Terahertz phased array secondary subarray subband dispersion compensation design method

Abstract

The invention discloses a terahertz phased array secondary sub-array sub-band dispersion compensation design method. The method comprises the following steps: step 1, constructing a terahertz phased array system primary sub-array unit and a sub-band bandwidth; step 2, constructing a quadratic subarray and sub-band decision variable constraint condition; step 3, constructing a quadratic subarray and a digital sub-band decision variable group; 4, phased array beam quality optimization target parameters are determined according to terahertz phased array application requirements; step 5, carrying out joint optimization solution on the secondary sub-array and the sub-banding topological structure; and step 6, optimal phase compensation parameter set calculation and compensation processing are carried out. Compared with the existing uniform division or single compensation mode, the subarray and the subband are smaller in scale, the spatial three-dimensional layout is easier to realize, the time dispersion and the spatial dispersion of the broadband large-scale terahertz phased array system are eliminated to a certain extent, and the accurate high-quality direction of the terahertz wave beam is realized.

Description

Technical Field

[0001] This invention relates to a design method for terahertz phased array sub-banding dispersion compensation, belonging to the field of phased array antenna technology. Background Technology

[0002] Currently, most terahertz band communication and radar systems utilize directional antennas to extend the propagation distance of terahertz signals. However, facing bottlenecks such as low beam alignment efficiency and difficulty in beam tracking for rapidly moving platforms, there is an urgent need to solve the problem of broadband, high-gain, fast wide-scan angle, and adaptive tracking terahertz phased array technology. However, when the operating frequency rises to the terahertz band, its frequency and wavelength are between 0.1-10 THz and 3mm-30μm, and traditional electronic and photonic methods and devices cannot be effectively used in this band. Its main performance is still one to two orders of magnitude behind microwave and millimeter-wave devices in terms of power and efficiency. Due to the short wavelength of terahertz waves and the small size of antenna array elements (below millimeters), the development and application of terahertz phased arrays require extremely high design and fabrication capabilities, making it a key research area both domestically and internationally. A typical example is:

[0003] In 2016, Y. Yang et al., using a 45-nm SOI CMOS process, achieved an eight-element phased array with a peak EIRP measurement of 8–8.5 dBm in the 380–400 GHz frequency range, and a beam scanning range exceeding 75°. In 2019, Professor Patrick Reynaert's team at KU Leuven released a 530 GHz injection-locked phased array chip, a 1×4 linear array using a 40-nm CMOS process, achieving a scanning angle of ±60° and an output power of -12 dBm at 531.5 GHz. In 2022, David del Rio of the University of Navarre in Spain, using a 22-nm SiGe BiCMOS process, integrated 16 transmitting and 16 receiving units and radiated them through an antenna on a PCB, achieving for the first time bidirectional beam control in the D-band with a scanning angle of ±30° and large-scale expansion capabilities. In 2024, Professor Rebeiz's research group at the University of California reported a wafer-level phased array transmitter front-end chip with an array size of 8×8 in the 140 GHz band, achieving an EIRP of 32 dBm and a data transmission rate of more than 16 Gbps.

[0004] Existing methods have addressed the development challenges of terahertz phased arrays to some extent, with some arrays exhibiting scalability for large-scale deployment. The use of the terahertz band offers a wide bandwidth, significantly improving application metrics such as communication speed and imaging resolution. Even with small-aperture antennas on the order of decimeters, array sizes can reach tens of thousands, greatly enhancing the antenna's energy efficiency ratio (EIRP). However, this research is still in its early stages and has not yet reached practical application. As research progresses, the temporal dispersion of broadband signals and the spatial dispersion of large-scale arrays have become critical considerations. Terahertz band phased array systems differ significantly from low-frequency band systems. Firstly, terahertz array elements are too small, while the required bandwidth is too wide, making it difficult to achieve element-by-element digital phase control. Summary of the Invention

[0005] The purpose of this invention is to propose a terahertz phased array sub-striping dispersion compensation design method to solve the serious dispersion problem existing in the broadband signal control of large-scale terahertz phased arrays in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for designing terahertz phased array subarray banding dispersion compensation includes the following steps:

[0008] Step 1, construct the primary subarray elements and subband bandwidth of the terahertz phased array system, including the following operations:

[0009] The center frequency f is designed according to the application requirements of terahertz phased array. c Bandwidth B r azimuth and pitch angle range And the full array size of half the wavelength spacing is M×N; the primary subarray unit M is determined according to the terahertz phased array subarray unit development capability, digital processing capability, and intermediate frequency filtering capability. c ×N c Maximum subband bandwidth B s,max And the number of sub-bands K;

[0010] Step 2, construct the constraints of the quadratic submatrix and subbanded decision variables, including the following operations:

[0011] Based on the results of the first-order subarray unit construction in step 1, determine the size (P) of the (p,q)th subarray in the second-order subarray. m Q n ) represents the size M of a primary subarray element. c ×N c The total array size is equal to M×N, which is an integer multiple of the total array size. Based on the results of the first-order subband construction in step 1, the bandwidth B of the second-order digitization subband within the k-th first-order subband is determined. kl sum satisfy Among them, B k This represents the bandwidth of the kth primary subband.

