Polarization isolation and inductance integrated tracking communication method based on adaptive metasurface

Abstract

The invention belongs to the field of metasurface electromagnetic regulation and wireless communication, and particularly discloses a polarization isolation and inductance integrated tracking communication method based on a self-adaptive metasurface. According to the method, the on-off state of a polarization isolation metasurface diode is controlled through an adaptive feedback network, and the functions of direction of arrival estimation and beam control are achieved in x-and y-polarization wave co-polarization channels respectively. The self-adaptive metasurface comprises M * N metasurface units, each unit is composed of four layers of metal structures and three layers of F4B dielectric plates, and each metal structure comprises an active adjustable double-T-shaped metal resonator, a metal floor with a closed circular ring groove and a feeder line layer for controlling a switching diode; by adjusting the on-off state of the switching diodes, the unit can independently regulate and control the electromagnetic wave phase of the co-polarization channel, and 1-bit phase regulation and control with the polarization isolation characteristic are achieved. According to the invention, the energy consumption is accurately reduced through adaptive tracking, and the wireless communication quality is improved while the system integration degree and the intelligent degree are higher.

Description

Technical Field

[0001] The present invention belongs to the fields of metasurface electromagnetic regulation and wireless communication, and specifically relates to a polarization isolation communication and sensing integrated tracking communication method based on an adaptive metasurface. Background Art

[0002] Digital programmable metasurfaces characterize electromagnetic properties through discrete coding (e.g., 0 represents 0°, 1 represents 180°), thereby realizing dynamic adjustment of electromagnetic waves. When combined with active devices (such as PIN diodes, varactor diodes, etc.), the bias voltage of the switching diode can be further controlled by a field-programmable gate array (FPGA), and electromagnetic function switching can be achieved according to different phase coding sequences. As a key technology of array signal processing, direction-of-arrival (DOA) estimation can obtain the azimuth information of the target in real time, which is of great significance for realizing functions such as target positioning, tracking, and imaging in 6G communication and sensing integration. However, in high-precision DOA estimation applications such as radar and communication, existing systems still face challenges such as large volume, high energy consumption, and high computational complexity, which are significantly in conflict with the requirements of the Internet of Things for device miniaturization and low power consumption, restricting their wide application in fields such as the Internet of Things.

[0003] In recent years, some programmable metasurface studies have begun to use adaptive feedback networks to achieve autonomous control of the system to cope with complex and changing electromagnetic environments. However, current research mostly relies on external sensors to collect environmental data to achieve the sensing function, resulting in additional complexity in system design and not realizing the integration of communication and sensing at the hardware level. In addition, existing metasurface arrays usually only deploy a few sensing units to detect features at limited points in space. This simple sensing method is difficult to meet the requirements of highly intelligent applications for precise sensing and response. Summary of the Invention

[0004] The present invention combines a programmable metasurface with an adaptive feedback network to achieve an adaptive tracking and precise communication method based on DOA estimation and beam control.

[0005] The present invention discloses a polarization isolation communication and sensing integrated tracking communication method based on an adaptive metasurface, and the polarization isolation communication and sensing integrated tracking communication method based on an adaptive metasurface includes the following steps:

[0006] Step 1, constructing a 1-bit phase independent regulation mode with polarization isolation characteristics based on a 1-bit programmable metasurface device with polarization isolation characteristics;

[0007] Step 2: Calculate the azimuth angle and elevation angle of the incident wave according to the functions of the adaptive metasurface in the co-polarization channels of the predetermined x- and y-polarized waves; and calculate the phase distribution of the metasurface device according to the predetermined beam control function to determine the topological structure of the programmable metasurface.

[0008] In step 2, the following steps are further included:

[0009] Step 21: Preset the function of angle of arrival estimation and calculate the azimuth angle and elevation angle of the incident wave.

[0010] Step 22: Preset the beam control function and calculate the corresponding phase distribution.

[0011] Furthermore, in step 1, the 1-bit programmable metasurface device with polarization isolation characteristics is composed of M×N metasurface units with the same structural parameters periodically extended at equal intervals in the plane.

[0012] The metasurface unit is square, with a period of p. The structure from top to bottom is the first metal layer, the first dielectric plate, the second metal layer, the second dielectric plate, the third metal layer, the third dielectric plate, and the fourth metal layer.

[0013] The first metal layer includes a square metal structure and two T-shaped metal resonators. The square metal structure is located at the center of the metasurface and is connected to the ground through a metal via at its center position. The two T-shaped metal resonators are respectively arranged in the positive x- and y-axis directions of the square metal structure. The long arms and short arms are respectively perpendicular and parallel to the corresponding x- and y-axes. The long arms are connected to the feeder through a metal via at its center position passing through the closed circular ring groove of the metal floor, and the short arms are connected to the square metal structure through switching diodes; the second metal layer is a metal floor with a closed circular ring groove, and the third and fourth metal layers are respectively the feeder layers of the two switching diodes. Each layer arranges the feeders for controlling the diodes of the same polarization. Its metal structure is rectangular and points to the polarization direction controlled by the diode. One end of the feeder is connected to the metal vias uniformly distributed at both ends of the row / column where the metasurface unit is located. The metal vias are used as the input terminals of the FPGA control signal; the other end of the feeder is connected to the metal via at the center position of the T-shaped metal resonant structure for controlling the corresponding polarization, and the control signal is transmitted through the metal via through the T-shaped metal resonant structure to the corresponding diode to realize on / off control; the first dielectric plate is a PCB board, and the second and third dielectric plates are the same F4B dielectric plates.

