Secondary grouping asynchronous rotating electric vector radar array antenna calibration method

Abstract

The present application belongs to the technical field of calibration of phased array radar, and relates to a two-stage grouping asynchronous rotating electric vector radar array antenna calibration method, and the specific process is as follows: an attenuator and a phase shifter are configured to each element channel of the array antenna to be measured, and signals received by all channels are synthesized through a power divider; the phased array radar to be measured is equally grouped by channel number in a first stage; a grouping matrix is constructed based on a Hadamard matrix, and the channels grouped in the first stage are divided into rotating groups and fixed groups according to elements in the grouping matrix; a phase shift matrix for phase shift measurement of each row in different grouping matrices is constructed based on a discrete Fourier transform matrix with an order of N, and phase shift is performed; linear equations are constructed according to measurement results and solved, and the ambiguity coefficient, the amplitude of each channel and the phase difference between each channel are obtained, and each field normalization amplitude and phase is solved; amplitude and phase compensation of the channels is completed based on each field normalization amplitude and phase, and finally the amplitude and phase of all channels are consistent.

Description

Technical Field

[0001] This invention belongs to the field of phased array radar calibration technology, specifically relating to a calibration method for a two-stage grouped asynchronous rotating electric vector radar array antenna. Background Technology

[0002] Phased array radars, utilizing array structures composed of multiple antenna elements and channel amplitude and phase weighting technology, can achieve beam scanning and beamforming, enabling precise target detection. They are widely used in satellite communications, automotive electronics, aerospace, and other fields. Amplitude and phase consistency is one of the key technical indicators of phased array radars. Inconsistencies in components can lead to differences in amplitude and phase among the antenna elements, making it difficult to achieve strictly equal-amplitude and in-phase excitation of the array surface. This severely affects the beamforming accuracy and pattern performance of the phased array radar, thus requiring channel amplitude and phase calibration. Currently, various channel amplitude and phase calibration techniques for phased array radars have been proposed, but calibration methods for large phased array systems generally suffer from low calibration accuracy and insufficient robustness, failing to meet the practical requirements of high-precision and high-reliability calibration for large phased array systems.

[0003] Existing phased array radar channel amplitude and phase calibration techniques can be broadly categorized into two types: complex signal measurement methods and pure amplitude measurement methods. Complex signal methods include near-field scanning, commutation, mutual coupling, and their improved versions. Near-field scanning calibrates the phased array by measuring the complex signal received by the probe element by element in the near-field of the array. However, it requires sequentially switching each element on and off, resulting in low efficiency. Furthermore, it requires a precisely controllable scanning frame and cannot calibrate errors caused by mutual coupling of active devices. Commutation measures the complex signal received by the probe while changing the phase of each channel, but this method relies on precise phase measurement, placing high demands on the equipment. Mutual coupling measures the amplitude and phase characteristics of each element based on the mutual coupling characteristics between antennas, but the calibration accuracy is affected by edge effects. In summary, all complex signal measurement methods rely on precise phase measurement, placing stringent requirements on the accuracy of equipment setup and measurement, thus increasing the difficulty of practical applications.

[0004] The Rotating Element Electric-field Vector (REV) method is a typical example of a pure amplitude measurement method. This method places the probe antenna within the far field of the array under test, adjusts the phase of a specific array element from 0° to 360° in steps, and measures the change in the probe's received power during this process. The amplitude and phase of that element can be calculated by measuring all array elements. By iterating through all array elements, the amplitude and phase of all channels can be calculated. Various improved schemes have been developed based on this method to enhance the calibration efficiency and measurement accuracy of the algorithm. However, for large phased array systems, both the classic and improved REV methods have inherent limitations: these methods rely on accurate measurement of the power curve. When only the phase of a single array element is changed each time, while the phases of other elements remain fixed, the range of power curve variation is small, making it susceptible to noise interference and reducing calibration accuracy. Furthermore, these methods involve two fuzzy solutions in the solution process, which cannot be correctly distinguished, further deteriorating the calibration effect. To improve noise immunity, recent technologies have employed group calibration strategies, which simultaneously change the phase of multiple channels to increase the range of power curve variation and improve the signal-to-noise ratio (SNR) of the received signal. However, this grouping strategy increases the condition number of the grouping matrix, amplifying errors in solving linear equations. Furthermore, this method does not address the fuzzy solution problem inherent in the classical REV method. Compared to complex signal measurement methods, pure amplitude measurement methods offer the significant advantage of requiring only the measurement of far-field received power without precise phase measurement, allowing for mathematical derivation of amplitude and phase information for each channel, thus enhancing engineering practicality. However, while various improved REV-based methods have been proposed, they fail to simultaneously address the two core technical challenges of reduced calibration accuracy due to decreased SNR in large phased arrays and the inherent non-uniqueness of solutions in the REV method. These challenges make it difficult to meet the high-precision calibration requirements of large phased array systems. Summary of the Invention

