Compact range dead zone plane wave amplitude phase characteristic test method and system based on scattering measurement

Abstract

The invention discloses a compact range quiet zone plane wave amplitude-phase characteristic test method based on scattering measurement, and mainly solves the problems that the existing compact range quiet zone plane wave amplitude-phase characteristic test is difficult and environment clutter interference is difficult to eliminate. According to the implementation scheme, space coordinate calibration is carried out on an area to be measured to determine coordinates of a sampling point, a standard scatterer is placed at the point, and single-station scattering data of the standard scatterer are measured; moving the standard scatterer to the next sampling point, and repeating the measurement process until the scattering data of the standard scatterer at all sampling points are obtained; environmental clutters in the data are obtained through range gate filtering; measuring a radiation pattern of the compact range feed source antenna, constructing a target scattered field compensation matrix, and performing scattering compensation on a filtered result through the matrix; and according to the compensation result, calculating the compact range quiet zone plane wave amplitude-phase characteristics, and determining the compact range quiet zone range by using the amplitude-phase characteristics. The compact range quiet zone amplitude-phase characteristic measurement method can simply realize compact range quiet zone amplitude-phase characteristic measurement, and can be applied to compact range quiet zone performance test and analysis.

Description

Technical Field

[0001] The present invention relates to the field of microwave technology, and in particular to a method and system for testing the amplitude and phase characteristics of plane waves in a compact quiet zone, which can be used for compact quiet zone testing and performance analysis. Background Art

[0002] Compact field test technology is a test method commonly used for high-performance radar antennas, radome characteristics testing, and radar target RCS measurement. It has significant advantages such as wide test range, high accuracy, and convenient operation. Especially with the rapid development of millimeter wave, submillimeter wave, and even terahertz frequency bands, more and more high-frequency large-size antennas are being used, and the far-field measurement distance is also greatly improved. However, such a large microwave darkroom is difficult to build, and if you choose to test outdoors, the outdoor environment will cause great interference to the test. Compact field technology is to greatly reduce the test distance after processing by certain technical methods, so as to reduce the demand for the size of the test site. Due to the convenience of the compact field antenna test method, it does not require a large site, can be deployed in a darkroom, and is not easily affected by the environment, and the measurement accuracy will also be increased. However, the quiet zone performance of different compact field systems is also quite different, and it is difficult for users to test the compact field quiet zone independently.

[0003] The patent document with publication number CN116559753A discloses a system and method for automatic calibration of the amplitude and phase characteristics of plane waves in a compact quiet zone. The system controls the microwave amplitude and phase units to measure the amplitude and phase information of different sampling points in the quiet zone at different frequencies, and calculates the amplitude and phase unevenness of the quiet zone field. However, this method requires the installation of a scanning system, which is difficult and costly to test, and the scanning frame needs to be placed within the compact test range. This larger scanning frame itself will interfere with the electromagnetic waves, causing errors in the measurement results that are difficult to eliminate.

[0004] The patent document with publication number CN108009355B discloses a method for analyzing the characteristic spectrum of the quiet zone of a spherical array in a darkroom, which designs the feed antenna, the reflector and the spherical array model according to the frequency band and the size of the compact field, extracts the electric field distribution of the quiet zone field sampling point through electromagnetic simulation software, and then calculates the angular spectrum distribution of the quiet zone field, and analyzes the diffraction field distribution according to the angular spectrum of the quiet zone field. However, this method is only simulated by electromagnetic simulation software, and does not consider the problems that may exist in actual testing, so it is difficult to apply to the actual testing of the compact field. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and to propose a method and system for testing the amplitude and phase characteristics of a plane wave in a compact quiet zone based on scattering measurement, so as to reduce the measurement complexity and improve the quiet zone test accuracy.

[0006] The technical idea for achieving the purpose of the present invention is: by dividing the sampling points in the area to be tested, measuring the single-station scattering data of the standard scatterer at different sampling points, thereby reducing the measurement complexity; filtering out the environmental clutter through the time domain gate method and compensating the scattering data after the clutter is filtered out by the scattering compensation matrix, thereby improving the quiet zone test accuracy.