[0014] Furthermore, in step 21, the following steps are further included:

[0015] Step 211: Estimate the azimuth angle and elevation angle of the incident wave based on the compressive sensing theory. The plane wave to be measured is received by the horn located at the center of the metasurface after being reflected by the metasurface.

[0016] Step 212: Control the high and low level outputs of the diodes according to the phase distribution of the random measurement matrix to obtain the 1-bit phase distribution of L groups of random matrices with cross-correlation lower than the threshold α.

[0017] Step 213: Estimate the angle of arrival based on the compressive sensing theory.

[0018] Furthermore, in Step 211, the air-fed received signal of the metasurface array satisfies:

[0019]

[0020] where K represents the sparsity, that is, the number of incident plane waves, s l represents the amplitude of the l-th signal, φ li represents the phase of the l-th signal, n(t i ) represents the additive Gaussian noise with power density σ 2 ; λ represents the wavelength; x m,n and y m,n respectively represent the abscissa and ordinate values of the unit with coordinates (m, n); B m,n represents the digital coding of the L groups of M×N 1-bit phase distribution random measurement matrices corresponding to the unit with coordinates (m, n); θ l and respectively represent the azimuth angle and elevation angle of the l-th incident wave; z f represents the height of the receiving horn located at the center of the metasurface.

[0021] Furthermore, in Step 212, for the L groups of M×N 1-bit phase distributions, by generating L groups of random 0-1 distribution matrices and calculating the cross-correlation, discarding the random measurement matrices with cross-correlation higher than the threshold α and regenerating new random 0-1 matrices, finally obtain the 1-bit phase distribution of L groups of random matrices with cross-correlation lower than the threshold α.

[0022] Furthermore, in Step 213, the angle of arrival estimation includes the following steps:

[0023] Step 2131: Collect the measurement result Y based on L groups of random measurement matrices. The measurement result Y satisfies:

[0024]

[0025] where the measurement result is obtained by the vector network analyzer collecting the reflected wave of the plane wave with incident angle θ i in the xoz plane from the metasurface with the phase distribution of L groups of random measurement matrices; H j (θ i ) represents the j-th random measurement matrix at the incident angle of θi Random measurement results at that time; K is the sparsity; Indicates the signal transmitted by the i-th incident wave; Indicates the power density of the additive Gaussian noise when the i-th incident wave is measured;

[0026] Step 2132, perform direction-of-arrival estimation by the orthogonal matching pursuit method:

[0027] Step 21321, initialize parameters, the sparsity is K, the index set: A = {}, the estimation vector: DOA = {}, let the iteration number i = 1, 1 ≤ i ≤ K, the initial residual r e (1) = y;

[0028] Step 21322, calculate the correlation between the i-th vector and the residual and update the column m with the highest correlation:

[0029] m = argmax{<r e (i), H>}

[0030] H represents the dictionary matrix, which is the received signal corresponding to all possible combinations of azimuth and elevation angles;

[0031] Step 21323, update the index set A = [A, m], and construct the dictionary matrix H corresponding to the index set a = H(:, A);

[0032] Step 21324, solve the least squares problem to obtain a new signal estimate;

[0033] DOA = H′ a ·r e (i)

[0034] Step 21325, update the direction-of-arrival estimation vector DOA(A) = DOA;

[0035] Step 21326, calculate the new residual:

[0036] r e (i) = y - H a ·DOA

[0037] r e (i) represents the new residual, and y represents the collected complex signal;

[0038] Step 21327, let i = i + 1;

[0039] Step 21328, determine whether the iteration number i is greater than K. If it is, end and obtain K combinations of azimuth and elevation angles corresponding to the number of incident plane waves: DOA. If not, return to Step 21322.

[0040] Further, in step 22, the following steps are also included:

[0041] Step 221, calculating the reflection focusing phase of the (m,n)th unit based on the elevation angle and azimuth angle of the reflected wave;

[0042] Step 222, calculating the reflection deflection phase of the (m,n)th unit based on the elevation angle and azimuth angle of the reflected wave;

[0043] Step 223, calculating the feed radiation beam control phase of the (m,n)th unit based on the reflection focusing phase and the reflection deflection phase;

[0044] Step 224, normalizing and encoding the phase distribution;

[0045] When the phase value is greater than or equal to 90° and less than 270°, make it equal to 180°; when the phase value is less than 90° or greater than or equal to 180°, make it equal to 0°;

[0046] Step 225, according to the predetermined function and the calculated phase distribution, finding the diode state distribution under the incident polarization wave;

[0047] Set 0° corresponding to the "off" state of the switch diode, represented by "0", and 180° corresponding to the "on" state of the switch diode, represented by "1".

