A dual-frequency dual-polarization multifunctional orbital angular momentum antenna

Abstract

The present invention discloses a dual-frequency dual-polarization multifunctional orbital angular momentum antenna, comprising a feed source, a dielectric substrate and a metal floor, wherein the metal floor is arranged below the dielectric substrate, and the upper surface of the dielectric substrate is provided with radiation units arranged in a periodic manner to form an electromagnetic metasurface, wherein the feed source is arranged above the dielectric substrate, and the feed source irradiates the electromagnetic metasurface and forms a plurality of vortex beams above the feed source, wherein the radiation unit is an annular structure, wherein the annular structure has an embedded circular ring, and the embedded circular ring has branches. The dual-frequency dual-polarization multifunctional orbital angular momentum antenna provided by the present invention has the characteristics of being multifunctional, i.e., it can generate multiple vortex beams, multiple orbital angular momentum modes, and multiple radiation directions, and the present invention has the advantages of planarization, single-layer structure, easy processing, high gain, and high aperture efficiency.

Description

Technical Field

[0001] The present invention relates to the field of microwave antennas, and in particular to a dual-frequency dual-polarization multifunctional orbital angular momentum antenna. Background Art

[0002] On June 6, 2019, the Ministry of Industry and Information Technology (MIIT) issued 5G commercial licenses to China Mobile, China Unicom, China Telecom, and China Broadcasting Corporation, marking China's official entry into the 5G commercial era. With the surge in user devices and the rapid development of technologies such as the Internet of Things, available spectrum resources are becoming increasingly scarce, making further improvements in communication capacity and spectrum efficiency a top priority. At this time, orbital angular momentum (OAM) technology, as a new multiplexing technology, has attracted significant attention. Because electromagnetic waves with a spiral phase distribution carry orbital angular momentum, and vortex waves of different modes are mutually orthogonal, and OAM modes can theoretically take on arbitrary real numbers, using each OAM mode as an independent information channel for encoding, transmission, and reception is expected to significantly increase the system's transmission rate and capacity. The generation of electromagnetic vortex waves has also become an important research topic.

[0003] Currently, common methods for generating OAM vortex waves in the RF microwave band include spiral phase plate antennas, circular array antennas, dielectric resonators, ring-shaped traveling-wave antennas, and artificial electromagnetic metasurface antennas. Spiral phase plate antennas are bulky and difficult to fabricate. Circular array antennas require complex feed networks. Dielectric resonators and ring-shaped traveling-wave antennas typically have low gain and generate a single OAM mode. Artificial electromagnetic metasurfaces, however, have attracted significant interest from researchers due to their ease of fabrication, high gain, and ability to arbitrarily manipulate electromagnetic waves.

[0004] Currently, artificial electromagnetic metasurfaces capable of generating OAM vortex waves operate only within a single frequency band and can only form a single vortex beam. Multifunctional orbital angular momentum antennas, with multiple beams, multiple modes, and multiple radiation directions, hold broader application prospects in point-to-point and satellite communications. However, few current OAM antenna designs can achieve multifunctional vortex wave generation. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the present invention provides a dual-frequency dual-polarization multifunctional orbital angular momentum antenna, which can operate in dual frequency bands and form multifunctional vortex beams with multiple beams, multiple modes and multiple radiation directions.

[0006] The technical solutions adopted in the present invention are as follows:

[0007] A dual-frequency, dual-polarization, multifunctional orbital angular momentum antenna comprises a feed, a dielectric substrate, and a metal floor. The metal floor is disposed below the dielectric substrate. The upper surface of the dielectric substrate is provided with periodically arranged radiation units to form an electromagnetic metasurface. The feed is disposed above the dielectric substrate and irradiates the electromagnetic metasurface to form multiple vortex beams above the feed. The radiation units are annular in structure, with an embedded circular ring within the annular structure. The embedded circular ring has branches.

[0008] Preferably, the ring structure is symmetrical in shape and is one in number, specifically a square ring or a circular ring.

[0009] Preferably, the branches are arc-shaped or L-shaped.

[0010] Preferably, the number of embedded rings is 2 or more.

[0011] Preferably, the feed source is a horn antenna or a microstrip antenna.

[0012] Preferably, an air layer is provided between the dielectric substrate and the metal floor.

[0013] Preferably, the periodically arranged radiation units form a rectangular, circular and polygonal structure.

[0014] Preferably, the lengths of the branches of the radiation element at different positions are related to the phase required to generate the position at the working frequency.

