An adaptive UCA array method for generating multi-mode whirling electromagnetic waves

Abstract

The application provides a self-adaptive UCA array arrangement method for generating a multi-mode vortex electromagnetic wave, which comprises the following steps: determining the number of concentric rings; determining the radius of a first concentric ring with the smallest radius; arranging every two adjacent concentric rings at equal intervals, and the interval is equal to the radius of the first concentric ring; dividing all the concentric rings into N equal parts according to the number N of array elements of the first concentric ring, and taking the N division points of the first concentric ring as the positions of the array elements of the first concentric ring; for each N division part of all the concentric rings, respectively placing array elements according to the positions of the array elements of the first concentric ring; taking all the concentric rings except the first concentric ring as the kth concentric ring, and dividing the N division part of the kth concentric ring into k equal parts, and taking the boundary points of the N division part and the k division points as the positions of the array elements of the kth concentric ring to place the array elements. The method can generate a high-quality OAM beam and has strong universality.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, specifically relating to an adaptive UCA array method for generating multimode vortex electromagnetic waves, which includes technologies such as OAM vortex electromagnetic wave generation, UCA design, and OAM multimode multiplexing, and is applicable to orbital angular momentum multiplexing communication systems. Background Technology

[0002] According to quantum mechanics and Maxwell's theory, electromagnetic waves radiated by an antenna exhibit wave-particle duality, meaning they can carry linear momentum and angular momentum like moving particles. The angular momentum of an electromagnetic wave comprises two parts: spin angular momentum (SAM), which describes the polarization state of the wave, and orbital angular momentum (OAM), which describes the spatial structure of the wave. [1] Vortex electromagnetic waves with a spiral phase wavefront structure can carry OAM. Each photon in a vortex electromagnetic wave carries... The orbital angular momentum, where Let be Planck's constant, and l be the topological charge number, which can take any integer value, representing the OAM mode. When the OAM mode is l, it indicates that the phase of the electromagnetic wave rotates by 2πl as it propagates one wavelength, as shown below. Figure 1 As shown, vortex electromagnetic waves carrying different mode numbers are orthogonal. Specifically, orthogonality means that transmitted energy can only be received when the receiving mode and the transmitting mode are the same. Therefore, OAM electromagnetic waves can theoretically carry an infinite number of multiplexed information streams simultaneously at the same frequency. Multiple data streams can be multiplexed and demultiplexed at the transmitter and receiver respectively, without interference between the information streams. This provides a new degree of freedom for information multiplexing independent of time, frequency, and polarization—namely, mode division multiplexing (MDF). This can significantly increase the capacity and spectral efficiency of communication systems without additionally occupying spectrum resources. [2][3] .

[0003] Vortex electromagnetic waves carrying orbital angular momentum (OAM) are a novel technology that enables efficient information transmission through the orbital angular momentum characteristics of electromagnetic waves. It can simultaneously transmit multiple information streams under conditions of the same frequency and polarization. Currently, this technology has been successfully applied to many cutting-edge fields such as free-space optical communication, fiber optic communication, visible light communication, millimeter-wave and terahertz communication. Research on OAM has also extended to many fields such as radio astronomy, atomic manipulation, correlation imaging, quantum communication, optics and photonics.

[0004] There are many methods for generating OAM vortex electromagnetic waves. In the optical and radio frequency bands, this can be achieved by feeding a Gaussian beam into a spiral phase plate. [4] Cylindrical lens [5] Holographic panel [6]The converter transforms the light into vortex electromagnetic waves (i.e., LG beams). In the microwave band, OAM vortex electromagnetic waves can be directly generated by specially designed OAM antennas, such as uniform circular ring array antennas. [7] Circular parabolic antenna [8] Ring resonator antenna [9] Metasurface materials

[10] Antennas, etc. UCA (Uniform Circular Array Antenna) has been widely studied due to its advantages such as simple structure, easy phase control, and low cost.

[11] .

