the third dielectric substrate are Rogers 5880 high-frequency dielectric substrates, whose dielectric constant is 2.2.

[0021] Preferably, the thickness of the first metal pattern patch, the second metal pattern patch, the third metal pattern patch and the fourth metal pattern patch is 0.035mm; the thickness of the first dielectric substrate and the second dielectric substrate is H1=H2=1.5mm; the thickness of the third dielectric substrate is H3=0.5mm; the length of the first equilateral L-shaped pattern patch is L1=1.4mm; the length of the rectangular pattern patch is L2=1.6mm; the length of the first arrow pattern patch is L4=2.5mm; the length of the rectangular connecting rod is L3=6.2mm; the length of the second equilateral L-shaped pattern patch is L5=1.0mm.

[0022] The width of the first equilateral L-shaped pattern patch and the rectangular pattern patch is W1=0.2mm; the width of the first arrow pattern patch, the rectangular connecting rod and the first equilateral L-shaped pattern patch is W2=0.4mm; the width of the square ring pattern patch is W3=1.8mm.

[0023] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0024] 1. The polarization conversion unit designed in the present invention is composed of a metal pattern patch and an attached dielectric substrate. By optimizing the structural parameters, the polarization conversion unit has a very high polarization conversion efficiency in an ultra-wideband.

[0025] 2. The present invention forms a metasurface by periodically arranging the designed metasurface unit 0 and metasurface unit 1 to realize polarization conversion of electromagnetic waves and achieve an ultra-wideband RCS reduction effect.

[0026] 3. The metasurface structure designed in the present invention is simple, low-cost and easy to integrate with other electromagnetic devices. Compared with traditional designs, it does not require the integration of other electronic components. At the same time, the size of the dielectric substrate and the attached metal pattern patch does not have high requirements on the processing technology.

[0027] 4. The metasurface profile designed by the present invention is very low, but the frequency band for achieving the RCS reduction effect is very wide. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the three-dimensional structure of a single super surface unit of the present invention;

[0029] Figure 2 Schematic diagram of the top structure of a single super surface unit of the present invention;

[0030] Figure 3 is a schematic diagram of the intermediate layer structure of a single supersurface unit of the present invention;

[0031] Figure 4 Schematic diagram of the underlying structure of a single super surface unit of the present invention;

[0032] Figure 5 is a graph showing co-polarization and cross-polarization reflection coefficients of an embodiment of the present invention when electromagnetic waves are incident vertically;

[0033] Figure 6 is a graph showing the polarization conversion rate of an embodiment of the present invention when the electromagnetic wave is incident vertically;

[0034] Figure 7 1 is a reflection phase curve diagram of unit 0 and unit 1 when the electromagnetic wave is incident vertically in an embodiment of the present invention;

[0035] Figure 8 This is a reflection phase difference curve diagram of unit 0 and unit 1 when the electromagnetic wave is incident vertically in an embodiment of the present invention;

[0036] Fig. 9 A schematic diagram of a polarization conversion metasurface according to an embodiment of the present invention;

[0037] Fig.10 A schematic diagram of RCS reduction of a complete polarization conversion metasurface and a metal plate of equal size when electromagnetic waves are incident vertically according to an embodiment of the present invention;

[0038] Fig.11 This is a curve diagram of the RCS reduction of the complete polarization conversion metasurface of an embodiment of the present invention when the electromagnetic wave is incident vertically. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the application is further elaborated in detail below in conjunction with the accompanying drawings. The described embodiments are only part of the embodiments involved in the present invention. All non-innovative embodiments of other researchers in the field based on this embodiment belong to the protection scope of the present invention.

[0040] It should be noted that the use of terms such as "first", "second", "third" and "fourth" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0041] In one embodiment of the present invention, a low-profile ultra-wideband RCS-reduced polarization conversion metasurface includes a plurality of metasurface units;

[0042] The super surface unit, such as Figure 1 As shown, it includes a top layer structure 1 , a middle layer structure 2 below the top layer, and a bottom layer structure 3 below the middle layer structure 2 .

[0043] The top layer structure 1 includes a first dielectric substrate and a first metal pattern patch attached to the upper surface of the first dielectric substrate; the middle layer structure 2 includes a second dielectric substrate and a second metal pattern patch attached to the upper surface of the second dielectric substrate; the bottom layer structure 3 includes a third dielectric substrate and a third metal pattern patch and a fourth metal pattern patch respectively attached to the upper surface and lower surface of the third dielectric substrate.