[0005] The purpose of this invention is to provide a two-stage grouped asynchronous rotating electric vector radar array antenna calibration method to overcome the shortcomings of the prior art and improve the robustness and accuracy of large-scale array channel calibration.

[0006] The technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for calibrating a two-stage grouped asynchronous rotating electric vector radar array antenna, the specific process of which is as follows: Test environment setup: Each element channel of the antenna under test is equipped with an attenuator and a phase shifter, and the signals received by all channels are combined through a power divider; Secondary grouping: The phased array radar under test is grouped according to the number of channels. Perform equal-weight first-level grouping , Grouping size; constructing a grouping matrix based on the Hadamard matrix. According to the grouping matrix The elements in the first-level grouping The channels are divided into rotating and fixed groups; Asynchronous phase shifting: based on order of The discrete Fourier transform matrix is ​​used to construct different grouping matrices. Each row in Phase shift matrix for sub-phase shift measurement And control the rotating phase shifter according to the phase shift matrix. Perform phase shifting; Linear equation construction and solution: based on Power matrix measured by sub-phase shift Establish and solve a system of linear equations between the channel amplitude and phase parameters and the power matrix to obtain an unknown matrix containing the amplitude and phase information of each combined field. ; Parameter solution: based on the unknown matrix to be solved Calculate the ambiguity coefficients, the amplitude of each channel, and the phase difference between each channel, and solve for the normalized amplitude and phase of each combined field; Amplitude and phase compensation for each channel: Based on the normalized amplitude and phase of each combined field, amplitude and phase compensation for each channel is completed, ultimately achieving amplitude and phase consistency for all channels.

[0008] Optionally, the present invention describes the construction of a grouping matrix based on the Hadamard matrix. According to the grouping matrix The elements in the first-level grouping The channels are divided into rotating and fixed groups; the specific process is as follows:

[0009] in, for Hadamard matrix of order 1 for A matrix with all rows being one. For matrix The first line, For matrix The second line; matrix Elements with a value of 1 represent the channel number that needs to be rotated in phase, i.e., the channel number of the rotation group; elements with a value of 0 represent the channel number that keeps the phase unchanged, i.e., the channel number of the fixed group.

[0010] Optionally, the present invention Unable to be During division, a compensation strategy is adopted, specifically: the array elements that have been measured are combined with the array elements that have not been measured to form a new group for experimental measurement. For array elements that are measured repeatedly, the average value of their amplitude and phase parameters is taken.

[0011] Optionally, the specific process of asynchronous phase shifting described in this invention is as follows: calculation

[0012] in, Based on phase-shifting stepping, For the rotation group Basic phase-shifting step, For the first Rotating group during the second measurement Phase shift value; for Perform on the same line respectively Second phase shift measurement to obtain the phase shift matrix The corresponding expression is as follows:

[0013] in, Grouped matrix The The first step The phase shift value of the second measurement, Dot product, .

[0014] Optionally, the present invention measures the far-field power of the antenna array under test and forms a measurement power matrix. ,by The The received power measurements of each row are used to construct a column vector. The coefficient matrix is ​​constructed based on the discrete Fourier transform matrix. Establish a system of linear equations Solving for the unknown matrix yields the solution. The expression is:

[0015] in, It is a column vector Each item in the middle; express The The amplitude of the combined field of the channel undergoing phase shifting. express The The phase of the combined field of the channel undergoing phase shifting. express The The amplitude of the combined field of all channels with fixed phases. express The The phase of the combined field of all channels with fixed phases.

[0016] Optionally, the phase difference between channels in this invention is calculated by solving the unknown matrix. Substitute into the following formula to calculate

[0017] Optionally, the calculation of the amplitude of each channel in this invention is as follows: The ambiguity coefficient is calculated as follows:

[0018] in, Take any value in [1, M] that is not equal to integers, It can take any value in [1, M] that is not equal to Integers; the amplitude values ​​of each combined field are: .