[0005] like Figure 2 As shown, the idea behind designing OAM waves using UCA is to arrange antenna array elements uniformly around a circle, feed each antenna with equal amplitude and phase difference excitation, and increase the phase by 2πl after one revolution, where l is an integer representing the OAM mode. Designing multimode OAM waves using UCA is flexible.

[12] It can generate vortex electromagnetic waves with different modes by adjusting the phase of the array elements. OAM multimode multiplexing generally adopts the coaxial transmission method of "large rings inside small rings", which uses concentric circular ring antenna arrays to generate vortex waves carrying different modes of OAM by different ring arrays. Since the different modes are orthogonal to each other, demultiplexing can be performed at the receiving end.

[0006] Current UCA designs for generating multimode vortex electromagnetic waves mainly suffer from low quality of the generated vortex electromagnetic waves and a lack of regularity and scalability in array design.

[0007] References:

[0008] [1]C.Guo, 2019,doi:10.1109 / LAWP.2019.2900265.

[0009] [2]G.Liangqi,M.R.Akram,L.Dandan,Z.Cong,Z.Zixiao and L.Qingxia,"Circular slot antenna systems for OAM waves generation",IEEE AntennasWireless Propag.Lett.,vol.16,pp.1443-1446,2017.

[0010] [3]Z.Weite et al.,"Mode division multiplexing communication usingmicrowave orbital angular momentum:An experimental study",IEEE Trans.WirelessCommun.,vol.16,no.2,pp.1308-1318,Feb.2017.

[0011] [4]F.Tamburini,E.Mari,A.Sponselli,et al.,“Encoding many channels onthe same frequency through radio vorticity:first experimental test,”NewJournal of Physics,vol.14,no.3,2012.

[0012] [5]M.W.Beijersbergen,L.Allen,H.van der Veen and J.P.Woerdman,"Astigmatic laser mode converters and transfer of orbital angular momentum",Opt.Commun.,vol.96,no.1,pp.123-132,1993.

[0013] [6]P.Genevet,J.Lin,M.A.Kats and F.Capasso,"Holographic detection ofthe orbital angular momentum of light with plasmonic photodiodes",NatureCommun.,vol.3,2012.

[0014] [7]L.Cheng,W.Hong and Z.-C.Hao,"Generation of electromagnetic waveswith arbitrary orbital angular momentum modes",Sci.Rep.,vol.4,no.1,May 2015.

[0015] [8]F.Tamburini,E.Mari,A.Sponselli,B.Thidé,A.Bianchini andF.Romanato,"Encoding many channels on the same frequency through radiovorticity:First experimental test",New J.Phys.,vol.14,no.3,Mar.2012.

[0016] [9]S.Zheng,X.Hui,X.Jin,H.Chi and X.Zhang,"TransmissionCharacteristics of a Twisted Radio Wave Based on Circular Traveling-WaveAntenna,"in IEEE Transactions on Antennas and Propagation,vol.63,no.4,pp.1530-1536,April 2015,doi:10.1109 / TAP.2015.2393885.

[0017]

[10] S.Yu,L.Li,G.Shi,C.Zhu and Y.Shi,"Generating multiple orbitalangular momentum vortex beams using a metasurface in radio frequency domain",Appl.Phys.Lett.,vol.108,no.24,Jun.2016.

[0018]

[11] L.Hui, K.Le, W.Feng, C.Yuanming and Y.Yingzeng, "Alow-profiledual-polarized microstrip antenna array for dual-mode OAM applications", IEEEAntennas Wireless Propag.Lett., vol.16, pp.3022-3025, 2017.

[0019]

[12] F.Qin, L.Li, Y.Liu, W.Cheng and H.Zhang, "A Four-Mode OAM AntennaArray With Equal Divergence Angle," in IEEE Antennas and Wireless Propagation Letters, vol.18, no.9, pp.1941-1945, Sept.2019, doi:10.1109 / LAWP.2019.2934524. Summary of the Invention

[0020] The purpose of this invention is to provide an adaptive UCA array method for generating multimode vortex electromagnetic waves, so as to improve the quality of the generated vortex electromagnetic waves.

