CN117518106A - External field measurement calibration error compensation system and compensation method - Google Patents
External field measurement calibration error compensation system and compensation method Download PDFInfo
- Publication number
- CN117518106A CN117518106A CN202311515353.0A CN202311515353A CN117518106A CN 117518106 A CN117518106 A CN 117518106A CN 202311515353 A CN202311515353 A CN 202311515353A CN 117518106 A CN117518106 A CN 117518106A
- Authority
- CN
- China
- Prior art keywords
- calibration
- target
- scattering
- horn antenna
- sphere
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000005259 measurement Methods 0.000 title claims abstract description 62
- 238000000034 method Methods 0.000 title claims abstract description 60
- 230000008569 process Effects 0.000 claims description 17
- 230000010287 polarization Effects 0.000 claims description 13
- 238000004088 simulation Methods 0.000 claims description 10
- 230000008878 coupling Effects 0.000 claims description 7
- 238000010168 coupling process Methods 0.000 claims description 7
- 238000005859 coupling reaction Methods 0.000 claims description 7
- 238000012937 correction Methods 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 6
- 238000012545 processing Methods 0.000 claims description 5
- 239000011358 absorbing material Substances 0.000 claims description 4
- 238000001228 spectrum Methods 0.000 claims description 4
- 238000012300 Sequence Analysis Methods 0.000 claims description 3
- 238000004364 calculation method Methods 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 3
- 230000005684 electric field Effects 0.000 claims description 3
- 238000009499 grossing Methods 0.000 claims description 3
- 230000001788 irregular Effects 0.000 claims description 3
- 230000000737 periodic effect Effects 0.000 claims description 3
- 230000009466 transformation Effects 0.000 claims description 3
- 238000003384 imaging method Methods 0.000 abstract description 3
- 238000012360 testing method Methods 0.000 description 16
- 239000002184 metal Substances 0.000 description 9
- 238000010586 diagram Methods 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 5
- 238000005314 correlation function Methods 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 238000012795 verification Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/40—Means for monitoring or calibrating
- G01S7/4004—Means for monitoring or calibrating of parts of a radar system
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/06—Systems determining position data of a target
Landscapes
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
The invention discloses an external field measurement calibration error compensation system, which comprises a vector network analyzer, wherein the output end of the vector network analyzer is connected with a microwave amplifier, a directional coupler and a transmitting horn antenna sequentially through radio frequency lines, the input end of the vector network analyzer is connected with a receiving horn antenna through radio frequency lines, the transmitting horn antenna and the receiving horn antenna are both connected with a scanning bracket, the bottom of the scanning bracket is connected with a sliding rail in a sliding way, the external field measurement calibration error compensation system also comprises a rotating control console, and the upper end of the rotating control console is opposite to the transmitting horn antenna and the receiving horn antenna; the error compensation system has simple structure and convenient operation. The invention also discloses an external field measurement calibration error compensation method, which compensates the position error of the small ball based on the vector rotation theory, compensates the error caused by spherical surface irregularity based on the estimation and compensation method of the calibration high-resolution range profile, and improves the accuracy of external field target radar scattering sectional area measurement and target one-dimensional distance imaging.
Description
Technical Field
The invention belongs to the technical field of electronic technology, and particularly relates to an external field measurement calibration error compensation system and an external field measurement calibration error compensation method.
Background
Radar cross-sectional area measurement technology is an important means for researching radar target characteristics, and according to different measurement scenes, radar cross-sectional area measurement can be divided into external field measurement and indoor measurement. Since indoor measurement has a limitation on the size of a measured target, radar cross-sectional area measurement of a large-size target is mainly performed in an external field. According to the state of the measuring radar, the measuring of the scattering sectional area of the external field radar can be divided into measuring of the scattering sectional area of the dynamic radar and measuring of the scattering sectional area of the static radar, the measuring of the scattering sectional area of the dynamic radar has higher performance requirements on the measuring radar, the frequency and polarization mode of the radar cannot be changed at any time, and the main flow mode of the measuring of the scattering sectional area of the external field radar is the measuring of the scattering sectional area of the static radar; according to different incident wave spectrums, the radar scattering sectional area measuring system can be further divided into point-frequency radar scattering sectional area measurement and broadband sweep-frequency radar scattering sectional area measurement.
For radar cross-sectional area measurement based on a vector network analyzer, its test procedure can be summarized as: the method comprises the steps of adjusting initial states of an antenna and a measuring instrument, measuring a background of a test site, measuring a calibration body, adjusting a turntable to measure a target at multiple angles, and processing measured data. The measurement errors in the measurement process mainly aim at errors brought by the calibration and calibration processes and errors in the data processing process. In the calibration process, when a metal ball is used as a calibration body, a perfect metal ball is difficult to make due to the technical problem in ball production, and the surface irregularity of the perfect metal ball can bring calibration errors; in the calibration process, if the geometric center of the calibration body on the turntable is not coincident with the rotation center of the turntable, the calibration result is not accurate enough, so that errors are caused; when one-dimensional high-resolution range profile data is processed, due to electromagnetic coupling, false peaks appear periodically in the high-resolution range profile, and the existence of the false peaks can affect the extraction of scattering centers.
Disclosure of Invention
The invention aims to provide an outfield measurement calibration error compensation system which is simple in structure and convenient to operate.