[0020] Optionally, the present invention describes the solution of the normalized amplitude and phase of each combined field; .

[0022] Optionally, the specific process of amplitude and phase compensation for each channel in this invention is as follows: Solve in sequence The normalized amplitude and phase of the resultant field of the rotating element with different phase shift steps in all rows are obtained, and the results are set in a matrix. middle:

[0023] in, ; The normalized electric field of each channel is calculated based on the normalized amplitude and phase of each combined field. :

[0024] in, Indicates the first group after the first-level grouping The normalized electric field vectors obtained by different linear combinations of elements in each group elements in For the first The normalized electric field of each channel is obtained; from this, the normalized amplitude and normalized phase value of each channel are obtained; Based on the normalized amplitude and normalized phase values ​​of each channel obtained from the solution, any channel is selected as a reference unit, and the amplitude ratio and phase difference between the other channels and the reference channel are calculated. This completes the amplitude and phase compensation for the non-reference channels, and finally achieves amplitude and phase consistency of all channels.

[0025] Beneficial effects: First, the present invention provides a two-stage grouped asynchronous rotating electric vector phased array radar channel amplitude and phase calibration method. This method can complete the amplitude and phase calibration of each channel by measuring the far-field power, without the need for additional measurement steps or hardware equipment, and can achieve high-precision channel calibration under the low signal-to-noise ratio conditions of large phased arrays.

[0026] Secondly, the present invention employs a two-level grouping strategy, namely, using a grouping matrix designed based on the Hadamard matrix in the second-level grouping. This is because the number of 1s in each row is fixed, the matrix is ​​full rank and strictly orthogonal, the condition number is small, and it is less affected by noise. Through this two-level grouping method, the dynamic range of the received power is expanded, the range of power curve variation is significantly improved, the noise immunity of the calibration is effectively enhanced, it can be applied to large arrays of any size, and the calibration accuracy is improved.

[0027] Third, the asynchronous phase-shifting method of this invention completely solves the inherent fuzzy solution problem of the traditional rotating electric vector method, which can significantly reduce estimated outliers and improve calibration accuracy.

[0028] Fourth, this invention accurately compensates non-reference channels based on the calculated amplitude compensation of each channel, enabling efficient, accurate, and low-cost phased array channel calibration, fully meeting the engineering application needs of large-scale phased array systems. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The diagram shown is a flowchart illustrating the two-level grouped asynchronous rotating electric vector radar array antenna calibration method provided by the present invention. Figure 2 The diagram shown illustrates the calibration environment. Figure 3 The image shown is based on M A schematic diagram of the two-level grouping method and asynchronous phase shifting strategy with a value of 4 as an example; Figure 4 The diagram shown is a flowchart based on an embodiment of the present invention. Figure 5 The figure shows the absolute amplitude error between the method of this invention and two conventional calibration methods; Figure 6 The figure shows the phase absolute error diagrams of the method of the present invention and two conventional calibration methods; Figure 7 The figure shows the amplitude and phase error box plots of the method of the present invention and two conventional calibration methods. Detailed Implementation

[0031] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0032] It should be noted that, in the absence of conflict, the following embodiments and features can be combined with each other; and, based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0033] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0034] Figure 1 A flowchart illustrating the two-stage grouped asynchronous rotating electric vector radar array antenna calibration method provided by the present invention is shown, including: Step 1, Test Environment Setup: The test environment uses a compact field microwave anechoic chamber. The transmitting antenna is connected to a vector network analyzer and placed in the far field of the phased array radar antenna under test. Each element channel of the phased array radar under test is equipped with an attenuator and a phase shifter. The signals received by all channels are combined through a power divider and received by a host computer.