[0048] Further, the polarization isolation communication and sensing integrated tracking method based on the adaptive metasurface further includes:

[0049] Step 3, building an adaptive feedback network to achieve the tracking function of the communication beam;

[0050] Step 3.1, initialization settings; performing communication configuration between MATLAB and the vector network analyzer, where: the scanning frequency is set to 5.8 GHz and the number of scanning times is set to L times; performing communication configuration between MATLAB and the FPGA, where: MATLAB sequentially transmits the phase encodings of the previously generated L groups of random measurement matrices to the FPGA in order;

[0051] Step 3.2, Data acquisition: First, after the FPGA obtains the phase encoding of the random measurement matrix, it controls the on / off states of the metasurface diodes in the order of high and low levels, generating a random electromagnetic field corresponding to the random measurement matrix in the co-polarization channel of the x-polarized wave. Subsequently, the VNA collects the vector data of the incident wave reflected by the metasurface under the current random electromagnetic field, constructing a vector data set corresponding to the random measurement matrix. Finally, through the MATLAB data acquisition function, the VNA vector data sets corresponding to the random measurement matrix are obtained in sequence and judged: If L times of data acquisition are completed, the program proceeds to the next step of angle-of-arrival estimation; if the data acquisition is not completed, the data acquisition process continues to be executed.

[0052] Step 3.3, Angle-of-arrival estimation: The angle-of-arrival estimation algorithm in Step 21 is used to process the L groups of randomly measured data collected, obtaining the azimuth angle and elevation angle of the incident wave.

[0053] Step 3.4, Beam control: After obtaining the azimuth angle and elevation angle of the incident wave, the beam control method in Step 22 is used to generate a feed radiation beam control phase distribution consistent with the azimuth angle and elevation angle of the incident wave, and the FPGA controls the on / off states of the metasurface diodes in the form of high and low levels, exciting the metasurface through the feed in the co-polarization channel of the y-polarized wave to generate a feed radiation beam consistent with the azimuth angle and elevation angle of the incident wave.

[0054] Step 3.5, Update the program status and repeat the above process.

[0055] Furthermore, in Step 1, the final structure of the metasurface unit at a scanning frequency of 5.8 GHz is as follows:

[0056] The period p = 25 mm, the side length a of the square metal structure = 12.2 mm, the long arm length b = 10 mm, the single side length c of the long arm = 4.1 mm, the width e of the T-shaped metal resonator = 1.8 mm, the short arm length d = 3.7 mm, the width l of the feeder 1 = 0.2 mm, the diameter l of the floor closed circular ring groove 2 = 0.7 mm, the diameter l of the metal through hole 3 = 0.27 mm, the metal is copper, the thickness h = 0.036 mm; the thickness h of the first dielectric plate 1 = 3 mm, the relative permittivity of the first dielectric plate is 3, the loss tangent value is 0.003, the relative permittivities of the second and third dielectric plates are 2.65, the loss tangent values are 0.001, and the thicknesses h 2 = h 3 = 0.2 mm.

[0057] Furthermore, in step 1, the model number of the switching diode is M / A-COM MADP-000907-14020x. When the switching diode is in the "on" state, it is equivalent to a resistor in series with an inductor, where the resistance value R 1 = 7.8 Ω, and the inductance value C 1 = 0.028 pF; when the switching diode is in the "off" state, it is equivalent to a capacitor in series with an inductor, where the capacitance value L 1 = 0.03 nH, and the inductance value C 1 = 0.028 pF.

[0058] The beneficial effects achieved by the present invention are as follows:

[0059] Compared with a single-polarization reconfigurable device, the present invention respectively realizes single functions in the co-polarization channels of x- and y-polarization waves and operates at the same frequency point, having higher functional integration and spectral efficiency.

[0060] Compared with traditional metasurfaces with communication and sensing functions, the present invention realizes the sensing function without relying on external sensors, having higher hardware integration and lower system complexity.

[0061] Compared with traditional metasurfaces that deploy a small number of sensing units in an array, the present invention realizes a higher-dimensional (all units serve as sensing units) sensing ability, having higher sensing accuracy and hardware utilization efficiency.

[0062] Compared with a tracking communication system using optical sensing devices, the present invention realizes tracking communication through electromagnetic sensing, is not affected by conditions such as light and visibility, and has higher adaptability.

[0063] The present invention adopts a polarization isolation communication and sensing integrated tracking communication method based on an adaptive metasurface, involves theoretical guidance including compressed sensing theory, generalized Snell's law, adaptive feedback network model, etc., breaks through the bottleneck of the single function of the method, and has a certain complexity. Description of the Drawings

[0064] Figure 1 is a schematic diagram of a polarization isolation communication and sensing integrated tracking communication method based on an adaptive metasurface;

[0065] Figure 2 is a structural diagram of a polarization isolation metasurface unit and the co-polarization amplitude and phase responses when the unit diode is in four on-off states respectively under the incidence of an x-polarization wave;

[0066] Figure 3 is the cross-polarization amplitude response when the diode is in four on-off states respectively under the incidence of an x-polarization wave.

[0067] Figure 4For the co-polarization amplitude and phase responses of the diode in four on-off states when the x-polarized wave is obliquely incident.

[0068] Figure 5 For the surface current distributions of the diode in four on-off states at 5.8 GHz when the x-polarized wave is incident.