It is another object of the present invention to provide a calibration error compensation method for external field measurement, which can improve the accuracy of the measurement of scattering characteristics of an external field target.
The first technical scheme adopted by the invention is that the system for compensating the calibration error of the external field measurement comprises a vector network analyzer connected with a computer, wherein the output end of the vector network analyzer is connected with a microwave amplifier, a directional coupler and a transmitting horn antenna sequentially through a radio frequency wire, the input end of the vector network analyzer is connected with a receiving horn antenna through a radio frequency wire, the transmitting horn antenna and the receiving horn antenna are both connected with a scanning bracket, the bottom of the scanning bracket is connected with a sliding rail in a sliding way, the system further comprises a rotary control console, and the upper end of the rotary control console is opposite to the transmitting horn antenna and the receiving horn antenna.
The invention is also characterized in that:
wave absorbing material is paved around the rotary control table.
The rotary control console is connected with the rotary table control module, and the rotary table control module is connected with the vector network analyzer.
The external field measurement calibration error compensation method uses an external field measurement calibration error compensation system, and the compensation method comprises the following steps: placing the calibration ball on a rotary console, driving a transmitting horn antenna and a receiving horn antenna to acquire calibration ball point frequency echo signals and sweep frequency echo signals under different angles by a sliding scanning bracket, and calculating a one-dimensional high-resolution range profile of the calibration ball according to the calibration ball sweep frequency echo signals; obtaining calibration sphere position error compensation and irregularity error compensation according to the point frequency echo signal and the sweep frequency echo signal; placing a target to be measured in the center of a rotary console, obtaining a point frequency echo signal and a sweep frequency echo signal of the target to be measured, and calculating a one-dimensional high-resolution range profile of the target to be measured according to the sweep frequency echo signal of the target to be measured; and determining the pseudo-scattering center position of the target to be detected, and determining the radar scattering sectional area value and the one-dimensional high-resolution range profile under a specific angle by combining the position error compensation and the irregular error compensation of the target to be detected.
The external field measurement calibration error compensation method is implemented according to the following steps:
step 1, setting the sweep frequency range of a vector network analyzer to be 24-40 GHz, the number of points to be 401 points, and the polarization mode to be two modes of horizontal polarization and vertical polarization;
step 2, placing the calibration ball on a rotary console, and adjusting the polarization states of the transmitting horn antenna and the receiving horn antenna; the vector network analyzer is utilized to emit electromagnetic waves with single frequency, the sliding scanning bracket drives the emitting horn antenna and the receiving horn antenna to collect calibration ball point frequency echo signals under different angles, the calibration balls transmit and receive power loss parameters under different angles and store the power loss parameters, the vector network analyzer is utilized to emit broadband sweep pulse signals to obtain sweep echo signals of the calibration balls, and one-dimensional high-resolution range images of the calibration balls are obtained according to the sweep echo signals;
placing a target to be tested in the center of a rotary console, transmitting a point frequency continuous signal by using a vector network analyzer, controlling a scanning bracket to change the point frequency angle, acquiring the receiving and transmitting power loss parameters of the target to be tested under different angles, transmitting a broadband sweep pulse signal by using the vector network analyzer, and acquiring a one-dimensional high-resolution range profile of the target to be tested;
step 3, compensating the position error of the calibration sphere according to the point frequency echo signal of the calibration sphere, and compensating the irregularity error of the calibration sphere according to the one-dimensional high-resolution distance of the calibration sphere to obtain the radar scattering sectional area after the compensation of the calibration sphere;
step 4, determining the pseudo scattering center position of the target to be detected according to the one-dimensional high-resolution range profile of the target to be detected;
step 5, extracting a scattering center of the target to be detected through the one-dimensional high-resolution distance of the target to be detected, and removing the pseudo scattering center position of the target to be detected; and calculating radar scattering sectional areas of the target to be measured at different angles after compensation of the calibration sphere, wherein the radar scattering sectional areas are compensated by the calibration sphere, the radar scattering sectional areas are collected by the vector network analyzer, and the radar scattering sectional areas are calculated by the calibration sphere.
In the step 3, the specific process of compensating the position error of the calibration ball according to the calibration ball point frequency echo signal is as follows:
establishing a Cartesian coordinate system, taking the rotation center of a rotary control console as the origin of the two-dimensional Cartesian coordinate system, setting the position of a calibration ball as an A point, the geometric centers of a transmitting horn antenna and a receiving horn antenna as B points, aligning the geometric centers of the antenna with the rotation center of the rotary control console, setting the distance from the geometric center of the antenna to the rotation center of the rotary control console as R, setting the distance from the calibration ball to the rotation center of the rotary control console as R, and expressing the coordinates of the A point and the B point as follows:
A(rcosθ,rsinθ),B(-R,0) (1)
the distance from the point A to the point B is calculated approximatelyExpressed as:
substituting (2) into the radar range equationWherein P is t And P r Respectively representing the transmitting power and the receiving power of the antenna, wherein L represents the distance from the position of the calibration sphere to the geometric center of the antenna, G is the antenna gain, sigma represents the radar scattering cross section area of the calibration sphere, and lambda is the working wavelength, so that the method comprises the following steps of:
at the same time consider P r Relative value of
P in the formula r,max P when θ=pi r The value of P r The range of (2) is expressed as:
the distance of the calibration sphere from the center of rotation of the rotary console is denoted by |oa|:
after data smoothing, P is calculated r The initial value of (2) is expressed as:
determining the section delta theta of the initial angle according to the initial value |OA| Thereby determining an error vector, which is expressed as:
correction vector
And performing error compensation on the position vector of the calibration sphere according to the correction vector.
