Near-field antenna array unit amplitude and phase calibration system and method based on extrapolation

Abstract

The present invention relates to an extrapolation-based near-field antenna array unit amplitude and phase calibration system and method. A probe antenna performs calibration measurements on each array unit within the near-field range of the array antenna to be measured and the far-field range of the array unit. During the measurement process, a scanning frame is used to assist the probe antenna in scanning. A vector network analyzer is used to record the radiation signals of each array unit received by the probe antenna. The recorded complex signals are split into amplitude and phase. Based on the relative positional relationship between the array unit and the probe antenna during the measurement process, the free-space transfer function is used to compensate for the signals. The amplitude and phase signals are then fitted with a quadratic curve using the least squares method. Extrapolation is then performed, and the extrapolated curves are compared to calculate the initial excitation for each unit to complete the calibration. The present invention reduces the requirement for scanning frame size for calibration measurement, reduces the cost of radar cross-section (RCS) measurement, and improves test efficiency.

Description

Technical Field

[0001] The present invention relates to the field of microwave measurement, and in particular to a near-field antenna array unit amplitude and phase calibration system and method based on extrapolation. Background Art

[0002] Radar cross section (RCS) measurement is the most critical concept in radar stealth technology. It is a physical quantity that characterizes the intensity of the echo generated by a target when illuminated by radar waves. RCS refers to the ratio of the return scattered power per unit solid angle in the radar incident direction to the power density of the target cross section. In RCS measurement, it is theoretically required to use a uniform plane wave to illuminate the target for measurement. Currently, there are three methods to achieve plane wave conditions: the far-field method, the compact field method, and the plane wave generator (PWG). Among them, the far-field method is limited by its large test distance and poor confidentiality, while the compact field requires precise design of the aperture to reduce edge diffraction. The PWG is highly favored due to its easy beam scanning and universal applicability to various frequency bands.

[0003] The key to ensuring the quality of the plane waves generated by a PWG lies in obtaining the initial excitation for each element of the antenna array, a process known as phased array calibration. Typically, phased array calibration is performed in the far field, using a probe antenna to measure each array element directly. The probe antenna's scanning area is at least the diameter of the array antenna. In recent years, phased array calibration technology has gradually developed in the near field. Due to test distance limitations, the probe antenna's scanning area needs to be larger than the array antenna's aperture to ensure that the test signal can be interpolated when the probe antenna and array elements are directly aligned. Existing technologies often require the probe antenna's scanning area to be greater than or equal to the array antenna's aperture. However, as the size of the test target increases, the plane wave area is also required to increase, corresponding to the size of the PWG. For example, aircraft are often larger than 20 meters. For large array antennas, if the probe antenna's scanning area is equivalent to the array antenna's aperture, measurement costs will increase significantly, and test efficiency will decrease significantly.

[0004] In summary, existing technologies for near-field phased array calibration are still immature, and the contradiction between the limited scanning area of ​​the probe antenna and the large array antenna has not been fully resolved. Summary of the Invention

[0005] The technology of the present invention solves the problem: Overcoming the shortcomings of the existing technology, providing a near-field antenna array unit amplitude and phase calibration system and method based on extrapolation. The probe antenna only needs to be within the near-field range of the array antenna to be measured, and its scanning area only needs to be 0.4 to 0.6 times the aperture of the array antenna to be measured to complete the calibration, which reduces the requirement for the scanning frame size of the calibration measurement, solves the contradiction between the limited scanning area of ​​the probe antenna and the large array antenna, reduces the experimental cost for radar cross section (RCS) measurement, and improves test efficiency.

[0006] Technical solution of the present invention:

[0007] In a first aspect, the present invention provides an extrapolation-based near-field antenna array unit amplitude and phase calibration system, comprising an array antenna to be measured, a probe antenna, a scanning frame, an amplitude and phase control network, and a vector network analyzer;

[0008] The probe antenna is placed on a scanning frame within the near field range of the array antenna to be tested and the far field range of the array antenna unit to be tested; the distance between the array antenna to be tested and the scanning frame is R, which should be less than is the far-field range of the array antenna to be measured, where D is the aperture of the array antenna to be measured, and λ is the wavelength corresponding to the operating frequency of the array antenna to be measured;