[0007] According to the above ideas, the implementation scheme of the present invention includes the following:

[0008] Divide the coordinates of the area to be tested in the compact field and determine the spatial sampling points;

[0009] Measure the single-station scattering data of the standard scatterer at all spatial sampling points;

[0010] The clutter in the single-station scattering data is filtered out by the range gate method to obtain the target scattering field time domain data U'(q,t);

[0011] Antenna pattern through compact field feed and sampling point P q (x q ,y q ,z q ) when the scattered wave of the standard scatterer is received by the receiving antenna Construct the target scattered field compensation matrix B(q,n);

[0012] The target scattered field is compensated by the target scattered field compensation matrix B(q,n), and the amplitude and phase characteristics of the quiet zone plane wave are calculated using the compensated target scattered field, and the range of the compact field quiet zone is determined using the amplitude and phase characteristics;

[0013] Where θ is the pitch angle, is the azimuth, t is the time dimension, q=1,2…,Q, Q is the total number of sampling points, (x q ,y q ,z q ) is the spatial coordinate of the qth sampling point, θ q is the incident elevation angle when the scattered wave of the standard scatterer at the qth sampling point is received by the receiving antenna, is the incident azimuth angle when the scattered wave of the standard scatterer at the qth sampling point is received by the receiving antenna.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] Firstly, the present invention fixes the standard scatterer by means of a drone or a small guide rail to measure the single-station scattering data of the standard scatterer. Compared with the traditional probe scanning method, the measuring device is simpler and the measuring method is simpler.

[0016] Secondly, the present invention performs compact field quiet zone amplitude and phase characteristic test based on scattering measurement. Different from the traditional probe scanning method which utilizes radiation data and is difficult to eliminate the influence of environmental clutter and measuring equipment in the microwave darkroom on the measurement results, the present invention can suppress clutter interference through the "range gate" method to achieve high-precision test of compact field quiet zone amplitude and phase characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flow chart for realizing the present invention;

[0018] Figure 2 A diagram of a compact field model used in the simulation of the present invention;

[0019] Figure 3 It is a test scene diagram of the present invention;

[0020] Figure 4 is a system block diagram of the present invention;

[0021] Figure 5 The feed antenna model diagram and 4GHz and 5GHz directional diagrams used in the simulation of the present invention;

[0022] Figure 6 It is the time domain diagram before and after the time domain gate filtering and the 4GHz scattering amplitude diagram after filtering of the present invention;

[0023] Figure 7 This is a graph showing the test results of the amplitude-phase characteristics of the present invention in a compact field quiet zone. DETAILED DESCRIPTION

[0024] In order to more clearly describe the technical solution and effects of the present invention, an embodiment of the present invention is described below with reference to the accompanying drawings, but the present invention is not limited to this embodiment.

[0025] Example 1: A method for testing the amplitude and phase characteristics of plane waves in a compact quiet zone based on scattering measurements.

[0026] Reference Figure 1 , the implementation steps of this example are as follows:

[0027] Step 1: Build a compact field model and determine the sampling points in the area to be tested.

[0028] Reference Figure 2 , the implementation of this step is as follows:

[0029] 1.1) Set up the simulation model

[0030] This example uses Altair Feko simulation software to set up a sawtooth reflector made of an ideal conductor. The reflector is a parabola with a focal length of 4.8m. The vertex of the parabola is located at (0,0,0), and the focus is located at (4.8,0,0). A rectangular part above the XOY plane with a size of 3.3m×3.3m is intercepted as the main body of the parabola. Triangular sawtooth is set on the edge to suppress edge diffraction interference. The sawtooth is 0.9m long and 0.4125m wide. The size of the entire reflector is 5.1m×5.1m. Two corrugated horn antennas, one for transmission and one for reception, are placed at the focus of the reflector. The phase center of the transmitting antenna is placed at the focus, and the receiving antenna is placed below the transmitting antenna, with the antenna pointing to the center of the reflector. A metal plate with a size of 0.3m×0.4m is placed parallel to the transmitting antenna.

[0031] A voltage source is used to feed the antenna unit, and the sweep frequency range of the antenna unit feeding is set to 4 GHz to 4.5 GHz, and the number of frequency points is N=81, that is, the frequency interval is 6.25 MHz.

