Complete polarization omnidirectional matching retroreflector based on optical cavity material

Abstract

The invention discloses a complete polarization omnidirectional matching retroreflector based on an optical cavity material. The fully-polarized omnidirectional matching retroreflector is mainly composed of a metal shell, the metal shell is a concave block, the end faces of two convex parts of the metal shell face the incidence direction of external electromagnetic waves and serve as the input end and the output end of the fully-polarized omnidirectional matching retroreflector respectively, and a TM wave air tunnel group and a TE wave air tunnel group which are hollow are formed in the metal shell. The whole TM wave air tunnel group and the whole TE wave air tunnel group are concave blocks consistent with the metal shell in shape, and the TM wave air tunnel group and the TE wave air tunnel group are communicated to the output end from the input end of the fully-polarized omnidirectional matching retroreflector. The device is simple in structure, can be realized only through metal, can work for full-polarization full-angle incident waves, and can be widely applied to the fields of radar target modeling, sensing and the like.

Description

Technical Field

[0001] The invention belongs to the field of artificial electromagnetic media, and in particular relates to a fully polarized omnidirectional matching retroreflector based on optical cavity materials. Background Art

[0002] Retroreflectors are able to reflect incident light back to its source. When reflected, the light is parallel to the direction in which it was emitted, but in the exact opposite direction. A corner-cone retroreflector is a device that is able to reflect incident electromagnetic waves back at a large oblique angle. Traditional corner-cone retroreflectors use two or three spatial metal plates (such as dihedrons or trihedrons) to reflect the incident waves. Corner-cone retroreflectors are widely used in many fields such as laser tracking, optical communications, radar target modeling and sensing.

[0003] In recent years, flexible corner-box retroreflectors have attracted extensive attention, and some related devices have been intensively studied, such as mechanical flexible corner-box retroreflectors and planar metasurface reflectors. However, planar retroreflectors that work for fully polarized incident waves with wide incident angles and significant operating bandwidth still face many technical challenges. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the present invention provides a fully polarized omnidirectional matching retro reflector based on optical cavity materials, which is constructed by a concave metal with an air tunnel to satisfy the conditions of an effective medium in terms of dielectric constant and magnetic permeability, and to make the propagation speed of electromagnetic waves of a specific frequency incident from an input end in the medium infinite. The material formed by the present invention can reflect the fully polarized wave back along the incident direction without a phase change.

[0005] The technical solution adopted by the present invention is as follows:

[0006] The fully polarized omnidirectional matching retro reflector is mainly composed of a metal shell, which is a concave block. The end faces of the two convex parts of the metal shell face the incident direction of the external electromagnetic wave and serve as the input end and the output end of the fully polarized omnidirectional matching retro reflector respectively. The interior of the metal shell is respectively provided with an internally hollow TM wave air tunnel group and a TE wave air tunnel group. The entire TM wave air tunnel group and the entire TE wave air tunnel group are both concave blocks with the same shape as the metal shell. The TM wave air tunnel group and the TE wave air tunnel group are connected from the input end to the output end of the fully polarized omnidirectional matching retro reflector. The input end and the output end of the TM wave air tunnel group are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located. The input end and the output end of the TE wave air tunnel group are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located. The geometric center of the vertical cross section of the TM wave air tunnel group and the geometric center of the vertical cross section of the TM wave air tunnel group are on the same straight line.

[0007] The material of the metal shell is copper, silver, gold, aluminum or tungsten.

[0008] The TM wave air tunnel group includes a plurality of I-shaped air tunnels evenly spaced from the inside to the outside of the recessed center of the metal shell, the horizontal cross-section of each of the I-shaped air tunnels is concave as a whole, the vertical cross-section of each of the I-shaped air tunnels is two "I" shapes, the input end and the output end of each I-shaped air tunnel are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located, and each I-shaped air tunnel is connected from the input end to the output end of the fully polarized omnidirectional matching retro reflector.

[0009] The vertical cross-section of each of the I-shaped air tunnels includes a long air tunnel with straight strips arranged in the vertical direction and two short air tunnels with straight strips arranged symmetrically on both sides of the long air tunnel in the horizontal direction; the vertical lengths of the long air tunnels of different I-shaped air tunnels are equal; the two horizontal lengths of the two short air tunnels of the I-shaped air tunnel are equal, and the horizontal lengths of the short air tunnels of different I-shaped air tunnels are not equal to each other.