[0021] To achieve the above objectives, the present invention provides an adaptive UCA array method for generating multimode vortex electromagnetic waves, comprising:

[0022] S1: Determine the number and radius of the concentric rings of the UCA;

[0023] Step S1 specifically includes:

[0024] S11: Determine the number of concentric rings based on the number of modes required by UCA in OAM multimodal multiplexing;

[0025] S12: Determine the radius of the first concentric ring with the smallest radius; then, set equal intervals between every two adjacent concentric rings, and the interval is equal to the radius of the first concentric ring;

[0026] S2: Determine the position of the array element of the first concentric ring;

[0027] Step S2 specifically includes:

[0028] S21: Determine the number of array elements in the first concentric ring;

[0029] S22: Divide all concentric rings into N equal parts according to the number N of the array elements of the first concentric ring, and take the N division points of the first concentric ring as the positions of the array elements of the first concentric ring.

[0030] S3: Perform multi-loop UCA expansion based on the position of the array element in the first concentric ring to obtain the position of the array element in the remaining concentric rings;

[0031] Step S3 specifically includes:

[0032] For each of the N equal divisions of all concentric rings, the expansion is performed according to the following expansion rules:

[0033] S31: Place array elements on the first concentric ring according to the positions of the array elements determined in step S2;

[0034] S32: Take all concentric rings other than the first concentric ring as the kth concentric ring, divide the N-division portion of the kth concentric ring into k equal parts, where k is a positive integer of at least 2, take the boundary point of the N-division portion of the kth concentric ring and the k-division point as the position of the array element of the kth concentric ring, and place the array element on the kth concentric ring.

[0035] In step S11, the number of non-zero modes is the number of concentric rings.

[0036] In step S12, the radius r of the first concentric ring is greater than 0.6 times the operating wavelength of UCA.

[0037] In step S12, the radius of the first concentric ring is one wavelength, and the radius of the nth concentric ring is n wavelengths.

[0038] In step S21, the generateable modes include at least l OAM A concentric ring, the number of its array elements is at least 2(|l OAM |+1) elements, and the number of elements in the first concentric ring is at most 4πr / λ, where r is the radius of the first concentric ring and λ is the operating wavelength of the UCA.

[0039] The number of array elements in the first concentric ring can be 4, 6, or 8, and the number of modes l in the first concentric ring is +1 or -1.

[0040] The adaptive UCA array method for generating multimode vortex electromagnetic waves further includes step S4: determining the phase difference between adjacent array elements of the concentric ring based on the number of modes and the number of array elements of each concentric ring.

[0041] The array element employs an antenna suitable for generating OAM vortex electromagnetic waves.

[0042] The array elements are microstrip antennas or dipoles.

[0043] The array element adopts a half-wave dipole, and the operating wavelength of the UCA is 100mm.

[0044] The adaptive UCA array method for generating multimode vortex electromagnetic waves of this invention employs equally spaced concentric rings, determines the element positions by dividing the rings equally, and performs multi-ring UCA expansion. This method achieves equal spacing between the rings, equal distribution of antenna elements within each ring, and equal element spacing across all rings. This helps reduce mutual coupling between antenna elements and generates high-quality OAM beams. It can be applied to OAM communication systems in microwave and millimeter-wave bands to achieve multimode OAM multiplexing and generate high-quality OAM beams, which is of great significance in realizing multimode OAM multiplexing. Furthermore, for any given number of OAM beams, the method of this invention can be used for UCA arraying, achieving equal spacing between UCA rings, uniform distribution of antenna elements within each ring, and equal distance between adjacent antennas in all rings. It has strong versatility and is of great significance in OAM multiplexing and demultiplexing, greatly increasing the number of OAM mode multiplexes and the spectral efficiency of the communication system. The multi-loop UCA designed according to the method of the present invention has advantages such as regularity, repeatability and scalability. Attached Figure Description

[0045] Figure 1 This is a schematic diagram illustrating the principle of typical vortex electromagnetic wave and orbital angular momentum multiplexing.

