Metasurface-based rectangular-circular waveguide mode conversion device and method

Abstract

The invention discloses a metasurface-based rectangular-circular waveguide mode conversion device and a metasurface-based rectangular-circular waveguide mode conversion method, which are used for realizing TE10-TE20-TE01 metal waveguide mode conversion, and comprise a first section of waveguide, a second section of waveguide, a third section of waveguide, a fourth section of waveguide, a fifth section of waveguide, a first metasurface structure and a second metasurface structure, wherein the first, third and fifth sections of waveguides are respectively used for transmitting a rectangular waveguide TE10 mode, a rectangular waveguide TE20 mode and a circular waveguide TE01 mode, and the second and fourth sections of waveguides are used for generating multimode interference; the first metasurface structure is used for realizing conversion from a TE10 mode to a TE20 mode, and the second metasurface structure is used for realizing conversion from the TE20 mode to a TE01 mode; the second section of waveguide, the first metasurface structure and the third section of waveguide form a TE10-TE20 mode converter; and the fourth section of waveguide and the second metasurface structure form a TE20-TE01 mode converter. By utilizing the regulation and control capability of the metasurface on the electromagnetic field, the rectangular waveguide TE10 mode can be converted into the circular waveguide TE01 mode in a relatively small space.

Description

Technical Field

[0001] The present invention relates to the field of supersurface technology and vacuum electronic device technology, and in particular to a device and method for converting a rectangular circular waveguide mode based on a supersurface. Background Art

[0002] Mode converter is an indispensable and important component of high-power devices. It can realize the conversion from fundamental mode to high-order mode and from rectangular waveguide to circular waveguide, and is widely used in millimeter wave antenna, satellite communication transmitter, high-power satellite radar and other application fields. 01 The mode has a wide range of applications in vacuum electronic devices, especially gyrotrons, due to its azimuthal symmetry of the electric field and low energy loss near the inner wall. m0 Mode (m = 2, 3, 4, ...) has a high application prospect in microwave devices because of its large size, simple processing and high power capacity performance. High-order mode is usually transformed from low-order mode, i.e. circular waveguide TE 11 Mode and rectangular waveguide TE 10 mode. Therefore, the conversion from fundamental mode to higher-order mode is crucial. There are many methods to convert the fundamental mode of rectangular waveguide to the higher-order mode of circular waveguide. Marie-type mode converter is a common conversion method. On this basis, the TE of the gradient of long waveguide structure is 10 -TE 01 Mode conversion devices also have many applications. It is worth mentioning that TE 20 mode can be used as a rectangular waveguide TE 10 Mode Circular Waveguide TE 01 In addition, there is also a method based on 1-4-1 power division to realize gyrotron TE 01 Mode conversion method. It is known that the modes of rectangular waveguides are highly correlated and the conversion is one-dimensional. 10 -TE 20 The conversion can be performed by gradient waveguides designed by microwave theory.

[0003] The current field of metal waveguide mode conversion has the following shortcomings: first, the waveguide design for mode conversion is too long, not compact enough, and occupies a large space area. Second, the design of the waveguide structure is complex, too many parameters need to be determined, the calculation is large, and it is not easy to make. Therefore, a simple and compact mode conversion device is urgently needed.

[0004] In recent years, metasurfaces have attracted more and more attention due to their ultra-small design structure and powerful ability to manipulate the phase, amplitude and polarization of electromagnetic waves. It can regulate free-space light and gradually expand its role to the field of integrated optics. In addition, in the field of optical fibers, metasurface mode converters can convert the transverse electric field mode TE01 or transverse magnetic field mode TM 01 Mode conversion to orthogonal polarization fundamental mode LP 01 Many related studies have been conducted in the field of vacuum electronics. For example, based on the phase control capability of metasurfaces, circular waveguide TE 01 The mode can be transformed into a circularly polarized Gaussian beam. Therefore, the metasurface can be used in the design of small microwave power modules. Summary of the invention

[0005] The object of the present invention is to provide a device and method for converting the mode of a rectangular circular waveguide based on a metasurface.