[0035] Step 2, Design of two-level grouping and asynchronous phase shifting strategy: Design the grouping matrix for secondary grouping as needed, and construct the phase shifting matrix based on the asynchronous phase shifting strategy designed by the discrete Fourier transform matrix. This experiment was conducted, and the number of tests was [number]. It is related to the designed phase-shifting matrix; the specific process is as follows: First-level grouping: Grouping the phased array radars under test according to the number of channels. When performing equal-number grouping, if the quantization bit depth of the phase shifter is limited, the group size is determined by the quantization bit depth of the phase shifter. For example, for a 6-bit phase shifter, the maximum group size is 5. This grouping is called the first-level grouping. The size of the first-level grouping can be 2-5, and an appropriate grouping size should be selected. This makes the total number of channels Divisible At this point, the number of channels in each group after the first-level grouping is ; Second-level grouping: This refers to grouping the components after the first-level grouping. The channels are further grouped, and only a portion of the channel's phase is rotated each time. The rotated portion of the channel within a group is called the rotating group, and the channel whose phase remains unchanged is called the fixed group. The phase of the rotating group is shifted in a certain phase step between [0°, 360°). The channels requiring phase rotation in this experiment are given based on the grouping matrix. The grouping matrix is ​​linearly independent and of full rank. Grouping matrix Based on the Hadamard matrix, the construction method is as follows: (1) in, for Hadamard matrix of order 1 for A matrix with all rows containing only one elements. Subtracting the second row from the first row gives the number of 1s in each row. That is, each rotation The phase of each channel. Elements with a value of 1 represent the channel number that needs phase rotation, i.e., the channel number of the rotation group, while elements with a value of 0 represent the channel number that keeps the phase unchanged, i.e., the channel number of the fixed group. They are all constructed in the same way, but they are different. When rotating the phase, an asynchronous phase-shifting strategy is used, and the phase step must be set to different values. Unable to be During division, a compensation strategy is adopted, specifically: the array elements that have been measured are combined with the array elements that have not been measured to form a new group for experimental measurement. For array elements that are measured repeatedly, the average value of their amplitude and phase parameters is taken.

[0036] Based on the order The discrete Fourier transform matrix, for different The formula for implementing the asynchronous phase-shifting strategy is as follows: (2) in, Based on phase-shifting stepping, For the rotation group Basic phase-shifting step, For the first Rotating group during the second measurement Phase shift value; for The same line (hereinafter referred to as the first line) (Example of behavior), to be carried out separately Second phase shift measurement to obtain the phase shift matrix The corresponding expression is as follows: (3) in, Grouped matrix The The first step The phase shift value of the second measurement, Dot product, .

[0037] Step 3: Phase shifting based on the phase shifting matrix and measuring the far-field received power, constructing and solving a system of linear equations; The far-field power of the antenna array under test was measured and a measurement power matrix was constructed. ,by The The received power measurements of each row are used to construct a column vector. The coefficient matrix is ​​constructed based on the discrete Fourier transform matrix. Establish a system of linear equations A system of linear equations is constructed between the channel amplitude and phase parameters and the measured power vector, where the power matrix... Power vector coefficient matrix and unknown matrix The specific expression is as follows: (4) in, express The The amplitude of the combined field of the channel undergoing phase shifting. express The The phase of the combined field of the channel undergoing phase shifting. express The The amplitude of the combined field of all channels with fixed phases. express The The phase of the combined field of all channels with fixed phases; Solving the linear equations yields an unknown matrix containing amplitude and phase information for each resultant field. Then, based on the predetermined formula, the ambiguity coefficients and the phase difference between each resultant field are calculated, and the results are obtained through a system of linear equations. The unknown matrix obtained by solving The expression is: (5) in, It is a column vector Each item in the middle; Step 4: Calculate the channel ambiguity coefficients and solve for the normalized amplitude and phase of each combined field and the normalized amplitude and phase of each channel; Fuzzy coefficient calculation: by solving the unknown matrix Substitute the values ​​into the following formula to calculate the fuzzy coefficient: (6) in, It can take [1, M Any not equal to integers, It can take [1, M Any not equal to Integers.

[0038] Phase difference calculation between channels: by solving the unknown matrix Substitute into the following formula to calculate (7) Calculation of amplitude for each channel: Based on the obtained fuzzy coefficients, a corresponding set of nonlinear equations is constructed. By solving this set of nonlinear equations, the amplitude value of each resultant field is obtained. The calculation formula for the amplitude of each channel is as follows: (8) in, and These correspond to the fuzzy coefficients in formula (6); Solving for the normalized amplitude and phase of each combined field includes: The channel parameters are normalized according to the predetermined analytical relationship to obtain the normalized amplitude and normalized phase of each combined field. Based on the relative phase and amplitude results of each combined field obtained by solving the above formulas (7) and (8), the calculation formulas for the normalized amplitude and normalized phase of each combined field are as follows: (9) Step 5: Solving for normalized amplitude and phase for each channel and compensating for amplitude and phase for each channel. Solve in sequence The normalized amplitude and phase of the resultant field of the rotating element with different phase shift steps in all rows are obtained, and the results are set in a matrix. middle: (10) in, ; Solving for the normalized amplitude and phase of each channel includes: The normalized amplitude and phase of each channel are obtained based on the normalized electric field of each combined field. The set of normalized amplitude and phase of each channel can be obtained by the following formula: (11) in, elements in For the first Normalized electric field of each channel; The amplitude and phase compensation for each channel includes: based on the normalized amplitude and normalized phase values ​​of each channel obtained by the solution, selecting any one channel as a reference unit, calculating the amplitude ratio and phase difference between the remaining channels and the reference channel, and then completing the amplitude and phase compensation for the non-reference channels, ultimately achieving amplitude and phase consistency of all channels.