[0046] Figure 2 This is a typical antenna model diagram of a uniform circular ring array;

[0047] Figure 3 This is an overall implementation flowchart of an adaptive UCA array method for generating multimode vortex electromagnetic waves according to an embodiment of the present invention.

[0048] Figure 4 Is it like this? Figure 3 The diagram shows the concentric ring arrangement of the adaptive UCA array method for generating multimode vortex electromagnetic waves.

[0049] Figure 5 Is it like this? Figure 3 The diagram shows the angle division principle of the adaptive UCA array method for generating multimode vortex electromagnetic waves.

[0050] Figure 6 Is it like this? Figure 3 The diagram shows the principle of the multi-turn UCA extension of the adaptive UCA array method for generating multimode vortex electromagnetic waves.

[0051] Figure 7This is a top view of the uniform circular array obtained by the adaptive UCA array method for generating multimode vortex electromagnetic waves according to the present invention.

[0052] Figure 8 This is a perspective view of the uniform circular array obtained by the adaptive UCA array method for generating multimode vortex electromagnetic waves according to the present invention.

[0053] Figures 9A-9C These are three-dimensional radiation maps and electric field phase maps generated by three concentric rings under three different modes: +1, +2, and +3. Figure 9A and Figure 9D These are the 3D radiation map and electric field phase map of mode +1, respectively. Figure 9B and Figure 9E These are the 3D radiation map and electric field phase map of mode +2, respectively. Figure 9C and Figure 9F These are the 3D radiation diagram and electric field phase diagram for mode +3, respectively. Detailed Implementation

[0054] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the description of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0055] The adaptive UCA array method for generating multimode vortex electromagnetic waves of the present invention can be applied to multimode OAM multiplexing wireless communication systems in microwave or millimeter-wave bands to improve the quality of the generated vortex electromagnetic waves.

[0056] The adaptive UCA array method for generating multimode vortex electromagnetic waves of the present invention is based on the following principles: First, for a given number of array elements and a given element spacing in a circular array, the method of the present invention ensures that there are no remaining antenna elements after the array element arrangement is completed, thereby improving the quality of the generated vortex electromagnetic waves. This is because if there are remaining antennas continuing to be arranged around the circumference, it will lead to an uneven array, which will prevent the generation of high-quality vortex electromagnetic waves. Second, the method of the present invention achieves equal distances between adjacent circular arrays to generate higher-quality OAM beams in the case of OAM multiplexing. Existing technologies usually do not require equal distances between adjacent rings. This is done to allow for subsequent array expansion and to reduce the antenna footprint. Finally, the method of the present invention not only ensures equal spacing between elements in each circular array, but also ensures equal spacing between elements in all concentric circular arrays, thereby making the array distribution more uniform, reducing current coupling and improving the quality of the generated vortex electromagnetic waves. In this way, ensuring that the spacing between array elements is above a certain critical value can reduce current coupling. When the distance exceeds this critical value, the spacing between array elements should be taken near the critical value and made as uniform as possible to greatly reduce the area occupied by the array. Moreover, the quality and purity of the vortex electromagnetic waves generated under the condition of uniform array will be higher.

[0057] like Figure 3 As shown, the adaptive UCA array method for generating multimode vortex electromagnetic waves of the present invention specifically includes the following main steps:

[0058] Step S1: Concentric ring design, that is, determining the number and radius of the concentric rings of the UCA (Uniform Circular Array Antenna);

[0059] Step S1 specifically includes:

[0060] Step S11: Determine the number of concentric rings based on the number of modes required by UCA in OAM multimodal multiplexing; where the number of non-zero modes is the number of concentric rings.

