A Method and System for Testing the Amplitude and Phase Characteristics of Plane Waves in the Quiet Region of a Compact Field Based on Scattering Measurement

Abstract

This invention discloses a method for testing the amplitude and phase characteristics of plane waves in a compact field quiet zone based on scattering measurements. It primarily addresses the shortcomings of existing methods, such as the difficulty in testing the amplitude and phase characteristics of plane waves in a compact field quiet zone and the challenge in eliminating environmental clutter interference. The implementation scheme is as follows: Spatial coordinate calibration of the area to be tested determines the coordinates of sampling points. A standard scatterer is placed at each point, and its single-station scattering data is measured. The standard scatterer is moved to the next sampling point, and this measurement process is repeated until scattering data from the standard scatterer at all sampling points are obtained. Environmental clutter in the data is filtered out using a range gate filter. The radiation pattern of the compact field feed antenna is measured, and a target scattering field compensation matrix is ​​constructed. This matrix is ​​used to compensate for the scattering of the filtered results. The amplitude and phase characteristics of the plane wave in the compact field quiet zone are calculated based on the compensation results, and the range of the compact field quiet zone is determined using these characteristics. This invention can achieve relatively simple measurement of the amplitude and phase characteristics of a compact field quiet zone and can be applied to the performance testing and analysis of compact field quiet zones.

Description

Technical Field

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

[0002] Compact field testing technology is a commonly used method for testing the characteristics of high-performance radar antennas and radomes, as well as measuring the RCS of radar targets. It boasts significant advantages such as a wide testing range, high accuracy, and ease of operation. Especially with the rapid development of millimeter-wave, submillimeter-wave, and even terahertz frequency bands, more and more high-frequency electrically large antennas are being used, greatly increasing far-field measurement distances. However, constructing such large microwave anechoic chambers is difficult, and outdoor testing can cause significant interference from the environment. Compact field technology, through certain technical processes, significantly reduces the testing distance, thus reducing the required testing space. Due to the convenience of compact field antenna testing methods, it does not require a large space, can be deployed in an anechoic chamber, and is less susceptible to environmental interference, resulting in increased measurement accuracy. However, the quiet zone performance of different compact field systems varies considerably, and users often find it difficult to independently test the quiet zone of a compact field system.

[0003] Patent document CN116559753A discloses an automated calibration system and method for the amplitude and phase characteristics of plane waves in a compact field quiet zone. This system, through the construction of a scanning device unit and a central control unit, controls a microwave amplitude and phase unit to measure the amplitude and phase information of different sampling points at different frequencies within the quiet zone, thereby calculating the amplitude and phase unevenness of the quiet field. However, this method requires the installation of a scanning system, making testing difficult and costly. Furthermore, the scanning frame needs to be placed within the compact field to be measured, and this large frame itself can interfere with electromagnetic waves, resulting in measurement errors that are difficult to eliminate.

[0004] Patent document CN108009355B discloses a method for analyzing the characteristic spectrum of the quiet zone in a compacted field of a spherical array in an anechoic chamber. Based on the frequency band and the size of the compacted field, it designs a feed antenna, reflector, and spherical array model. It then extracts the electric field distribution at the sampling points of the quiet zone using electromagnetic simulation software, calculates the angular spectrum distribution of the quiet zone, and analyzes the diffraction field distribution based on the angular spectrum. However, this method only relies on electromagnetic simulation software and does not consider potential problems in actual testing, making it difficult to apply to real-world testing of compacted fields. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the prior art by proposing a method and system for testing the amplitude and phase characteristics of plane waves in a compact field quiet zone based on scattering measurements, so as to reduce measurement complexity and improve the accuracy of quiet zone testing.

[0006] The technical approach to achieving the objective of this invention is as follows: by dividing the area to be tested into sampling points, the single-station scattering data of the standard scatterer at different sampling points is measured, thereby reducing the measurement complexity; by using a time-domain gate method to filter out environmental clutter and a scattering compensation matrix to compensate for the scattering data after clutter removal, the accuracy of quiet zone testing is improved.

[0007] Based on the above ideas, the implementation scheme of the present invention includes the following:

[0008] The coordinate system is used to divide the area to be tested in the compacted field and determine the spatial sampling points.

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

[0010] By filtering out clutter in the single-station scattering data using the range gate method, the time-domain data U'(q,t) of the target scattering field is obtained.

