Antenna for multi-mode terahertz orbital angular momentum waves

Abstract

The application belongs to the technical field of communication, and specifically relates to an antenna for generating multiple mode orbital angular momentum waves. The antenna is composed of three spiral phase plates; the first spiral phase plate is circular and solid, and is located at the center; the second spiral phase plate is annular, and is located at the periphery of the first spiral phase plate; the third spiral phase plate is annular, and is located at the periphery of the second spiral phase plate; the three spiral phase plates are coaxial; the three spiral phase plates are respectively composed of eight gradient surfaces with synchronous increment, each gradient surface has the same area, and adjacent gradient surfaces are sequentially increased by the same height; the three spiral phase plates are separated by metal rings. The super material surface can simultaneously convert the linear polarization mode incident plane wave into three mode orbital angular momentum waves, and different mode orbital angular momentum waves can be formed by changing the height of the spiral phase plate, and the application has the advantages of multi-mode multiplexing, flexible design, simple structure, low cost and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of communication, and particularly relates to an antenna for generating a multi-mode terahertz orbital angular momentum wave. BACKGROUND

[0002] With the rapid development of contemporary science and technology, especially the increasing demand for the communication field, higher frequency band utilization and channel capacity have become the current popular development direction. Orbital angular momentum (OAM) can carry topological charges with mutual orthogonal characteristics, can maintain independent transmission of each phase, improve the frequency band utilization, and effectively improve the anti-interference ability of the beam.

[0003] When the electromagnetic wave carries the orbital angular momentum, it becomes a vortex electromagnetic wave. The phase wave front of the vortex electromagnetic wave spirally twists with the direction of propagation, and the vortex beam produces a center point with low or zero intensity. There are many current research methods for generating OAM, mainly including circular array antennas, spiral phase plates, spiral reflectors or super surfaces. However, the array antenna for generating terahertz frequency band OAM needs a very complex feed network, and other methods have limitations in generating single-frequency multi-mode terahertz OAM waves. SUMMARY

[0004] The purpose of the application is to overcome the deficiencies and defects in the prior art, and to provide an antenna capable of generating multi-mode terahertz orbital angular momentum (OAM) electromagnetic waves, which is multi-mode multiplexing, flexible in design, simple in structure and low in cost.

[0005] The antenna capable of generating a multi-mode terahertz orbital angular momentum wave provided by the application has the structure as shown in Figure 1 、 Figure 2 The antenna is composed of three spiral phase plates. The first spiral phase plate 1 is a circular solid and is located at the center position. The second spiral phase plate 2 is annular and is located at the periphery of the first spiral phase plate 1. The third spiral phase plate 3 is also annular and is located at the periphery of the second spiral phase plate 2. The three spiral phase plates are coaxial (concentric). There is a gap between the second spiral phase plate 2 and the first spiral phase plate 1, and a first metal ring 4 is arranged therebetween. There is also a gap between the third spiral phase plate 3 and the second spiral phase plate 2, and a second metal ring 5 is arranged therebetween.

[0006] The three spiral phase plates each have eight gradient faces with increasing heights. The area of each gradient is the same, and the adjacent gradient faces increase by the same height in turn. That is, the eight gradient faces of the spiral phase plate each correspond to a central angle of 45 degrees. Furthermore, the eight gradient faces of the three spiral phase plates are synchronized, that is, they increase synchronously from low to high.

[0007] In the present invention:

[0008] The radius of the first spiral phase plate (1) is 2-4.5mm;

[0009] The inner diameter of the ring of the second spiral phase plate (2) is 5-9mm, and the width of the ring is 3-7mm;

[0010] The inner diameter of the ring of the third spiral phase plate (3) is 13-17mm, and the width of the ring is 3-7mm.

[0011] In the present invention:

[0012] The lowest step height of the first spiral phase plate (1) is 0.61-0.63mm; the highest step height is 4.88-5.04mm;

[0013] The lowest step height of the second spiral phase plate (1) is 1.05-1.07mm; the highest step height is 8.4-8.56mm;

[0014] The lowest step height of the third spiral phase plate (1) is 1.69-1.71mm; the highest step height is 13.52-13.68mm.

[0015] In the embodiment:

[0016] The radius of the first spiral phase plate 1 is 4mm;

[0017] The inner diameter of the ring of the second spiral phase plate 2 is 6mm, and the width of the ring is 6mm;

[0018] The inner diameter of the ring of the third spiral phase plate 3 is 13.5mm, and the width of the ring is 6.5mm.