[0061] Step S12: Determine the radius of the first concentric ring with the smallest radius; then, set equal intervals between every two adjacent concentric rings, and the interval is equal to the radius of the first concentric ring;

[0062] That is, such as Figure 4 As shown, if the radius of the first concentric ring is r, then the radius of the kth concentric ring from the inside out is kr, so that the interval between two adjacent concentric rings is r, which achieves the requirement of equal interval between adjacent ring arrays.

[0063] The radius r of the first concentric ring cannot be arbitrary. To prevent low OAM beam purity due to coupling effects between antenna elements, the spacing between two adjacent concentric rings must be maintained at more than 0.6 to 0.8 wavelengths (see reference [Xu Qiang, Xie Yuelei. Design and implementation of OAM beam generation system based on circular array [J]. Telecommunications Technology, 2022, 62(10): 1399-1406]). Therefore, the radius r of the first concentric ring must be greater than 0.6 UCA operating wavelengths, so that the spacing between any two adjacent concentric rings is greater than 0.6 wavelengths.

[0064] Step S2: Select the reference array element position, that is, determine the position of the array element in the first concentric ring;

[0065] Step S2 specifically includes:

[0066] Step S21: Determine the number of array elements in the first concentric ring;

[0067] As mentioned above, the radius of the first concentric ring is r, therefore the circumference of the first ring is 2πr. To ensure high continuity in the phase distribution and prevent mutual coupling between array elements, the number of array elements in a single concentric ring must be neither too many nor too few.

[0068] The lower limit of the number of array elements is determined by the modes to prevent low mode purity due to discontinuities in phase distribution. Given N antenna elements, the number of modes that can be generated is... OAM To satisfy:

[0069]

[0070] The number of antenna elements in the rings is determined by the number of antenna elements in the first concentric ring. If the number of antenna elements in the first concentric ring is 4, then the mode l of the first concentric ring is... OAM The values ​​can be -1, 0, or +1. If the number of antenna elements in the first concentric ring is 6, then the mode l of the first concentric ring... OAM The possible values ​​are -2, -1, 0, +1, +2; if it is 8, then the mode l of the first concentric ring... OAM The possible values ​​are -3, -2, -1, 0, +1, +2, +3. The mode of any concentric ring array can be 0.

[0071] Therefore, for the generateable modes, at least l OAM A concentric ring, the number of its array elements is at least 2(|l OAM |+1) items.

[0072] In satisfying Under certain conditions, theoretically, the modes in each ring can be arranged arbitrarily. However, in order to ensure the continuity of the phase of the concentric ring array, the ring with larger modes increases the phase more when it is surrounded by the circumference, thus requiring more array elements. Therefore, in this invention, the number of modes that can be generated is increased by increasing the concentric rings in an order from the inside to the outside.

[0073] The upper limit of the number of array elements is determined by the coupling between array elements. In order to prevent mutual coupling between array elements, the interval between adjacent array elements is at least half a wavelength. Therefore, the number of array elements in the first concentric ring is at most 4πr / λ, where r is the radius of the first concentric ring and λ is the operating wavelength of the UCA.

[0074] Generally, it is more appropriate to use 4, 6, or 8 array elements in the first concentric ring. This ensures phase continuity and facilitates the design of the feed network. Too few array elements will result in insufficient phase continuity and failure to generate vortex electromagnetic waves, while too many array elements will increase the design difficulty of the feed network, increase power consumption, and cause mutual coupling due to excessive array element density.

[0075] In this embodiment, the number of array elements in the first concentric ring is 6, and the number of modes l in the first concentric ring is +1.

[0076] Step S22: Divide all concentric rings into N equal parts according to the number N of the array elements of the first concentric ring, and take the N division points of the first concentric ring as the positions of the array elements of the first concentric ring.

[0077] like Figure 5 As shown, the number of array elements in the first concentric ring is N. Therefore, the angle θ between two adjacent array elements in the first concentric ring is chosen to be 2π / N, thus dividing the first concentric ring into N equal parts around the circumference according to angle θ. Figure 5 Taking N=6 as an example, the first concentric ring is divided into N equal parts. This ensures that the number of antennas in each ring is an integer, the spacing between the array elements in each ring is equal, and there are no extra array elements after arranging one ring. Placing the antenna array elements at the equal division points of the rings ensures that the antennas in each ring are evenly distributed.

