Method and device for receiving vortex electromagnetic wave mode by array antenna

Abstract

The invention relates to the technical field of vortex electromagnetic waves, in particular to a method and device for receiving vortex electromagnetic wave modals through an array antenna, and the method comprises the steps: arranging a transmitting array at one side, and transmitting vortex electromagnetic waves; a receiving end rectangular receiving array is arranged on the other side, after parallel calibration of the two ends, the receiving end rectangular receiving array carries out phase calibration through the middle column, phases are measured through any two groups of the two ends with the middle column as the symmetry axis, and modes of vortex electromagnetic waves are separated; the invention further discloses a device applied to the method. According to the invention, the disadvantage that the azimuth included angle needs to be measured in the existing vortex electromagnetic wave receiving process is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of vortex electromagnetic waves, and in particular to a method and a device for receiving vortex electromagnetic wave modes by an array antenna. Background Art

[0002] Vortex electromagnetic waves are a type of electromagnetic waves with a spiral phase structure. They not only show application potential in traditional communication and radar systems, but have also been widely studied and applied in optical transmission, quantum information, and imaging. A notable feature of vortex electromagnetic waves is that the phase of their wavefronts rotates spirally along the propagation direction to form different orbital angular momentum. This feature gives vortex electromagnetic waves a rich spatial structure, which can carry more information within the same frequency band, thereby improving signal capacity and anti-interference capabilities.

[0003] In the prior art, the reception of vortex electromagnetic waves mainly depends on the array antenna system. The array antenna can restore the spatial distribution information of the wavefront through precise signal acquisition and phase measurement. Typical array antennas include uniform arrays and non-uniform arrays. These arrays can effectively receive vortex electromagnetic waves in a variety of application scenarios through proper arrangement. The design of the array antenna requires it to have strong directivity and high-precision phase measurement capabilities to ensure that the phase information of the vortex wave can be accurately captured. In order to extract the information of the vortex wave from the received signal, a variety of signal demodulation methods are used in the prior art. Among them, the demodulation technology based on phase gradient is widely used in the phase recovery of vortex electromagnetic waves. By measuring the phase difference of the received signal, the phase distribution of the vortex wavefront can be calculated, thereby inferring the propagation characteristics of the wavefront. In addition to the phase gradient method, interference method, wavefront fitting method, Fourier transform method, etc. are also common signal demodulation methods. In terms of digital signal processing, the prior art has widely used fast Fourier transform (FFT), adaptive filtering, beamforming and other technologies to improve the performance of the receiving system; the signal processing algorithm can filter, enhance and demodulate the received vortex electromagnetic wave, thereby effectively extracting the information it carries. In addition, with the improvement of computing power, advanced technologies such as machine learning and deep learning have also begun to be applied to the reception and demodulation process of vortex electromagnetic waves; these technologies can improve the reception accuracy and anti-interference ability in complex environments by automatically learning signal characteristics. The current vortex electromagnetic wave reception technology has achieved good application results in many fields, such as high-speed data transmission, remote imaging, wireless communication and the Internet of Things. The current vortex electromagnetic wave reception methods are mainly divided into four categories: single-point detection reception, full arc length reception, Doppler reception, and partial arc reception.

[0004] However, when the vortex electromagnetic wave is received using the two methods of full arc length reception and partial arc reception, there is a problem that the azimuth angle needs to be measured, and the measurement of the azimuth angle is very difficult. Summary of the invention

[0005] In view of this, an object of the present invention is to provide a method and device for receiving vortex electromagnetic wave modes by an array antenna, so as to solve the disadvantage that the existing vortex electromagnetic wave reception still needs to measure the angle in the azimuth direction.

[0006] In the first aspect, the present invention discloses a method for receiving vortex electromagnetic wave modes by an array antenna, wherein one side is a transmitting array that emits vortex electromagnetic waves; the other side is a receiving end rectangular receiving array. After the two ends are calibrated in parallel, the receiving end rectangular receiving array performs phase calibration through the middle column, and the phase is measured by any two groups at the two ends with the middle column as the axis of symmetry to separate the mode of the vortex electromagnetic wave.