[0006] The technical solution to achieve the purpose of the present invention is: a rectangular waveguide mode conversion device based on a metasurface, used to realize TE 10 -TE 20 -TE 01 Metal waveguide mode conversion, including first to fifth waveguide sections, and first to second metasurface structures, wherein:

[0007] The first, third and fifth waveguide sections are used to transmit rectangular waveguide TE 10 Mode, rectangular waveguide TE 20 Mode and Circular Waveguide TE 01 mode, the second and fourth waveguides are used to generate multimode interference; the first metasurface structure is used to realize TE 10 Mode to TE 20 Mode transformation, the second metasurface structure is used to achieve TE 20 Mode to TE 01 Mode transformation; the second waveguide, the first metasurface structure and the third waveguide constitute TE 10 -TE 20 Mode converter; the fourth waveguide and the second metasurface structure constitute TE 20 -TE 01 Mode converter.

[0008] Furthermore, the first section of the waveguide is a rectangular waveguide with a size of 3.56 mm×7.12 mm×20 mm. The material of the first section of the waveguide is metal copper with an electrical conductivity of 2e7 S / m.

[0009] Furthermore, the second section of the waveguide is a rectangular waveguide with a size of 3.56 mm×14.23 mm×5.5 mm. The material of the second section of the waveguide is metallic copper with an electrical conductivity of 2e7 S / m.

[0010] Furthermore, the third section of the waveguide is a rectangular waveguide, the size of the third section of the waveguide is 3.56 mm×14.23 mm×5 mm, the material of the third section of the waveguide is metal copper, and the conductivity is 2e7 S / m.

[0011] Furthermore, the fourth waveguide section is a circular waveguide, the length of the fourth waveguide section is 5.6 mm, and the radius thereof is 8 mm.

[0012] Furthermore, the fifth waveguide is a circular waveguide with a length of 0.5 mm and a radius of 8 mm.

[0013] Furthermore, the first metasurface structure includes 8 perforated structural units and 8 non-perforated structural units, which are located on the left and right sides respectively. The metasurface unit structure period is 1.77mm and the height is 3mm. The perforation radius of the perforated metasurface unit structure is 0.8mm. The material of the first metasurface structure is aluminum oxide, and its dielectric constant ε is 9.4.

[0014] Furthermore, the second metasurface structure is a three-layer structure of metal-dielectric-metal. The two metal layers have the same structure. Each metal structure is composed of 9 rotated and overlapped metal rods. The length of the metal rods is 16 mm, the width is 0.5 mm, and the thickness is 5 um. The distribution characteristics of the 9 metal rods are as follows: the midpoints of the 9 metal rods coincide with the center of the dielectric layer structure, and the angle between each metal rod is 90°. The overall distribution of the metal structure is radial, and the length direction of the metal rods is distributed radially. The dielectric layer is aluminum oxide with a dielectric constant of ε=9.4, a thickness of 1.6 mm, and a radius of 17 mm.

[0015] Furthermore, the mode transformation process is as follows:

[0016] TE excited by the incident port 10 The mode is converted into TE after passing through the first waveguide, the second waveguide and the first metasurface structure. 20 mode, resulting in TE 20 After the mode passes through the second metasurface structure and then through the third and fourth waveguides, it is modulated by the second metasurface structure and finally generates a circular waveguide TE. 01 Mode;TE 10 The mode passes through the fifth waveguide and is finally output from the output port.

[0017] A method for converting a rectangular waveguide mode based on a metasurface, through which a rectangular waveguide mode conversion device based on a metasurface is used to realize TE 10 -TE 01 mode change.

[0018] Compared with the prior art, the present invention adopts the above technical solution, which has the following technical effects: using the ability of the metasurface to regulate the electromagnetic field, a rectangular waveguide TE can be realized in a smaller space. 10 Mode transformation into circular waveguide TE 01A device and method for modulating a mode, which modulates a guided electromagnetic wave by combining a transition waveguide with a metasurface structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the modes and their transformation process in the present invention; according to the transformation process, they are respectively: TE 10 Mode, TE 20 Mode, TE 20 Mode, TE 21 Mode, TE 01 model.

[0020] Figure 2 TE in the present invention 10 -TE 01 Schematic diagram of the mode converter structure.

[0021] Figure 3 It is the implementation class TE designed in the present invention 20 Mode conversion to TE 20 The supersurface unit structure diagram of the pattern and the topological diagram of the supersurface structure; among them, (a) is the supersurface unit structure diagram, and (b) is the topological diagram of the first supersurface structure.

[0022] Figure 4 It is a relationship diagram between the ratio of the radius size to the wavelength and the phase in the super surface unit structure of the present invention.

[0023] Figure 5 TE in the present invention 10 -TE 20 S-parameters of the mode converter and the energy distribution inside the waveguide.