The specific process of the irregularity error compensation of the calibration ball according to the one-dimensional high-resolution distance pair of the calibration ball is as follows:
processing sweep frequency echo signals of a calibration ball of the vector network analyzer, and representing the total echo amplitude according to an electromagnetic scattering theory:
wherein c represents the speed of light, E m Is the back scattering intensity of the Mth scattering center, x m The coordinates of the Mth scattering center, M is the total number of scattering centers, and the coordinates are obtained through Fourier transformation:
f in 1 And f 2 Respectively representing the initial frequency and the final frequency of the sweep frequency signal, obtaining one-dimensional high-resolution range images of all angles of the calibration sphere, obtaining one-dimensional high-resolution range image of the perfect calibration sphere under the same condition by using simulation software, and subtracting the two one-dimensional high-resolution range images to obtain the one-dimensional high-resolution range image:
e rr (t,s)＝H d (t,s)-H a,s (t,s) (11)
H d (t, s) represents H (x), H of a perfect sphere obtained by simulation a,s (t, s) represents the H (x) of the calibration sphere, t is the unit index between two one-dimensional high-resolution range profile sequences, and s is the measurement angle of the calibration sphere;
using sweep frequency echo signals of the calibration balls as original data, and using e rr (t, s) defining the irregularities of the scaled sphere as:
in which A d Is H d Maximum value of (t, s), I RG,s Representing the error of the spherical surface unevenness at this point when the measured angle is s, after traversing all the raw data using the median filtering method, we get:
by means ofFor H a,s And (t, s) performing error compensation to obtain:
for a pair ofFourier transform is performed to obtain the compensation electric field of the calibration sphere:
the radar cross-sectional area after calibration sphere compensation is calculated as follows:
the specific process of the step 4 is as follows:
step 4.1, setting a peak value of a one-dimensional high-resolution range profile sequence of a target to be detected as 1, setting a non-peak value as 0, filtering out a weak peak value by setting a threshold value, eliminating the influence of noise, and marking the processed sequence as X;
step 4.2, constructing a coupling template between true and false scattering centers, and setting a template expression as
Wherein Y is (l) Is a periodic discrete series of length N,equal to the number 0 or 1, where 1 denotes the peak value, dy denotes the interval between two nearest peaks, which is an integer multiple of the distance resolution cell dimension, by varying dy, a plurality of spaced templates Y are constructed (l) Representing different pairs of scattering centers;
step 4.3, setting an optimal matching threshold, and matching according to the relation between the sequence X and the template Y, wherein the relation between X and Y is expressed as follows:
k represents the number of shifted cells in the series X, and a successful matching template is found by analyzing the degree of cross-correlation between each template and the series X, the degree of cross-correlation of the first template being calculated by the following formula:
if phi (l) If the optimal matching threshold is reached, the template matching is successful;
step 4.4, after the templates successfully matched are determined, the method is carried outSequence analysis, ->Representation template Y (l) Similarity to sequence X at k by finding the sequence with +.>The first false scattering center is determined from the k value corresponding to the first peak of the spectrum, and then the other false scattering centers are found according to the k values corresponding to the peaks.
The specific process for calculating the radar scattering sectional areas of different angles of the target to be measured after compensation in the step 5 is as follows:
according to the power loss parameters of the receiving and transmitting of the calibration sphere under different angles, the power loss parameters of the receiving and transmitting of the target to be measured under different angles and the radar scattering sectional area of the target to be measured after the compensation of the calibration sphere, the radar scattering sectional area of the target to be measured under different angles is calculated, wherein the calculation formula is as follows:
p in the formula r2 To calibrate the power loss parameters of the ball under different angles, P r1 Receiving and transmitting power loss parameters sigma of target to be measured under different angles 2 The radar cross-sectional area after the ball compensation is calibrated.
The invention has the beneficial effects that:
the system for compensating the calibration error in the external field measurement has the advantages of simple structure and convenient operation.
According to the method for compensating the calibration error of the external field measurement, the position error of the small ball is compensated based on the vector rotation theory, and through experiments, the estimated error of the maximum radar scattering cross section area is less than 10%; the error caused by spherical surface irregularity is compensated based on the estimation and compensation method of the calibration high-resolution range profile, and experimental results show that the root mean square error of the compensated metal ball measured data is reduced by 50% before being compared and compensated with the root mean square error of the theoretical data; based on the iterative physical optical theory, a coupling template between the false scattering center and the true scattering center is constructed, the position of the false scattering center is determined by using a correlation function, and the experimental result and the simulation result achieve high fitting, so that the accuracy of measuring the radar scattering cross section of the external field target and imaging the target in one-dimensional distance is improved.