[0007] Specifically, the receiving array unit is a 2*2 receiving array; the receiving array element here is a basic receiving array of 4 elements, that is, a receiving unit; when the receiving array is calibrated, the phases of two vortex electromagnetic wave arcs with different radii on the arc are detected simultaneously.

[0008] Specifically, the receiving array is a 3*3 rectangular receiving array (calibration condition); on the basis of a 2*2 basic array, the base array is placed on a 3*3 array to describe the central calibration array elements I, D, and H.

[0009] Specifically, the receiving array is an N*N array, the array element spacing between the array elements AB is d, the array element spacing between the array elements FG is td, and the array element spacing between the array elements BG is pd.

[0010] In the second aspect, the present invention discloses a system for receiving vortex electromagnetic wave modes by an array antenna, characterized in that: it is applied to the above-mentioned method for receiving vortex electromagnetic wave modes by an array antenna, including an encoder, the encoder is electrically connected to multiple phase shifters through a control processor 1, and the phase shifters are electrically connected to a frequency signal source through a one-to-eight power divider; the control processor 1, the phase shifters, and the one-to-eight power divider together constitute a phase distributor; the phase distributor is connected to a transmitting antenna; it also includes a receiving antenna, the receiving antenna is electrically connected to multiple phase detectors through a one-to-two power divider; the one-to-two power divider and the phase detector together constitute a phase receiver; the phase detector is electrically connected to a control processor 2, and the control processor 2 is electrically connected to a decoder; a calibration gimbal is provided on one side of the receiving antenna, and the calibration gimbal is respectively connected to the control processor 2 and the receiving antenna.

[0011] Specifically, the transmitting antenna adopts an 8-element UCA array antenna.

[0012] Specifically, the receiving antenna adopts a 3*3 rectangular array antenna.

[0013] Specifically, the calibration gimbal adopts a two-degree-of-freedom gimbal.

[0014] The beneficial effects of the present invention are:

[0015] The basic array element unit of the present invention is a four-element array antenna. By measuring two groups of phase values ​​on circular arcs at two positions with different radii, the modal values ​​of the vortex electromagnetic waves can be separated, thereby avoiding the measurement of the azimuth angle during the previous full arc length reception or partial arc reception. At the same time, in the calibration array element, the present invention uses central equidistant array elements to realize the calibration of the circular arc, thereby reducing the difficulty of alignment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram for sending and receiving

[0017] Figure 2 Schematic diagram of the rectangular receiving array structure.

[0018] Figure 3 This is a schematic diagram of the 3*3 rectangular receiving array structure.

[0019] Figure 4 A schematic diagram of a set of base structures for an N*N array.

[0020] Figure 5 Schematic diagram of the N*N moving process.

[0021] Figure 6 This is the phase distribution diagram when L=1.

[0022] Figure 7 This is the phase distribution diagram when L=2.

[0023] Figure 8 This is the phase distribution diagram when L=3.

[0024] Fig. 9 This is a graph showing how the mode changes with radius.

[0025] Fig.10 This is the modal error diagram caused by radius.

[0026] Fig.11 This is a graph showing how the mode changes with distance.

[0027] Fig.12 This is the modal error diagram caused by distance.

[0028] Fig.13 This is the error diagram of theoretical radius-actual radius as the radius changes.

[0029] Fig.14 This is the error diagram of the theoretical angle - actual angle as the radius changes.

[0030] Fig.15 This is the error diagram of theoretical radius-actual radius changing with distance.

[0031] Fig.16 This is the error diagram of the theoretical angle - actual angle as the radius changes.

[0032] Fig.17 This is a schematic diagram of the simulation of the change of the angle between AB array elements with radius.

[0033] Fig.18 Schematic diagram of the simulation radius changing with radius.

[0034] Fig.19 Schematic diagram of the simulation mode changing with radius.