[0009] The output of the amplitude and phase control network is respectively connected to each array unit of the antenna to be tested, so as to give the amplitude and phase of the excitation to each array unit; a single probe antenna is used to scan each array unit in the antenna array to be tested. When measuring a certain array unit, only the array unit is in the on state, and the other array units are in the off state, that is, the amplitude and phase control network is controlled to set a certain array unit to be tested to the on state, and the other array units are set to the off state; the scanning area of ​​the probe antenna is L, and L is in the range of 0.4D to 0.6D, that is, the scanning area of ​​the probe antenna does not need to cover the entire aperture of the array antenna to be tested during measurement; an air interface measurement method is adopted to control the probe antenna to move at a fixed interval on the scanning frame, and a vector network analyzer is used to record the test signal received by the probe antenna;

[0010] The complex signal received by the vector network analyzer is split into amplitude and phase. The amplitude and phase are compensated based on the difference between the free-space transfer function and a quadratic curve. The quadratic curve is obtained by fitting the free-space transfer function using the least squares method within the range of Ω, where Ω is the interval formed by the relative positions of the probe antenna and the array antenna elements under test. The quadratic curve is then fitted to the amplitude and phase curves using the least squares method based on the relative positions of the probe antenna and the array elements of the antenna under test. The coefficients of the fitted quadratic curve corresponding to the amplitude and phase curves of each element are obtained, and the quadratic curve is then extrapolated to the range of Ω based on the coefficients. The extrapolated amplitude and phase curves of each array element of the antenna under test are compared, and the initial excitation of each array element in the antenna under test, namely the initial amplitude and initial phase, is calculated, thereby completing the amplitude and phase calibration of the near-field antenna array elements based on extrapolation.

[0011] Furthermore, the method for compensating the amplitude and phase according to the difference between the free space transfer function and the quadratic curve is as follows:

[0012] Within the range of Ω, a quadratic curve is fitted to the free space transfer function using the least squares method, and the difference between the free space transfer function and the quadratic curve is subtracted from the measured amplitude and phase signals; the free space transfer function formula is: Where r is the distance between the probe antenna and the array antenna unit to be measured, and k is the free space wave number.

[0013] Furthermore, the least squares method is used to fit the amplitude and phase curves with a quadratic curve as follows:

[0014] The measured amplitude and phase signals are fitted using a quadratic curve. The equation of the quadratic curve can be expressed as: f(x) = ax 2 +bx+c, where x represents the relative position between the probe antenna and each unit in the array antenna to be measured; based on the measured amplitude and phase signals, the coefficients a, b, and c of the fitted quadratic curve are solved using the least squares method to establish the matrix equation: AX=B, the matrix Based on the relative position relationship, X = [abc] T is the vector of coefficients of the quadratic curve to be solved, vector B=[y1 y2 … y m ] T is the measured amplitude and phase signal, where m represents the number of times the probe antenna measures when scanning a certain array antenna unit to be measured; the vector composed of the quadratic curve coefficients is solved by the least squares method: X=(A T A) -1 A T B.

[0015] Furthermore, the fixed pitch in the fixed pitch movement is (0.5-1) times λ, and sufficient signals are measured to ensure calibration accuracy.

[0016] Furthermore, the range of Ω is 0.9 to 1.1 times

[0017] Furthermore, the method for calculating the initial excitation of each unit in the array antenna to be tested by comparing the extrapolated amplitude and phase curves of each array unit of the antenna to be tested is as follows: the amplitude and phase curves of the central unit are selected as a reference, the initial excitation amplitude of each unit is obtained by subtracting the reference amplitude curve from the amplitude quadratic curve corresponding to each unit within the scanning area and then taking the average value; the initial excitation phase of each unit is obtained by subtracting the vertex of the phase quadratic curve corresponding to each unit from the reference phase curve.

[0018] Furthermore, the amplitude and phase control network is controlled to set a certain array unit to be tested to an on state, ie, 0 dB, 0°, and the remaining array units to an off state, ie, 105 dB, 0°.