[0011] Through the radiation pattern of the compact field feed antenna and sampling point P q (x q ,y q ,z q The angle of incidence when the scattered wave from the standard scatterer at point ( ) is received by the receiving antenna Construct the target scattering field compensation matrix B(q,n);

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

[0013] Where θ is the pitch angle. Let be the azimuth angle, t be the time dimension, q = 1, 2, ..., Q, and Q be the total number of sampling points. q ,y q ,z q Let θ be the spatial coordinates of the q-th sampling point. q Let be the incident elevation angle when the scattered wave from the standard scatterer at the q-th sampling point is received by the receiving antenna. θ is the incident azimuth angle when the scattered wave from the standard scatterer at the q-th sampling point is received by the receiving antenna.

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

[0015] Firstly, this invention uses a drone or a small guide rail to fix a standard scatterer and measure the single-station scattering data of the standard scatterer. Compared with the traditional probe scanning method, the measurement device is simpler and the measurement method is simpler.

[0016] Secondly, this invention is based on scattering measurement to test the amplitude and phase characteristics of the quiet zone of a compact field. Unlike the traditional probe scanning method, which uses radiation data but is difficult to eliminate the influence of environmental clutter and measurement equipment in the microwave anechoic chamber on the measurement results, this invention can suppress clutter interference through the "distance gate" method to achieve high-precision testing of the amplitude and phase characteristics of the quiet zone of a compact field. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the implementation of the present invention;

[0018] Figure 2 This is a diagram of the compression field model used in the simulation of this invention;

[0019] Figure 3 This is a test scenario diagram for the present invention;

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

[0021] Figure 5 The feed antenna model diagram and 4GHz and 5GHz radiation patterns used in the simulation of this invention;

[0022] Figure 6 The images show the time-domain plots before and after time-domain gating in this invention, as well as the 4GHz scattering amplitude plot after filtering.

[0023] Figure 7 This is a graph showing the amplitude and phase characteristics test results of the present invention in the static region of a compressed field. Detailed Implementation

[0024] To more clearly describe the technical solution and effects of the present invention, the embodiments of the present invention will be described below with reference to the accompanying drawings, but are not limited to these embodiments.

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

[0026] Reference Figure 1 The implementation steps for 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) Setting up the simulation model

[0030] This example utilizes Altair Feko simulation software to set up a sawtooth reflector made of ideal electrical conductor. This reflector is a parabola with a focal length of 4.8m, with its vertex at (0,0,0) and focal point at (4.8,0,0). A rectangular section of 3.3m × 3.3m above the XOY plane is taken as the main body of the parabola. Triangular sawtooth edges are added to suppress edge diffraction interference. The sawtooth is 0.9m long and 0.4125m wide, and the entire reflector is 5.1m × 5.1m in size. Two corrugated horn antennas, one transmitting and one receiving, are placed at the focal point of the reflector. The phase center of the transmitting antenna is placed at the focal point, and the receiving antenna is placed below the transmitting antenna, pointing towards the center of the reflector. A metal plate of 0.3m × 0.4m in size is placed parallel above the transmitting antenna.

[0031] The antenna element is fed using a voltage source, and the frequency sweep range of the antenna element is set to 4GHz to 4.5GHz, with N=81 frequency points, i.e., a frequency interval of 6.25MHz.

[0032] 1.2) Determine spatial sampling points

[0033] The direction of electromagnetic wave propagation is defined as X, the direction perpendicular to the direction of electromagnetic wave propagation in the horizontal plane is defined as Y, and the direction perpendicular to the horizontal plane and upwards in space is defined as Z. A right-handed spatial rectangular coordinate system is established with the vertex of the parabola as the origin. The area to be measured is defined as a 4m long straight line with Z = 2.75m and X = 10m. 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 a case study in this example.

[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) Based on the frequency sweep range of 4GHz to 4.5GHz determined above, at spatial sampling point P q (x q ,y q ,z q A rectangular metal plate measuring 0.1m × 0.1m is placed at position 0.1m, with the metal plate parallel to the YOZ plane. Two metal plates are placed above the metal plate as interference sources.

[0038] 2.2) Measure the rectangular metal plate at sampling point P. q Single-station scattering amplitude A 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 For frequency measurement, 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 a distance 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] Where j represents the imaginary part sign;

[0045] 3.2) Perform an inverse Fourier transform on the frequency dimension of the complex matrix I(q,n) to obtain a one-dimensional distance profile 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 performing an inverse Fourier transform on each column of matrix I(q,n);

[0048] 3.3) Calculate the propagation path R(q) and propagation delay t of the electromagnetic wave from the feed source to the metal target based on the sampling point location of the metal plate. q :

[0049]

[0050] Where c is the speed of light, (x j ,y j ,z j (x') represents the coordinates of the focal point of the reflecting surface. q ,y' q ,z' q Let x' be the coordinates of a point on the reflecting surface. 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 filter to remove 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 scattering field compensation matrix.