[0024] Figure 6 The different radius values ​​of the super surface unit structure in the present invention are related to TE 10 -TE 20 Relationship between the S parameters of the mode converter.

[0025] Figure 7 It is the implementation class TE designed in the present invention 21 Mode conversion to TE 01 The supersurface structure diagram of the mode and the electric field intensity distribution diagram when placed in a waveguide; among them, (a) is the topological diagram of the second supersurface structure, and (b) is the electric field intensity distribution diagram in the waveguide.

[0026] Figure 8 TE in the present invention 20 -TE 01 S-parameters of the mode converter and the energy distribution inside the waveguide.

[0027] Fig. 9 In the present invention, TE 10 -TE 20 Mode converter and TE 20 -TE 01 S-parameters after the mode converter and energy distribution in the waveguide. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] The present invention discloses a rectangular waveguide mode conversion device based on a metasurface, which utilizes the control capability of the metasurface on the electromagnetic field to realize rectangular waveguide TE in a smaller space. 10 Mode transformation into circular waveguide TE 01 mode, modulating the guided electromagnetic wave by combining the transition waveguide with the metasurface structure.

[0030] A rectangular waveguide mode conversion device based on a metasurface, using TE 10 -TE 20 -TE 01 The metal waveguide mode conversion system consists of five waveguide sections and two metasurface structures. The first, third and fifth waveguide sections are used to transmit rectangular waveguide TE 10 Mode, rectangular waveguide TE 20 Mode and Circular Waveguide TE 01 mode, the second and fourth waveguides are used to generate multimode interference. The first metasurface is used to realize TE 10 Mode to TE 20 The second metasurface is used to realize TE 20 Mode to TE 01 Change of mode.

[0031] The second waveguide, the first metasurface structure and the third waveguide constitute TE 10 -TE 20 Mode converter. The second and third waveguides are rectangular waveguides. The dimensions of the second waveguide are: 3.56mm×14.23mm×5.5mm. The dimensions of the third waveguide are 3.56mm×14.23mm×5mm. The three waveguide structures are made of copper metal with a conductivity of 2e7 S / m. The first metasurface structure consists of 8 perforated structural units and 8 non-perforated structural units, located on the left and right sides respectively. Its material is alumina with a dielectric constant ε of 9.4. The period of the metasurface unit structure is 1.77mm, the height is 3mm, and the perforation radius of the perforated metasurface unit structure is 0.8mm.

[0032] The fourth waveguide and the second metasurface structure form TE20 -TE 01 Mode converter. The fourth waveguide is a circular waveguide with a length of 5.6 mm and a radius of 8 mm. The second metasurface unit structure is composed of a metal-medium-metal three-layer structure. The two metal layers have the same structure. It is composed of 9 metal rods, with a metal length of 16 mm, a width of 0.5 mm, and a thickness of 5 um. The distribution characteristics of the nine metal rods are as follows: the midpoints of the nine metal rods coincide with the center of the dielectric layer structure, and the angle between each metal rod is 90°, that is, the overall distribution is radial, and the length direction of the metal rods is distributed radially.

[0033] The first waveguide is a rectangular waveguide with a size of 3.56 mm × 7.12 mm × 20 mm, which is used to transmit TE 10 The fifth waveguide is a circular waveguide with a length of 0.5 mm and a radius of 8 mm. It is used to transmit TE 01 Mode. The dielectric layer is aluminum oxide, with a dielectric constant of ε = 9.4, a thickness of 1.6 mm, and a radius of 17 mm.

[0034] The five segmented waveguides and two metasurface structures constitute TE 10 -TE 20 -TE 01 Metal waveguide mode conversion system, the mode conversion process is as follows:

[0035] Rectangular waveguide TE excited by the incident port 10 The mode is transmitted through the first waveguide to the second waveguide, where the electromagnetic field generates multimode interference, thus generating a TE-like 20 mode, after passing through the first metasurface structure, is converted into a rectangular waveguide TE 20 mode, resulting in TE 20 The mode is transmitted to the second metasurface through the third and fourth waveguides, and is modulated by the second metasurface structure to finally generate a circular waveguide TE. 01 Mode;TE 10 The mode passes through the fifth waveguide and is finally output from the output port.