[0019] In a second aspect, the present invention provides a near-field antenna array unit amplitude and phase calibration method based on extrapolation, comprising the following steps:

[0020] (1) Place the probe antenna on the scanning frame within the near field range of the array antenna to be tested and within the far field range of the array antenna unit to be tested; the distance between the array antenna to be tested and the scanning frame is R, which should be less than is the far-field range of the array antenna to be measured, where D is the aperture of the array antenna to be measured, and λ is the wavelength corresponding to the operating frequency of the array antenna to be measured;

[0021] (2) The output of the amplitude and phase control network is connected to each array element of the antenna to be tested, which is used to provide the excitation amplitude and phase of each array element. The amplitude and phase control network is controlled by a computer to set a certain array element in the array antenna to be tested to the open state, that is, 0 dB, 0°, and the remaining array elements are set to the closed state, that is, 105 dB, 0°;

[0022] (3) Using an air interface measurement method, the probe antenna is used to measure the array elements to be measured one by one, and the probe antenna is controlled to move at a fixed interval on the scanning frame. The fixed interval is 0.5 to 1 times λ. The vector network analyzer is used to record the test signal received by the probe antenna. λ is the wavelength corresponding to the operating frequency of the array antenna to be measured; the scanning area of ​​the probe antenna is L, which is within the range of 0.4D to 0.6D. That is, the scanning area of ​​the probe antenna does not need to cover the entire aperture of the array antenna to be measured during measurement;

[0023] (4) Split the complex signal under test into amplitude and phase, and compensate the amplitude and phase according to the difference between the free space transfer function and the quadratic curve in Ω, where Ω is the interval formed by the relative positions of the probe antenna and the array antenna unit under test;

[0024] (5) According to the relative position of the probe antenna scanning area and the array antenna unit to be measured, the amplitude and phase curve of the measured signal is fitted with a quadratic curve using the least squares method; the amplitude and phase curves are extrapolated to the Ω range according to the curve equation calculated by the least squares method, and Ω is 0.9 to 1.1 times

[0025] (6) Compare the extrapolated amplitude and phase curves of each array unit of the antenna to be tested, calculate the initial excitation of each array unit in the antenna to be tested, that is, the initial amplitude and initial phase, and thus complete the amplitude and phase calibration of the near-field antenna array unit based on extrapolation.

[0026] The advantages of the present invention compared with the prior art are:

[0027] (1) The present invention reduces the requirement for the scanning frame size for calibration measurement, solves the contradiction between the limited scanning area of ​​the probe antenna and the large array antenna, reduces the experimental cost for radar cross section (RCS) measurement, and improves test efficiency.

[0028] (2) Different from the prior art, the present invention proposes a new calibration scheme under the signal model of near-field measurement, which has good robustness and strong anti-interference ability against multiple reflections and random noise in the test environment.

[0029] (3) The present invention performs calibration measurement within the near field of the array antenna to be measured, which reduces the requirement of RCS measurement on the size of the microwave darkroom and expands the application scenarios of indoor RCS measurement with confidentiality. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the extrapolation-based over-the-air near-field antenna array unit amplitude and phase calibration test system;

[0031] The meanings of the reference numerals in the figure are: 1 is a scanning frame; 2 is a probe antenna; 3 is a vector network analyzer; 4 is an array antenna to be measured; 5 is an array unit; 6 is an amplitude and phase control network; 7 is a computer; 8 is an absorbing material; 9 is a microwave darkroom;

[0032] Figure 2 Taking the Vivaldi antenna as an example, the radiation field distribution was simulated within a scanning area of ​​-1m to 1m within the near field of the array antenna under test and the far field of the array antenna unit under test. The radiation field amplitude distribution was then fitted with a quadratic curve using the least squares method. The solid line in the figure shows the simulated radiation field amplitude distribution, and the dashed line shows the fitted quadratic amplitude curve.

[0033] Figure 3 Taking the Vivaldi antenna as an example, the radiation field distribution was simulated over a scanning area of ​​-1m to 1m within the near-field and far-field ranges of the array antenna element under test. The radiation field phase distribution was then fitted with a quadratic curve using the least squares method. The solid line in the figure shows the simulated radiation field phase distribution, and the dashed line shows the fitted quadratic phase curve. DETAILED DESCRIPTION

[0034] The present invention is further described below with reference to the accompanying drawings and specific embodiments.

[0035] like Figure 1 As shown, the calibration measurement system of the present invention includes:

[0036] The entire calibration measurement process is performed in a microwave anechoic chamber 9. The chamber's surface is covered with absorbing material 8 to absorb interference signals from the environment, minimizing the impact on the calibration measurement. These signals, such as multiply reflected electromagnetic waves and ambient noise, are then absorbed. The array antenna 4 under test consists of multiple array elements 5. A computer 7 controls an amplitude and phase control network 6 to assign the amplitude and phase of excitation to each element. When the amplitude and phase control network is set to 0 dB and 0° for each element under test, the element is in the active state; when set to 105 dB and 0°, the element is in the passive state. A scanning gantry 1 is aligned with the array antenna under test, and a probe antenna 2 is placed on the gantry 1. The gantry 1 is positioned within the near-field of the array antenna 2 under test and within the far-field of the elements under test. A vector network analyzer 3 is connected to the probe antenna to record the test signal collected by the probe antenna. It is also connected to the amplitude and phase control network to generate excitation signals and transmit them to the amplitude and phase control network.