Drawings
FIG. 1 is a schematic diagram of an external field measurement calibration error compensation system;
FIG. 2 is a diagram of a flat object of the external field measurement;
FIG. 3 is a schematic diagram of a vector network analyzer;
FIG. 4 is a schematic measurement of a calibration sphere;
FIG. 5 is a schematic diagram of a Cartesian coordinate system established in the plane of a calibration sphere;
FIG. 6 is a graph showing the results of the false peak matching experiment compared with the simulation results.
In the figure, a vector network analyzer 1, a microwave amplifier 3, a directional coupler 4, a transmitting horn antenna 5, a receiving horn antenna 6, a scanning bracket 7, a sliding rail 8, a rotary console 9, a wave absorbing material 10, a computer 11 and a turntable control module.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings and detailed description.
Example 1
The invention relates to an external field measurement calibration error compensation system, which is shown in figure 1, and comprises a vector network analyzer 1 connected with a computer 10, wherein the output end of the vector network analyzer 1 is connected with a microwave amplifier 2, a directional coupler 3 and a transmitting horn antenna 4 sequentially through radio frequency wires, the input end of the vector network analyzer 1 is connected with a receiving horn antenna 5 through radio frequency wires, the transmitting horn antenna 4 and the receiving horn antenna 5 are both connected with a scanning bracket 6, the bottom of the scanning bracket 6 is in sliding connection with a sliding rail 7, and the external field measurement calibration error compensation system further comprises a rotary control console 8, and the upper end of the rotary control console 8 is opposite to the transmitting horn antenna 4 and the receiving horn antenna 5.
The rotary control table 8 is connected with a rotary table control module 11, the rotary table control module 11 is connected with the vector network analyzer 1, and the rotary table control module 11 is used for controlling the rotation of the rotary control table 8.
The scanning bracket 6 moves along the sliding rail 7 at the bottom, so that the scanning angle of the transmitting horn antenna 4 is changed, the transmitting horn antenna 4 is controlled by the vector network analyzer 1 to emit microwave signals, echo signals are obtained after passing through a calibration ball or a target to be measured, and the echo signals are transmitted to the vector network analyzer 1 after being received by the receiving horn antenna 5.
The wave absorbing material 9 is paved around the rotary console 8, so that the influence of background interference on the measurement accuracy is reduced.
The invention relates to an external field measurement calibration error compensation method, which uses an external field measurement calibration error compensation system, and comprises the following steps: placing the calibration ball on a rotary console, driving a transmitting horn antenna 4 and a receiving horn antenna 5 by a sliding scanning bracket 6 to acquire calibration ball point frequency echo signals and sweep frequency echo signals under different angles, and calculating a one-dimensional high-resolution range profile of the calibration ball according to the calibration ball sweep frequency echo signals; obtaining calibration sphere position error compensation and irregularity error compensation according to the point frequency echo signal and the sweep frequency echo signal; placing a target to be measured in the center of a rotary console, obtaining a point frequency echo signal and a sweep frequency echo signal of the target to be measured, and calculating a one-dimensional high-resolution range profile of the target to be measured according to the sweep frequency echo signal of the target to be measured; and determining the pseudo-scattering center position of the target to be detected, and determining the radar scattering sectional area value and the one-dimensional high-resolution range profile under a specific angle by combining the position error compensation and the irregular error compensation of the target to be detected. The method is implemented according to the following steps:
step 1, selecting a test field, namely selecting a flat sandy ground as the test field in order to reduce the influence of background scattering on the scattering characteristics of a target, wherein no shielding objects such as soil piers, trees, buildings and the like exist in the test direction.
The schematic diagram of the outfield measurement platform is shown in fig. 2, and is composed of an outfield measurement bracket, a slide rail 7 and the like, a measurement system composed of a vector network analyzer 1, a computer and a horn antenna is placed on the measurement platform, the output end of the network analyzer is connected with a radio frequency line for a transmitting antenna after passing through a power amplifier, and the input end of the network analyzer is connected with a receiving antenna through the radio frequency line for receiving echo signals. The measuring platform drives the radio frequency system to carry out equidistant sweep frequency measurement. The vector network analyzer 1 is agilent N9951A type as shown in fig. 3.
Setting the sweep frequency range of the vector network analyzer 1 to be 24-40 GHz, the number of points to be 401 points, and the polarization mode to be two modes of horizontal polarization and vertical polarization; after the parameter setting is completed, the system is started, the background level is measured and the data is recorded.