[0036] Example

[0037] Rectangular waveguide TE 10 Mode and circular waveguide TE 01 modes are very different, so a rectangular waveguide TE is required 20 Mode is used as a transition mode to achieve the conversion between the two modes, such as Figure 1As shown, L1, a, b represent the length, width and height of waveguide 1 respectively; L2, w1, h1 represent the length, width and height of waveguide 2 respectively; L3, w2, h2 represent the length, width and height of metasurface 1 respectively; L4 represents the length of waveguide 3, and its width and height are the same as those of waveguide 2; L5 represents the length of waveguide 4, and R represents the radius of waveguide 4; L6 represents the length of metasurface 2; L7 represents the length of waveguide 5, and its radius is the same as that of waveguide 4. TE 20 The generation of modes can be achieved through dual images produced by multimode interference of the waveguide and phase modulation of the metasurface.

[0038] The new TE designed 10 -TE 20 -TE 01 Metallic waveguide mode conversion systems such as Figure 2 Waveguide 1, waveguide 3 and waveguide 5 are used to transmit TE 10 TE 20 and TE 01 mode, waveguide 2 and waveguide 4 are used to generate multimode interference.

[0039] Designed TE 10 -TE 01 The mode converter consists of two parts. The first part is through TE 10 -TE 20 Mode converter from rectangular waveguide TE 10 Mode conversion to rectangular waveguide TE 20 mode, the mode converter consists of waveguide 1, waveguide 2, metasurface 1 and waveguide 3. TE excited by port 1 10 The mode is converted to TE through waveguide 1, waveguide 2 and metasurface 1 20 mode. The second part is through TE 20 -TE 01 Mode converter from TE 20 Mode conversion to TE 01 mode, the mode converter consists of a waveguide 4, a metasurface 2 and a waveguide 5. TE 20 The mode is converted into the required circular waveguide TE through the waveguide 4 and the metasurface 2 01 mode and is finally output by waveguide 5.

[0040] In TE 10 -TE 20 In the process of mode conversion, the metasurface 1 composed of a perforated alumina unit structure and a solid alumina structure is used to realize the transition from TE to 10 Mode to TE 20The inner dimensions of waveguide 1 and waveguide 2 are 3.56 mm × 7.12 mm × 20 mm and 3.56 mm × 14.23 mm × 5.5 mm, respectively. 10 and TE 20 The electric field of the modes can be characterized by the formulas: Where ω is the frequency of the electromagnetic wave, A 10 and A 20 is the electromagnetic field intensity, kc is the cutoff wave number, and β is the propagation constant. Waveguide 1 and waveguide 2 were simulated based on CST electromagnetic simulation software. The simulated electric field distribution is close to the standard TE 20 mode. But the polarization directions on both sides are the same, which can be expressed as: It should be noted that the absolute value in the formula indicates that the polarization direction of the electric field on the left and right sides of the central axis of the waveguide 2 cross section is the same. Therefore, the formula is converted into the standard TE 20 The mode can take advantage of the flexible phase control capability of metamaterials.

[0041] Figure 3 (b) is the designed alumina metasurface 1 structure, which consists of 16 unit structures and a peripheral dielectric layer, with 8 perforated structures and 8 non-perforated structures on the left and right sides respectively. The dielectric constant ε of alumina is 9.4. The period of the metasurface unit structure is 1.77 mm and the height is 3 mm. Figure 3 (a). The unit structure is simulated using CST electromagnetic simulation software. The relationship between r / λ and phase is shown in Figure 4 As shown. The curves corresponding to different frequencies are basically parallel, indicating that the designed metasurface has stable performance. In order to achieve an approximate π phase shift in the frequency range of 29-34GHz and obtain better simulation results, the radius of the punched part of the designed metasurface 1 is 0.8mm. At a center frequency of 32GHz, an aperture with a radius of 0.8mm cannot achieve a complete π phase change. However, it can still achieve mode conversion. This is because there is a certain phase deviation in the multi-mode interference before the metasurface 1, and it is impossible to achieve a complete TE-like 20 model.

[0042] The modulation process of the electromagnetic field in the waveguide can be summarized as follows: when the electromagnetic wave passes through the transition section at both ends of the waveguide, the electromagnetic field is divided into two directions due to the sudden change of the waveguide 2 structure. It can be clearly seen that when it passes through the precisely designed metasurface 1 structure, the electromagnetic wave on the left is modulated by the metasurface 1, and the phase passing on the left side is π more than the phase passing on the right side. Finally, when the guided electromagnetic wave completely passes through the metasurface structure, perfect TE can be achieved. 20 Mode.TE 10 -TE 20 The s-parameter simulation results of the mode transformation are as follows Figure 5 As shown. The optimized reflection S11 It has good performance in the frequency range of 31.5~32.9GHz, and the conversion efficiency is S 21 It has good conversion performance in the frequency range of 31.6~33.4GHz.