[0010] The TE wave air tunnel group includes a plurality of wavy air tunnels evenly spaced from the center of the recess of the metal shell from the inside to the outside, each wavy air tunnel is mainly symmetrically composed of a W-shaped air tunnel located on the upper side and an M-shaped air tunnel located on the lower side, the vertical cross-section of each W-shaped air tunnel is two "W" shapes, the vertical cross-section of each M-shaped air tunnel is two "M" shapes, the horizontal cross-sections of each W-shaped air tunnel and each M-shaped air tunnel are both concave, the input end and the output end of each W-shaped air tunnel are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located, the input end and the output end of each M-shaped air tunnel are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located, each W-shaped air tunnel is connected from the input end to the output end of the fully polarized omnidirectional matching retro reflector, and each M-shaped air tunnel is connected from the input end to the output end of the fully polarized omnidirectional matching retro reflector.

[0011] The vertical cross-section of each W-shaped air tunnel includes seven straight air tunnels vertically connected end to end in sequence; the vertical cross-section of each M-shaped air tunnel includes seven straight air tunnels vertically connected end to end in sequence.

[0012] The horizontal lengths of the W-shaped air tunnel and the M-shaped air tunnel in the wavy air tunnel are equal; the horizontal lengths of the W-shaped air tunnels in different wavy air tunnels are different, and the horizontal lengths of the M-shaped air tunnels in different wavy air tunnels are different.

[0013] The geometric center point of the vertical cross section of the I-shaped air tunnel and the geometric center point of the vertical cross section of the wavy air tunnel are on the same straight line.

[0014] A wave-shaped air tunnel is arranged between every two adjacent I-shaped air tunnels.

[0015] The tunnel widths of each of the wavy air tunnels and each of the I-shaped air tunnels are equal, that is, the width of each straight strip in the vertical cross section is the same.

[0016] The propagation direction of the fully polarized omnidirectional matching retro reflector of the present invention is that the external electromagnetic wave of the external device enters the input end of the fully polarized omnidirectional matching retro reflector from the incident direction of the fully polarized omnidirectional matching retro reflector, is transmitted along the concave shape of the fully polarized omnidirectional matching retro reflector, and is output from the output end of the fully polarized omnidirectional matching retro reflector to be received by the external device.

[0017] The beneficial effects of the present invention are:

[0018] 1. The present invention can realize the reflection of fully polarized waves of a specified working frequency incident from any incident direction back in the original direction.

[0019] 2. The present invention has a simple structure and can be realized only by metal, which perfectly matches the free space and can be widely used in various military fields such as radar, target modeling and sensing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a three-dimensional diagram of the structure of the present invention;

[0021] Figure 2 A three-dimensional stereogram of the structure of the present invention;

[0022] Figure 3 This is a schematic diagram of the porous metal structure in Example 2;

[0023] Figure 4 Graph showing the simulation results of the vertical incidence S parameters in Example 2;

[0024] Figure 5 This is the simulation result diagram of the vertical incident field diagram in Example 2. DETAILED DESCRIPTION

[0025] The present invention is further described below with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1 and Figure 2As shown, the fully polarized omnidirectional matching retro reflector of this embodiment 1 is mainly composed of a metal shell, which is a concave block. The end faces of the two convex parts of the metal shell face the incident direction of the external electromagnetic wave and serve as the input end and the output end of the fully polarized omnidirectional matching retro reflector respectively. The interior of the metal shell is respectively provided with an internally hollow connected TM wave air tunnel group and a connected TE wave air tunnel group. The TM wave air tunnel group as a whole and the TE wave air tunnel group as a whole are both concave blocks with the same shape as the metal shell. The TM wave air tunnel group and the TE wave air tunnel group are connected from the input end to the output end of the fully polarized omnidirectional matching retro reflector. The input end and the output end of the TM wave air tunnel group are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located. The input end and the output end of the TE wave air tunnel group are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located. The geometric center of the vertical cross section of the TM wave air tunnel group and the geometric center of the vertical cross section of the TM wave air tunnel group are on the same straight line.

[0027] In a specific implementation, the material of the metal shell is copper, silver, gold, aluminum or tungsten.

[0028] The TM wave air tunnel group includes a plurality of I-shaped air tunnels evenly spaced from the center of the recess of the metal shell from the inside to the outside, the horizontal cross-section of each I-shaped air tunnel is concave as a whole, the vertical cross-section of each I-shaped air tunnel is two spaced "I" shapes, the input end and the output end of each I-shaped air tunnel are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located, and each I-shaped air tunnel is connected from the input end to the output end of the fully polarized omnidirectional matching retro reflector.