Step 2, measuring a calibration ball: as shown in fig. 4, the calibration balls are placed on the rotary console, and the polarization states of the transmitting horn antenna 4 and the receiving horn antenna 5 are adjusted; the vector network analyzer 1 is utilized to emit electromagnetic waves with single frequency, the sliding scanning bracket 6 drives the emitting horn antenna 4 and the receiving horn antenna 5 to collect calibration ball point frequency echo signals under different angles, the calibration balls receive and transmit power loss parameters under different angles and store the parameters, the vector network analyzer 1 is utilized to emit broadband sweep pulse signals to obtain sweep echo signals of the calibration balls, and one-dimensional high-resolution range images of the calibration balls are obtained according to the sweep echo signals;
placing a target to be measured at the center of a rotary console, transmitting a point frequency continuous signal by using a vector network analyzer 1, controlling a scanning bracket 6 to change the point frequency angle, acquiring the receiving and transmitting power loss parameters of the target to be measured under different angles, transmitting a broadband sweep frequency pulse signal by using the vector network analyzer 1, and acquiring a one-dimensional high-resolution range profile of the target to be measured;
step 3, compensating the position error of the calibration sphere according to the point frequency echo signal of the calibration sphere, and compensating the irregularity error of the calibration sphere according to the one-dimensional high-resolution distance of the calibration sphere to obtain the radar scattering sectional area after the compensation of the calibration sphere;
the specific process of compensating the position error of the calibration ball according to the calibration ball point frequency echo signal is as follows:
a Cartesian coordinate system is established as shown in FIG. 5, the rotation center of the rotary console is taken as the origin of the two-dimensional Cartesian coordinate system, the point O is set, the position of the calibration ball is set as the point A, the geometric centers of the transmitting horn antenna 4 and the receiving horn antenna 5 are set as the point B, the geometric centers of the antennas are aligned with the rotation center of the rotary console, the distance from the geometric center of the antennas to the rotation center of the rotary console is set as R, the distance from the calibration ball to the rotation console center is set as R, and the coordinates of the point A and the point B are expressed as:
A(rcosθ,rsinθ),B(-R,0) (20)
the distance from the point A to the point B is calculated approximatelyExpressed as:
substituting (2) into the radar range equationWherein P is t And P r Respectively representing the transmitting power and the receiving power of the antenna, wherein L represents the distance from the position of the calibration sphere to the geometric center of the antenna, G is the antenna gain, sigma represents the radar scattering cross section area of the calibration sphere, and lambda is the working wavelength, so that the method comprises the following steps of:
at the same time consider P r Relative value of
P in the formula r,max P when θ=pi r The value of P r The range of (2) is expressed as:
the distance of the calibration sphere from the center of rotation of the rotary console is denoted by |oa|:
after data smoothing, P is calculated r The initial value of (2) is expressed as:
determining the section delta theta of the initial angle according to the initial value |OA| Thereby determining an error vector, which is expressed as:
correction vector
And performing error compensation on the position vector of the calibration sphere according to the correction vector.
The specific process of the irregularity error compensation of the calibration ball according to the one-dimensional high-resolution distance pair of the calibration ball is as follows:
the sweep echo signals of the calibration sphere of the vector network analyzer 1 are processed, and the total echo amplitude is represented according to the electromagnetic scattering theory:
wherein c represents the speed of light, E m Is the back scattering intensity of the Mth scattering center, x m The coordinates of the Mth scattering center, M is the total number of scattering centers, and the coordinates are obtained through Fourier transformation:
f in 1 And f 2 Respectively representing the initial frequency and the final frequency of the sweep frequency signal, obtaining one-dimensional high-resolution range images of all angles of the calibration sphere, obtaining one-dimensional high-resolution range image of the perfect calibration sphere under the same condition by using simulation software, and subtracting the two one-dimensional high-resolution range images to obtain the one-dimensional high-resolution range image:
e rr (t,s)＝H d (t,s)-H a,s (t,s) (30)
H d (t, s) represents H (x), H of a perfect sphere obtained by simulation a,s (t, s) represents the H (x) of the calibration sphere, t is the unit index between two one-dimensional high-resolution range profile sequences, and s is the measurement angle of the calibration sphere;
using sweep frequency echo signals of the calibration balls as original data, and using e rr (t, s) defining the irregularities of the scaled sphere as:
in which A d Is H d Maximum value of (t, s), I RG,s Representing the error of the spherical surface unevenness at this point when the measured angle is s, after traversing all the raw data using the median filtering method, we get:
by means ofFor H a,s And (t, s) performing error compensation to obtain:
for a pair ofFourier transform is performed to obtain the compensation electric field of the calibration sphere:
the radar cross-sectional area after calibration sphere compensation is calculated as follows:
step 4, determining the pseudo scattering center position of the target to be detected according to the one-dimensional high-resolution range profile of the target to be detected; the specific process is as follows:
step 4.1, setting a peak value of a one-dimensional high-resolution range profile sequence of a target to be detected as 1, setting a non-peak value as 0, filtering out a weak peak value by setting a threshold value, eliminating the influence of noise, and marking the processed sequence as X;
step 4.2, constructing a coupling template between true and false scattering centers, and setting a template expression as
Wherein Y is (l) Is a periodic discrete series of length N,equal to the number 0 or 1, where 1 denotes the peak value, dy denotes the interval between two nearest peaks, which is an integer multiple of the distance resolution cell dimension, by varying dy, a plurality of spaced templates Y are constructed (l) Representing different pairs of scattering centers;
step 4.3, setting an optimal matching threshold, and matching according to the relation between the sequence X and the template Y, wherein the relation between X and Y is expressed as follows:
k represents the number of shifted cells in the series X, and a successful matching template is found by analyzing the degree of cross-correlation between each template and the series X, the degree of cross-correlation of the first template being calculated by the following formula:
if phi (l) If the optimal matching threshold is reached, the template matching is successful;
step 4.4, after the templates successfully matched are determined, the method is carried outSequence analysis, ->Representation template Y (l) Similarity to sequence X at k by finding the sequence with +.>The first false scattering center is determined from the k value corresponding to the first peak of the spectrum, and then the other false scattering centers are found according to the k values corresponding to the peaks.