[0032] 1.2) Determine the spatial sampling points

[0033] The propagation direction of the electromagnetic wave is determined to be the X direction, the direction perpendicular to the propagation direction of the electromagnetic wave in the horizontal plane of space is the Y direction, the upward direction perpendicular to the horizontal plane in space is the Z direction, and the vertex of the parabola is used as the coordinate origin to establish a right-handed spatial rectangular coordinate system; the area to be measured is determined to be a 4m long straight line with Z=2.75m and X=10m, and the sampling points are 41 points evenly distributed from Y=-2m to Y=2m.

[0034] These sampling points can be set according to the needs of the space to be tested. This data is only an example in this instance.

[0035] Step 2: Measure the single-station scattering data of the metal plate.

[0036] Reference Figure 3 , the implementation of this step includes the following:

[0037] 2.1) According to the above determined 4 GHz to 4.5 GHz frequency sweep range, at the spatial sampling point P q (x q ,y q ,z q ) is placed at the YOZ plane, with a rectangular metal plate of 0.1m×0.1m in size. The metal plate is parallel to the YOZ plane, and two metal plates are placed above the metal plate as interference sources.

[0038] 2.2) Measure the rectangular metal plate at the sampling point P q The single-station scattering amplitude A at q,n (x q ,y q ,z q ,fn ) and phase Phi q,n (x q ,y q ,z q ,f n ), where f n is the measurement frequency, n=1,2,…,N;

[0039] 2.3) Move the rectangular metal plate to the next sampling point and repeat step 2.2) until the scattering amplitude A(q,n) and phase Phi(q,n) at all sampling points are obtained:

[0040]

[0041] Step 3: Filter out clutter using the range gate method.

[0042] 3.1) Integrate the target scattering amplitude and phase data into a complex matrix I(q,n):

[0043] I(q,n)=A(q,n)exp(jPhi(q,n))

[0044] Wherein, j represents the sign of the imaginary part;

[0045] 3.2) Perform an inverse Fourier transform on the frequency dimension of the complex matrix I(q,n) to obtain the one-dimensional distance image U(q,t):

[0046] U(q,t)=IFFT(I(q,n),2)

[0047] Where t represents the time dimension, t = (0:N-1) / Br, Br is the bandwidth, Br = f N -f1, IFFT(I(q,n),2) means to perform inverse Fourier transform on each column of the matrix I(q,n);

[0048] 3.3) Calculate the propagation distance R(q) and propagation delay t of the electromagnetic wave from the feed source to the metal target according to the sampling point position of the metal plate q :

[0049]

[0050] Where c is the speed of light, (x j ,y j ,z j ) is the focal coordinate of the reflection surface, (x' q ,y' q ,z' q ) is the coordinate of a point on the reflection surface and x' q =x q , y′ q =yq , J is the focal length of the reflecting surface;

[0051] 3.3) At t = t q Add a time domain gate to filter out clutter and obtain the filtered target scattering field time domain data U'(q,t):

[0052] U'(q,t)=U(q,t)·H(t)

[0053] Where H(t) is a rectangular window function.

[0054] Step 4: Construct the target scattered field compensation matrix.

[0055] Although the existing probe scanning method does not need to rely on the compensation matrix for compensation, it has the problems of greater measurement difficulty and inability to effectively filter out clutter interference. The method of the present invention measures the target scattering field data to calculate the amplitude and phase characteristics of the compact field quiet zone, and needs to construct a compensation matrix in combination with the directional pattern of the feed antenna for compensation. The construction steps include the following:

[0056] 4.1) Measuring the antenna pattern of the compact feeder Where θ is the pitch angle, is the azimuth;

[0057] 4.2) Calculate the incident angle θ when the scattered wave of the metal target at the sampling point is received by the receiving antenna q and

[0058] θ q =angle((x' q ,y' q ,z' q ),(x' q ,0,J),(0,0,0))

[0059]

[0060] Among them, angle(a,b,c) is the angle between the three points with point b as the vertex, J is the focal length of the reflection surface, (x' q ,y' q ,z' q ) is the coordinate of a point on the reflection surface and x' q =x q ,y' q =y q ,

[0061] 4.3) Take the incident angle θ calculated in step 4.2) q and Antenna pattern at the feed The reciprocal of the corresponding value in The value is normalized according to the sampling point dimension as the compensation matrix B(q,n):

[0062]

[0063] Among them, normal2(K) means normalizing each column of matrix K, and K is an arbitrary matrix.

[0064] Step 5: Compensate for the target scattered field.