[0078] Step S3: Perform multi-loop UCA expansion based on the position of the array elements in the first concentric ring to obtain the positions of the array elements in the remaining concentric rings.

[0079] Since each of the N equal parts is equivalent in position when all concentric rings are divided into N equal parts in step S2, in step S3, one of the N equal parts can be selected first for multi-loop UCA extension, and then this extension scheme can be extended to each N equal part to realize the extension of the entire multi-loop UCA.

[0080] Step S3 specifically includes:

[0081] For each of the N equal divisions of all concentric rings, the expansion is performed according to the following expansion rules:

[0082] Step S31: Place array elements on the first concentric ring according to the positions of the array elements determined in step S2;

[0083] Therefore, the number of array elements in the first concentric ring is N, and the distance between any two adjacent antenna array elements in the first concentric ring around the circumference is 2πr / N.

[0084] Step S32: Take all concentric rings other than the first concentric ring as the k-th concentric ring. Divide the N-division portion of the k-th concentric ring into k equal parts, where k is a positive integer of at least 2. Use the boundary points of the N-division portion and the k-division points as the positions of the array elements in the k-th concentric ring. Place array elements on the k-th concentric ring. Thus, a total of kN array elements are placed on the k-th concentric ring, with k array elements placed in each N-division portion.

[0085] The second concentric ring is the second ring closest to the center, and its radius is twice that of the first concentric ring. It is divided into two equal parts, such that the distance between two adjacent division points of the second ring around the circumference is equal to the distance between two adjacent antenna elements in the first ring around the circumference. Therefore, the number of elements in the second concentric ring is 2N.

[0086] The third concentric ring is the third ring closest to the center, and its radius is three times that of the first concentric ring. Array elements are placed at three equal division points, with a total of 3N array elements. This process continues, with array elements placed at N equal division points for the nth ring, resulting in a total of nN array elements. The array element placement positions are as follows... Figure 6 As shown by the center dot.

[0087] Therefore, by expanding all the N equal parts into an array according to the above steps S31 and S32, it can be extended to the entire UCA, thereby achieving that the array element spacing of all concentric rings is equal and the spacing is equal to 2πr / N.

[0088] The UCA generated according to steps S1 to S3 above is equivalent to providing a UCA template, which can be used to select the appropriate circular array based on the number of modes required by the OAM wave. Furthermore, even with a pre-designed UCA, new OAM modes can be added to the array simply by expanding the UCA outwards without altering the existing array.

[0089] In addition, step S4 may be included: determining the phase difference between adjacent array elements of the concentric ring based on the number of modes and the number of array elements of each concentric ring.

[0090] The formula for calculating the phase difference between adjacent array elements is 2πl / N, where l is the number of modes of the concentric rings and N is the number of array elements of the concentric rings.

[0091] Experimental results:

[0092] Taking a UCA that outputs a four-mode multiplexed OAM wave as an example, this UCA consists of three concentric rings, each representing a mode. Here, all modes are positive, designated +1, +2, and +3. To ensure high continuity in phase distribution even with higher modes, rings with more array elements are used to generate higher modes. Therefore, the OAM wave modes generated on each ring from the inside out are set to +1, +2, and +3, respectively. A mode of 'l' means that the phase increases by 2πl after one revolution of the array element around the circumference. The first concentric ring has 6 array elements, and its OAM wave mode is +1. However, to generate a higher-quality OAM beam, it is preferable to generate an OAM wave with an increasing number of modes through multiple concentric rings from the inside out.