Step 5, extracting a scattering center of the target to be detected through the one-dimensional high-resolution distance of the target to be detected, and removing the pseudo scattering center position of the target to be detected; and calculating radar scattering sectional areas of the target to be measured at different angles after compensation of the calibration sphere, wherein the radar scattering sectional areas are compensated by the calibration sphere, the radar scattering sectional areas are collected by the vector network analyzer 1, and the radar scattering sectional areas are calculated by the calibration sphere.
The specific process for calculating the radar scattering sectional areas of different angles of the target to be measured after compensation is as follows:
according to the power loss parameters of the calibration sphere transmitted and received under different angles, the power loss parameters of the target to be measured transmitted and received under different angles and the radar scattering sectional area compensated by the calibration sphere collected by the vector network analyzer 1, the radar scattering sectional area of the target to be measured under different angles after compensation is calculated, and the calculation formula is as follows:
p in the formula r2 To calibrate the power loss parameters of the ball under different angles, P r1 Receiving and transmitting power loss parameters sigma of target to be measured under different angles 2 The radar cross-sectional area after the ball compensation is calibrated.
Example 2
And (3) selecting calibration balls with the radius of 15cm, respectively measuring radar scattering sectional areas of aircraft, ships and space station models, and compensating and verifying position errors and irregularity errors of the balls.
Position error and verification of spheres
Test site selection and test platform assembly, and then a vector network analyzer is used to measure background levels and record data.
Performing measurement on the calibration sphere:
the measurement schematic diagram of the calibration sphere is shown in fig. 4, and the turntable is adjusted to the initial position in combination with step 2. And the vector network analyzer collects echo data of the standard ball and stores the data in a range of 360 degrees, so that calibration is completed.
Performing target measurement and calibration ball position error compensation:
an airplane, a ship and a space station model are selected as targets, and a metal calibration sphere with the radius of 15cm is selected. Based on the method of the invention, the test frequency is determined to be 5-40 GHz. And 2, respectively carrying out radar scattering sectional area measurement on the airplane, the ship and the space station model according to the step 2, carrying out simulation by using electromagnetic simulation software, and comparing error results between simulation data and experimental data as shown in table 1.
TABLE 1
As can be seen from table 1, the maximum radar cross-sectional area estimation error of this method is less than 10%. The method remarkably improves the testing precision in radar scattering cross-sectional area measurement, and further verifies the effectiveness of the method.
Calibration sphere irregularity error compensation verification
Test site selection and test platform assembly, and then a vector network analyzer is used to measure background levels and record data.
After the test frequency range of 24-32 GHz is determined, radar scattering cross-sectional area measurement is carried out on the calibration balls of 10cm and 15cm respectively, and electromagnetic simulation software is utilized to simulate the calibration balls of 10cm and 15 cm.
According to the steps, comparing the one-dimensional high-resolution range profile value of the calibration sphere measured by the test with the theoretical one-dimensional high-resolution range profile value of the calibration sphere to obtain an error curve, and obtaining the complete irregularity of the calibration sphere and the angular distribution characteristic of the calibration sphere. According to step 3, error compensation is performed using the method of the present invention. The following table shows the comparison of the Root Mean Square Error (RMSE) of the measured data of the metal ball with and without compensation with the theoretical data, and the results are shown in table 2.
TABLE 2
According to the table 2, at 24GHz, for a calibration sphere of 10cm, the error between the measured data and the theoretical data is 4.632 dbm without error compensation, and after error compensation, the error is reduced to 2.804 dbm; for a calibration sphere of 15cm, when no error compensation exists, the error between the measured data and the theoretical data is 4.235dBsm, and after error compensation, the error is reduced to 2.054dBsm. Experimental results show that the root mean square error of the compensated metal ball measured data is reduced by 50% before compensation compared with the theoretical data, and the effectiveness of the method is verified.
Example 3
And acquiring a one-dimensional high-resolution range profile of the space station model, and removing false peaks of the acquired one-dimensional high-resolution range profile data.
Test site selection and test platform assembly, and then a vector network analyzer is used to measure background levels and record data.
Obtaining a one-dimensional range profile of a space station model:
in the embodiment, a space station metal proportion model with the length of 26cm and the spacing of the solar panels of 17.5cm is adopted, and the test frequency range is 24-40 GHz. And placing the space station model on a turntable, transmitting a broadband pulse signal by using a vector network analyzer, obtaining a radar scattering cross-sectional area time domain test value of a target under a certain specific angle, and then processing data.
False peak removal of one-dimensional high-resolution range profile data:
according to step 4, the position of the false scattering center is determined by the template matching method provided by the invention. This embodiment extracts 6 real scattering centers and 3 false scattering centers. And comparing the one-dimensional high-resolution range profile obtained by the experiment with a simulation result, wherein the obtained comparison chart is shown in fig. 6, and the experimental result shows that the one-dimensional high-resolution range profile obtained by the experiment has high fitting with the simulation result.
The invention relates to a method for compensating error of scattering cross section of an external field target radar, which compensates the position error of a small sphere based on a vector rotation theory; based on an estimation and compensation method of a calibration high-resolution range profile (one-dimensional high-resolution range profile), compensating errors caused by spherical surface irregularities; based on an iterative physical optical theory, a coupling template between a false scattering center and a true scattering center is constructed, and the position of the false scattering center is determined by using a correlation function; the accuracy of measuring the scattering characteristics of the external field target is improved; the applicability of the method of the invention was demonstrated.