[0015] Preferably, the nested rings with branches resonate at different frequencies and are not coupled to each other.

[0016] Preferably, the phase compensation formula of the radiation unit is: In the formula represents the position coordinates of the radiation unit, represents the direction of the vortex wave beam, l represents the number of modes of the generated vortex wave, and m represents the number of beams.

[0017] Beneficial effects of the present invention:

[0018] (1) This antenna can operate in two frequency bands. The orbital angular momentum antenna of this embodiment can operate in both the 10 GHz and 20 GHz frequency bands.

[0019] (2) This antenna is multifunctional, which can form multiple vortex beams, multiple OAM modes, and multiple radiation directions, and can achieve multifunctionality according to the different phase compensation of the radiation unit.

[0020] (3) The radiating unit of the present invention has a large phase modulation range, which is 425° at 10 GHz and 436° at 20 GHz.

[0021] (4) The orbital angular momentum antenna of the present invention has the advantages of high gain (15.4 dBi at 10 GHz and 20.3 dBi at 20 GHz), high aperture efficiency (13.53% at 10 GHz and 10.33 dBi at 20 GHz), small divergence angle (7.5° at 10 GHz and 6° at 20 GHz), planar structure, and easy processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a three-dimensional view of Example 1 of the present invention;

[0023] Figure 2 Schematic diagram of the dimensions of the radiation unit according to embodiment 1 of the present invention;

[0024] Figure 3 is a phase shift curve diagram of the radiating unit of Example 1 of the present invention at 10 GHz;

[0025] Figure 4 is a phase shift curve diagram of the radiation unit of Example 1 of the present invention at 20 GHz;

[0026] Figure 5 1 is a phase compensation diagram of the outer ring branches of the electromagnetic metasurface according to embodiment 1 of the present invention;

[0027] Figure 6 1 is a phase compensation diagram of the inner ring branch of the electromagnetic metasurface according to embodiment 1 of the present invention;

[0028] Figure 7 is the far-field pattern of the antenna of Example 1 of the present invention at 10 GHz;

[0029] Figure 8 is the far-field pattern of the antenna of Example 1 of the present invention at 20 GHz;

[0030] Figure 9 1 is a phase compensation diagram of the outer ring branches of the electromagnetic metasurface according to embodiment 2 of the present invention;

[0031] Figure 10 1 is a phase compensation diagram of the inner ring branches of the electromagnetic metasurface according to embodiment 2 of the present invention;

[0032] Figure 11 is the far-field pattern of the antenna of Example 2 of the present invention at 10 GHz;

[0033] Figure 12 is the far-field pattern of the antenna of Example 2 of the present invention at 20 GHz;

[0034] Figure 13 3 is a phase compensation diagram of the outer ring branches of the electromagnetic metasurface according to embodiment 3 of the present invention;

[0035] Figure 143 is a phase compensation diagram of the inner ring branch of the electromagnetic metasurface according to embodiment 3 of the present invention;

[0036] Figure 15 is the far-field pattern of the antenna of Example 3 of the present invention at 10 GHz;

[0037] Figure 16 This is the far-field pattern of the antenna of Example 3 of the present invention at 20 GHz. DETAILED DESCRIPTION

[0038] The present invention will be further described in detail below with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0039] Example 1

[0040] like Figure 1 As shown, a dual-frequency, dual-polarization, multifunctional orbital angular momentum antenna comprises a feed source 2, a dielectric substrate 3, and a metal floor 5. The metal floor is located below the dielectric substrate, 3 mm away from the dielectric substrate. Radiating elements 4 are provided on the upper surface of the dielectric substrate. N radiating elements are periodically arranged to form an electromagnetic metasurface. The feed source illuminates the electromagnetic metasurface, forming multiple vortex beams 1 above the feed source. The radiating elements are annular in structure, with an embedded circular ring having branches. Figure 1 The middle ring structure is a square ring. The square ring in the radiating unit is used to remove the coupling between the periodically arranged units. The nested circular rings with branches in the radiating unit with phase modulation function are used to work in dual-frequency dual-polarization. Each circular ring and the attached branches can independently work in a frequency and polarization, and generate the required phase shift by changing the angle of the branches; there is an air layer between the metal floor and the metasurface to reduce the phase shift sensitivity of the electromagnetic metasurface.

[0041] The feed source is a horn antenna or a microstrip antenna, and in this embodiment, a horn antenna is preferred.