[0065] 5.1) Perform Fourier transform on the target scattered field time domain data matrix U'(q,t) obtained in step 3.3) after filtering out clutter to obtain frequency domain data I'(q,n):

[0066] I'(q,n)=FFT(U'(q,t),2)

[0067] Among them, FFT(U'(q,t),2) means Fourier transform of each column of the matrix U'(q,t);

[0068] 5.2) Multiply the scattering data I'(q,n) obtained in step 5.1) by the compensation matrix and normalize it to obtain the compensated result IB(q,n):

[0069] IB(q,n)=normal2(I'(q,n)·B(q,n))

[0070] Among them, normal2(K) means normalizing each column of matrix K, and K is an arbitrary matrix.

[0071] Step 6: Use the compensated target scattered field data to calculate the quiet zone plane wave amplitude and phase characteristics, and use the amplitude and phase characteristics to determine the compact field quiet zone range.

[0072] 6.1) Use the compensated result IB(q,n) obtained in step 5.2) to calculate the amplitude A'(q,n) and phase Phi'(q,n):

[0073] A'(q,n)=|IB(q,n)|

[0074]

[0075] Among them, arctan(·) represents the inverse tangent function, Im(·) represents taking the imaginary part of the complex number, and Re(·) represents taking the real part of the complex number.

[0076] 6.2) Find the sampling point P q (x q ,y q ,z q) The amplitude result A'(q,n) fluctuates less than ±0.5dB, and the phase result Phi'(q,n) fluctuates less than ±10°, that is, the compact field quiet zone.

[0077] Example 2: A compact field quiet zone plane wave amplitude and phase characteristics test system based on scattering measurement.

[0078] Reference Figure 4 The present example provides a compact field quiet zone plane wave amplitude and phase characteristic test system based on scattering measurement, including: a compact field system module 1, a scattering test module 2, a time domain gate filter module 3, a scattering compensation module 4 and a quiet zone characteristic calculation module 5.

[0079] The compact range system module 1, which is composed of a reflective surface, a feed antenna and a baffle, is used to perform a scattering test on the scattering test module 2;

[0080] The scattering test module 2 is used to perform a target single-station scattering test on the compact range system module 1, test the scattering data of the metal plate target at different spatial sampling points, and transmit the scattering data to the time domain gate filter module 3;

[0081] The time domain gate filtering module 3 is used to perform time domain gate filtering on the data output by the scattering test module 2, and transmit the data after the clutter interference is filtered out to the scattering compensation module 4;

[0082] The scattering compensation module 4 is used to calculate the scattering compensation matrix, and use the compensation matrix to compensate the filtered scattering data transmitted by the time domain gate filtering module 3, and transmit the compensated data to the quiet zone characteristic calculation module 5; it includes a compensation matrix calculation submodule 41 and a scattering compensation submodule 42.

[0083] The compensation matrix calculation submodule 41 is used to calculate the incident angle of the scattered wave when it is received by the receiving antenna, calculate the scattering compensation matrix in combination with the feed antenna pattern, and transmit the compensation matrix to the scattering compensation submodule 42;

[0084] The scattering compensation submodule 42 is used to compensate the filtered scattering data transmitted by the time domain gate filtering module 3 using the compensation matrix transmitted by the compensation matrix calculation submodule 41 , and transmit the compensated data to the quiet zone characteristic calculation module 5 .

[0085] The quiet zone characteristic calculation module 5 is used to calculate the compact field quiet zone amplitude and phase characteristics based on the data transmitted by the scattering compensation module 4, and determine the quiet zone range according to the data.

[0086] The effect of the present invention can be further illustrated by the following simulation.

[0087] 1. Simulation Experiment Conditions

[0088] This example uses Altair Feko simulation software to set up a sawtooth reflector made of an ideal conductor. The reflector is a parabola with a focal length of 4.8m. The vertex of the parabola is located at (0,0,0), and the focus is located at (4.8,0,0). A rectangular part above the XOY plane with a size of 3.3m×3.3m is intercepted as the main body of the parabola. Triangular sawtooth is set on the edge to suppress edge diffraction interference. The sawtooth is 0.9m long and 0.4125m wide. The size of the entire reflector is 5.1m×5.1m. Two corrugated horn antennas, one for transmission and one for reception, are placed at the focus of the reflector. The phase center of the transmitting antenna is placed at the focus, and the receiving antenna is placed below the transmitting antenna, with the antenna pointing to the center of the reflector. A metal plate with a size of 0.3m×0.4m is placed parallel to the transmitting antenna.