[0012] Step 3, construct the quadratic subarray and the digitized sub-band decision variable set, including the following operations:

[0013] Following the constraints established in step 2, generate M. G G, a two-dimensional subarray topology PQ and M B Subband topology B KL , forming N GB =M G ×M B A quadratic subarray and a digitized sub-band of decision variables are initialized to i=1, and the total number of iterations is set to N. i,max ;

[0014] Step 4, construct the target parameters for phased array beam quality optimization, including the following operations:

[0015] Based on the application requirements of terahertz phased arrays, the target parameters for beam quality optimization of the phased array are determined, and the maximum sidelobe level (SLL) within the broadband scanning range is selected. max Maximize gate lobe level GLL max and maximizing beam pointing deviation As the optimization objective parameter, the fitness function is adopted. i Evaluate the quadratic subarray and digitized subband decision variables that meet the application constraints;

[0016] Step 5, joint optimization solution of the secondary subarray and subbanded topology, including the following operations:

[0017] Initialize the iteration count i to 1, and obtain N in step 3. GB A set of decision variables is randomly selected from the set of decision variables for the quadrature subarray and the digitized sub-band. The phased array beam quality optimization target parameters constructed in step 4 are simulated and calculated to verify whether the target parameters meet the application constraints set in step 4. If they do, the fitness function is compared. i Update the minimum fitness i The corresponding optimal subarray topology two-dimensional structure G PQ Sub-band topology B KL If the conditions are not met, a new set of decision variables is randomly selected, and the iteration count i is incremented by 1 until N is completed. i,max In the next iteration, the minimum Fitness i The corresponding two-dimensional topology G PQ Sub-band topology B KLAs the optimal quadratic subarray and subbanding topology;

[0018] Step 6, Optimize the phase compensation parameter set calculation and compensation processing, including the following operations:

[0019] Based on the optimized two-dimensional subarray topology G obtained in step 5 PQ Sub-band topology B KL Determine the relative position of the center of each subarray (Ps) p Ps q ) and sub-band center f kl Then, the delay compensation amount of each subarray and subband is calculated to form the optimal phase compensation parameter set; during phased array beam control, the optimal phase compensation is performed on each quadratic subband in each subarray to complete the phased array dispersion compensation process.

[0020] The advantages of this invention compared to the prior art are:

[0021] (1) In this invention, the difficulty of directly processing broadband intermediate frequency signals is avoided by using secondary subbanding of intermediate frequency signals. This makes it possible for terahertz phased array antennas to use intermediate frequency signal processing for phase shift compensation and delay processing. Moreover, subband processing is inherently parallel, and each subband can be processed independently, which can continuously expand the bandwidth of terahertz phased array antennas. (2) In this invention, the large-scale terahertz phased array antenna is designed by joint optimization of secondary subarrays and subbands. Compared with the existing uniform division or single compensation method, the subarrays and subbands are smaller in scale and the spatial three-dimensional layout is easier to realize, which greatly reduces the difficulty of developing large-scale terahertz phased arrays. This can eliminate the time dispersion and spatial dispersion of broadband large-scale terahertz phased array systems to a certain extent and realize precise and high-quality pointing of terahertz beams. Attached Figure Description

[0022] Figure 1 The flowchart of the terahertz phased array secondary subarray subband dispersion compensation design method of the present invention is as follows: In the figure, the steps are in the following order: (1) Construction of primary subarray units and subband bandwidth of terahertz phased array system, (2) Construction of secondary subarray and subband decision variable constraints, (3) Construction of secondary subarray and digital subband decision variable group, (4) Construction of phased array beam quality optimization target, (5) Joint optimization solution of secondary subarray and subband topology, (6) Calculation and compensation processing of optimal phase compensation parameter set;

[0023] Figure 2 This is a schematic diagram of the strategy for generating decision variable sets in a quadratic subarray.