[0069] Figure 6 For the beam control simulation effect on the xoz plane at 5.8 GHz when the x-polarized wave is incident.

[0070] Figure 7 For the phase coding sequences on the xoz plane and yoz plane when the beam directions are 10°, 20°, 30° and 40° respectively.

[0071] Figure 8 For the flowchart of the direction-of-arrival estimation algorithm.

[0072] Figure 9 For the adaptive control flowchart to achieve the tracking communication function.

[0073] Figure 10 For the equivalent circuits of the switching diode in the "on" and "off" states. Specific implementation manners

[0074] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description progresses. However, these embodiments are exemplary only and do not constitute any limitation to the scope of the present invention. Those skilled in the art should understand that the details and forms of the technical solutions of the present invention can be modified or replaced without departing from the spirit and scope of the present invention, but such modifications and replacements all fall within the protection scope of the present invention.

[0075] Embodiment 1:

[0076] The present invention proposes a polarization isolation communication and sensing integrated tracking communication method based on an adaptive metasurface. First, it is necessary to design a 1-bit programmable metasurface device with polarization isolation characteristics. The 1-bit programmable metasurface device with polarization isolation characteristics is a reconfigurable metasurface multifunctional device based on an active tunable double-T metal resonator and a switching diode, which constructs a reflective anisotropic unit and can achieve independent phase regulation in both the co-polarization channels of x- and y-polarized waves. As Figure 1 shown, the invented 1-bit programmable metasurface device with polarization isolation characteristics realizes the direction-of-arrival estimation function in the co-polarization channel of the x-polarized wave; and realizes the beam control function in the co-polarization channel of the y-polarized wave.

[0077] The 1-bit programmable metasurface device with polarization isolation characteristics designed by the present invention is composed of M×N metasurface units with the same structural parameters periodically extended at equal intervals in the plane; in order to endow the metasurface with polarization isolation characteristics, the metal structure on the surface of each metasurface unit is designed as a geometric structure symmetric about the x- or y-axis; in order to achieve independent regulation of different linear polarizations, two switching diodes parallel to the regulation polarization direction are loaded on each metasurface unit to form an anisotropic structure. The metasurface unit is square with a period of p, and is designed with a structure of "metal structure - dielectric plate - metal backplane - dielectric plate - metal layer - dielectric plate - metal layer". The four metal structures from top to bottom are respectively named the first metal layer, the second metal layer, the third metal layer and the fourth metal layer; the three dielectric plates from top to bottom are respectively named the first dielectric plate, the second dielectric plate and the third dielectric plate; the first metal layer includes a square metal structure and two T-shaped metal resonators. The square metal structure is located at the center of the metasurface and is connected to the ground through a metal via at its center position. The two T-shaped metal resonators are respectively arranged in the positive x- and y-axis directions of the square metal structure. The long arms and short arms are respectively perpendicular and parallel to the corresponding x- and y-axes. The long arm is connected to one end of the feeder through a metal via at its center position passing through the metal ground to close the circular ring slot. The short arm is connected to the square metal structure through a switching diode; the second metal layer is a metal ground with a closed circular ring slot. The third metal layer and the fourth metal layer are respectively the feeder layers of the two switching diodes. Each layer arranges the feeders for controlling the diodes of the same polarization. Its metal structure is rectangular and points to the polarization direction controlled by the diode. One end of the feeder is connected to the metal vias evenly distributed at both ends of the row (column) where the metasurface unit is located. The metal vias are used as the input ends of the FPGA control signals; the other end of the feeder is connected to the metal via at the center position of the T-shaped metal resonant structure for controlling the corresponding polarization, and the control signal is transmitted through the metal via through the T-shaped metal resonant structure to the corresponding diode to realize on-off control; the first dielectric plate is a PCB board, and the second dielectric plate and the third dielectric plate are identical F4B dielectric plates.

[0078] The square metal structure, double T-shaped resonators, switching diodes, etc. are introduced into the metasurface for optimized design of the unit structure, and high-isolation phase-independent regulation modes are respectively constructed under the co-polarization channels of x- and y-polarized waves. The specific implementation process is as follows: when a linearly polarized wave excites the metal structure on the surface of the unit, it will be coupled with the T-shaped resonant unit in the same direction, while the T-shaped resonant unit in the perpendicular direction will not be affected, resulting in two different induced currents, as Figure 5 shown. By controlling the on-off state of the switching diode, the path and intensity of the surface induced current on the two T-shaped metal resonators are changed, realizing independent regulation of the reflection phase of the co-polarization channels of x- and y-polarized waves.

[0079] The model number of the switching diode is M / A-COM MADP-000907-14020x. The equivalent circuit diagrams of the switching diode in the "on" and "off" states are as Figure 10 shown: When in the "on" state, it is equivalent to a resistor and an inductor in series, where the resistance value R 1 = 7.8 Ω, and the inductance value C 1 = 0.028 pF; when in the "off" state, it is equivalent to a capacitor and an inductor in series, where the capacitance value L 1 = 0.03 nH, and the inductance value C 1 = 0.028 pF.