[0089] A voltage source is used to feed the antenna unit, and the sweep frequency range of the antenna unit feeding is set to 4 GHz to 4.5 GHz, and the number of frequency points is 81, that is, the frequency interval is 6.25 MHz.

[0090] The area to be measured is determined to be a 4m long straight line with Z=2.75m and X=10m, and the sampling points are 41 points evenly distributed from Y=-2m to Y=2m.

[0091] 2. Simulation experiment content

[0092] Simulation experiment 1: Under the above experimental conditions, the down-radius pattern of the compact feed antenna of the present invention at different frequencies was measured. The results are as follows: Figure 5 ,in:

[0093] Figure 5 (a) is the feed antenna model diagram.

[0094] Figure 5 (b) is the E-plane and H-plane radiation pattern of the feed antenna at a frequency of 4 GHz. Figure 5 (b) It can be seen that the antenna can achieve maximum gain at azimuth angle Theta = 0°, with a gain of 13dB and a sidelobe level of approximately -25dB.

[0095] Figure 5 (c) is the E-plane and H-plane radiation pattern of the feed antenna at a frequency of 4.5 GHz. Figure 5 (c) It can be seen that the antenna can achieve maximum gain at azimuth angle Theta = 0°, with a gain of 14dB and a sidelobe level of approximately -30dB.

[0096] Simulation experiment 2: Under the above experimental conditions, the single-station scattering results measured by the present invention are subjected to time-domain gate filtering.

[0097] The results are as follows Figure 6 ,in:

[0098] Figure 6 (a) is a time domain gate filtering diagram of the present invention, the solid line represents the one-dimensional range image, the middle peak is the target, and the dotted line is the time domain gate, which filters out interference except the target peak;

[0099] Figure 6 (b) is a one-dimensional range image after being filtered by the range gate of the present invention;

[0100] Figure 6 (c) is the scattering amplitude diagram in the 4 GHz frequency domain before and after range gate filtering. Figure 6 (c) It can be seen that the dotted line is the scattering amplitude before the range gate filtering, the dashed line is the scattering amplitude after the range gate filtering, and the solid line is the scattering amplitude without interference. From the comparison of the three curves, it can be seen that the scattering amplitude after filtering is well matched with the scattering amplitude without interference;

[0101] Simulation experiment 3: Under the above experimental conditions, the present invention is subjected to scattering compensation after time domain gate filtering. The results are as follows Figure 7 ,in:

[0102] Figure 7 (a) is a plane wave amplitude characteristic diagram in a compact field quiet zone, wherein the solid line is the amplitude result calculated by the method proposed in the present invention, and the dotted line is the ideal sampling amplitude result of the radiation field in the compact field quiet zone;

[0103] Figure 7 (b) is a diagram showing the phase characteristics of a plane wave in a compact quiet zone, wherein the solid line is the phase result calculated by the method proposed in the present invention, and the dotted line is the ideal sampling phase result of the radiation field in the compact quiet zone;

[0104] contrast Figure 7 (a) The results of the present invention and the ideal radiation field amplitude characteristics, and the comparison Figure 7 It can be seen from the results of the present invention and the ideal radiation field phase characteristics in (b) that the results calculated by the present invention have a high degree of fit with the ideal sampling results of the radiation field in the compact field quiet zone, thus realizing the test of the amplitude-phase characteristics of plane waves in the compact field quiet zone.

[0105] The above descriptions are only two specific examples of the present invention and do not constitute any limitation to the present invention. Obviously, after understanding the content and principle of the present invention, professionals in the field may make various modifications and changes in form and details without departing from the principle and structure of the present invention. For example, in addition to the compact field model diagram given in this example, other compact field models may be used, and the gate function during time domain gate filtering may be changed. However, these modifications and changes based on the idea of ​​the present invention are still within the scope of protection of the claims of the present invention.

[0106] It should be noted that the numbers in the above description and the claims are only for clearly describing the implementation scheme of the present invention and facilitating understanding, and the sequence of the numbers is not limited.