Through the mode, the outfield measurement calibration error compensation system is simple in structure and convenient to operate. According to the method for compensating the calibration error of the external field measurement, the position error of the small ball is compensated based on the vector rotation theory, and through experiments, the estimated error of the maximum radar scattering cross section area is less than 10%; the error caused by spherical surface irregularity is compensated based on the estimation and compensation method of the calibration high-resolution range profile, and experimental results show that the root mean square error of the compensated metal ball measured data is reduced by 50% before being compared and compensated with the root mean square error of the theoretical data; based on the iterative physical optical theory, a coupling template between the false scattering center and the true scattering center is constructed, the position of the false scattering center is determined by using a correlation function, and the experimental result and the simulation result achieve high fitting, so that the accuracy of measuring the radar scattering cross section of the external field target and imaging the target in one-dimensional distance is improved.
Claims (9)
1. The system is characterized by comprising a vector network analyzer connected with a computer, wherein the output end of the vector network analyzer is connected with a microwave amplifier, a directional coupler and a transmitting horn antenna sequentially through radio frequency lines, the input end of the vector network analyzer is connected with a receiving horn antenna through radio frequency lines, the transmitting horn antenna and the receiving horn antenna are both connected with a scanning support, the bottom of the scanning support is in sliding connection with a sliding rail, the system further comprises a rotary control console, and the upper end of the rotary control console is opposite to the transmitting horn antenna and the receiving horn antenna.
2. The outfield measurement calibration error compensation system of claim 1, wherein said rotary console is peripherally lined with a wave absorbing material.
3. The outfield measurement calibration error compensation system of claim 1, wherein said rotary console is coupled to a turret control module, said turret control module being coupled to a vector network analyzer.
4. The external field measurement calibration error compensation method is characterized in that the external field measurement calibration error compensation system as claimed in any one of claims 1-3 is used, and the compensation method comprises the following steps: placing the calibration ball on a rotary console, driving a transmitting horn antenna and a receiving horn antenna to acquire calibration ball point frequency echo signals and sweep frequency echo signals under different angles by a sliding scanning bracket, and calculating a one-dimensional high-resolution range profile of the calibration ball according to the calibration ball sweep frequency echo signals; obtaining calibration sphere position error compensation and irregularity error compensation according to the point frequency echo signal and the sweep frequency echo signal; placing a target to be measured in the center of a rotary console, obtaining a point frequency echo signal and a sweep frequency echo signal of the target to be measured, and calculating a one-dimensional high-resolution range profile of the target to be measured according to the sweep frequency echo signal of the target to be measured; and determining the pseudo-scattering center position of the target to be detected, and determining the radar scattering sectional area value and the one-dimensional high-resolution range profile under a specific angle by combining the position error compensation and the irregular error compensation of the target to be detected.
5. The method for compensating for the scaling error of the external field measurement according to claim 4, wherein the method is implemented according to the following steps:
step 1, setting the sweep frequency range of a vector network analyzer to be 24-40 GHz, the number of points to be 401 points, and the polarization mode to be two modes of horizontal polarization and vertical polarization;
step 2, placing the calibration ball on a rotary console, and adjusting the polarization states of the transmitting horn antenna and the receiving horn antenna; the vector network analyzer is utilized to emit electromagnetic waves with single frequency, the sliding scanning bracket drives the emitting horn antenna and the receiving horn antenna to collect calibration ball point frequency echo signals under different angles, the calibration balls transmit and receive power loss parameters under different angles and store the power loss parameters, the vector network analyzer is utilized to emit broadband sweep pulse signals to obtain sweep echo signals of the calibration balls, and one-dimensional high-resolution range images of the calibration balls are obtained according to the sweep echo signals;
placing a target to be tested in the center of a rotary console, transmitting a point frequency continuous signal by using a vector network analyzer, controlling a scanning bracket to change the point frequency angle, acquiring the receiving and transmitting power loss parameters of the target to be tested under different angles, transmitting a broadband sweep pulse signal by using the vector network analyzer, and acquiring a one-dimensional high-resolution range profile of the target to be tested;
step 3, compensating the position error of the calibration sphere according to the point frequency echo signal of the calibration sphere, and compensating the irregularity error of the calibration sphere according to the one-dimensional high-resolution distance of the calibration sphere to obtain the radar scattering sectional area after the compensation of the calibration sphere;
step 4, determining the pseudo scattering center position of the target to be detected according to the one-dimensional high-resolution range profile of the target to be detected;
step 5, extracting a scattering center of the target to be detected through the one-dimensional high-resolution distance of the target to be detected, and removing the pseudo scattering center position of the target to be detected; and calculating radar scattering sectional areas of the target to be measured at different angles after compensation of the calibration sphere, wherein the radar scattering sectional areas are compensated by the calibration sphere, the radar scattering sectional areas are collected by the vector network analyzer, and the radar scattering sectional areas are calculated by the calibration sphere.