[0093] In other embodiments, if the first concentric ring is used to generate an OAM wave of mode 1, its number of array elements can be either 6 or 4. If the radius of the first concentric ring is large, the number of array elements in the first concentric ring can also be 8, 12, or more to increase phase continuity. In this embodiment, since the number of array elements is set to 6, the phase difference between adjacent array elements in the first concentric ring is π / 3. According to the array expansion method, the number of array elements in the k-th concentric ring is k times that of the first concentric ring, and the corresponding number of OAM modes is also k times that of the first concentric ring (generally, the number of OAM modes in the k-th concentric ring can only be +n, because under the condition of a well-designed feed network, the phase increase of an array element around the ring is fixed). Therefore, the phase difference between adjacent array elements in each ring is π / 3. The feed phase of each element in each concentric ring increases by the same value around the circumference. The difference between the feed phase of one element and the feed phase of the next is the phase difference between adjacent elements in the concentric ring. The formula for calculating the phase difference is 2πl / N, where l is the number of modes in the concentric ring and N is the number of elements in the concentric ring. The phase difference is determined based on the number of modes and the number of elements in the concentric ring. If the number of modes is l and the number of elements is N, then the phase difference is 2πl / N. Assuming the first ring has 8 elements and 1 mode, then the phase difference between the elements is π / 4.

[0094] To prevent coupling effects between antenna elements, in step S12, the radius of the first concentric ring is one wavelength, and the radius of the nth concentric ring is n wavelengths. In this embodiment, the distance between all elements and adjacent elements is approximately one wavelength, and the element placement is as follows: Figure 7 As shown by the center dot.

[0095] The array elements can be selected from antennas suitable for generating OAM, such as microstrip antennas and dipoles. In this embodiment, a half-wave dipole is selected as the antenna array element, with an operating wavelength of 100mm. The dipoles are arranged as follows: Figure 8 The concentric rings are shown. Using HFSS software to simulate the antenna array, three-dimensional radiation maps and electric field phase maps of the three concentric rings under three different modes (+1, +2, and +3) are obtained, as shown below. Figures 9A-9F As shown. Among them, the first concentric ring from the inside out generates the +1 mode, the second concentric ring generates the +2 mode, and the third concentric ring generates the +3 mode. Figure 9A , Figure 9D This corresponds to only feeding the first concentric ring and not feeding the other two concentric rings. Figure 9A and Figure 9D These are the 3D radiation diagram and electric field phase diagram for mode +1, respectively; Figure 9B , Figure 9E This corresponds to only powering the second ring while leaving the other two rings unpowered. Figure 9B and Figure 9E These are the 3D radiation diagram and electric field phase diagram for mode +2, respectively; Figure 9C , Figure 9F This corresponds to only powering the third ring while leaving the other two rings unpowered. Figure 9C and Figure 9F These are the 3D radiation diagram and electric field phase diagram for mode +3, respectively. The electric field phase diagram shows that the antenna array has a spiral phase wavefront. Therefore, the array arrangement method proposed in this patent can generate multimode vortex electromagnetic waves.

[0096] If modes need to be added in subsequent designs, simply follow step S3 of the method of this invention to expand the array, such as adding a fourth concentric ring with a radius of 4 wavelengths, and placing 24 array elements at equal intervals on the concentric ring, with a phase difference of π / 3 between adjacent array elements, to generate an OAM beam with mode +4.

[0097] The adaptive UCA array method for generating multimode vortex electromagnetic waves of this invention employs equally spaced concentric rings, determines the element positions by dividing the rings equally, and performs multi-ring UCA expansion. This method achieves equal spacing between the rings, equal distribution of antenna elements within each ring, and equal element spacing across all rings. This helps reduce mutual coupling between antenna elements and generates high-quality OAM beams. It can be applied to OAM communication systems in microwave and millimeter-wave bands to achieve multimode OAM multiplexing and generate high-quality OAM beams, which is of great significance in realizing multimode OAM multiplexing. Furthermore, for any given number of OAM beams, the method of this invention can be used for UCA arraying, achieving equal spacing between UCA rings, uniform distribution of antenna elements within each ring, and equal distance between adjacent antennas in all rings. It has strong versatility and is of great significance in OAM multiplexing and demultiplexing, greatly increasing the number of OAM mode multiplexes and the spectral efficiency of the communication system. The multi-loop UCA designed according to the method of the present invention has advantages such as regularity, repeatability and scalability.