Claims

1. A method for testing the amplitude and phase characteristics of plane waves in a compact quiet zone based on scatterometry, characterized by: include: Divide the coordinates of the area to be tested in the compact field and determine the spatial sampling points; Measure the single-station scattering data of the standard scatterer at all spatial sampling points; The clutter in the single-station scattering data is filtered out by the range gate method to obtain the target scattering field time domain data U'(q,t); Antenna pattern through compact field feed and sampling point P q (x q ,y q ,z q ) when the scattered wave of the standard scatterer is received by the receiving antenna Construct the target scattered field compensation matrix B(q,n); The target scattered field is compensated by the target scattered field compensation matrix B(q,n), and the amplitude and phase characteristics of the quiet zone plane wave are calculated using the compensated target scattered field, and the range of the compact field quiet zone is determined using the amplitude and phase characteristics; Where θ is the pitch angle, is the azimuth, t is the time dimension, q=1,2…,Q, Q is the total number of sampling points, (x q ,y q ,z q ) is the spatial coordinate of the qth sampling point, θ q is the incident elevation angle when the scattered wave of the standard scatterer at the qth sampling point is received by the receiving antenna, is the incident azimuth angle when the scattered wave of the standard scatterer at the qth sampling point is received by the receiving antenna.

2. The method according to claim 1, characterized in that The coordinate division of the area to be measured in the compact field to determine the spatial sampling points includes: Determine the propagation direction of the electromagnetic wave as the X direction, the direction perpendicular to the propagation direction of the electromagnetic wave in the horizontal plane of space as the Y direction, the upward direction perpendicular to the horizontal plane in space as the Z direction, take the vertex of the parabola as the coordinate origin, and establish a right-handed space rectangular coordinate system; According to the divided rectangular coordinate system, the spatial sampling point is determined as P q (x q ,y q ,z q ), where q = 1, 2…, Q, Q is the total number of sampling points, (x q ,y q ,z q ) is the spatial coordinate of the qth sampling point.

3. The method according to claim 1, characterized in that The single-station scattering data of the measuring standard scatterer at all spatial sampling points is implemented by the following steps: (3a) At sampling point P q (x q ,y q ,z q ) so that its main scattering structure is facing the YOZ plane and the measurement frequency f is determined. n , n=1,2,…,N, N is the number of frequency points; (3b) Measure the standard scatterer at the sampling point P q At a frequency of f n The single-station scattering amplitude A q,n (x q ,y q ,z q ,f n ) and phase Phi q,n (x q ,y q ,z q ,f n ); (3c) Move the standard scatterer to the next sampling point and repeat step (3b) until the scattering amplitude A(q,n) and phase Phi(q,n) at all sampling points are obtained:

4. The method according to claim 1, characterized in that The steps of filtering out clutter in the single-station scattering data by the range gate method include the following: (4a) The scattered amplitude and phase data are expressed in complex form I(q,n): I(q,n)=A(q,n)exp(jPhi(q,n)) Wherein, j represents the imaginary part sign, n=1,2,…,N, N is the number of frequency points, q=1,2…,Q, Q is the total number of sampling points; (4b) Perform an inverse Fourier transform of the frequency dimension on the data in (4a) to obtain a one-dimensional distance image U(q,t): U(q,t)=IFFT(I(q,n),2) Where t represents the time dimension, t = (0:N-1) / Br, Br is the bandwidth, Br = f N -f1, IFFT(K,2) means to perform inverse Fourier transform on each column of matrix K; (4c) Calculate the propagation distance R(q) and propagation delay t of the electromagnetic wave from the feed source to the standard scatterer according to the sampling point position of the standard scatterer q : Where c is the speed of light, (x j ,y j ,z j ) is the focal coordinate of the reflection surface, (x' q ,y' q ,z' q ) is the coordinate of a point on the reflection surface and x' q =x q , y′ q =y q , J is the focal length of the reflecting surface, (x q ,y q ,z q ) is the spatial coordinate of the qth sampling point; (4d) At t = t q Add a time domain gate to filter out clutter and obtain the filtered target scattering field time domain data U'(q,t): U'(q,t)=U(q,t)·H(t q ) Where H(·) is a rectangular window function.