[0037] The calibration theory of the present invention is based on the following:

[0038] When the probe antenna is located in the near field of the array antenna to be measured and the array antenna unit is measured in the far field of the array unit, its signal model can be approximately represented by a linear system. The mathematical model is as follows:

[0039] s n =h n c n a n g n

[0040] Among them, s n is the signal received by the probe antenna when measuring array element n, h n represents the initial excitation of array element n, c n represents the field distribution of array element n at the probe antenna position, a n represents the free space transfer function between array element n and the probe antenna, g n Represents the field distribution of the probe antenna at array element n.

[0041] As the probe antenna scans, the above parameters will become vectors and map to the relative positions of the probe antenna and the array element to be measured. Figure 2 , Figure 3As shown, the solid line represents the simulation curve, and the dashed line is the fitted quadratic curve. The far-field pattern of the array element approximates a quadratic curve within its half-power beamwidth (HPBW). The far-field pattern of the probe antenna also approximates a quadratic curve. Usually, the probe antenna pattern is known, allowing probe compensation. The free-space transfer function can be calculated from the relative positional relationship between the probe antenna and the array element under test and compensated to a quadratic curve. When the probe antenna's scanning area is limited, the measured data is also limited. The probe antenna cannot measure directly on some array elements. Therefore, extrapolation is used to extrapolate the data when it is directly on the array element, and the initial excitation is calculated based on the extrapolated data.

[0042] The dynamic working process, i.e. the calibration method, is given below. The details are as follows:

[0043] (1) Place the probe antenna on the scanning frame within the near field range of the array antenna to be tested and the far field range of the array antenna unit to be tested; the distance between the array antenna to be tested and the scanning frame is R, which should be less than is the far-field range of the array antenna to be measured, where D is the aperture of the array antenna to be measured, and λ is the wavelength corresponding to the operating frequency of the array antenna to be measured;

[0044] (2) The outputs of the amplitude and phase control network are connected to each array element of the array antenna to be tested, so as to give each array element the amplitude and phase of the excitation. The amplitude and phase control network is controlled by a computer to set the array element to be tested to the open state, i.e., 0 dB, 0°, and the remaining elements to the closed state, i.e., 105 dB, 0°.

[0045] (3) Using an air interface measurement method, the probe antenna is used to measure the array elements to be measured one by one; the probe antenna is controlled to move at a fixed interval on the scanning frame, and the fixed interval is 0.5 to 1 times λ, and a vector network analyzer is used to record the test signal received by the probe antenna, where λ is the wavelength corresponding to the operating frequency of the array antenna to be measured; the scanning area of ​​the probe antenna is L, and L is within the range of 0.4D to 0.6D, that is, the scanning area of ​​the probe antenna does not need to cover the entire aperture of the array antenna to be measured during measurement;

[0046] (4) Split the measured complex signal into amplitude and phase, and compensate the amplitude and phase according to the difference between the free space transfer function and the quadratic curve in the range of Ω, where Ω is the interval formed by the relative position of the probe antenna and the array antenna unit to be measured; the range of Ω is 0.9 to 1.1 times The specific compensation method is: within the range of Ω, the free space transfer function is fitted with a quadratic curve using the least squares method, and the difference between the free space transfer function and the quadratic curve is subtracted from the measured amplitude and phase signals. The free space transfer function formula is: Where r is the distance between the probe antenna and the array antenna unit to be measured, and k is the free space wave number;