[0029] The planes where the input and output ends of the fully polarized omnidirectional matching retro reflector are located are both perpendicular to the incident direction of the external electromagnetic wave, the vertical cross section is the plane where the input and output ends of the fully polarized omnidirectional matching retro reflector are located, and the horizontal cross section is a plane perpendicular to the vertical cross section.

[0030] The vertical cross-section of each I-shaped air tunnel includes a long air tunnel with straight strips arranged in the vertical direction and two short air tunnels with straight strips arranged symmetrically on both sides of the long air tunnel in the horizontal direction; the vertical lengths of the long air tunnels of different I-shaped air tunnels are equal; the two horizontal lengths of the two short air tunnels of each I-shaped air tunnel are equal, and the horizontal lengths of the short air tunnels of different I-shaped air tunnels are not equal to each other.

[0031] The horizontal direction is the direction of the line connecting the vertical distance between the input end and the output end of the I-shaped air tunnel; the vertical direction is the direction of the line connecting the vertical distance between the input end and the output end of the I-shaped air tunnel; the vertical length is the distance in the vertical direction, and the horizontal direction is the distance in the horizontal direction.

[0032] The TE wave air tunnel group includes a plurality of wavy air tunnels evenly spaced from the center of the concave portion of the metal shell from the inside to the outside, each wavy air tunnel is mainly symmetrically composed of a W-shaped air tunnel located on the upper side and an M-shaped air tunnel located on the lower side, the vertical cross-section of each W-shaped air tunnel is two spaced "W" shapes, the vertical cross-section of each M-shaped air tunnel is two spaced "M" shapes, the horizontal cross-sections of each W-shaped air tunnel and each M-shaped air tunnel are both concave, the input end and the output end of each W-shaped air tunnel are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located, the input end and the output end of each M-shaped air tunnel are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located, each W-shaped air tunnel is connected from the input end to the output end of the fully polarized omnidirectional matching retro reflector, and each M-shaped air tunnel is connected from the input end to the output end of the fully polarized omnidirectional matching retro reflector.

[0033] The vertical cross section of each W-shaped air tunnel includes seven straight air tunnels vertically connected end to end in sequence; the vertical cross section of each M-shaped air tunnel includes seven straight air tunnels vertically connected end to end in sequence.

[0034] In a specific implementation, the vertical cross-section of each W-shaped air tunnel includes four long air tunnels arranged in the vertical direction and three short air tunnels arranged in the horizontal direction. The four long air tunnels are evenly spaced along the same horizontal direction. A short air tunnel is connected between two adjacent long air tunnels. Two adjacent short air tunnels are staggered, so that the vertical cross-section constituting the W-shaped air tunnel forms a serpentine connection.

[0035] The vertical cross section of each M-shaped air tunnel includes four long air tunnels arranged in the vertical direction and three short air tunnels arranged in the horizontal direction. The four long air tunnels are evenly spaced along the same horizontal direction. A short air tunnel is connected between two adjacent long air tunnels. Two adjacent short air tunnels are staggered, so that the vertical cross section constituting the W-shaped air tunnel forms a serpentine connection. Staggered means not in the same horizontal direction.

[0036] The horizontal lengths of the W-shaped air tunnel and the M-shaped air tunnel in each wavy air tunnel are equal; the horizontal lengths of the W-shaped air tunnels in different wavy air tunnels are unequal, and the horizontal lengths of the M-shaped air tunnels in different wavy air tunnels are unequal.

[0037] The geometric center point of the vertical cross section of the I-shaped air tunnel and the geometric center point of the vertical cross section of the wavy air tunnel are on the same straight line.

[0038] The geometric center point is the center point of the I-shaped geometric figure or the wavy geometric figure.

[0039] A wave-shaped air tunnel is arranged between every two adjacent I-shaped air tunnels.

[0040] The tunnel widths of each wavy air tunnel and each I-shaped air tunnel are all equal, that is, the width of each straight strip of the vertical cross section is the same.

[0041] Tunnel Width is the width of the long air tunnel / short air tunnel / air tunnel of each cuboid.

[0042] The propagation direction of the fully-polarized omnidirectional matching retro reflector of this embodiment is that the external electromagnetic wave of the external device enters from the incident direction of the fully-polarized omnidirectional matching retro reflector to the input end of the fully-polarized omnidirectional matching retro reflector, is transmitted along the concave shape of the fully-polarized omnidirectional matching retro reflector, and is output from the output end of the fully-polarized omnidirectional matching retro reflector to be received by the external device.

[0043] The TM wave air tunnel group targets TM waves, and the TE wave air tunnel group targets TE waves.