[0035] Fig. 20 This is a statistical chart of the number of modes whose mode is a 5*5 array.

[0036] Fig.21 The mode with L=1 is a statistical diagram of the number of modes of a 7*7 array.

[0037] Fig. 22 The mode with L=1 is a statistical diagram of the number of modes of a 9*9 array.

[0038] Fig.23 The mode for L=2 is a statistical diagram of the number of modes of a 5*5 array.

[0039] Fig.24 The mode for L=2 is a statistical diagram of the number of modes of a 7*7 array.

[0040] Fig.25 The mode for L=2 is a statistical diagram of the number of modes of a 9*9 array.

[0041] Fig.26 The mode for L=3 is a statistical diagram of the number of modes of a 5*5 array.

[0042] Fig. 27 The mode for L=3 is a statistical diagram of the number of modes of a 7*7 array.

[0043] Fig.28 The mode for L=3 is a statistical diagram of the number of modes of a 9*9 array.

[0044] Fig.29 It is a schematic diagram of the system structure of the present invention.

[0045] Fig.30 It is a flow chart of the system operation of the present invention.

[0046] In the figure, 1. encoder; 2. control processor 1; 3. phase shifter; 4. one-to-eight power divider; 5. frequency signal source; 6. phase distributor; 7. transmitting antenna; 8. receiving antenna; 9. one-to-two power divider; 10. phase detector; 11. phase receiver; 12. control processor 2; 13. calibration pan / tilt. DETAILED DESCRIPTION

[0047] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below in conjunction with the specific embodiments. Preferred embodiments of the present invention are provided in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0049] Example 1

[0050] This embodiment provides a method for receiving a vortex electromagnetic wave mode by an array antenna, referring to Figure 1 , which shows a schematic diagram of transmitting and receiving. It can be seen from the figure that the specific steps of the method are: the left side is the transmitting array antenna, which emits a vortex electromagnetic wave; the right side is the receiving end rectangular receiving array antenna. After the two ends are parallelly calibrated, the right side receiving end rectangular receiving array antenna is phase-calibrated through the middle column, and the phase is measured by any two groups at both ends with the middle column as the symmetry axis to separate the mode of the vortex electromagnetic wave.

[0051] The basic receiving principle is as follows:

[0052] The total angular momentum of the vortex electromagnetic wave can be decomposed into J = L + S, where L and S represent orbital angular momentum and self-selected angular momentum respectively; the orbital angular momentum of the vortex electromagnetic wave can be measured by the phase gradient method. Two single antennas are placed on the wave plane of the vortex electromagnetic wave, both located on concentric circles with the wave axis as the center of the vortex electromagnetic wave, and the phases of the vortex electromagnetic wave are measured as follows: and The angle between the two receiving antennas is β, and the mode can be obtained by the following formula (1), where β usually needs to satisfy β<2π / |L max |:

[0053]

[0054] When the distance between the transmitting array antenna and the receiving array antenna of the vortex electromagnetic wave is far enough, or when the distance is close, the radius of the concentric circle of the vortex electromagnetic wave is large enough, so that a small segment of the arc can be roughly approximated as a straight line; therefore, an antenna parallel to the plane of the transmitting antenna is placed at the two end points of the above-mentioned small arc to measure the phase of the vortex electromagnetic wave, and there is no need to measure the angle. Repeat the above operation, take another arc at a position with a slightly shorter radius of the concentric circle, and place two antennas at both ends of the arc, and measure the phase of the vortex electromagnetic wave, so as to measure a set of phase values; four array elements are a unit, and a rectangular array antenna or a trapezoidal array antenna is constructed.

[0055] The specific process is as follows:

[0056] First, receiving array antenna unit: 2*2 rectangular receiving array antenna.

[0057] The receiving array element here is a basic receiving array of 4 elements, that is, a receiving unit; when the receiving array is calibrated, the arc phases of two vortex electromagnetic waves with different radii on the arc are detected simultaneously, such as Figure 2 As shown ( Figure 2 It is described as a rectangular base array, and the base array can also be a trapezoidal array of four elements).