[0039] Example: Figure 2 The setup process for the illustrated environment is as follows: In a microwave anechoic chamber, the probe antenna is positioned along the normal direction of the phased array, with a spacing greater than 10 times the operating wavelength to meet far-field testing conditions. The transmitter outputs an excitation signal to the probe antenna, which radiates electromagnetic waves. After the phased array under test receives these electromagnetic waves, the signal undergoes phase adjustment via a phase shifter and is then transmitted to the receiver via a frequency conversion channel. The receiver processes the received signal and ultimately outputs the received power data.

[0040] Figure 3 The diagram shows a two-level grouping method and asynchronous phase shifting strategy with M=4 as an example.

[0041] This embodiment uses a two-stage grouped asynchronous rotating electric vector radar array antenna calibration method to achieve amplitude and phase calibration of the phased array channel. The specific implementation plan is as follows: First, based on the far-field test conditions, a phased array antenna containing 128 test elements is placed as the receiver in the far-field normal direction of the probe antenna; the probe antenna is used as the transmitter, and the phased array antenna as the receiver. The test system uses a built-in signal processor to complete real-time acquisition of the received power. A schematic diagram of the test environment is shown below. Figure 2 As shown. Furthermore, the remaining calculation process diagrams of this method are shown below. Figure 4 As shown, it includes: SS1: Setting M , K , N s Calculate the phase step, grouping matrix, and phase shift matrix of asynchronous phase shifting; SS2: Perform phase shifting based on the phase shifting matrix and measure the array received power. P Construct power vector Pj ; SS3:2 M+1 The discrete Fourier matrix of order 1 as A Establish linear equations P j = AX j Solve this problem; SS4: Determine by looking up the table X j The physical meaning of each item; SS5: Calculation M Calculation of fuzzy coefficients for each combined field; SS6: Calculation M The normalized amplitude and phase of each combined field are obtained, and the above operation is repeated until all combined fields are solved.

[0042] SS7: Solve for the normalized amplitude and phase of all channels.

[0043] This embodiment follows step SS1, letting... M = 4 Divide the array into first-level groups, let K=8, and calculate the grouping matrix according to formula (1). G 1, G 2, G 3, G 4. Set the number of phase shifts N s = 32 can be calculated according to formula (3). G 1, G 2, G 3, G 4 Basic Phase Shifting Steps ω 1,step , ω 2,step , ω 3,step , ω 4,step They are π / 16, 3π / 16, 5π / 16, and 7π / 16 respectively.

[0044] In turn, different ω i,n as follows: (12) Then, the phase shift matrix is ​​calculated according to formula (2). Ψ .

[0045] Following step SS2, the 128-channel phased array antenna is phase-shifted according to the phase-shifting matrix, and the array's received power is measured. P ,Will N s Second measurement PConstruct a success rate vector P j The format is as follows: (13) Further following step SS3, the obtained power vector P j Establish a system of linear equations, coefficient matrix A 2 M+1 A discrete Fourier matrix of order 1, for M = 4, K =8, N s The coefficient matrix A of 32 is: (14) Establish a linear equation from the first two steps P j = AX j Solving for the results X j , X j The terms of the unknown vector can be represented as G i The j The channel field of phase shifting and G k The j The result obtained by multiplying the pairwise conjugates of the combined field of the phase-shifting channels (0 indicates...) G The j (The combined field of all channels with fixed phases) is shown in the table below. M When =5, their correspondence.

[0046]

[0047] for M =4, X j The formula for the meaning of each item is as follows: (15) Then, following step SS4, determine X The physical meaning of each term is determined, and then obtained through solving. X j Calculate the fuzzy coefficients and the normalized amplitude and phase of each resultant field.