[0044] The arrangement of multiple supersurface units is as follows: the supersurface unit is named unit 0, unit 0 is rotated 90 degrees around the center to obtain unit 1, and unit 0 and unit 1 are periodically arranged to form a supersurface.

[0045] In particular, in this embodiment, the super surface unit adopts a square shape.

[0046] The first metal pattern patch, such as Figure 2 As shown, equilateral L-shaped 1-pattern patches and rectangular pattern patches are used, and the equilateral L-shaped 1-pattern patches and rectangular pattern patches are attached to the diagonal direction of the upper surface of the first dielectric substrate.

[0047] The equilateral L-shaped 1 pattern patch includes: a first equilateral L-shaped 1 pattern patch and a second equilateral L-shaped 1 pattern patch; the first equilateral L-shaped 1 pattern patch and the second equilateral L-shaped 1 pattern patch have the same size on both sides; the first equilateral L-shaped 1 pattern patch and the second equilateral L-shaped 1 pattern patch have the same size; the rectangular pattern patch is located in the middle of the first equilateral L-shaped 1 pattern patch and the second equilateral L-shaped 1 pattern patch.

[0048] Among them, the length of the first equilateral L-shaped 1-pattern patch is L1, the length of the rectangular pattern patch is L2, the width of the first equilateral L-shaped 1-pattern patch and the rectangular pattern patch is W1, and the width of the first dielectric substrate is P.

[0049] The second metal pattern patch, such as Figure 3 As shown, a double-arrow pattern patch is used, and the double-arrow pattern patch is attached to the diagonal direction of the upper surface of the second dielectric substrate.

[0050] The double arrow pattern patch includes a first arrow pattern patch, a second arrow pattern patch and a rectangular connecting rod; the first arrow pattern patch and the second arrow pattern patch are of the same size; the vertex of the first arrow pattern patch is connected to one end of the rectangular connecting rod; the other end of the rectangular connecting rod is connected to the vertex of the second arrow pattern patch.

[0051] The length of the first arrow pattern patch is L4, the length of the rectangular connecting rod is L3, the width of the first arrow pattern patch and the rectangular connecting rod is W2, and the width of the second dielectric substrate is P.

[0052] The third metal pattern patch adopts an equilateral L-shaped 2 pattern patch, and the equilateral L-shaped 2 pattern patch is attached to the diagonal direction of the upper surface of the third dielectric substrate; the equilateral L-shaped 2 pattern patch includes a first equilateral L-shaped 2 pattern patch and a second equilateral L-shaped 2 pattern patch; the two sides of the first equilateral L-shaped 2 pattern patch and the second equilateral L-shaped 2 pattern patch have the same size; the first equilateral L-shaped 2 pattern patch and the second equilateral L-shaped 2 pattern patch have the same size.

[0053] Among them, the length of the first equilateral L-shaped 2-pattern patch is L5, and the width of the first equilateral L-shaped 2-pattern patch is W2.

[0054] Fourth metal pattern patch, such as Figure 4 As shown, a square square ring pattern patch is used, and the square square ring pattern patch is attached to the lower surface of the third dielectric substrate.

[0055] The width of the square ring pattern patch is W3, and the width of the third dielectric substrate is P.

[0056] Preferably, in this embodiment, the first metal pattern patch, the second metal pattern patch, the third metal pattern patch and the fourth metal pattern patch are made of copper with a thickness of 0.035 mm.

[0057] Preferably, in this embodiment, the thickness of the first dielectric substrate is H1, the thickness of the second dielectric substrate is H2, and the thickness of the third dielectric substrate is H3. The first dielectric substrate, the second dielectric substrate, and the third dielectric substrate are all Rogers 5880 high-frequency dielectric substrates, whose dielectric constant is 2.2, the loss tangent is 0.0009, and the thickness is H1=H2=1.5mm and H3=0.5mm.

[0058] Preferably, in this embodiment, the peripheral length of the polarization conversion unit is P=5 mm, and other unit geometric parameters are as follows: L1=1.4 mm, W1=0.2 mm, L2=1.6 mm, L3=6.2 mm, L4=2.5 mm, L5=1.0 mm, W2=0.4 mm, W3=1.8 mm.

[0059] Furthermore, this embodiment was tested using the three-dimensional electromagnetic field simulation software CST2023 version, with open (addspace) boundaries all around to simulate a complete metasurface, confirming that the metasurface of this embodiment has good characteristics, and the frequency sweep range was set to 8 to 42 GHz during the test.