[0058] Figure 2 It is a 2*2 rectangular array antenna. Assume that the length and width of the 2*2 rectangular array are both d, the angle between antenna A and B is β1, the angle between antenna F and G is β2, and the radius of arc AB is r1. The formula can be listed as follows:

[0059]

[0060] d = r1β1(3);

[0061] d=(r1+d)β2(4);

[0062] Solve the above three-variable equation system, and then we can get the corresponding radius solution:

[0063]

[0064] The angle solution is:

[0065]

[0066] The modal solution is:

[0067]

[0068] in

[0069] From the above, we can see that the entire formula only measures the phase values ​​of the four points ABFG, and does not involve the measurement of the azimuth angle. Moreover, through this method, the azimuth angle β1 and the corresponding radius r1 of arc AB can be inferred, and the measurement is relatively simple.

[0070] Second, rectangular receiving array antenna: 3*3 rectangular receiving array antenna (calibration conditions).

[0071] On the basis of the 2*2 basic array, the base array is placed on the 3*3 array to describe the center calibration array elements I, D, and H; Figure 3 shown.

[0072] Assume that the spacing between array A and array B of the 3*3 rectangular array is 2d, the spacing between array C and array E is 2d, the spacing between array F and array G is 2d, and the spacing between arrays H, D, and I is d. The angle between antenna A and B is β1, the angle between antenna C and E is β2, and the angle between antenna F and G is β3. Assume that the radius of arc AB is r1, and the length of AB is approximately replaced by the spacing between AB, 2d; the radius of arc CE is r2, and the length of CE is approximately replaced by the spacing between CE, 2d. The formula can be listed as follows:

[0073]

[0074] 2d = r1β1(9);

[0075] 2d=(r1+d)β2(10);

[0076] 2d=(r1+2d)β3(11);

[0077] The above equations, combined with array elements A, B, C, and E, can be obtained with angle β1, radius r1, and mode L as:

[0078]

[0079] The above equations, combined with array elements A, B, F, G, can be obtained with angle β1, radius r1, and mode L as:

[0080]

[0081] The above equations, combined with the array elements C, E, F, G, can be obtained with the angle β1, radius r1, and mode L as:

[0082]

[0083] in

[0084] Three sets of solutions can be calculated above, and the modal values ​​are distributed near the correct modal values.

[0085] L = round[L ABCE ]=round[L ABFG ]=round[L CEFG ](15);

[0086] You can also take non-integer values ​​and calculate the arithmetic mean as follows. Combining the three solutions, we get:

[0087]

[0088] The alignment condition is known from the phase composition of the vortex electromagnetic wave:

[0089]

[0090] Third, the receive antenna of the N*N array is derived.

[0091] Based on the above derivation, we can get the calibration conditions of the basic four-element base array and the 3*3 receiving array composed of the base array. Next, this array is extended to the array of N*N elements (here N is N>=3, when N is an odd number, there is a calibration condition, when N is an even number, this method is still applicable, and there is no calibration condition at this time), such as Figure 4 shown.

[0092] Assuming that the array element spacing between elements AB is d, the array element spacing between elements FG is td, and the array element spacing between elements BG is pd, combined with the array formula proposed above, the general expression of the array element angle of this type of array antenna can be summarized.

[0093] The formula for the array element angle is:

[0094]

[0095] The radius of the array element is:

[0096]

[0097] The modal is:

[0098]

[0099] in t is the multiple of the horizontal FG and AB, and p is the multiple of the vertical FG and AB; the movement process is demonstrated as follows Figure 5 shown.