[0047] (5) According to the relative position of the probe antenna and the array unit of the antenna to be measured, the amplitude and phase curves are fitted with a quadratic curve using the least squares method to obtain the coefficients of the fitting quadratic curve corresponding to the amplitude and phase curve of each unit. Then, the quadratic curve is extrapolated to the range of Ω based on the coefficients; the measured amplitude and phase signals are fitted with a quadratic curve. The equation of the quadratic curve can be expressed as: f(x) = ax 2 +bx+c, where x represents the relative position between the probe antenna and each unit in the array antenna to be measured; based on the measured amplitude and phase signals, the coefficients a, b, and c of the fitted quadratic curve are solved using the least squares method to establish the matrix equation: AX=B, the matrix Based on the relative position relationship between the probe antenna and the array unit to be measured, X=[abc] T is the vector of coefficients of the quadratic curve to be solved, vector B=[y1 y2 … y m ] T is the measured amplitude and phase signal, where m represents the number of times the probe antenna measures when scanning a certain array antenna unit to be measured; the vector composed of the quadratic curve coefficients is solved by the least squares method: X=(A T A) -1 A T B. Extrapolate the amplitude and phase curves to the Ω range based on the quadratic curve equation calculated by the least squares method;

[0048] (6) Compare the extrapolated amplitude and phase curves of each array element of the antenna to be tested, and calculate the initial excitation of each element in the array antenna to be tested. The amplitude and phase curves of the central element are selected as a reference. The initial excitation amplitude of each element is the average value of the amplitude quadratic curve corresponding to each element and the reference amplitude curve within the scanning area; the initial excitation phase of each element is obtained by subtracting the vertex of the phase quadratic curve corresponding to each element from the reference phase curve. In this way, the initial amplitude and initial phase of each element are obtained, thereby completing the amplitude and phase calibration of the near-field antenna array element based on extrapolation.

Claims

1. A near-field antenna array element amplitude and phase calibration system based on extrapolation, characterized by: Including array antenna to be tested, probe antenna, scanning frame, amplitude and phase control network and vector network analyzer; The probe antenna is placed on a scanning frame within the near field range of the array antenna to be tested and the far field range of the array antenna unit to be tested; the distance between the array antenna to be tested and the scanning frame is R, which should be less than is the far-field range of the array antenna to be measured, where D is the aperture of the array antenna to be measured, and λ is the wavelength corresponding to the operating frequency of the array antenna to be measured; The output of the amplitude and phase control network is respectively connected to each array element of the antenna to be tested, so as to give the amplitude and phase of the excitation to each array element; a single probe antenna is used to scan each array element in the antenna array to be tested. When measuring a certain array element, only the array element is in the on state, and the other array elements are in the off state, that is, the amplitude and phase control network is controlled to set the array element to be tested to the on state, and the other array elements are set to the off state; the scanning area of ​​the probe antenna is L, and L is in the range of 0.4D to 0.6D, that is, the scanning area of ​​the probe antenna does not need to cover the entire aperture of the array antenna to be tested during measurement; an air interface measurement method is adopted to control the probe antenna to move at a fixed interval on the scanning frame, and a vector network analyzer is used to record the test signal received by the probe antenna; The complex signal received by the vector network analyzer is split into amplitude and phase, and the amplitude and phase are compensated based on the difference between the free-space transfer function and a quadratic curve. The quadratic curve is obtained by least squares fitting the free-space transfer function over the range of Ω, where Ω is the interval formed by the relative positions of the probe antenna and the array antenna element under test. Then, according to the relative positions of the probe antenna and the array elements of the antenna under test, the amplitude and phase curves are fitted with a quadratic curve using the least squares method to obtain the coefficients of the fitted quadratic curve corresponding to the amplitude and phase curve of each element. Then, the quadratic curve is extrapolated to the Ω range based on the coefficients. The extrapolated amplitude and phase curves of each array element of the antenna under test are compared, and the initial excitation of each array element in the antenna under test, that is, the initial amplitude and initial phase, is calculated, thereby completing the amplitude and phase calibration of the near-field antenna array element based on extrapolation.

2. The near-field antenna array unit amplitude and phase calibration system based on extrapolation according to claim 1, characterized in that: The method for compensating amplitude and phase based on the difference between the free space transfer function and the quadratic curve is as follows: Within the range of Ω, a quadratic curve is fitted to the free space transfer function using the least squares method, and the difference between the free space transfer function and the quadratic curve is subtracted from the measured amplitude and phase signals; the free space transfer function formula is: Where r is the distance between the probe antenna and the array antenna unit to be measured, and k is the free space wave number.