[0024] Figure 3 This is a schematic diagram of the strategy for generating decision variable sets in the quadratic subbanding method;

[0025] Figure 4It is the center frequency f c =220GHz, bandwidth B r =20GHz, phased array M×N=128×128, uncompensated, pointing at 60 degrees, 210GHz (right peak), 220GHz (middle peak) and 230GHz (left peak) frequency beam patterns;

[0026] Figure 5 The beam pattern of the phased array is 210GHz (right peak), 220GHz (middle peak) and 230GHz (left peak) when the phased array is pointed at 60 degrees with 16×16 sub-arrays and 128 sub-bands, and the sub-arrays and sub-bands are evenly divided.

[0027] Figure 6 It involves optimizing the subarray and subband topology to obtain beam patterns at frequencies of 210 GHz (blue solid line), 220 GHz (red solid line), and 230 GHz (yellow solid line) when pointing at 60 degrees. Detailed Implementation

[0028] A specific embodiment of the present invention will be further described below with reference to the accompanying drawings.

[0029] This invention provides a design method for sub-banding dispersion compensation of terahertz phased arrays, such as... Figure 1 As shown, the specific steps are as follows:

[0030] (1) Construct the primary subarray units and subband bandwidth of the terahertz phased array system.

[0031] The center frequency f is designed according to the application requirements of terahertz phased array. c =220GHz, bandwidth B r =20GHz, azimuth and elevation angle range (±60°, ±60°) and half-wavelength spacing full array size M×N=128×128; the primary subarray unit M is determined according to the terahertz phased array subarray unit development capability, digital processing capability, and intermediate frequency filtering capability. c ×N c =8×8, maximum subband bandwidth B s,max =5GHz and the number of primary subbands K=4.

[0032] (2) Construct the constraints of the quadratic subarray and subband decision variables.

[0033] Based on the results of the first subarray construction in step 1, determine the size (P) of the (p,q)th subarray in the second subarray construction. m Q nThe size of the first-order subarray unit is an integer multiple of 8×8, and the total array size is equal to 128×128; based on the first-order subband construction results in step 1, the bandwidth B of the second-order digitization subband within the k-th first-order subband is determined. kl sum satisfy Among them, B k This represents the bandwidth of the kth primary subband.

[0034] (3) Construction of quadratic subarray and digitized subband decision variable set

[0035] Following the constraints established in step 2, generate M. G = 50 subarrays in a two-dimensional topology G PQ and M B =20 sub-band topology B KL , forming N GB =M G ×M B =1000 quadratic subarrays and digitized sub-bands of decision variables, with the number of decision variables initialized to N. i =1, set the total number of optimization iterations to N. i,max =100.

[0036] Among them, the secondary subarray generation strategy is as follows: Figure 2 As shown, the subarray partitioning search of the surface array is changed to the subarray partitioning search of the linear array. That is, the 16 subarray elements in the horizontal direction and the 16 subarray elements in the vertical direction are respectively divided into secondary subarrays. The subarray partitioning of the surface array is extended from the secondary subarray partitioning scheme in the horizontal direction and the secondary subarray partitioning scheme in the vertical direction.

[0037] The secondary subband is generated randomly within each primary subband based on the maximum bandwidth requirement of the subband. B =20 sub-band topology B KL ,like Figure 3 As shown.

[0038] (4) Construct target parameters for phased array beam quality optimization.

[0039] Based on the application requirements of terahertz phased arrays, the target parameters for beam quality optimization of the phased array are determined, and the maximum sidelobe level (SLL) within the broadband scanning range is selected. max Maximize gate lobe level GLL max and maximizing beam pointing deviation As optimization target parameters, the application constraints that each phased array beam quality optimization target parameter should meet are determined according to application requirements, namely:

[0040]

[0041] Preferably, the following adaptive function is used to evaluate the quadratic subarray and digitized subband decision variables that satisfy the application conditions:

[0042]

[0043] That is, w i =0.25, f i (x i )=x i，max / x i,lim .

[0044] (5) Joint optimization solution of quadratic subarray and subbanded topology. Initialize the iteration number i to 1, and obtain N in step 3. GB A set of decision variables is randomly selected from the group of decision variables for the secondary subarray and the digitized sub-band. The phased array beam quality optimization target parameters constructed in step 4 are simulated and calculated to verify whether the target parameters meet the application constraints. If they do, the performance is compared with the physical parameters. i Update the minimum fitness i The corresponding optimal subarray topology two-dimensional structure G PQ Sub-band topology B KL If the conditions are not met, a new set of decision variables is randomly selected, and the iteration count i is incremented by 1 until N is completed. i,max In the next iteration, the minimum Fitness i The corresponding two-dimensional topology G PQ Sub-band topology B KL As the optimal quadratic subarray and subbanding topology.