[0100] Assume that the total number of array elements is N*N, let the array element "1" in the above array elements be the coordinate origin, the coordinates of array element B are (n,m), and the coordinates of array element G are (i,j)

[0101] The coordinate of B can be moved to the right, and the horizontal coordinate is (n+1) after moving one element. After A moves synchronously and symmetrically with B, the coordinate of A becomes (-n-1). B can also be moved upward, and the vertical coordinate is (m+1) after moving one element. After A moves synchronously and symmetrically with B, the coordinate of A becomes (m+1). At the same time, the coordinate of G can be moved to the right, and the horizontal coordinate is (i+1) after moving one element. After F moves synchronously and symmetrically with G, the coordinate of F becomes (-i-1). G can also be moved upward, and the vertical coordinate is (j+1) after moving one element. After F moves synchronously and symmetrically with G, the coordinate of F becomes (j+1). Similarly, m, n, i, and j can also move different numbers of elements at the same time, all following the above rules. The following is the expression of the mobile mode L of the array and its calibration conditions.

[0102]

[0103] The calibration conditions in the middle column meet:

[0104] Where 1≤n≤N-1, m<j, and n, m, i, and j are all integers.

[0105] The results of the theoretical formula analysis are as follows.

[0106] Figure 6-8 The phase distribution diagrams obtained by plotting the theoretical formula of the UCA transmitting array antenna with the code; Figure 6 is the phase distribution diagram when L=1, Figure 7 is the phase distribution diagram of L=2, Figure 8 This is the phase distribution diagram when L=3.

[0107] Figure 9-16 is the theoretical modal radius azimuth angle and error analysis diagram; among them, Fig. 9 is the diagram of the change of mode with radius, Fig.10 is the modal error diagram caused by radius, Fig.11 is a graph showing the variation of the mode with distance, Fig.12 is the modal error diagram caused by distance, Fig.13 is the error diagram of theoretical radius-actual radius as the radius changes, Fig.14 is the error diagram of theoretical angle-actual angle changing with radius, Fig.15 is the error diagram of theoretical radius-actual radius changing with distance, Fig.16 This is the error diagram of the theoretical angle - actual angle as the radius changes.

[0108] (I) Relationship between mode, transmission and reception distance and receiving radius

[0109] Fig.13is the modal change when the radius of the receiving antenna changes from 0.5 meters to 1.5 meters when the transmission and reception distance is one meter, Fig.10 is the modal error when the receiving distance is 1 meter and the radius of the receiving antenna increases from 0.5 meter to 1.5 meter. Fig. 9 and Fig.10 It can be concluded that when other conditions remain unchanged, the modal error of the mode received by the array antenna becomes smaller and smaller as the radius increases. Fig.11 When the radius of the transmitting and receiving position is 1.5 meters, the modal change of the distance between the receiving antenna and the transmitting antenna from 1.0 meters to 2.0 meters, Fig.12 is the modal error when the distance between the receiving antenna and the transmitting antenna changes from 1.0 m to 2.0 m when the radius of the transmitting and receiving position is 1.5 m. Fig.11 and Fig.12 It can be concluded that when other conditions remain unchanged, the mode received by the array antenna does not change with the increase of distance, that is, the modal error is independent of the receiving distance. Fig. 9 and Fig.11 It can be seen that the modal curve received by this method is relatively smooth. Fig.11 and Fig.12 It can be concluded that at the same position, the lower the modal value, the smaller the modal error at the receiving end will be, and the higher the modal value, the larger the modal error at the receiving end will be.

[0110] (II) Relationship between theoretical radius and angle

[0111] Fig.13 When the receiving and transmitting distance is 1 meter, as the radius gradually increases, the error between the radius obtained by this method and the actual radius gradually decreases, and when the mode numbers are 1, 2, and 3 respectively, the radius errors coincide, indicating that the radius error is independent of the mode number. Fig.14 When the receiving and transmitting distance is 1 meter, as the radius gradually increases, the error between the angle obtained by this method and the actual angle gradually decreases, and when the mode numbers are 1, 2, and 3 respectively, the radius errors coincide, indicating that the angle error is also unrelated to the mode number. Fig.15 When the receiving and transmitting radius is 1.5 meters, as the distance gradually increases, the error between the radius obtained by this method and the actual radius remains basically unchanged, and when the mode numbers are L=1, L=2, and L=3, the radius errors coincide, indicating that the mode number is independent of the radius error. Fig.16 When the transmitting and receiving radius is 1.5 meters, as the distance gradually increases, the error between the azimuth angle obtained by this method and the actual angle remains basically unchanged, and when the mode numbers are L=1, L=2, and L=3, the radius errors coincide, indicating that the mode number is independent of the azimuth angle error.