[0019] In the embodiment:

[0020] The highest height of the first spiral phase plate (1) is 4.96mm, and the height of one step is 0.62mm;

[0021] The highest height of the second spiral phase plate (2) is 8.48mm, and the height of one step is 1.06mm;

[0022] The highest height of the third spiral phase plate (3) is 13.6mm, and the height of one step is 1.7mm.

[0023] In the present invention, the two metal rings 4, 5 can use any metal material, and the thickness is set to 0.6mm in the embodiment.

[0024] In the application, the helical phase plate medium material can be made by 3D printing technology, and in the embodiment, the medium material is ABS resin, and the relative dielectric constant is 2.5.

[0025] Specifically, by reasonably designing the antenna structure, the phase delay of the incident wave can be changed with the change of the height gradient of the helical phase plate, and by setting the height of each of the three helical phase plates, three different modes of OAM waves can be formed at the same time. The simulation results of the embodiment show that the three helical phase plates simultaneously convert the incident plane wave of 220 GHz into OAM waves, the first helical phase plate 1 makes the adjacent phase delay 45°, so that the incident plane wave can be converted into +1 mode OAM wave, the second helical phase plate 2 makes the adjacent phase delay 90°, so that the incident plane wave can be converted into +2 mode OAM wave, and the third helical phase plate 3 makes the adjacent phase delay 180°, so that the incident plane wave can be converted into +4 mode OAM wave.

[0026] The antenna designed in the application can generate multi-mode terahertz orbital angular momentum electromagnetic waves.

[0027] The literature retrieval results show that there is no antenna that can simultaneously generate multi-mode OAM waves at 220 GHz.

[0028] The antenna designed in the application is composed of three helical phase plates at 220 GHz, has a simple structure, is convenient to process by using 3D printing technology, and is low in cost. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The antenna for simultaneously generating multi-mode terahertz orbital angular momentum waves in the application.

[0030] Figure 2 The top view of the antenna for simultaneously generating multi-mode terahertz orbital angular momentum waves in the application.

[0031] Figure 3 The side view of the antenna for simultaneously generating multi-mode terahertz orbital angular momentum waves in the application.

[0032] Figure 4 The +1, +2 and +4 mode phase distribution diagrams of the antenna for simultaneously generating multi-mode terahertz orbital angular momentum waves in the application in the near field when a linearly polarized plane wave is incident at 220 GHz.

[0033] Figure 5 The +1, +2 and +4 mode amplitude distribution diagrams of the antenna for simultaneously generating multi-mode terahertz orbital angular momentum waves in the application in the near field when a linearly polarized plane wave is incident at 220 GHz.

[0034] The numbers in the diagram are: 1 is the first spiral phase plate, 2 is the second spiral phase plate, 3 is the third spiral phase plate, 4 is the first metal ring, and 5 is the second metal ring. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments; this embodiment provides detailed implementation methods and specific operation processes, but the scope of protection of the present invention is not limited to the following embodiments.

[0036] like Figures 1-3 As shown, this invention provides an antenna capable of simultaneously generating multimode terahertz orbital angular momentum waves, operating at a frequency of 220 GHz, with overall dimensions of 20 × 20 × 13.6 mm. 3 (Length × Width × Height) This embodiment includes an antenna composed of three spiral phase plates of different heights.

[0037] like Figure 1 As shown, in this embodiment, the first circular solid spiral phase plate is located at the center, the second annular spiral phase plate is located around the first spiral phase plate, and the third annular spiral phase plate is located around the second spiral phase plate. The three spiral phase plates are spaced apart by a first metal ring and a second metal ring, respectively. The height of each of the three spiral phase plates is composed of eight spirally increasing gradient surfaces, each with the same area, and adjacent gradient surfaces increasing in height by the same amount.

[0038] In this embodiment, the first spiral phase plate has a maximum height of 4.96 mm, a radius of 4 mm, and a step height of 0.62 mm, used to generate a +1 mode OAM wave; the second spiral phase plate has a maximum height of 8.48 mm, inner and outer radii of 6 mm and 12 mm respectively, and a step height of 1.06 mm, used to generate a +2 mode OAM wave; the third spiral phase plate has a height of 13.6 mm, inner and outer radii of 13.5 mm and 20 mm respectively, and a step height of 1.70 mm, used to generate a +4 mode OAM wave. All three spiral phase plates are made of ABS resin material with a relative permittivity of 2.5.