[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. All simple and equivalent changes and modifications made in accordance with the claims and description of this application fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. An adaptive UCA array method for generating multi-mode whirling electromagnetic waves, characterized in that, Comprising: Step S1: determining the number and radius of the concentric circular rings of the UCA; The step S1 specifically comprises: Step S11: determining the number of the concentric circular rings according to the number of the modes used by the UCA in OAM multi-mode multiplexing; Step S12: determining the radius of the first concentric circular ring with the smallest radius; then, every two adjacent concentric circular rings are arranged at equal intervals, and the interval is equal to the radius of the first concentric circular ring; Step S2: determining the position of the elements of the first concentric circular ring; The step S2 specifically comprises: Step S21: determining the number of the elements of the first concentric circular ring; Step S22: dividing all the concentric circular rings into N equal parts according to the number N of the elements of the first concentric circular ring, and taking the N division points of the first concentric circular ring as the positions of the elements of the first concentric circular ring; Step S3: expanding the UCA in multiple turns according to the positions of the elements of the first concentric circular ring to obtain the positions of the elements of the remaining concentric circular rings; The step S3 specifically comprises: For each N equal part of all the concentric circular rings, the expansion rules are as follows: Step S31: placing elements on the first concentric circular ring according to the positions of the elements of the first concentric circular ring determined in step S2; Step S32: taking all the concentric circular rings other than the first concentric circular ring as the kth concentric circular ring, dividing the N equal part of the kth concentric circular ring into k equal parts, k being a positive integer at least 2, taking the boundary points and the k equal division points of the N equal part of the kth concentric circular ring as the positions of the elements of the kth concentric circular ring, and placing elements on the kth concentric circular ring.

2. The adaptive UCA array method for generating multi-mode whirling electromagnetic waves according to claim 1, wherein, In the step S11, the number of non-zero modes is the number of concentric circular rings.

3. The adaptive UCA array method for generating multi-mode whirling electromagnetic waves according to claim 1, wherein, In the step S12, the radius r of the first concentric circular ring is greater than 0.6 times the working wavelength of the UCA.

4. The adaptive UCA array method for generating multi-mode whirling electromagnetic waves according to claim 3, wherein, In the step S12, the radius of the first concentric circular ring is one wavelength, and the radius of the nth concentric circular ring is n wavelengths.

5. The adaptive UCA array method for generating multi-mode whirling electromagnetic waves according to claim 1, wherein, In the step S21, at least one of the modals that can be generated includes l OAM concentric rings, the number of elements of which is at least 2(|l OAM |+1), and the number of elements of the first concentric ring is at most 4πr / λ, where r is the radius of the first concentric ring, and λ is the working wavelength of the UCA.

6. The adaptive UCA array method for generating multi-mode whorm electromagnetic wave according to claim 1, wherein, The number of elements of the first concentric circular ring is 4, 6 or 8, and the mode number l of the first concentric circular ring is +1 or -1.

7. The adaptive UCA array method for generating multi-mode whorm electromagnetic wave according to claim 1, wherein, Further comprising step S4: determining the phase difference between adjacent elements of each concentric circular ring according to the mode number and the number of elements of the concentric circular ring.

8. The adaptive UCA array method for generating multi-mode whirling electromagnetic waves according to claim 1, wherein, The elements use an antenna suitable for generating an OAM vortex electromagnetic wave.

9. The adaptive UCA array method for generating multi-mode whirling electromagnetic waves according to claim 8, wherein, The elements use a microstrip antenna or a dipole.

10. The adaptive UCA array method for generating multi-mode whorm electromagnetic wave according to claim 1, wherein, The elements use a half-wave dipole, and the working wavelength of the UCA is 100 mm.

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