[0045] The optimization of the phased array beam quality target parameters constructed in step 4 above requires frequent calls to the phased array electromagnetic simulation model to calculate the radiation pattern of the phased array. Furthermore, through the radiation pattern of the phased array The target parameters for optimizing the phased array beam quality within the broadband scanning range are calculated, and the radiation pattern of the terahertz phased array antenna is calculated using the parameterized model shown in the following formula:

[0046]

[0047] in, It is the radiation pattern of the phased array. As unit factor, Let (P,Q) be the matrix factor, and (P,Q) be the two-dimensional subarray topology G. PQ The size of the subarray in f kl The center frequency of the k-th primary sub-band and the l-th secondary digitized sub-band is given. They are respectively the (p,q)th subarray. m ,q n The unit points to any angle. Delay and pointing to a specified angle The delay, The center of the (p,q)th subarray points to The delay. The radiation pattern of the phased array obtained through calculation. Extracting the maximum sidelobe level SLL within the wideband scanning range max Maximize gate lobe level GLL max and maximizing beam pointing deviation

[0048] The main function of a phased array antenna is to point the beam in a specific direction. In application, the angle at which the beam is pointed at a given moment is... However, the beam is not a line; it can only point the beam center in that direction. The radiation pattern, on the other hand, shows the beam's performance at any angle when the beam is pointed at that specified angle. The distribution of the sidelobe level (SLL) can be calculated based on the distribution at different frequencies and angles. max Maximize gate lobe level GLL max and maximizing beam pointing deviation

[0049] (6) Calculation and compensation of the optimal phase compensation parameter set.

[0050] Based on the optimized two-dimensional subarray topology G obtained in step 5 PQ Sub-band topology B KL Determine the relative position of the center of each subarray (Ps) p Ps q ) and sub-band center f kl Then, the delay compensation for each subarray and subband is calculated as follows: Forming the optimal phase compensation parameter set During phased array beam control, the signals of each quadratic subband are superimposed in each subarray. Complete the phased array dispersion compensation process.

[0051] Based on the above parameters and steps, Figure 4 Typical uncompensated beam patterns at 210 GHz (right peak), 220 GHz (middle peak), and 230 GHz (left peak) with a pointing angle of 60 degrees are presented. As can be seen from the figure, in the broadband case, large angular deviations at different frequencies result in a shift exceeding the beamwidth. This will significantly broaden the broadband signal beam and affect beam usage.

[0052] Figure 5The beam patterns at 210 GHz, 220 GHz, and 230 GHz with a pointing angle of 60 degrees are presented under typical uniform quadratic subarray and subbanding conditions. The number of subarrays is 16×16, and the number of subbands is 4×32. Phase and delay compensation using the quadratic subarray and subbanding methods of this invention is achieved, concentrating the broadband signal within a single beam range, resulting in excellent compensation performance. Because the center positions of the subarrays and subbands are used instead of the test frequencies for compensation, grating lobes appear in the beam, but their amplitude is within an acceptable range.

[0053] Furthermore, through optimization, the beam patterns at 210GHz, 220GHz, and 230GHz with horizontal subarray sizes of [8 8 16 32 32 16 88] and a subband quantity of 2×4, pointing at 60 degrees, are obtained, as shown below. Figure 6 As shown, although the beam is somewhat broadened and the large-angle grating lobes in the low-frequency band are slightly higher, the number of subarrays is optimized to 8×8, the number of subbands is 8, the array structure is simpler, and the digital phase and delay are improved.

[0054] Time-compensation processing requires less resources.

[0055] The parts of this invention not described in detail are common knowledge to those skilled in the art.