[0055] While existing probe scanning methods do not rely on compensation matrices, they suffer from limitations such as high measurement difficulty and ineffective filtering of clutter interference. The method of this invention calculates the amplitude and phase characteristics of the compressed field quiet region by measuring target scattered field data. This requires constructing a compensation matrix based on the radiation pattern of the feed antenna. The construction steps include the following:

[0056] 4.1) Measure the radiation pattern of the compact field feed antenna Where θ is the pitch angle. It is the azimuth angle;

[0057] 4.2) Calculate the incident angle θ when the scattered wave from the metallic 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] Where angle(a,b,c) is the angle between the three points connected with point b as the vertex, J is the focal length of the reflecting surface, and (x' q ,y' q ,z' q Let x' be the coordinates of a point on the reflecting surface. q =x q y' q =y q ,

[0061] 4.3) Take the incident angle θ calculated in step 4.2). q and In the feed antenna pattern The reciprocal of the corresponding value Normalize this value according to the dimension of the sampling points to obtain the compensation matrix B(q,n):

[0062]

[0063] Here, normal2(K) represents the normalization of each column of matrix K, where K is any matrix.

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

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

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

[0067] Where FFT(U'(q,t),2) represents performing a Fourier transform on each column of matrix U'(q,t);

[0068] 5.2) Multiply the scattering data I'(q,n) obtained in step 5.1) with 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] Here, normal2(K) represents the normalization of each column of matrix K, where K is any matrix.

[0071] Step 6: Calculate the plane wave amplitude and phase characteristics of the quiet zone using the compensated target scattering field data, and use these amplitude and phase characteristics to determine the range of the quiet zone of the compacted field.

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

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

[0074]

[0075] Where arctan(·) represents the arctangent 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) Locating sampling point P q (x q ,y q ,z qThe region where the amplitude result A'(q,n) fluctuates less than ±0.5dB and the phase result Phi'(q,n) fluctuates less than ±10° is the quiet region of the compressed field.

[0077] Example 2: Test system for plane wave amplitude and phase characteristics in the static region of a compact field based on scattering measurement.

[0078] Reference Figure 4 This example is a compact field still zone plane wave amplitude and phase characteristic test system based on scattering measurement, which includes: compact field system module 1, scattering test module 2, time domain gate filter module 3, scattering compensation module 4, and still zone characteristic calculation module 5.

[0079] The compacted field system module 1, which consists of a reflector, a feed antenna and a baffle, is used to perform scattering tests on the scattering test module 2.

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

[0081] The time-domain gate filter 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 filtering out clutter interference 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 filter 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 when the scattered wave 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 filter module 3 with the compensation matrix transmitted by the compensation matrix calculation submodule 41, and then 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 amplitude and phase characteristics of the quiet zone of the compacted field based on the data transmitted by the scattering compensation module 4, and to determine the quiet zone range based on the data.

[0086] The effects of this invention can be further illustrated by the following simulation.

[0087] I. Simulation Experiment Conditions

[0088] This example utilizes Altair Feko simulation software to set up a sawtooth reflector made of ideal electrical conductor. This reflector is a parabola with a focal length of 4.8m, with its vertex at (0,0,0) and focal point at (4.8,0,0). A rectangular section of 3.3m × 3.3m above the XOY plane is taken as the main body of the parabola. Triangular sawtooth edges are added to suppress edge diffraction interference. The sawtooth is 0.9m long and 0.4125m wide, and the entire reflector is 5.1m × 5.1m in size. Two corrugated horn antennas, one transmitting and one receiving, are placed at the focal point of the reflector. The phase center of the transmitting antenna is placed at the focal point, and the receiving antenna is placed below the transmitting antenna, pointing towards the center of the reflector. A metal plate of 0.3m × 0.4m in size is placed parallel above the transmitting antenna.

[0089] The antenna elements are fed using a voltage source, and the frequency sweep range of the antenna element feed is set to 4GHz to 4.5GHz, with 81 frequency points, i.e., a frequency interval of 6.25MHz.

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

[0091] II. Simulation Experiment Content

[0092] Simulation Experiment 1: Under the above experimental conditions, the radiation pattern of the compact field feed antenna in this invention was measured at different frequencies. The results are as follows: Figure 5 ,in:

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

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

[0095] Figure 5 (c) shows the E-plane and H-plane radiation patterns of the feed antenna at a frequency of 4.5 GHz, derived from... Figure 5 (c) It can be seen that the antenna can achieve the maximum gain at the 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 in this invention were subjected to time-domain gating. The results are as follows: Figure 6 ,in:

[0097] Figure 6(a) is a time-domain gated filter diagram using the present invention. The solid line represents a one-dimensional range profile, the middle peak is the target, and the dashed line is the time-domain gate, which filters out interference except for the target peak.