[0043] It is worth noting that the simulation results also show that the length of the waveguide (L4) does not affect the S-parameters, which indicates that the system can be more compact when a shorter L4 is adopted.

[0044] TE20-TE01 mode conversion and TE based on phase modulation 10 -TE 20 Mode conversion is different, TE 20 -TE 01 The mode conversion uses a metal-dielectric-metal supersurface structure, in which the metal structure is a copper structure with an electrical conductivity of 2e7S / m.

[0045] TE 01 The electric field distribution can be expressed as: E ρ =0, E z =0. In the formula, A represents the electric field intensity, J′0 represents the first-order zero-order Bessel function. It can be seen that the polarization direction of the electric field at each point in the waveguide is perpendicular to the radial direction. Therefore, the principle of metal layer design is the metal structure along the radial direction. Figure 7 As shown in (a), in the designed metal-dielectric-metal metasurface structure, the metal layer is composed of nine identical metal rods, each of which is 16 mm long and 0.5 mm wide. All metal blocks have the same center point, which is located at the center of the second layer in the XY plane, and the spacing between the metal sheets and the adjacent metal sheets is 20°. The bottom and top layers are designed the same. The dielectric layer is aluminum oxide, with a dielectric constant of ε = 9.4, a thickness of 1.6 mm, and a radius of 17 mm.

[0046] As we all know, when the polarization direction of the electromagnetic wave is the same as the distribution direction of the metal sheet, the electromagnetic wave will be transmitted. On the contrary, when the polarization direction of the electromagnetic wave is opposite to the distribution direction of the metal sheet, the electromagnetic wave will be reflected. Therefore, the metal layer of the metasurface 2 is radial, which is similar to TE 01 The electric field polarization directions of the modes are completely opposite. Figure 7 (a) is shown. TE 20 -TE 01 The simulation results of the mode converter are shown in Figure 8 As shown. The optimized S 11 It has good performance in the frequency range of 31.6~32.6GHz. 21 It has good performance in the frequency range of 31.4 to 33 GHz.

[0047] The parameters of the two metasurface structures are adjusted to ensure that the optimal operating frequency of the two structures is the same. In this way, when the two converters are integrated into one system, the same power conversion efficiency can be achieved from rectangular waveguide TE 10 Mode to circular waveguide TE 01 The highest conversion rate of the mode.

[0048] Five segmented waveguides and two metasurface structures are connected into one system. The whole mode conversion process is as follows: When the TE excited by the incident port 10 After passing through waveguide 2 and metasurface 1, the mode is converted into TE 20 Mode. The generated TE 20 After the mode passes through metasurface 2 and then through waveguide 3 and waveguide 4, it is modulated by metasurface 2 and finally generates a circular waveguide TE 01 mode. The latter passes through waveguide 5 and is finally output from port 2. TE 10 -TE 01 The overall length of the mode converter is 20.7 mm.

[0049] Fig. 9 is the result of simulating the entire structure. 11 At 31.8 ～ The reflection coefficient is small in the 32.9GHz frequency range, S 21 At 31.4 ～ It has a high conversion coefficient in the 33GHz frequency range. Compared with existing research, it can achieve a high transmission coefficient in a narrow but acceptable bandwidth. Compared with other similar works, its conversion efficiency can reach a higher level and its overall structure is very compact.

[0050] The structure of this embodiment is made of aluminum oxide TE 10 -TE 20 Metasurface mode converter, copper-aluminum-copper TE 20 -TE 01 It consists of a mode converter and several waveguide structures. 10 -TE 20 The metasurface mode converter consists of eight perforated alumina metasurface unit structures and eight solid alumina material structures. 20 -TE 01 The mode converter consists of an aluminum oxide dielectric layer and copper films on both sides. 10 The mode is transferred from waveguide 1 to waveguide 2, and self-imaging is generated due to multi-mode interference to form a TE-like 20 Mode.TE 10 -TE 20 The mode converter achieves TE by modulating the phase to achieve a phase shift of π. 10 -TE20 Transformation. The resulting TE 20 The mode is transferred from waveguide 3 to waveguide 4 to generate TE-like 21 Mode, TE-like 21 Mode by TE 20 -TE 01 The mode converter generates phase redistribution to achieve TE 20 -TE 01 The cascade of two metasurface structures and transition waveguide structures ultimately achieves TE 10 -TE 01 mode change.