[0112] The simulation analysis is as follows.

[0113] like Figure 17-19 As shown, from Fig.17 It can be seen that the measured radius with L = 1, L = 2, and L = 3 generally conforms to the theoretical change trend, but when the radius is Radius = 1.6m and the modal value L = 1, the change fluctuates. Fig.18 It can be seen that L = 1, L = 2, and L = 3 are all roughly in line with this trend. When the receiving radius is Radius = 1.6m, the modal value L = 1 has a large fluctuation. Fig.19 It can be seen that the modal values ​​at most positions from the radius r = 0.5m to 2.0m are distributed near the corresponding theoretical values, but there are also individual position points with large errors. For example, when the receiving radius is Radius = 1.6m and the modal value L = 1, the received mode L>1.5, and the correct modal value cannot be obtained by rounding; when the receiving radius is Radius = 1.7m and the modal value is L = 2, the received mode L<1.5, and the correct modal value cannot be obtained by rounding; when the receiving radius is Radius = 1.9m and the modal value is L = 3, the received mode L<2.5, and the correct modal value still cannot be obtained by rounding.

[0114] The optimization analysis is as follows.

[0115] Formula (21) will be used to calculate the mode, and the number and proportion of the modes will be counted. The process and formula are as follows:

[0116] ① Round the obtained modal data to the nearest integer, where [·] means rounding down:

[0117] L int =[L (n,m,i,j) +0.5] (23);

[0118] ②L int It is represented as {L1,L2,...,L num}, num means taking the whole number down, and the number of statistics C(k) is expressed as:

[0119]

[0120] in is the labeling function, when L int =L, the value is 1, otherwise it is 0;

[0121] ③For each value L, calculate the modal proportion as:

[0122]

[0123] Set up an n*n array (where n=5, 7, 9) of receiving antennas, with the spacing of array elements AB being d=0.1m. By alternating the horizontal axis td and the column axis pd, the modal reception at a receiving radius of 100λ is explored by increasing the number of array elements. The effect of different numbers of array elements on modal reception is mainly compared by analyzing the ratio of the number of correct modal identifications to the number of errors. According to formula (21), a specific analysis is performed as follows: Figure 20-28 As shown: Among them, Fig. 20 The mode for L=1 is the mode number statistics of the 5*5 array; Fig.21 The mode for L=1 is the mode number statistics of the 7*7 array; Fig. 22 The mode for L=1 is the mode number statistics of the 9*9 array; Fig.23 The mode for L=2 is the mode number statistics of 5*5 array; Fig.24 The mode for L=2 is the mode number statistics of the 7*7 array; Fig.25 The mode for L=2 is the mode number statistics of the 9*9 array; Fig.26 The mode for L=3 is the mode number statistics of 5*5 array; Fig. 27 The mode for L=3 is the mode number statistics of the 7*7 array; Fig.28 The mode for L=3 is a statistical diagram of the number of modes of a 9*9 array.

[0124] Figure 20-28 The horizontal axis uses numbers to represent the corresponding modal values ​​(where abn_v represents abnormal modal values, such as abnormally high absolute values ​​of the modal or the denominator is 0 in the formula), and the vertical axis represents the number of corresponding modes. The correct mode is marked in red, and the wrong mode is marked in other colors; from Figure 20-22 It can be seen from the figure that for the modal value L = 1, as the number of array elements increases, the proportion of correct modal values ​​gradually increases; Figure 23-25 It can be seen from the figure that for the modal value L = 2, as the number of array elements increases, the proportion of correct modal values ​​gradually increases; Figure 26-28 It can be seen that for the modal value L=3, as the number of array elements increases, the proportion of correct modal values ​​gradually increases.