[0098] Figure 6 (b) is a one-dimensional range image after being filtered using the range gate of the present invention;

[0099] Figure 6 (c) shows the scattering amplitude diagrams in the 4GHz frequency domain before and after range-gate filtering, derived from... Figure 6 (c) It can be seen that the dotted line is the scattering amplitude before the range gate filter, the dashed line is the scattering amplitude after the range gate filter, and the solid line is the scattering amplitude under no interference. From the comparison of the three curves, it can be seen that the scattering amplitude after filtering fits the scattering amplitude under no interference well.

[0100] Simulation Experiment 3: Under the above experimental conditions, scattering compensation was performed on the time-domain gated filter of this invention. The results are as follows: Figure 7 ,in:

[0101] Figure 7 (a) is a plane wave amplitude characteristic diagram in the quiet region of the compact field, where the solid line is the amplitude result calculated by the method proposed in this invention, and the dashed line is the ideal sampling amplitude result of the radiation field in the quiet region of the compact field.

[0102] Figure 7 (b) is a diagram of the phase characteristics of plane waves in the quiet region of the compacted field, where the solid line is the phase result calculated by the method proposed in this invention, and the dashed line is the ideal sampled phase result of the radiation field in the quiet region of the compacted field.

[0103] contrast Figure 7 (a) The results of this invention are compared with the amplitude characteristics of the ideal radiation field, and the comparison is as follows. Figure 7 (b) As can be seen from the results of the present invention and the phase characteristics of the ideal radiation field, the results calculated by the present invention have a high degree of fit with the ideal sampling results of the radiation field in the quiet zone of the compact field, and the plane wave amplitude phase characteristics test of the quiet zone of the compact field is realized.

[0104] The above descriptions are merely two specific examples of the present invention and do not constitute any limitation on the present invention. Obviously, those skilled in the art, after understanding the content and principles of the present invention, may make various modifications and changes in form and detail without departing from the principles and structure of the present invention. For example, in addition to the compressed field model diagram given in this example, other compressed field models can be used, and the gate function in the time-domain gating filter can be changed. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

[0105] It should be noted that the reference numerals in the above specification and claims are only for clearly describing the implementation of the present invention and for ease of understanding, and their order is not limited.

Claims

1. A method for testing the amplitude and phase characteristics of plane waves in a compacted field static region based on scattering measurements, characterized in that: include: The coordinate system is used to divide the area to be tested in the compacted field and determine the spatial sampling points. Measure the single-station scattering data of a standard scatterer at all spatial sampling points; By filtering out clutter in the single-station scattering data using the range gate method, the time-domain data U'(q,t) of the target scattering field is obtained. Through the radiation pattern of the compact field feed antenna and sampling point P q (x q ,y q ,z q The angle of incidence when the scattered wave from the standard scatterer at point ( ) is received by the receiving antenna Construct the target scattering field compensation matrix B(q,n); The target scattering field is compensated by the target scattering field compensation matrix B(q,n), the amplitude and phase characteristics of the plane wave in the quiet zone are calculated using the compensated target scattering field, and the range of the quiet zone of the compacted field is determined using these amplitude and phase characteristics. Where θ is the pitch angle. Let be the azimuth angle, t be the time dimension, q = 1, 2, ..., Q, and Q be the total number of sampling points. q ,y q ,z q Let θ be the spatial coordinates of the q-th sampling point. q Let be the incident elevation angle when the scattered wave from the standard scatterer at the q-th sampling point is received by the receiving antenna. θ is the incident azimuth angle when the scattered wave from the standard scatterer at the q-th sampling point is received by the receiving antenna.

2. The method according to claim 1, characterized in that, The process of dividing the compacted field test area into coordinates and determining spatial sampling points includes: The direction of electromagnetic wave propagation is defined as X-axis, the direction perpendicular to the direction of electromagnetic wave propagation in the horizontal plane is defined as Y-axis, and the direction perpendicular to the horizontal plane and upwards in space is defined as Z-axis. A right-handed spatial rectangular coordinate system is established with the vertex of the parabola as the origin. Based on the defined 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 ) represents the spatial coordinates of the q-th sampling point.