[0051] In summary, the present invention can pave the way for the miniaturization and integration of mode converters by replacing complex waveguide structures with metasurface structures. This design method can also be extended to various applications, including the design of vacuum electronic devices and satellite specific mode transmitters.

[0052] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A rectangular waveguide mode conversion device based on a metasurface, characterized in that: To achieve TE 10 -TE 20 -TE 01 Metal waveguide mode conversion, including first to fifth waveguide sections, and first to second metasurface structures, wherein: The first, third and fifth waveguide sections are used to transmit rectangular waveguide TE 10 Mode, rectangular waveguide TE 20 Mode and Circular Waveguide TE 01 mode, the second and fourth waveguides are used to generate multimode interference; the first metasurface structure is used to realize TE 10 Mode to TE 20 Mode transformation, the second metasurface structure is used to achieve TE 20 Mode to TE 01 Mode transformation; the second waveguide, the first metasurface structure and the third waveguide constitute TE 10 -TE 20 Mode converter; the fourth waveguide and the second metasurface structure constitute TE 20 -TE 01 Mode converter.

2. The device for converting a rectangular circular waveguide mode based on a metasurface according to claim 1, characterized in that: The first section of waveguide is a rectangular waveguide with a size of 3.56 mm×7.12 mm×20 mm. The material of the first section of waveguide is metal copper with an electrical conductivity of 2e7 S / m.

3. The device for converting a rectangular waveguide mode based on a metasurface according to claim 1, characterized in that: The second waveguide section is a rectangular waveguide with dimensions of 3.56 mm × 14.23 mm × 5.5 mm. The material of the second waveguide section is metallic copper with a conductivity of 2e7 S / m.

4. The device for converting a rectangular circular waveguide mode based on a metasurface according to claim 1, characterized in that: The third section of the waveguide is a rectangular waveguide, the size of the third section of the waveguide is 3.56mm×14.23mm×5mm, the material of the third section of the waveguide is metal copper, and the conductivity is 2e7 S / m.

5. The device for converting a rectangular waveguide mode based on a metasurface according to claim 1, characterized in that: The fourth waveguide section is a circular waveguide, the length of the fourth waveguide section is 5.6 mm, and the radius thereof is 8 mm.

6. The device for converting a rectangular circular waveguide mode based on a metasurface according to claim 1, characterized in that: The fifth waveguide is a circular waveguide with a length of 0.5 mm and a radius of 8 mm.

7. The device for converting a rectangular circular waveguide mode based on a metasurface according to claim 1, characterized in that: The first metasurface structure includes 8 perforated structural units and 8 non-perforated structural units, which are located on the left and right sides respectively. The metasurface unit structure period is 1.77mm and the height is 3mm. The perforation radius of the perforated metasurface unit structure is 0.8mm. The material of the first metasurface structure is aluminum oxide, and its dielectric constant ε is 9.

4.

8. The device for converting a rectangular circular waveguide mode based on a metasurface according to claim 1, characterized in that: The second metasurface structure is a three-layer structure of metal-dielectric-metal. The two metal layers have the same structure. Each metal structure is composed of 9 rotated and overlapped metal rods. The length of the metal rod is 16mm, the width is 0.5mm, and the thickness is 5um. The distribution characteristics of the 9 metal rods are as follows: the midpoints of the 9 metal rods coincide with the center of the dielectric layer structure, and the angle between each metal rod is 90°. The overall distribution of the metal structure is radial, and the length direction of the metal rods is distributed radially. The dielectric layer is aluminum oxide with a dielectric constant of ε=9.4, a thickness of 1.6mm, and a radius of 17mm.

9. The device for converting a rectangular circular waveguide mode based on a metasurface according to claim 1, characterized in that: The mode conversion process is as follows: TE excited by the incident port 10 The mode is converted into TE after passing through the first waveguide, the second waveguide and the first metasurface structure. 20 mode, resulting in TE 20 After the mode passes through the second metasurface structure and then through the third and fourth waveguides, it is modulated by the second metasurface structure and finally generates a circular waveguide TE. 01 Mode;TE 10 The mode passes through the fifth waveguide and is finally output from the output port.

10. A method for converting rectangular waveguide modes based on a metasurface, characterized in that: By using the metasurface-based rectangular waveguide mode conversion device according to any one of claims 1 to 9, TE is realized 10 -TE 01 mode change.

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