[0044] Example 2

[0045] The working principle of the design of the present invention is: according to the principle of transformation optics, when there is an anisotropic material, the dielectric constant and the magnetic permeability satisfy ε=μ={Δ,Δ,1 / Δ}, where Δ represents a constant. When Δ→0, the material can be regarded as an optical cavity. When the light wave passes through it, the speed of light can be regarded as infinite, without any phase accumulation. The electromagnetic parameters required for a perfect optical cavity material are difficult to achieve, so it can be considered as follows Figure 3 The porous metal structure shown is used to simulate optical cavity materials at a specific frequency. The side length of the square hole is a, and the distance between the metal holes is d, as shown in Figure 3 (a) When the working wavelength λ satisfies λ>>d, a / d→0, the effective dielectric constant and magnetic permeability of the porous metal structure can be regarded as That is, optical cavity material. Its operating frequency is the cutoff frequency of a square waveguide with a side length of a and filled with a medium. However, this structure often requires a high refractive index material to fill the hole, which is not easy to achieve in practical applications, especially at high frequencies. To solve this problem, we can consider using a cross-section of a x ×a y , where a x <<a y or a x >>a y If a narrow rectangular hole is used instead of a square hole, there is no need to fill it with a high refractive index material, such as Figure 3 (b) as shown.

[0046] According to the above theory, the concave metal shell with I-shaped air tunnel and wavy air tunnel of the present invention can achieve perfect transmission effect, and the working frequency is the cutoff frequency of the tunnel. At this time, the transmission efficiency of the fully polarized wave is about 1, and there is no phase change. According to the above description, a fully polarized omnidirectional matching retroreflector is constructed, and an air tunnel structure is adopted. By simulating optical cavity materials at the working frequency, the reflected electromagnetic wave is parallel and opposite to the incident wave.

[0047] like Figure 1 As shown, the tunnel width of each wavy air tunnel and each I-shaped air tunnel in this embodiment is 1 mm.

[0048] In this embodiment, three I-shaped air tunnels and two wavy air tunnels are evenly distributed on the concave metal shell to obtain a fully polarized omnidirectional matching retroreflector. The width of each tunnel is 1 mm. Figure 1 The coordinate system is established as shown in the figure. The height of the two ports of the concave metal in the y direction is 28.6mm, the length in the x direction is 36mm, the depth in the z direction is 42mm, and the total length in the x direction of the full-polarization omnidirectional matching retroreflector is 84mm. Among them, the width of each I-shaped air tunnel in the x direction is different, the length of each wavy air tunnel in the y direction is different, and the other specific parameters are as follows Figure 1 The models in the table are as follows:

[0049] <![CDATA[I x (mm)]]> <![CDATA[I y (mm)]]> <![CDATA[I1]]> 3.14 25 <![CDATA[I2]]> 8.66 25 <![CDATA[I3]]> 3.18 25 <![CDATA[W x (mm)]]> <![CDATA[W y (mm)]]> <![CDATA[W1]]> 6 8.49 <![CDATA[W2]]> 6 6.605

[0050] I1, I2 and I3 represent the first, second and third I-shaped air tunnels respectively. x and I y represent the lengths of the I-shaped air tunnel in the x and y directions, W1 and W2 represent the first and second wavy air tunnels, respectively. x and W y Respectively represent the length of the wavy air tunnel in the x and y directions.

[0051] According to the arrangement of this embodiment, the S parameters of vertical incidence are obtained by simulation using Ansys HFSS software as follows: Figure 4 As shown, Figure 4 The left picture shows TM polarization, and the right picture shows TE polarization. It can be seen that the present invention ensures that after the 6 GHz TM wave and TE wave are incident from the input end, the amplitude and phase at the output end do not change, and both the TM wave and the TE wave can be reflected back from the original angle. Figure 5 This is the simulation result of the vertical incident field diagram. It can be seen that the device works normally.

[0052] The present invention can realize fully polarized waves incident in any direction at 6 GHz, and its reflected wave is parallel to the incident wave and in the opposite direction. If the present invention is to work at other frequencies, it is necessary to adjust the width of the I-shaped air tunnel in the x direction and the length of the wavy air tunnel in the y direction according to the operating frequency, so that it is equivalent to an optical cavity material at the operating frequency.

[0053] The invention has a simple structure and can be realized only by metal, and can work for fully polarized and full-angle incident waves, and can be widely used in the fields of radar target modeling and sensing.