[0125] The specific proportions are shown in the following table (modal proportion):

[0126] By analyzing the above data and tables, the present invention has come to the conclusion that when the mode is constant, the mode proportion can be increased by increasing the number of array elements, thereby achieving improved accuracy.

[0127] Example 2

[0128] This embodiment provides a system for receiving vortex electromagnetic wave modes by an array antenna, referring to the method for receiving vortex electromagnetic wave modes by an array antenna in Embodiment 1, referring to Fig.29 ,in, Fig.29 What is shown is a schematic diagram of the system structure of the present invention. It can be seen from the figure that the system includes an encoder 1 (for example, the model is 79A4T5MHC148), the encoder 1 is electrically connected to multiple phase shifters 3 (for example, the model is 0-3GHz1.4°) through a control processor 2 (for example, the model is stm32 minimum system), the phase shifter 3 is electrically connected to a frequency signal source 5 (for example, the model is HT008 MAX2871) through a one-to-eight power divider 4 (for example, the model is 380-2500MHz); the control processor 2, the phase shifter 3, and the one-to-eight power divider 4 together constitute a phase distributor 6; the phase distributor 6 is connected to a transmitting antenna 7 (for example, an 8-element UCA array antenna).

[0129] The system also includes a receiving antenna 8 (for example, a 3*3 rectangular array antenna), which is electrically connected to a plurality of phase detectors 10 (for example, model AD8302) via a one-to-two power divider 9; the one-to-two power divider 9 and the phase detector 10 together constitute a phase receiver 11; the phase detector 10 is electrically connected to a control processor 2 12 (for example, model stm32 minimum system), and the control processor 2 12 is electrically connected to a decoder (for example, model SN74HC138N); a calibration gimbal 13 (for example, a two-degree-of-freedom gimbal can be used) is provided on one side of the receiving antenna 8, and the calibration gimbal 13 is respectively connected to the control processor 2 12 and the receiving antenna 8.

[0130] refer to Fig.30 , which shows the system operation flow chart of the present invention. It can be seen from the figure that the system operation flow of receiving the vortex electromagnetic wave mode by the array antenna is as follows:

[0131] Step 1, start;

[0132] Step 2, the digital signal is passed to the encoder, and the encoder encodes the digital signal into a modal signal L; the next step is to send the modal signal to the phase distributor;

[0133] Step 3, the phase distributor is composed of a power divider, a phase shifter and a control processor to achieve the phase distribution task;

[0134] Step 4, generating a frequency from a frequency source, and sending the generated frequency signal to a phase distributor;

[0135] Step 5, the power divider in the phase distributor is responsible for receiving the frequency signal sent by the frequency signal source, and equally divides it into multiple signals and then sends them to multiple phase shifters;

[0136] Step 6, the control processor in the phase distributor is responsible for processing the modal signal in the encoder into a corresponding phase signal and sending it to the phase shifter;

[0137] Step 7, the phase shifter in the phase distributor first receives the phase signal from the control processor and sets the corresponding phase shifter to the corresponding phase value, and the formula satisfies, where represents the phase value that the nth phase shifter should move, N represents the number of array elements of the transmitting antenna, and n represents the nth phase shifter;

[0138] Step 8, the phase shifter in the phase distributor receives the frequency signal received by the power divider, and sends the electromagnetic wave with phase information to the UCA transmitting antenna. The phase feed of the transmitting antenna is clockwise or counterclockwise, and still satisfies, where represents the phase value of the nth array element, N represents the number of array elements of the transmitting antenna, and n represents the nth array element;

[0139] Step 9: At this time, the vortex electromagnetic wave is generated by the transmitting end, the transmitting part is finished, and then it goes to the receiving end;

[0140] Step 10, the receiving end first passes through a rectangular array antenna, which is responsible for receiving the vortex electromagnetic wave signal;

[0141] Step 11, the electromagnetic wave signal is sent to the phase receiver after passing through the receiving antenna. The phase receiver is composed of a one-to-two power divider and a phase detector;