[0048] Defined by step SS4 X j The physical meaning of each item, and the calculations obtained in step SS3. X j =A -1P j The solution can be determined as follows: (16) Further, following step SS5, substitute the values ​​into the ambiguity coefficient calculation formula to determine the ambiguity coefficient for each channel: (17) The calculated fuzzy coefficients are used for subsequent normalization amplitude calculations to solve the multi-solution problem of conventional calibration methods and make the algorithm more robust.

[0049] Further calculate according to step SS6. G 1, G 2, G 3, G 4th j The normalized amplitude and phase of the combined field of each channel, which is phase-shifted according to its respective phase-shifting step, are calculated using the normalized amplitude calculation formulas for each combined field in steps SS3 and SS5: (18) The phase difference between each combined field is: (19) Then calculate M Normalized amplitude and phase of the combined field: (20) because M =4, the number of array elements N is 128, then G There are 32 rows, and the above operation needs to be repeated 32 times until all the combined field matrices are obtained. C Solution complete.

[0050] Further, follow step SS7 to solve for the normalized electric field of each channel. s n .

[0051] (twenty one) in, S elements in s n For the first n The normalized electric field of each channel can be used to obtain the normalized amplitude and phase of each channel.

[0052] Based on the above procedure, experiments were conducted, and the amplitude error experimental results for the 128-channel phased array radar antenna are as follows: Figure 5 As shown, compared with the conventional REV method and the grouped REV method, the method proposed in this invention has higher calibration accuracy, with its amplitude error controlled within 1dB; the phase error experimental results are as follows. Figure 6 As shown, similarly, the phase calibration accuracy of the proposed method is significantly higher than that of the two comparative methods, with the phase error stably controlled within 10°. To further quantify and analyze the error distribution characteristics, Figure 7 Box plots of amplitude and phase errors for the three methods are presented. The figures show that the maximum amplitude and phase errors of the proposed method are smaller than those of the conventional REV method and the grouped REV method, and the number of outliers in the error sequence is also less. These experimental results demonstrate that the proposed two-stage grouped asynchronous rotating electric vector radar array antenna calibration method achieves higher calibration accuracy, confirming its superior robustness and higher accuracy in phased array calibration scenarios.

[0053] The calibration requirements for practical engineering are an amplitude error within 1 dB and a phase error within 10°. Based on the experimental results, the mean square error and maximum error of each element of the 128-channel phased array radar antenna were obtained, as shown in Table 1: Table 1: Amplitude and phase errors of the proposed method

[0054] As shown in Table 1, the amplitude and phase errors meet the engineering requirements, proving the effectiveness of the method of the present invention.

[0055] By obtaining the normalized amplitude and phase of each unit through the above steps, an amplitude and phase compensation table can be established, thereby completing the phased array channel calibration.

[0056] This embodiment provides a phased array channel calibration method that combines high robustness and high accuracy. This method only requires measuring power values ​​and effectively solves the key problems of conventional algorithms in phased array calibration, such as difficulty in distinguishing fuzzy solutions and poor robustness under low signal-to-noise ratio conditions. Compared with existing technologies, the proposed method not only significantly improves computational accuracy and robustness but also has the advantages of low cost and ease of engineering implementation, making it more suitable for practical application scenarios.

[0057] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for calibrating a two-stage grouped asynchronous rotating electric vector radar array antenna, characterized in that, The specific process is as follows: Test environment setup: Each element channel of the antenna under test is equipped with an attenuator and a phase shifter, and the signals received by all channels are combined through a power divider; Secondary grouping: The phased array radar under test is grouped according to the number of channels. Perform equal-weight first-level grouping , Group size; Constructing a grouping matrix based on the Hadamard matrix According to the grouping matrix The elements in the first-level grouping The channels are divided into rotating and fixed groups; Asynchronous phase shifting: based on order of The discrete Fourier transform matrix is ​​used to construct different grouping matrices. Each row in Phase shift matrix for sub-phase shift measurement And control the rotating phase shifter according to the phase shift matrix. Perform phase shifting; Linear equation construction and solution: based on Power matrix measured by sub-phase shift Establish and solve a system of linear equations between the channel amplitude and phase parameters and the power matrix to obtain an unknown matrix containing the amplitude and phase information of each combined field. ; Parameter solution: based on the unknown matrix to be solved Calculate the ambiguity coefficients, the amplitude of each channel, and the phase difference between each channel, and solve for the normalized amplitude and phase of each combined field; Amplitude and phase compensation for each channel: Based on the normalized amplitude and phase of each combined field, amplitude and phase compensation for each channel is completed, ultimately achieving amplitude and phase consistency for all channels.