3. The near-field antenna array unit amplitude and phase calibration system based on extrapolation according to claim 1, characterized in that: The least squares method is used to fit the amplitude and phase curves with a quadratic curve as follows: The measured amplitude and phase signals are fitted using a quadratic curve. The equation of the quadratic curve can be expressed as: f(x) = ax 2 +bx+c, where x represents the relative position between the probe antenna and each unit in the array antenna to be measured; based on the measured amplitude and phase signals, the coefficients a, b, and c of the fitted quadratic curve are solved using the least squares method to establish the matrix equation: AX=B, the matrix Based on the relative position relationship between the probe antenna and the array unit to be measured, X=[abc] T is the vector of coefficients of the quadratic curve to be solved, vector B=[y1 y2 … y m ] T is the measured amplitude and phase signal, where m represents the number of times the probe antenna measures when scanning a certain array antenna unit to be measured; the vector composed of the quadratic curve coefficients is solved by the least squares method: X=(A T A) -1 A T B.

4. The near-field antenna array unit amplitude and phase calibration system based on extrapolation according to claim 1, characterized in that: The fixed pitch in the fixed pitch movement is (0.5-1)λ, and sufficient signals are measured to ensure calibration accuracy.

5. The near-field antenna array unit amplitude and phase calibration system based on extrapolation according to claim 1, characterized in that: The interval Ω formed by the relative positions of the probe antenna and the array antenna unit to be measured is 0.9 to 1.1 times scope.

6. The near-field antenna array unit amplitude and phase calibration system based on extrapolation according to claim 1, characterized in that: The method for calculating the initial excitation of each unit in the array antenna to be tested by comparing the extrapolated amplitude and phase curves of each array unit of the antenna to be tested is as follows: the amplitude and phase curves of the central unit are selected as a reference, the initial excitation amplitude of each unit is obtained by subtracting the reference amplitude curve from the amplitude quadratic curve corresponding to each unit within the scanning area and then taking the average value; the initial excitation phase of each unit is obtained by subtracting the vertex of the phase quadratic curve corresponding to each unit from the reference phase curve.

7. The near-field antenna array unit amplitude and phase calibration system based on extrapolation according to claim 1, characterized in that: The control amplitude and phase regulation network sets a certain array unit to be tested to an on state, that is, 0 dB, 0°, and sets the remaining array units to an off state, that is, 105 dB, 0°.

8. A near-field antenna array unit amplitude and phase calibration method based on extrapolation, characterized in that: The following steps are involved: (1) Place the probe antenna on the scanning frame within the near field range of the array antenna to be tested and within the far field range of the array antenna unit to be tested; the distance between the array antenna to be tested and the scanning frame is R, which should be less than is the far-field range of the array antenna to be measured, where D is the aperture of the array antenna to be measured, and λ is the wavelength corresponding to the operating frequency of the array antenna to be measured; (2) The output of the amplitude and phase control network is connected to each array element of the antenna to be tested, so as to assign the amplitude and phase of the excitation to each array element. The amplitude and phase control network is controlled by a computer to set a certain array element in the array antenna to be tested to the open state, i.e., 0 dB, 0°, and the remaining array elements to the closed state, i.e., 105 dB, 0°. (3) Using an air interface measurement method, the probe antenna is used to measure the array elements to be measured one by one, and the probe antenna is controlled to move at a fixed interval on the scanning frame. The fixed interval is 0.5 to 1 times λ. The vector network analyzer is used to record the test signal received by the probe antenna. λ is the wavelength corresponding to the operating frequency of the array antenna to be measured; the scanning area of ​​the probe antenna is L, which is within the range of 0.4D to 0.6D. That is, the scanning area of ​​the probe antenna does not need to cover the entire aperture of the array antenna to be measured during measurement; (4) Split the complex signal under test into amplitude and phase, and compensate the amplitude and phase according to the difference between the free space transfer function and the quadratic curve in Ω, where Ω is the interval formed by the relative positions of the probe antenna and the array antenna unit under test; (5) According to the relative position of the probe antenna scanning area and the array antenna unit to be measured, the amplitude and phase curve of the measured signal is fitted with a quadratic curve using the least squares method; the amplitude and phase curves are extrapolated to the Ω range according to the curve equation calculated by the least squares method, and Ω is 0.9 to 1.1 times (6) Compare the extrapolated amplitude and phase curves of each array unit of the antenna to be tested, calculate the initial excitation of each array unit in the antenna to be tested, that is, the initial amplitude and initial phase, and thus complete the amplitude and phase calibration of the near-field antenna array unit based on extrapolation.

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