[0042] The radiation unit is a ring structure, and other symmetrical shapes can be selected according to specific circumstances. The ring is a square ring or a circular ring, the number is one, and the number of nested circular rings with branches is more than two.

[0043] In this embodiment, there are preferably two nested rings, which are spaced a certain distance apart. The two branches of the outer ring are arranged on a vertical line, and the two branches of the inner ring are arranged on a horizontal line.

[0044] The shape of the branches can be arc-shaped or L-shaped, and the length of the branches can be adjusted.

[0045] The lengths of the branches at different positions of the radiating element are different, so that it generates the phase required at that position at the operating frequency.

[0046] The phase of the radiation unit is related to multiple factors. First, the position of the radiation unit on the upper surface of the dielectric substrate is related. Second, the number, mode number, and direction of the vortex beams.

[0047] The direction of the beam, l represents the mode number of the generated vortex wave, and m represents the number of beams.

[0048] like Figure 2 As shown, the preferred dimensions of this embodiment are:

[0049] In this embodiment, the dielectric substrate 3 is made of F4B material with a dielectric constant of 2.25 and a thickness of 0.55 mm. Figure 2 The dimensions of the radiation unit are D1=D2=9.6mm, L1=0.35mm, L2=0.3mm, W1=0.45mm, W2=0.4mm, a1=3.3mm, a2=3mm, b1=0.2mm, b2=0.1mm, r1=1.11mm, r2=1mm, ag1=3°~176°, ag2=3°~176°.

[0050] See Figure 3 At 10 GHz, using x-polarized waves incident on the radiation unit, the outer ring branch angle ag2 changes continuously from 3° to 176°, corresponding to a phase shift coverage range of 425°. At this time, when ag1 is taken as any value, the phase shift curves with ag2 as the function function all coincide (taking 3°, 63°, 123°, and 153° as examples), indicating that the change of the inner ring branch has no effect on the 10 GHz phase modulation.

[0051] See Figure 4 At 20 GHz, using a y-polarized wave incident on the radiating element, the inner ring branch angle ag1 continuously varied from 3° to 176°, corresponding to a phase shift coverage range of 436°. At this point, for any value of ag2, the phase shift curves using ag1 as a function all overlap (taking 3°, 63°, 123°, and 153° as examples), indicating that the variation in the outer ring branch has no effect on phase modulation at 20 GHz. Furthermore, the amplitudes of the curves are all close to 1, indicating that the element has good reflection characteristics.

[0052] like Figure 1 In the example, 16×16 radiation units are arranged periodically on the upper surface of the dielectric substrate. According to the formula Calculate the phase compensation required for each radiating element when different numbers of beams, modes, and radiation directions are required.

[0053] The angle of the outer ring branch in this embodiment is shown in FIG. Figure 5 To compensate, refer to the angle of the inner ring branch Figure 6 Compensation is performed to obtain the electromagnetic metasurface of this embodiment.

[0054] See Figure 7 , set the operating frequency to 10 GHz, use an x-polarized feed horn to illuminate the metasurface, and obtain the far-field radiation pattern of this embodiment at 10 GHz. From the far-field radiation pattern, it can be seen that the orbital angular momentum antenna of this embodiment forms two OAM vortex beams at 10 GHz. The mode number and direction of the vortex wave are: (l1 = 1, θ1 = 30°, )、(l2=1,θ2=-30°, ). See Figure 8 , set the operating frequency to 20 GHz, use the y-polarized feed horn to illuminate the metasurface, and obtain the far-field radiation pattern of this embodiment at 20 GHz. From the far-field radiation pattern, it can be seen that the orbital angular momentum antenna of this embodiment forms two OAM vortex beams at 20 GHz, and the mode number and direction of the vortex wave are: (l1 = 1, θ1 = 30°, )、(l2=1,θ2=-30°, ).

[0055] Thus, the dual-band, dual-polarization, multifunctional orbital angular momentum antenna of the present invention can operate simultaneously in the 10 GHz and 20 GHz frequency bands, with the two frequency bands corresponding to two perpendicular polarizations. Furthermore, the OAM antenna is multifunctional, capable of generating multi-beam, multi-mode, and multi-directional vortex waves.

[0056] Example 2

[0057] The difference between this embodiment and embodiment 1 is that the phase of the radiation unit compensation is different, and the rest is the same as embodiment 1. Figure 9 To compensate, refer to the angle of the inner ring branch Figure 10 Compensation is performed to obtain the electromagnetic metasurface of this embodiment.