[0080] The final structural parameters of the metasurface unit are optimized and determined as follows: The period p = 25 mm, the side length a of the square metal structure = 12.2 mm, the long arm length b = 10 mm, the single side length c of the long arm = 4.1 mm, the width e of the T-shaped metal resonator = 1.8 mm, the short arm length d = 3.7 mm, the feeder width l 1 = 0.2 mm, the diameter l of the floor closed circular ring groove 2 = 0.7 mm, the diameter l of the metal through hole 3 = 0.27 mm, the metal is copper, the thickness h = 0.036 mm, the first dielectric plate 1 uses PCB, the dielectric constant is 3, the loss tangent value is 0.003, and the thickness h 1 = 3 mm, the second dielectric plate 2 and the third dielectric plate 3 use F4B, the dielectric constant is 2.65, the loss tangent value is 0.001, and the thickness h 2 = h 3 = 0.2 mm.

[0081] Example 2:

[0082] The present invention designs the phase distribution of the metasurface according to the functional requirements, and the specific steps are as follows:

[0083] Step 1, introduce modulation elements such as the active tunable double-T metal resonator structure, switching diode, and dielectric layer dielectric constant into the programmable metasurface unit design. At the working frequency point f, under the excitation of x- and y-polarized waves, the co-polarization channels maintain a high reflection amplitude and a 180° phase change, and maintain a high isolation degree for the cross-polarization channels, and construct a 1-bit phase-independent modulation mode with polarization isolation characteristics;

[0084] Step 2, calculate the corresponding phase distribution according to the functions of the adaptive metasurface under the co-polarization channels of the predetermined x- and y-polarized waves; determine the topological structure of the programmable metasurface according to the predetermined functions and the calculated phase distribution, that is, the states of the two diodes on each metasurface unit, to realize the functional reconfiguration;

[0085] The functions include the angle of arrival estimation function and the beam control function;

[0086] Step 21, presetting the angle of arrival estimation function and calculating the azimuth and elevation angles of the incident wave;

[0087] Step 211, based on the compressed sensing theory, the azimuth and elevation angles of the incident wave are estimated. The plane wave to be measured is reflected by the metasurface and received by the speaker located at the center of the metasurface. In a more general form, the air-fed received signal of the metasurface array with M rows and N columns satisfies:

[0088]

[0089] Where K represents the sparsity, that is, the number of incident plane waves, s l represents the amplitude of the lth signal, φ li represents the phase of the lth signal, n(t i ) represents the power density σ 2 Additive Gaussian noise; λ represents the wavelength; x m,n and m,n Respectively represent the horizontal and vertical coordinate values ​​of the unit with coordinates (m, n); B m,n represents the digital encoding of the L groups of random measurement matrices corresponding to the units with coordinates (m, n); θ l and denote the azimuth and elevation angles of the lth incident wave respectively; z f Represents the height of the receiving horn located at the center of the metasurface.

[0090] Step 212 controls the high and low level outputs of the diode according to the phase distribution of the random measurement matrix, collects the amplitude and phase information received by each random matrix, and obtains a set of L×1 dimensional complex measurement data. Among them, the 1-bit phase distribution of the L groups of M rows and N columns is obtained by generating L groups of random 01 distribution matrices and calculating the mutual correlation, discarding the random measurement matrices with mutual correlation higher than the threshold α and regenerating new random 01 matrices, and finally obtaining the 1-bit phase distribution of the L groups of random matrices with mutual correlation lower than the threshold α.

[0091] Step 213 performs angle of arrival estimation based on compressed sensing theory, and the estimation process is as follows:

[0092] Step 2131, collect measurement results Y based on L groups of random measurement matrices, which are described here in one-dimensional form using angle of arrival perception (two-dimensional form is the same method expanded in one dimension in pitch angle). The measurement results Y satisfy:

[0093]

[0094] Among them, the measurement results Obtained from the reflected wave of the incident wave by the metasurface that collects the phase distribution of L groups of random measurement matrices in the xoz plane through a vector network analyzer. H i (θ i ) represents the random measurement result of the i-th random measurement matrix at the incident angle of θ i ; K is the sparsity; represents the signal transmitted by the i-th incident wave; represents the power density of the additive Gaussian noise when the i-th incident wave is measured.

[0095] Step 2132, perform direction-of-arrival estimation through the orthogonal matching pursuit method, and the algorithm flow is as follows:

[0096] Step 21321, initialize the parameters, the sparsity is K, the index set: A = {}, the estimated vector: DOA = {}, let the iteration number i = 1, 1 ≤ i ≤ K, and the initial residual r e (i) = y;

[0097] Step 21322, calculate the correlation between the i-th vector and the residual and update the column m with the highest correlation:

[0098] m = argmax{<r e (i), H>}

[0099] H represents the dictionary matrix, which is the received signal corresponding to all possible combinations of azimuth and elevation angles;

[0100] Step 21323, update the index set A = [A, m], and construct the dictionary matrix H corresponding to the index set a = H(:, A);

[0101] Step 21324, solve the least squares problem to obtain a new signal estimate;

[0102] DOA = H′ a ·r e (i)

[0103] Step 21325, update the direction-of-arrival estimation vector DOA(A) = DOA;

[0104] Step 21326, calculate the new residual:

[0105] r e (i) = y - H a ·DOA

[0106] r e (i) represents the new residual, and y represents the collected complex signal;

[0107] Step 21327, let i = i + 1;

[0108] Step 21328: Determine whether the iteration count i is greater than K. If so, end and obtain K azimuth and elevation angle combinations corresponding to the number of incident plane waves: DOA. If not, return to Step 21322.