[0054] The above examples are not intended to limit the present invention in any form. Any technician familiar with the profession can use the technical content disclosed above to change or modify it into an equivalent example with equivalent changes. However, any simple modifications, equivalent changes and modifications made to the above examples based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A fully polarized omnidirectional matching retroreflector based on optical cavity material, characterized in that: The fully polarized omnidirectional matching retro reflector is mainly composed of a metal shell, which is a concave block. The end faces of the two convex parts of the metal shell face the incident direction of the external electromagnetic wave and serve as the input end and the output end of the fully polarized omnidirectional matching retro reflector respectively. The interior of the metal shell is respectively provided with an internally hollow TM wave air tunnel group and a TE wave air tunnel group. The entire TM wave air tunnel group and the entire TE wave air tunnel group are both concave blocks with the same shape as the metal shell. The TM wave air tunnel group and the TE wave air tunnel group are connected from the input end to the output end of the fully polarized omnidirectional matching retro reflector. The input end and the output end of the TM wave air tunnel group are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located. The input end and the output end of the TE wave air tunnel group are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located. The geometric center of the vertical cross section of the TM wave air tunnel group and the geometric center of the vertical cross section of the TM wave air tunnel group are on the same straight line.

2. The fully polarized omnidirectional matching retroreflector based on optical cavity material according to claim 1, characterized in that: The material of the metal shell is copper, silver, gold, aluminum or tungsten.

3. The fully polarized omnidirectional matching retroreflector based on optical cavity material according to claim 1, characterized in that: The TM wave air tunnel group includes a plurality of I-shaped air tunnels evenly spaced from the inside to the outside of the recessed center of the metal shell, the horizontal cross-section of each of the I-shaped air tunnels is concave as a whole, the vertical cross-section of each of the I-shaped air tunnels is two "I" shapes, and the input end and the output end of each I-shaped air tunnel are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located.

4. The fully polarized omnidirectional matching retroreflector based on optical cavity material according to claim 3, characterized in that: The vertical cross section of each of the I-shaped air tunnels includes a long air tunnel arranged in the vertical direction and two short air tunnels arranged symmetrically on both sides of the long air tunnel in the horizontal direction; The vertical lengths of the long air tunnels of different I-shaped air tunnels are all equal; The two horizontal lengths of the two short air tunnels of the I-shaped air tunnel are equal, and the horizontal lengths of the short air tunnels of different I-shaped air tunnels are not equal to each other.

5. The fully polarized omnidirectional matching retroreflector based on optical cavity material according to claim 3, characterized in that: The TE wave air tunnel group includes a plurality of wavy air tunnels evenly spaced from the center of the recess of the metal shell from the inside to the outside, each wavy air tunnel is mainly symmetrically composed of a W-shaped air tunnel located on the upper side and an M-shaped air tunnel located on the lower side, the vertical cross-section of each W-shaped air tunnel is two "W" shapes, the vertical cross-section of each M-shaped air tunnel is two "M" shapes, the horizontal cross-sections of each W-shaped air tunnel and each M-shaped air tunnel are concave, the input end and the output end of each W-shaped air tunnel are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located, and the input end and the output end of each M-shaped air tunnel are respectively located on the plane where the input end and the output end of the fully polarized omnidirectional matching retro reflector are located.

6. The fully polarized omnidirectional matching retroreflector based on optical cavity material according to claim 5, characterized in that: The vertical cross-section of each W-shaped air tunnel includes seven straight air tunnels vertically connected end to end in sequence; the vertical cross-section of each M-shaped air tunnel includes seven straight air tunnels vertically connected end to end in sequence.

7. The fully polarized omnidirectional matching retroreflector based on optical cavity material according to claim 5, characterized in that: The horizontal lengths of the W-shaped air tunnel and the M-shaped air tunnel in the wavy air tunnel are equal; The horizontal lengths of the W-shaped air tunnels of different wavy air tunnels are different from each other, and the horizontal lengths of the M-shaped air tunnels of different wavy air tunnels are different from each other.

8. The fully polarized omnidirectional matching retroreflector based on optical cavity material according to claim 5, characterized in that: The geometric center point of the vertical cross section of the I-shaped air tunnel and the geometric center point of the vertical cross section of the wavy air tunnel are on the same straight line.

9. The fully polarized omnidirectional matching retroreflector based on optical cavity material according to claim 5, characterized in that: A wave-shaped air tunnel is arranged between every two adjacent I-shaped air tunnels.

10. The fully polarized omnidirectional matching retroreflector based on optical cavity material according to claim 1, characterized in that: The tunnel widths of each of the wavy air tunnels and each of the I-shaped air tunnels are equal.

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