[0058] See Figure 11 , set the operating frequency to 10 GHz, use an x-polarized feed horn to illuminate the metasurface, and obtain the far-field radiation pattern of this embodiment at 10 GHz. From the far-field radiation pattern, it can be seen that the orbital angular momentum antenna of this embodiment forms an OAM vortex wave beam at 10 GHz, and the mode number and direction of the vortex wave are: (l1=1,θ1=0°, ). Referring to 12, the operating frequency is set to 20 GHz, and the y-polarized feed horn is used to illuminate the metasurface to obtain the far-field radiation pattern of this embodiment at 20 GHz. From the far-field radiation pattern, it can be seen that the orbital angular momentum antenna of this embodiment forms four OAM vortex beams at 20 GHz, and the mode numbers and directions of the vortex waves are: (l1 = 1, θ1 = 30°, ),(l2=1,θ2=-30°, ),(l3=1,θ3=30°, ),and(l4=1,θ4=-30°, ).

[0059] Example 3

[0060] The difference between this embodiment and embodiment 1 is that the phase of the radiation unit compensation is different, and the rest is the same as embodiment 1. Figure 13 To compensate, refer to the angle of the inner ring branch Figure 14 Compensation is performed to obtain the electromagnetic metasurface of this embodiment.

[0061] See Figure 15 , set the operating frequency to 10 GHz, use an x-polarized feed horn to illuminate the metasurface, and obtain the far-field radiation pattern of this embodiment at 10 GHz. From the far-field radiation pattern, it can be seen that the orbital angular momentum antenna of this embodiment forms an OAM vortex beam at 10 GHz. The mode number and direction of the vortex wave are: (l1 = 1, θ1 = 30°, ). Referring to 16, the operating frequency is set to 20 GHz, and the y-polarized feed horn is used to illuminate the metasurface to obtain the far-field pattern of this embodiment at 20 GHz. From the far-field pattern, it can be seen that the orbital angular momentum antenna of this embodiment forms two OAM vortex beams at 20 GHz, and the mode numbers and directions of the vortex waves are: (l1 = 1, θ1 = -30°, ) and (l2=2,θ2=30°, ).

[0062] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A dual-frequency dual-polarization multifunctional orbital angular momentum antenna, characterized in that: It comprises a feed source, a dielectric substrate and a metal floor, wherein the metal floor is arranged below the dielectric substrate, and the upper surface of the dielectric substrate is provided with radiation units arranged in a periodic manner to form an electromagnetic metasurface, the feed source is arranged above the dielectric substrate, the feed source irradiates the electromagnetic metasurface and forms a plurality of vortex beams above the feed source, the radiation unit is an annular structure, the annular structure has an embedded circular ring, and the embedded circular ring has branches; The ring structure is a symmetrical shape, the number is one, specifically a square ring or a circular ring, and the ring structure is used to remove the coupling between the periodically arranged units; the radiation unit with phase modulation function is embedded with an embedded circular ring with branches, so that the antenna works in dual-frequency dual-polarization, each circular ring and the attached branches work independently at a frequency and polarization, and the required phase shift is generated by changing the angle of the branches; The number of the embedded circular rings with branches is more than 2.

2. The dual-frequency dual-polarization multifunctional orbital angular momentum antenna according to claim 1, characterized in that: The branches are arc-shaped or L-shaped.

3. The dual-frequency dual-polarization multifunctional orbital angular momentum antenna according to claim 1, characterized in that: The feed source is a horn antenna or a microstrip antenna.

4. The dual-frequency dual-polarization multifunctional orbital angular momentum antenna according to claim 1, characterized in that: An air layer is arranged between the dielectric substrate and the metal floor.

5. The dual-frequency dual-polarization multifunctional orbital angular momentum antenna according to claim 1, characterized in that: The periodically arranged radiation units form rectangular, circular and polygonal structures.

6. The dual-frequency dual-polarization multifunctional orbital angular momentum antenna according to claim 1, characterized in that: The length of the branches of the radiating element at different positions is related to the phase required to produce that position at the operating frequency.

7. The dual-frequency dual-polarization multifunctional orbital angular momentum antenna according to claim 1, characterized in that: The nested rings with branches resonate at different frequencies and are not coupled to each other.

8. The dual-frequency dual-polarization multifunctional orbital angular momentum antenna according to claim 1, characterized in that: The phase compensation formula of the radiating unit is: In the formula represents the position coordinates of the radiation unit, represents the direction of the vortex wave beam, l represents the mode number of the generated vortex wave, and m represents the number of beams.

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