[0060] The co-polarization and cross-polarization reflection coefficient curves when the electromagnetic wave is incident vertically, such as Figure 5 As shown, it can be seen that in this embodiment, within the frequency band range of 10.35 to 41.63 GHz, the co-polarization reflection coefficients are all below -10 dB, and within the frequency band range of 10.38 to 38.87 GHz, the cross-polarization reflection coefficients are all above -0.5 dB, confirming that the co-polarization component of the electromagnetic wave in this frequency band is converted into the cross-polarization component.

[0061] Since the metal patch on the metasurface unit is attached obliquely along the diagonal of the unit, when the x- or y-polarized wave is incident, the electromagnetic wave resonates with the same metal structure and exhibits the same reflection characteristics. However, for orthogonally polarized electromagnetic waves, different phase responses will be generated due to the different metal structures resonating in the diagonal direction of the metasurface unit. If the phase difference between the orthogonal polarized waves in the diagonal direction reaches ±180°, the conversion from linear polarization wave to orthogonal polarization wave is achieved. The polarization conversion efficiency PCR can be used to characterize the polarization conversion efficiency of the polarization conversion metasurface unit, and the expression is:

[0062]

[0063] In the formula, R yy represents the co-polarization reflection coefficient, the conversion of y-polarized incident wave to y-polarized reflected wave, R xy It represents the cross-polarization reflection coefficient, which is the conversion of the y-polarized incident wave to the x-polarized reflected wave. The meaning of PCR is the ratio of the energy of the electromagnetic wave that undergoes polarization conversion to the total energy of the incident wave.

[0064] The polarization conversion rate curve when the electromagnetic wave is incident vertically is as follows: Figure 6 As shown in FIG. 1 , it can be seen that in the frequency band range of 9.6 to 41.0 GHz, the polarization conversion rate PCR of this embodiment is greater than 0.9, and Figure 5 The frequency bands of the co-polarization and cross-polarization reflection coefficients are basically consistent.

[0065] The reflection phase curves of unit 0 and unit 1 when the electromagnetic wave is incident vertically in this embodiment are as follows: Figure 7 As shown; the reflection phase difference curve of unit 0 and unit 1 when the electromagnetic wave is incident vertically, as shown Figure 8 shown.

[0066] It can be seen that the reflection phase difference between unit 0 and unit 1 in this embodiment is about ±180°, which proves that the co-polarization component of the electromagnetic wave in this frequency band is converted into the cross-polarization component.

[0067] The polarization conversion metasurface of this embodiment is as follows Fig. 9As shown, unit 0 is composed of 20×20 metaspores, named 0, unit 1 is composed of 20×20 metaspores, named 1, and the metaspores numbered 0 and 1 are arranged alternately, finally forming a complete hypersurface with a checkerboard-like number of 40×40 units.

[0068] The RCS reduction of the complete polarization conversion metasurface and the metal plate of the same size when the electromagnetic wave is perpendicularly incident, such as Fig.10 When electromagnetic waves are incident vertically, the RCS of metal plates of equal size increases steadily with increasing frequency, while the RCS reduction of the metasurface is basically based on Figure 5 The co-polarization and cross-polarization reflection coefficient curves change when the electromagnetic wave is vertically incident. The frequency where the reduction is larger corresponds to the resonance point in the reflection coefficient curve, which has a significant RCS reduction effect compared with metal plates of the same size.

[0069] The RCS reduction curve of the complete polarization conversion metasurface when the electromagnetic wave is incident vertically, such as Fig.11 As shown in FIG. 1 , it can be seen that the RCS reduction of this embodiment in the 11.2-40.6 GHz frequency band exceeds 10 dB, and Figure 6 The frequency band range where the polarization conversion rate is greater than 0.9 is basically consistent.

[0070] It can be seen that this embodiment designs a low-profile ultra-wideband RCS-reduced polarization conversion metasurface by utilizing multi-layer polarization conversion units. When the metasurface has a thin profile of only 3.5 mm, an RCS reduction effect of more than 10 dB can be achieved in an ultra-wide frequency range. The manufacturing process is simple and it has the characteristics of high performance and low cost.

[0071] In summary, the present invention designs a low-profile ultra-wideband RCS-reduced electromagnetic metasurface using a polarization conversion unit, wherein the polarization conversion unit has a very high polarization conversion efficiency in the ultra-wideband, does not need to integrate other electronic components, and the designed metasurface has a very low profile, but the frequency band for achieving the RCS reduction effect is very wide.