[0142] Step 12, the one-to-two power divider is responsible for dividing the electromagnetic signal of the geometric center element of the array into two equal parts, and then sending it to two phase detectors (for example, phase detector 4 and phase detector 5), and then sending the electromagnetic signal of the remaining middle column to the phase detector for comparison, and obtaining the phase difference, and sending it to the control processor to perform phase discrimination according to equation (22) to determine whether it is calibrated;

[0143] Step 13, if no, that is, not calibrated, the control processor feeds back the signal to the self-gimbal, and the gimbal will adjust the array in two degrees of freedom (left and right, up and down). Each time the gimbal moves, the process of 12 will be repeated until the calibration condition is 'yes', that is, it has been calibrated;

[0144] Step 14: After calibration, the control processor receives the phases of the remaining phase detectors (e.g., phase detector 1, phase detector 2, and phase detector 3) and calculates the modal value according to formula (21);

[0145] Step 15, sending the calculated modal value to the decoder to obtain the data of the transmitting end.

Claims

1. A method for receiving vortex electromagnetic wave modes by an array antenna, characterized in that: A transmitting array is set on one side to emit vortex electromagnetic waves; a receiving rectangular receiving array is set on the other side. After the two ends are parallelly calibrated, the receiving rectangular receiving array performs phase calibration through the middle column, and the phase is measured by any two groups at both ends with the middle column as the symmetry axis to separate the mode of the vortex electromagnetic wave.

2. The method for receiving vortex electromagnetic wave modes by an array antenna according to claim 1, characterized in that: The receiving array unit is a 2*2 receiving array; the receiving array element here is a basic receiving array of 4 elements, that is, one receiving unit; when the receiving array is calibrated, the phases of two vortex electromagnetic wave arcs with different radii on the arc are detected simultaneously.

3. The method for receiving vortex electromagnetic wave modes by an array antenna according to claim 1, characterized in that: The receiving array is a 3*3 rectangular receiving array (calibration condition); on the basis of the 2*2 basic array, the base array is placed on the 3*3 array to describe the central calibration array elements I, D, and H.

4. The method for receiving vortex electromagnetic wave modes by an array antenna according to claim 1, characterized in that: The receiving array is an N*N array, the array element spacing between the array elements AB is d, the array element spacing between the array elements FG is td, and the array element spacing between the array elements BG is pd.

5. A system for receiving vortex electromagnetic wave modes by an array antenna, characterized in that: The method for receiving vortex electromagnetic wave modes by an array antenna as described in any one of claims 1 to 4 comprises an encoder (1), the encoder (1) is electrically connected to a plurality of phase shifters (3) through a control processor (2), the phase shifters (3) are electrically connected to a frequency signal source (5) through a one-to-eight power divider (4); the control processor (2), the phase shifters (3), and the one-to-eight power divider (4) together constitute a phase distributor (6); a transmitting antenna (7) is connected to the phase distributor (6); and The invention comprises a receiving antenna (8), wherein the receiving antenna (8) is electrically connected to a plurality of phase detectors (10) via a one-to-two power divider (9); the one-to-two power divider (9) and the phase detector (10) together constitute a phase receiver (11); the phase detector (10) is electrically connected to a second control processor (12), and the second control processor (12) is electrically connected to a decoder; a calibration platform (13) is provided on one side of the receiving antenna (8), and the calibration platform (13) is respectively connected to the second control processor (12) and the receiving antenna (8).

6. The system for receiving vortex electromagnetic wave modes by array antenna according to claim 5, characterized in that: The transmitting antenna (7) adopts an 8-element UCA array antenna.

7. The system for receiving vortex electromagnetic wave modes by an array antenna according to claim 5, characterized in that: The receiving antenna (8) adopts a 3*3 rectangular array antenna.

8. The system for receiving vortex electromagnetic wave modes by an array antenna according to claim 5, characterized in that: The calibration platform (13) adopts a two-degree-of-freedom platform.

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