[0039] like Figure 4As shown in the figure, the near-field phase distribution characteristics of the OAM wave described in the embodiment, the incident wave is a linearly polarized plane wave, at the near-field plane 40 mm away from the metamaterial surface, a square face with a width of 50 mm is selected to collect the electromagnetic field of the transmitted wave beam, for the first spiral phase plate generating +1 mode OAM wave, the near-field phase distribution obtained from simulation can see that the transmitted wave is a vortex wave beam carrying +1 mode orbital angular momentum, for the second spiral phase plate generating +2 mode OAM wave, the near-field phase distribution obtained from simulation can see that the transmitted wave is a vortex wave beam carrying +2 mode orbital angular momentum, for the third spiral phase plate generating +4 mode OAM wave, the near-field phase distribution obtained from simulation can see that the transmitted wave is a vortex wave beam carrying +4 mode orbital angular momentum.

[0040] As Figure 5 As shown in the figure, the near-field amplitude distribution characteristics of the OAM wave described in the embodiment, at the near-field plane 40 cm away from the metamaterial surface, a square face with a width of 50 cm is selected to collect the electromagnetic field of the transmitted wave beam, for the first spiral phase plate generating +1 mode OAM wave, the near-field amplitude distribution obtained from simulation can see that the transmitted wave is a vortex wave beam carrying +1 mode orbital angular momentum, for the second spiral phase plate generating +2 mode OAM wave, the near-field amplitude distribution obtained from simulation can see that the transmitted wave is a vortex wave beam carrying +2 mode orbital angular momentum, for the third spiral phase plate generating +4 mode OAM wave, the near-field amplitude distribution obtained from simulation can see that the transmitted wave is a vortex wave beam carrying +4 mode orbital angular momentum.

[0041] The technical scheme of the application is not limited to the above specific embodiments, such as the application is an antenna capable of simultaneously generating multi-mode orbital angular momentum wave at 220 GHz, any technical modification made according to the technical scheme of the application falls within the protection scope of the application.

Claims

1. A multi-mode terahertz orbital angular momentum wave antenna, characterized in that, The three spiral phase plates are coaxial; there is a gap between the second spiral phase plate (2) and the first spiral phase plate (1), and a first metal ring (4) is arranged between the two; there is also a gap between the third spiral phase plate (3) and the second spiral phase plate (2), and a second metal ring (5) is arranged between the two. The three spiral phase plates are respectively composed of eight gradient surfaces with increasing spiral, and the area of each gradient in each spiral phase plate is the same, and the adjacent gradient surfaces are sequentially increased by the same height; that is, the eight gradient surfaces of the spiral phase plate each correspond to a central angle of 45 degrees; and the eight gradients of the three spiral phase plates are synchronously increased from low to high.

2. The antenna of the multi-mode terahertz orbital angular momentum wave according to claim 1, wherein: the radius of the first spiral phase plate (1) is 2-4.5 mm; the inner diameter of the ring of the second spiral phase plate (2) is 5-9 mm, and the width of the ring is 3-7 mm; the inner diameter of the ring of the third spiral phase plate (3) is 13-17 mm, and the width of the ring is 3-7 mm.

3. The antenna of the multi-mode terahertz orbital angular momentum wave according to claim 2, wherein: the lowest step height of the first spiral phase plate (1) is 0.61-0.63 mm; and the highest step height is 4.88-5.04 mm; the lowest step height of the second spiral phase plate (2) is 1.05-1.07 mm; and the highest step height is 8.4-8.56 mm; the lowest step height of the third spiral phase plate (3) is 1.69-1.71 mm; and the highest step height is 13.52-13.68 mm.

4. The antenna of the multi-mode terahertz orbital angular momentum wave according to claim 3, wherein: the radius of the first spiral phase plate (1) is 4 mm; the inner diameter of the ring of the second spiral phase plate (2) is 6 mm, and the width of the ring is 6 mm; the inner diameter of the ring of the third spiral phase plate (3) is 13.5 mm, and the width of the ring is 6.5 mm.

5. The antenna of the multi-mode terahertz orbital angular momentum wave according to claim 4, wherein: the highest height of the first spiral phase plate (1) is 4.96 mm, and the height of one step is 0.62 mm; the highest height of the second spiral phase plate (2) is 8.48 mm, and the height of one step is 1.06 mm; the highest height of the third spiral phase plate (3) is 13.6 mm, and the height of one step is 1.7 mm.

6. The multi-mode terahertz orbital angular momentum wave antenna of claim 5, wherein, The thickness of the first metal ring (4) and the second metal ring (5) is 0.6 mm.

7. The multi-mode terahertz orbital angular momentum wave antenna of any of claims 1-6, wherein, The spiral phase plate is made of a dielectric material and is made by 3D printing technology.

8. The multi-mode terahertz orbital angular momentum wave antenna of any of claims 1-6, wherein, The 220GHz incident plane wave is converted into an OAM wave; by setting the heights of the three spiral phase plates, three different modes of OAM waves are formed at the same time.

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