5. The method according to claim 1, characterized in that The antenna pattern of the compact field feed and sampling point P q (x q ,y q ,z q ) when the scattered wave of the standard scatterer is received by the receiving antenna Construct the target scattered field compensation matrix B(q,n), and its implementation steps include the following: (5a) Calculate the incident angle θ when the scattered wave of the standard scatterer at the sampling point is received by the receiving antenna q and It is expressed as: θ q =angle((x' q 'y' q 'from' q ),(x' q ,0,J),(0,0,0)) Among them, angle(a,b,c) represents the angle between the three points with point b as the vertex, J is the focal length of the reflection surface, (x' q ,y' q ,z' q ) is the coordinate of a point on the reflection surface and x' q =x q ,y' q =y q , (5b) Take the incident angle θ q and Antenna pattern at the feed The reciprocal of the corresponding value in The value is normalized according to the sampling point dimension as the compensation matrix B(q,n), which is expressed as: Among them, normal2(K) means normalizing each column of the matrix K, n=1,2,…,N, N is the number of frequency points.

6. The method according to claim 1, characterized in that The method of compensating the target scattered field by using a target scattered field compensation matrix includes the following steps: (6a) Perform Fourier transform on the time domain data of the target scattering field to obtain the frequency domain data I'(q,n) of the target scattering field: I'(q,n)=FFT(U'(q,t),2) Among them, FFT(K,2) means Fourier transform of each column of matrix K, U'(q,t) is the time domain data of the target scattering field, q=1,2…,Q, Q is the total number of sampling points, n=1,2,…,N, N is the number of frequency points, t represents the time dimension, t=(0:N-1) / Br, Br is the bandwidth, Br=f N -f1; (6b) Multiply the frequency domain data I'(q,n) by the compensation matrix and normalize it to obtain the compensated result IB(q,n): IB(q,n)=normal2(I'(q,n)·B(q,n)) Among them, normal2(K) means normalizing each column of matrix K.

7. The method according to claim 1, characterized in that The calculating of the amplitude-phase characteristics of the compact field quiet zone and determining the compact field quiet zone range by using the amplitude-phase characteristics includes the following steps: (7a) Calculate the amplitude A'(q,n) and phase Phi'(q,n) of the compensated data IB(q,n): A'(q,n)=|IB(q,n)| Wherein, arctan(·) represents the inverse tangent function, Im(·) represents the imaginary part of a complex number, Re(·) represents the real part of a complex number, q=1,2…,Q, Q is the total number of sampling points, n=1,2,…,N, N is the number of frequency points; (7b) Find the sampling point P q (x q ,y q ,z q ) The amplitude result A'(q,n) fluctuates less than ±0.5dB, and the phase result Phi'(q,n) fluctuates less than ±10 ° area, that is, the compact field quiet zone.

8. A compact field quiet zone plane wave amplitude and phase characteristics test system based on scatterometry, characterized in that: include: The compact range system module 1 is mainly composed of a reflective surface, a feed antenna and a baffle, and is used to perform a scattering test on the scattering test module 2; The scattering test module 2 is used to perform a target single-station scattering test on the compact range system module 1, test the scattering data of the metal plate target at different spatial sampling points, and transmit the scattering data to the time domain gate filter module 3; The time domain gate filtering module 3 is used to perform time domain gate filtering on the data output by the scattering test module 2, and transmit the data after the clutter interference is filtered out to the scattering compensation module 4; The scattering compensation module 4 is used to calculate the scattering compensation matrix, and use the compensation matrix to compensate the filtered scattering data transmitted by the time domain gate filtering module 3, and transmit the compensated data to the quiet zone characteristic calculation module 5; The quiet zone characteristic calculation module 5 is used to calculate the compact field quiet zone amplitude and phase characteristics based on the data transmitted by the scattering compensation module 4, and determine the quiet zone range according to the data.

9. According to claim 8, it is characterized in that: The scatter compensation module 4 comprises: The compensation matrix calculation submodule 41 is used to calculate the incident angle of the scattered wave when it is received by the receiving antenna, calculate the scattering compensation matrix in combination with the feed antenna pattern, and transmit the compensation matrix to the scattering compensation submodule 42; The scattering compensation submodule 42 is used to compensate the filtered scattering data transmitted by the time domain gate filtering module 3 with the compensation matrix transmitted by the compensation matrix calculation submodule 41 , and transmit the compensated data to the quiet zone characteristic calculation module 5 .

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