[0109] Step 22: Prescribe the beam control function and calculate the corresponding phase distribution.

[0110] Calculate the metasurface phase distribution based on the generalized Snell's theorem as follows:

[0111] Step 221: Calculate the reflection focusing phase of the (m,n)th cell.

[0112]

[0113] where is the free-space wave vector, λ is the wavelength corresponding to the operating frequency f; x m,n and y m,n are the distances of the (m,n)th cell from the x-axis and y-axis in the Cartesian coordinate system; m is the cell coordinate in the x-direction in the two-dimensional plane coordinate system, and n is the cell coordinate in the y-direction; θ and are the elevation angle and azimuth angle of the reflected wave respectively; the initial phase of the metasurface is defaulted to 0°.

[0114] Step 222: Calculate the reflection deflection phase of the (m,n)th cell.

[0115]

[0116] Step 223: Calculate the feed radiation beam control phase of the (m,n)th cell.

[0117]

[0118] Step 224: Normalize and encode the phase distribution, including:

[0119] Step 2241: Normalize the maximum value 360 of the phase distribution.

[0120] Step 2242: Perform 1-bit encoding on the normalized phase distribution. When the phase value is greater than or equal to 90° and less than 270°, set it equal to 180°. When the phase value is less than 90° or greater than or equal to 180°, set it equal to 0°.

[0121] Step 225: According to the predetermined function and the calculated phase distribution, find the diode state distribution corresponding to the incident polarized wave: 0° corresponds to the "off" state of the switching diode, represented by "0", and 180° corresponds to the "on" state of the switching diode, represented by "1". Select the vertical / horizontal arrangement of the metal layer 3 / metal layer 4 feeder to control the vertical / horizontal switching diodes of the metasurface unit respectively. Control the switching diodes by outputting high or low levels through the FPGA to achieve the reconfiguration of the function.

[0122] Embodiment 3:

[0123] The present invention processes the collected data and realizes the adaptive control of beam control by building an adaptive feedback network. The specific steps are as follows:

[0124] Step 3: The built adaptive feedback network realizes the tracking function of the communication beam, including: initialization setting, data acquisition, angle of arrival estimation, and beam control. The operation process is as follows:

[0125] Step 3.1: Initialization setting. Configure the communication between MATLAB and the vector network analyzer (VNA), where: the scanning frequency is set to 5.8 GHz, and the number of scanning times is set to 100 times; configure the communication between MATLAB and the FPGA, where: MATLAB sequentially transmits the phase encodings of 100 groups of pre-generated random measurement matrices to the FPGA in order.

[0126] Step 3.2: Data acquisition. First, after obtaining the phase encoding of the random measurement matrix, the FPGA controls the on / off state of the metasurface diodes according to the high / low level order, and generates a random electromagnetic field corresponding to the random measurement matrix in the co-polarization channel of the x-polarized wave; then, the VNA collects the vector data of the incident wave reflected by the metasurface under the current random electromagnetic field, and constructs a vector data set corresponding to the random measurement matrix; finally, through the MATLAB data acquisition function, the VNA vector data sets corresponding to the random measurement matrix are obtained in sequence and judged: if 100 times of data acquisition are completed, the program enters the next step of angle of arrival estimation; if the data acquisition is not completed, the data acquisition process continues to be executed.

[0127] Step 3.3: Angle of arrival estimation. Use the angle of arrival estimation algorithm in claim 4 to process the 100 groups of randomly collected measurement data to obtain the azimuth angle and elevation angle of the incident wave.

[0128] Step 3.4, beam control. After obtaining the azimuth angle and elevation angle of the incident wave, the beam control method in claim 5 is used to generate a feed radiation beam control phase distribution consistent with the azimuth angle and elevation angle of the incident wave, and the on / off state of the metasurface diode is controlled by the FPGA in the form of high and low levels, and the metasurface is excited by the feed in the y-polarized wave co-polarization channel to generate a feed radiation beam consistent with the azimuth angle and elevation angle of the incident wave.

[0129] Step 3.5, update the program status and repeat the above process.

[0130] The above are only the specific steps of the present invention and do not constitute any limitation to the protection scope of the present invention; any technical solutions formed by equivalent transformation or equivalent substitution fall within the scope of the protection of the present invention; the parts not elaborated in detail in the present invention belong to the well-known technologies of those skilled in the art.

Claims

1. A polarization isolation synaesthesia integrated tracking communication method based on adaptive metasurface, characterized in that: The polarization isolation synaesthesia integrated tracking communication method based on the adaptive metasurface comprises the following steps: Step 1, constructing a 1-bit phase-independent control mode with polarization isolation characteristics based on a 1-bit programmable metasurface device with polarization isolation characteristics; Step 2, calculating the azimuth and elevation angles of the incident wave according to the functions of the adaptive metasurface in the predetermined x- and y-polarized wave co-polarization channel; and calculating the phase distribution of the metasurface device according to the predetermined beam control function to determine the topological structure of the programmable metasurface; In step 2, the following steps are also included: Step 21, presetting the angle of arrival estimation function and calculating the azimuth and elevation angles of the incident wave; Step 22, predetermine the beam steering function and calculate the corresponding phase distribution.