3. The method according to claim 2, characterized in that, The steps for measuring the single-station scattering data of the standard scatterer at all spatial sampling points include the following: (3a) At sampling point P q (x q ,y q ,z q Place a standard scatterer at position f, with its principal scattering structure facing the YOZ plane, and determine the measurement frequency f. n n = 1, 2, ..., N, where N is the number of frequency points; (3b) Measure the standard scatterer at sampling point P. q Location, frequency f n The single-station scattering amplitude A at that time 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 3, characterized in that, The steps for filtering clutter from monostation scattering data using the range gate method include the following: (4a) Represent the scattering amplitude and phase data in complex form I(q,n): I(q,n)=A(q,n)exp(jPhi(q,n)) Where j represents the imaginary part sign, n = 1, 2, ..., N, N is the number of frequency points, and q = 1, 2, ..., Q, Q is the total number of sampling points; (4b) Perform an inverse Fourier transform on the data in (4a) along the frequency dimension to obtain a one-dimensional distance profile 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 performing an inverse Fourier transform on each column of matrix K; (4c) Calculate the propagation path R(q) and propagation delay t of the electromagnetic wave from the feed source to the standard scatterer based on the location of the sampling point where the standard scatterer is located. q : Where c is the speed of light, (x j ,y j ,z j (x') represents the coordinates of the focal point of the reflecting surface. q ,y' q ,z' q Let x' be the coordinates of a point on the reflecting surface. q =x q , J is the focal length of the reflecting surface, (x q ,y q ,z q Let q be the spatial coordinates of the q-th sampling point; (4d) at t = t q Add a time-domain gate filter to remove 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 4, characterized in that, The radiation pattern of the compressed field feed antenna and sampling point P q (x q ,y q ,z q The angle of incidence when the scattered wave from the standard scatterer at point ( ) is received by the receiving antenna The steps to construct the target scattering field compensation matrix B(q,n) are as follows: (5a) Calculate the angle of incidence θ when the scattered wave from the standard scatterer at the sampling point is received by the receiving antenna. q and Represented as: θ q =angle((x' q 'y' q 'from' q ),(x' q ,0,J),(0,0,0)) Where angle(a,b,c) represents the angle between the three points connected by a vertex b, J is the focal length of the reflecting surface, and (x' q ,y' q ,z' q Let x' be the coordinates of a point on the reflecting surface. q =x q y' q =y q , (5b) Take the incident angle θ q and In the feed antenna pattern The reciprocal of the corresponding value Normalize this value according to the dimension of the sampling points and use it as the compensation matrix B(q,n), as follows: Where normal2(K) represents the normalization of each column of matrix K, n = 1, 2, ..., N, and N is the number of frequency points.

6. The method according to claim 5, characterized in that, The compensation of the target scattering field through the target scattering field compensation matrix includes the following: (6a) Perform a Fourier transform on the time-domain data of the target scattered field to obtain the frequency-domain data I'(q,n) of the target scattered field: I'(q,n)=FFT(U'(q,t),2) Where FFT(K,2) represents the 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, where Q is the total number of sampling points, n=1,2,…,N, where 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)) Here, normal2(K) represents the normalization of each column of matrix K.

7. The method according to claim 6, characterized in that, The calculation of the amplitude and phase characteristics of the quiet zone of the compacted field, and the determination of the range of the quiet zone of the compacted field using these amplitude and phase characteristics, includes the following: (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)| Where arctan(·) represents the arctangent function, Im(·) represents the imaginary part of the complex number, Re(·) represents the real part of the complex number, q = 1, 2, ..., Q, where Q is the total number of sampling points, and n = 1, 2, ..., N, where N is the number of frequency points; (7b) Finding sampling point P q (x q ,y q ,z q The region where the amplitude result A'(q,n) fluctuates less than ±0.5dB and the phase result Phi'(q,n) fluctuates less than ±10° is the quiet region of the compressed field.

8. A compact field still region plane wave amplitude and phase characteristic testing system based on scattering measurement, characterized in that, include: Compact field system module 1, which mainly consists of a reflector, a feed antenna and a baffle, is used to perform scattering tests on scattering test module 2; The scattering test module 2 is used to perform single-station scattering tests on the compacted field system module 1, test the scattering data of the metal plate target at different spatial sampling points, and transmit it to the time-domain gate filter module 3. The time-domain gate filter 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 filtering out clutter interference 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 filter 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 amplitude and phase characteristics of the quiet zone of the compacted field based on the data transmitted by the scattering compensation module 4, and to determine the quiet zone range based on the data. The scattering compensation module 4 includes: The compensation matrix calculation submodule 41 is used to calculate the incident angle when the scattered wave 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 filter module 3 with the compensation matrix transmitted by the compensation matrix calculation submodule 41, and then transmit the compensated data to the quiet zone characteristic calculation module 5.

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