2. The calibration method for a two-stage grouped asynchronous rotating electric vector radar array antenna according to claim 1, characterized in that, The construction of grouping matrices based on the Hadamard matrix According to the grouping matrix The elements in the first-level grouping The channels are divided into rotating and fixed groups; the specific process is as follows: in, for Hadamard matrix of order 1 for A matrix with all rows being one. For matrix The first line, For matrix The second line; matrix Elements with a value of 1 represent the channel number that needs to be rotated in phase, i.e., the channel number of the rotation group; elements with a value of 0 represent the channel number that keeps the phase unchanged, i.e., the channel number of the fixed group.

3. The calibration method for a two-stage grouped asynchronous rotating electric vector radar array antenna according to claim 2, characterized in that, when Unable to be During division, a compensation strategy is adopted, specifically: the array elements that have been measured are combined with the array elements that have not been measured to form a new group for experimental measurement. For array elements that are measured repeatedly, the average value of their amplitude and phase parameters is taken.

4. The calibration method for a two-stage grouped asynchronous rotating electric vector radar array antenna according to claim 2, characterized in that, The specific process of the asynchronous phase shift is as follows: Calculation in, Based on phase-shifting stepping, For the rotation group Basic phase-shifting step, For the first Rotating group during the second measurement Phase shift value; for Perform on the same line respectively Second phase shift measurement to obtain the phase shift matrix The corresponding expression is as follows: in, Grouped matrix The The first step The phase shift value of the second measurement, Dot product, .

5. The calibration method for a two-stage grouped asynchronous rotating electric vector radar array antenna according to claim 4, characterized in that, The far-field power of the antenna array under test is measured and a measurement power matrix is ​​formed. ,by The The received power measurements of each row are used to construct a column vector. The coefficient matrix is ​​constructed based on the discrete Fourier transform matrix. Establish a system of linear equations Solving for the unknown matrix yields the solution. The expression is: in, It is a column vector Each item in the middle; express The The amplitude of the combined field of the channel undergoing phase shifting. express The The phase of the combined field of the channel undergoing phase shifting. express The The amplitude of the combined field of all channels with fixed phases. express The The phase of the combined field of all channels with fixed phases.

6. The calibration method for a two-stage grouped asynchronous rotating electric vector radar array antenna according to claim 5, characterized in that, Phase difference calculation between channels: by solving the unknown matrix Substitute into the following formula to calculate 。 7. The calibration method for a two-stage grouped asynchronous rotating electric vector radar array antenna according to claim 6, characterized in that, Calculation of amplitude for each channel: The ambiguity coefficient is calculated as follows: in, Take any value in [1, M] that is not equal to integers, It can take any value in [1, M] that is not equal to Integers; the amplitude values ​​of each combined field are: 。 8. The calibration method for a two-stage grouped asynchronous rotating electric vector radar array antenna according to claim 7, characterized in that, The solution is to obtain the normalized amplitude and phase of each combined field; 。 9. The calibration method for a two-stage grouped asynchronous rotating electric vector radar array antenna according to claim 8, characterized in that, The specific process of amplitude and phase compensation for each channel is as follows: Solve in sequence The normalized amplitude and phase of the resultant field of the rotating element with different phase shift steps in all rows are obtained, and the results are set in a matrix. middle: in, ; The normalized electric field of each channel is calculated based on the normalized amplitude and phase of each combined field. : in, Indicates the first group after the first-level grouping The normalized electric field vectors obtained by different linear combinations of elements in each group elements in For the first The normalized electric field of each channel is obtained; from this, the normalized amplitude and normalized phase values ​​of each channel are obtained, which are used to achieve amplitude and phase compensation for each channel.

10. The calibration method for a two-stage grouped asynchronous rotating electric vector radar array antenna according to claim 9, characterized in that, The specific process of amplitude and phase compensation for each channel is as follows: Based on the normalized amplitude and normalized phase values ​​of each channel obtained by the solution, any channel is selected as a reference unit, and the amplitude ratio and phase difference between the remaining channels and the reference channel are calculated. Then, amplitude and phase compensation for non-reference channels is completed, and finally, the amplitude and phase of all channels are consistent.

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