2. According to claim 1, the polarization isolation synaesthesia integrated tracking communication method based on the adaptive metasurface is characterized in that: In step 1, the 1-bit programmable metasurface device with polarization isolation characteristics is composed of M×N metasurface units with the same structural parameters that are periodically extended at equal intervals in a plane; The metasurface unit is square, with a period of p, and the structures from top to bottom are respectively the first metal layer, the first dielectric plate, the second metal layer, the second dielectric plate, the third metal layer, the third dielectric plate and the fourth metal layer; The first metal layer includes a square metal structure and two T-shaped metal resonators. The square metal structure is located at the center of the metasurface and is connected to the floor through a metal through-hole at its center. The two T-shaped metal resonators are arranged in the positive directions of the x- and y-axes of the square metal structure, respectively. The long arm and the short arm are perpendicular and parallel to the corresponding x- and y-axes, respectively. The long arm passes through the closed circular groove of the metal floor through the metal through-hole at its center and is connected to the feeder. The short arm is connected to the square metal structure through a switching diode. The second metal layer is a metal floor with a closed circular groove. The third and fourth metal layers are respectively The feeder layer of the two switching diodes has a feeder for controlling the diodes with the same polarization in each layer, and the metal structure is a rectangular shape pointing to the polarization direction controlled by the diode. One end of the feeder is connected to metal through holes evenly distributed at both ends of the row / column where the metasurface unit is located, and the metal through hole serves as the input end of the FPGA control signal; the other end of the feeder is connected to a metal through hole at the center position of a T-shaped metal resonant structure that controls the corresponding polarization, and the control signal is transmitted to the corresponding diode through the metal through hole and the T-shaped metal resonant structure to realize on-off control; the first dielectric board is a PCB board, and the second dielectric board and the third dielectric board are the same F4B dielectric boards.

3. According to claim 1, the polarization isolation synaesthesia integrated tracking communication method based on the adaptive metasurface is characterized in that: In step 21, the following steps are also included: Step 211, estimating the azimuth and elevation angles of the incident wave based on the compressed sensing theory, and the plane wave to be measured is received by the speaker located at the center of the metasurface after being reflected by the metasurface; Step 212, controlling the high and low level outputs of the diode according to the phase distribution of the random measurement matrix, and obtaining 1-bit phase distributions of L groups of random matrices whose mutual correlation is lower than a threshold α; Step 213: estimate the angle of arrival based on compressed sensing theory.

4. According to claim 3, the polarization isolation synaesthesia integrated tracking communication method based on the adaptive metasurface is characterized in that: In step 211, the empty-feed received signal of the metasurface array satisfies: Where K represents the sparsity, that is, the number of incident plane waves, s l represents the amplitude of the lth signal, φ li represents the phase of the lth signal, n(t i ) represents the power density σ 2 Additive Gaussian noise; λ represents the wavelength; x m,n and m,n Respectively represent the horizontal and vertical coordinate values ​​of the unit with coordinates (m, n); B m,n Represents the digital encoding of L groups of M rows and N columns of 1-bit phase distribution random measurement matrices corresponding to the unit with coordinates (m, n); θ l and denote the azimuth and elevation angles of the lth incident wave respectively; z f Represents the height of the receiving horn located at the center of the metasurface.

5. According to claim 3, the polarization isolation synaesthesia integrated tracking communication method based on the adaptive metasurface is characterized in that: In step 212, the 1-bit phase distribution of the L groups of M rows and N columns is obtained by generating L groups of random 01 distribution matrices and calculating the cross-correlation, discarding the random measurement matrices with cross-correlation higher than the threshold α and regenerating new random 01 matrices, and finally obtaining the 1-bit phase distribution of the L groups of random matrices with cross-correlation lower than the threshold α.

6. According to claim 3, the polarization isolation synaesthesia integrated tracking communication method based on adaptive metasurface is characterized in that: In step 213, the angle of arrival estimation includes the following steps: Step 2131, collect measurement results Y based on L groups of random measurement matrices, and the measurement results Y satisfy: Among them, the measurement results The metasurface with incident angle θ is used to collect L groups of random measurement matrix phase distributions on the xoz plane through a vector network analyzer. i The reflected wave of the plane wave is obtained; H j (θ i ) represents the jth random measurement matrix at an incident angle of θ i The random measurement result when ; K is the sparsity; represents the signal transmitted by the i-th incident wave; represents the power density of the additive Gaussian noise when the i-th incident wave is measured; Step 2132, estimate the angle of arrival by using the orthogonal matching pursuit method: Step 21321, initialize parameters, sparsity is K, index set: A = {}, estimated vector: DOA = {}, set the number of iterations i = 1, 1 ≤ i ≤ K, the initial residual r e (1) = y; Step 21322, calculate the correlation between the i-th vector and the residual and update the column m with the highest correlation: m=argmax{<r e (i),H>} H represents the dictionary matrix, which is the received signals corresponding to all possible combinations of azimuth and elevation angles; Step 21323, update the index set A = [A, m], and construct the dictionary matrix H corresponding to the index set a =H(:, A); Step 21324, solving the least squares problem to obtain a new signal estimate; DOA=H′ a ·r e (i) Step 21325, update the angle of arrival estimation vector DOA(A)=DOA; Step 21326, calculate the new residual: r e (i)=y-H a ·DOA r e (i) represents the new residual, and y represents the acquired complex signal; Step 21327, let i=i+1; Step 21328, determine whether the number of iterations i is greater than K. If so, end and obtain K azimuth and elevation angle combinations corresponding to the number of incident plane waves: DOA; if not, return to step 21322.