[0072] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low-profile ultra-wideband RCS-reduced polarization conversion metasurface, characterized in that: The polarization conversion metasurface is formed by a periodic arrangement of multiple metasurface units, and each metasurface unit is sequentially arranged with a top layer structure, a middle layer structure and a bottom layer structure from top to bottom; The top structure includes a first dielectric substrate and a first metal pattern patch attached to the upper surface of the first dielectric substrate; The intermediate layer structure includes a second dielectric substrate and a second metal pattern patch attached to the upper surface of the second dielectric substrate; The bottom layer structure comprises a third dielectric substrate and a third metal pattern patch and a fourth metal pattern patch respectively attached to the upper surface and the lower surface of the third dielectric substrate.

2. The low-profile ultra-wideband RCS-reduced polarization conversion metasurface according to claim 1, characterized in that: The arrangement of multiple metasurface units is as follows: the metasurface unit is regarded as unit 0, unit 0 is rotated 90 degrees around the center to obtain unit 1, and unit 0 and unit 1 are arranged periodically to form the polarization conversion metasurface to perform polarization conversion of electromagnetic waves.

3. The low-profile ultra-wideband RCS-reduced polarization conversion metasurface according to claim 2, characterized in that: The super surface unit is in the form of a square.

4. The low-profile ultra-wideband RCS-reduced polarization-conversion metasurface according to claim 1, characterized in that: The first metal pattern patch includes two first equilateral L-shaped pattern patches and one rectangular pattern patch; The two first equilateral L-shaped pattern patches have the same size and are respectively attached to a diagonal edge of the upper surface of the first dielectric substrate; the rectangular pattern patch is arranged in the middle of the two first equilateral L-shaped pattern patches and is attached to the diagonal direction of the other diagonal of the upper surface of the first dielectric substrate.

5. The low-profile ultra-wideband RCS-reduced polarization conversion metasurface according to claim 4, characterized in that: The second metal pattern patch is a double-arrow pattern patch, attached to the diagonal side of the upper surface of the second dielectric substrate; The double arrow pattern patch includes a first arrow pattern patch, a second arrow pattern patch and a rectangular connecting rod; the first arrow pattern patch and the second arrow pattern patch have the same size; the two ends of the rectangular connecting rod respectively connect the vertices of the first arrow pattern patch and the second arrow pattern patch.

6. The low-profile ultra-wideband RCS-reduced polarization conversion metasurface according to claim 5, characterized in that: The third metal pattern patch includes two second equilateral L-shaped pattern patches of the same size, and the two second equilateral L-shaped pattern patches are attached to the diagonal direction of the upper surface of the third dielectric substrate.

7. The low-profile ultra-wideband RCS-reduced polarization-conversion metasurface according to claim 6, characterized in that: The fourth metal pattern patch is a square ring pattern patch and is attached to the lower surface of the third dielectric substrate.

8. The low-profile ultra-wideband RCS-reduced polarization-conversion metasurface according to claim 1, characterized in that: The first metal pattern patch, the second metal pattern patch, the third metal pattern patch and the fourth metal pattern patch are made of copper.

9. The low-profile ultra-wideband RCS-reduced polarization-conversion metasurface according to claim 1, characterized in that: The first dielectric substrate, the second dielectric substrate and the third dielectric substrate are Rogers 5880 high-frequency dielectric substrates with a dielectric constant of 2.

2.

10. The low-profile ultra-wideband RCS-reduced polarization conversion metasurface according to claim 7, characterized in that: The thickness of the first metal pattern patch, the second metal pattern patch, the third metal pattern patch and the fourth metal pattern patch are all 0.035mm; the thickness of the first dielectric substrate and the second dielectric substrate are both 1.5mm; the thickness of the third dielectric substrate is 0.5mm; the length of the first equilateral L-shaped pattern patch is 1.4mm; the length of the rectangular pattern patch is 1.6mm; the length of the first arrow pattern patch is 2.5mm; the length of the rectangular connecting rod is 6.2mm; the length of the second equilateral L-shaped pattern patch is 1.0mm; the width of the first equilateral L-shaped pattern patch and the rectangular pattern patch is 0.2mm; the width of the first arrow pattern patch, the rectangular connecting rod and the second equilateral L-shaped pattern patch is 0.4mm; the width of the square ring pattern patch is 1.8mm.

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