Claims

1. A method for designing sub-banding dispersion compensation for terahertz phased arrays, characterized in that, Includes the following steps: Step 1, construct the primary subarray elements and subband bandwidth of the terahertz phased array system, including the following operations: The center frequency f is designed according to the application requirements of terahertz phased array. c Bandwidth B r azimuth and pitch angle range And the full array size of half the wavelength spacing is M×N; the primary subarray unit M is determined according to the terahertz phased array subarray unit development capability, digital processing capability, and intermediate frequency filtering capability. c ×N c Maximum subband bandwidth B s,max And the number of sub-bands K; Step 2, construct the constraints of the quadratic submatrix and subbanded decision variables, including the following operations: Based on the results of the first-order subarray unit construction in step 1, determine the size (P) of the (p,q)th subarray in the second-order subarray. m Q n ) represents the size M of a primary subarray element. c ×N c The total array size is equal to M×N, which is an integer multiple of the total array size. Based on the results of the first-order subband construction in step 1, the bandwidth B of the second-order digitization subband within the k-th first-order subband is determined. kl sum satisfy Among them, B k This represents the bandwidth of the kth primary subband. Step 3, construct the quadratic subarray and the digitized sub-band decision variable set, including the following operations: Following the constraints established in step 2, generate M. G G, a two-dimensional subarray topology PQ and M B Subband topology B KL , forming N GB =M G ×M B A quadratic subarray and a digitized sub-band of decision variables are initialized to i=1, and the total number of iterations is set to N. i,max ; Step 4, construct the target parameters for phased array beam quality optimization, including the following operations: Based on the application requirements of terahertz phased arrays, the target parameters for beam quality optimization of the phased array are determined, and the maximum sidelobe level (SLL) within the broadband scanning range is selected. max Maximize gate lobe level GLL max and maximizing beam pointing deviation As the optimization objective parameter, the fitness function is adopted. i Evaluation of quadratic subarrays and digitized subband decision variables that satisfy application constraints: Step 5, joint optimization solution of the secondary subarray and subbanded topology, including the following operations: Initialize the iteration count i to 1, and obtain N in step 3. GB A set of decision variables is randomly selected from the set of decision variables for the quadrature subarray and the digitized sub-band. The phased array beam quality optimization target parameters constructed in step 4 are simulated and calculated to verify whether the target parameters meet the application constraints set in step 4. If they do, the fitness function is compared. i Update the minimum fitness i The corresponding optimal subarray topology two-dimensional structure G PQ Sub-band topology B KL If the conditions are not met, a new set of decision variables is randomly selected, and the iteration count i is incremented by 1 until N is completed. i,max In the next iteration, the minimum Fitness i The corresponding two-dimensional topology G PQ Sub-band topology B KL As the optimal quadratic subarray and subbanding topology; Step 6, Optimize the phase compensation parameter set calculation and compensation processing, including the following operations: Based on the optimized two-dimensional subarray topology G obtained in step 5 PQ Sub-band topology B KL Determine the relative position of the center of each subarray (Ps) p Ps q ) and sub-band center f kl Then, the delay compensation amount of each subarray and subband is calculated to form the optimal phase compensation parameter set; during phased array beam control, phase compensation is performed on each quadratic subband in each subarray to complete the phased array dispersion compensation process.

2. The terahertz phased array secondary subarray banding dispersion compensation design method as described in claim 1, characterized in that, In step 4, following the phased array size and bandwidth established in step 1, and considering application requirements, the application constraints that the target parameters for optimizing the beam quality of each phased array should meet are determined, namely: The following fitness function is used to evaluate the quadratic subarray and digitized subband decision variables that meet the application conditions: in, With w i and f i (x i ) represents the weights and normalization functions for each optimization objective parameter.

3. The terahertz phased array secondary subarray banding dispersion compensation design method as described in claim 2, characterized in that, In step 5, the target parameters for optimizing the phased array beam quality constructed in step 4 are specifically calculated using the radiation pattern of the phased array. Calculate and extract the target parameters for optimizing the phased array beam quality within the broadband scanning range.

4. The terahertz phased array secondary subarray banding dispersion compensation design method as described in claim 3, characterized in that, In step 5, the radiation pattern of the terahertz phased array antenna is calculated using the parameterized model shown in the following formula: in, It is the radiation pattern of the phased array. As a unit factor, preferably, Let (P,Q) be the matrix factor, and (P,Q) be the two-dimensional subarray topology G. PQ The size of the subarray in f kl The center frequency of the k-th primary sub-band and the l-th secondary digitized sub-band is given. They are respectively the (p,q)th subarray. m ,q n The unit points to any angle. Delay and pointing to a specified angle The delay, The center of the (p,q)th subarray points to The delay.

5. The terahertz phased array secondary subarray banding dispersion compensation design method as described in claim 1, characterized in that, In step 6, based on the optimized two-dimensional subarray topology G obtained in step 5... PQ Sub-band topology B KL Determine the relative position of the center of each subarray (Ps) p Ps q ) and sub-band center f kl Then, the delay compensation for each subarray and subband is calculated as follows: Forming the optimal phase compensation parameter set During phased array beam control, the signals of each quadratic subband are superimposed in each subarray. Complete the phased array dispersion compensation process.

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