7. The polarization isolation synaesthesia integrated tracking communication method based on adaptive metasurface according to claim 1 is characterized in that: In step 22, the following steps are also included: Step 221, calculating the reflection focusing phase of the (m, n)th unit based on the pitch angle and azimuth angle of the reflected wave; Step 222, calculating the reflection deflection phase of the (m, n)th unit based on the elevation angle and azimuth angle of the reflected wave; Step 223, calculating the feed radiation beam control phase of the (m, n)th unit based on the reflection focusing phase and the reflection deflection phase; Step 224, normalizing and encoding the phase distribution; When the phase value is greater than or equal to 90° and less than 270°, set it equal to 180°; when the phase value is less than 90° or greater than or equal to 180°, set it equal to 0°; Step 225, finding the diode state distribution under the incident polarized wave according to the predetermined function and the calculated phase distribution; Setting 0° corresponds to the "off" state of the switching diode, represented by "0", and setting 180° corresponds to the "on" state of the switching diode, represented by "1".

8. The polarization isolation synaesthesia integrated tracking communication method based on adaptive metasurface according to claim 1 is characterized in that: The polarization isolation synaesthesia integrated tracking communication method based on the adaptive metasurface also includes: Step 3: The adaptive feedback network is constructed to realize the tracking function of the communication beam; Step 3.1, initialization settings; communication configuration is performed with the vector network analyzer through MATLAB, wherein: the scanning frequency is set to 5.8 GHz, and the number of scans is set to L times; communication configuration is performed with the FPGA through MATLAB, wherein: MATLAB sequentially transmits the phase encoding of the pre-generated L groups of random measurement matrices to the FPGA in sequence; Step 3.2, data acquisition; first, after obtaining the phase encoding of the random measurement matrix, the FPGA controls the on-off state of the metasurface diode in the order of high and low levels, and generates a random electromagnetic field corresponding to the random measurement matrix in the x-polarization wave co-polarization channel; then, the VNA collects the vector data of the incident wave after reflection by the metasurface under the current random electromagnetic field, and constructs a vector data set corresponding to the random measurement matrix; finally, the VNA vector data set corresponding to the random measurement matrix is ​​obtained in turn through the MATLAB data acquisition function, and a judgment is made: if L data acquisitions are completed, the program enters the next step of arrival angle estimation; if the data acquisition is not completed, the data acquisition process continues; Step 3.3, angle of arrival estimation: Use the angle of arrival estimation algorithm in step 21 to process the collected L groups of random measurement data to obtain the azimuth and elevation angles of the incident wave. Step 3.4, beam control: after obtaining the azimuth and elevation angles of the incident wave, the beam control method in step 22 is used to generate a feed radiation beam control phase distribution that is consistent with the azimuth and elevation angles of the incident wave, and the on-off state of the metasurface diode is controlled by the FPGA in a high and low level manner, and the feed source excites the metasurface in the y-polarization wave co-polarization channel to generate a feed radiation beam that is consistent with the azimuth and elevation angles of the incident wave; Step 3.5, update the program status, repeat the above process.

9. The polarization isolation synaesthesia integrated tracking communication method based on adaptive metasurface according to claim 2 is characterized in that: In step 1, the final structure of the metasurface unit at a scanning frequency of 5.8 GHz is: The period p is 25 mm, the side length of the square metal structure is a=12.2 mm, the long arm length is b=10 mm, the single side length of the long arm is c=4.1 mm, the width of the T-type metal resonator is e=1.8 mm, the short arm length is d=3.7 mm, the feed line width is l1=0.2 mm, the closed circular groove diameter of the floor is l2=0.7 mm, the metal through hole diameter is l3=0.27 mm, the metal is copper, and the thickness is h=0.036 mm; the thickness of the first dielectric plate is h1=3 mm, the dielectric constant of the first dielectric plate is 3, and the loss tangent value is 0.003, the dielectric constant of the second dielectric plate and the third dielectric plate is 2.65, the loss tangent value is 0.001, and the thickness is h2=h3=0.2 mm.

10. The polarization isolation synaesthesia integrated tracking communication method based on adaptive metasurface according to claim 2 is characterized in that: In step 1, the model of the switching diode is M / A-COM MADP-000907-14020x. When the switching diode is in the "on" state, it is equivalent to a resistor and an inductor connected in series, wherein the resistance value R1=7.8Ω, and the inductance value C1=0.028pF; when the switching diode is in the "off" state, it is equivalent to a capacitor and an inductor connected in series, wherein the capacitance value L1=0.03nH, and the inductance value C1=0.028pF.

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