6. The method for compensating calibration errors in external field measurement according to claim 5, wherein the specific process of compensating the calibration sphere position errors according to the calibration sphere point frequency echo signal in step 3 is as follows:
establishing a Cartesian coordinate system, taking the rotation center of a rotary control console as the origin of the two-dimensional Cartesian coordinate system, setting the position of a calibration ball as an A point, the geometric centers of a transmitting horn antenna and a receiving horn antenna as B points, aligning the geometric centers of the antenna with the rotation center of the rotary control console, setting the distance from the geometric center of the antenna to the rotation center of the rotary control console as R, setting the distance from the calibration ball to the rotation center of the rotary control console as R, and expressing the coordinates of the A point and the B point as follows:
A(rcosθ,rsinθ),B(-R,0) (39)
the distance from the point A to the point B is calculated approximatelyExpressed as:
substituting (2) into the radar range equationWherein P is t And P r Respectively representing the transmitting power and the receiving power of the antenna, wherein L represents the distance from the position of the calibration sphere to the geometric center of the antenna, G is the antenna gain, sigma represents the radar scattering cross section area of the calibration sphere, and lambda is the working wavelength, so that the method comprises the following steps of:
at the same time consider P r Relative value of
P in the formula r,max P when θ=pi r Is used as a reference to the value of (a),P r the range of (2) is expressed as:
the distance of the calibration sphere from the center of rotation of the rotary console is denoted by |oa|:
after data smoothing, P is calculated r The initial value of (2) is expressed as:
determining the section delta theta of the initial angle according to the initial value |OA| Thereby determining an error vector, which is expressed as:
correction vector
And performing error compensation on the position vector of the calibration sphere according to the correction vector.
7. The method for compensating for the error of the calibration of the external field measurement according to claim 5, wherein the specific process of compensating for the error of the irregularity of the calibration sphere according to the one-dimensional high-resolution distance pair of calibration spheres is as follows:
processing sweep frequency echo signals of a calibration ball of the vector network analyzer, and representing the total echo amplitude according to an electromagnetic scattering theory:
wherein c represents the speed of light, E m Is the back scattering intensity of the Mth scattering center, x m The coordinates of the Mth scattering center, M is the total number of scattering centers, and the coordinates are obtained through Fourier transformation:
f in 1 And f 2 Respectively representing the initial frequency and the final frequency of the sweep frequency signal, obtaining one-dimensional high-resolution range images of all angles of the calibration sphere, obtaining one-dimensional high-resolution range image of the perfect calibration sphere under the same condition by using simulation software, and subtracting the two one-dimensional high-resolution range images to obtain the one-dimensional high-resolution range image:
e rr (t,s)＝H d (t,s)-H a,s (t,s) (49)
H d (t, s) represents H (x), H of a perfect sphere obtained by simulation a,s (t, s) represents the H (x) of the calibration sphere, t is the unit index between two one-dimensional high-resolution range profile sequences, and s is the measurement angle of the calibration sphere;
using sweep frequency echo signals of the calibration balls as original data, and using e rr (t, s) defining the irregularities of the scaled sphere as:
in which A d Is H d Maximum value of (t, s), I RG,s Representing the error of the spherical surface unevenness at this point when the measured angle is s, after traversing all the raw data using the median filtering method, we get:
by means ofFor H a,s And (t, s) performing error compensation to obtain:
for a pair ofFourier transform is performed to obtain the compensation electric field of the calibration sphere:
the radar cross-sectional area after calibration sphere compensation is calculated as follows:
8. the method for compensating for the calibration error of the external field measurement according to claim 5, wherein the specific process of step 4 is as follows:
step 4.1, setting a peak value of a one-dimensional high-resolution range profile sequence of a target to be detected as 1, setting a non-peak value as 0, filtering out a weak peak value by setting a threshold value, eliminating the influence of noise, and marking the processed sequence as X;
step 4.2, constructing a coupling template between true and false scattering centers, and setting a template expression as
Wherein Y is (l) Is a periodic discrete series of length N,equal to the number 0 or 1, where 1 denotes the peak value, dy denotes the interval between two nearest peaks, which is an integer multiple of the distance resolution cell dimension, by varying dy, a plurality of spaced templates Y are constructed (l) Representing different pairs of scattering centers;
step 4.3, setting an optimal matching threshold, and matching according to the relation between the sequence X and the template Y, wherein the relation between X and Y is expressed as follows:
k represents the number of shifted cells in the series X, and a successful matching template is found by analyzing the degree of cross-correlation between each template and the series X, the degree of cross-correlation of the first template being calculated by the following formula:
if phi (l) If the optimal matching threshold is reached, the template matching is successful;
step 4.4, after the templates successfully matched are determined, the method is carried outSequence analysis, ->Representation template Y (l) Similarity to sequence X at k by finding the sequence with +.>The first false scattering center is determined from the k value corresponding to the first peak of the spectrum, and then the other false scattering centers are found according to the k values corresponding to the peaks.
9. The method for compensating for calibration errors in external field measurement according to claim 5, wherein the specific process of calculating the radar cross-sectional areas of different angles of the target to be measured after compensation in step 5 is as follows:
according to the power loss parameters of the receiving and transmitting of the calibration sphere under different angles, the power loss parameters of the receiving and transmitting of the target to be measured under different angles and the radar scattering sectional area of the target to be measured after the compensation of the calibration sphere, the radar scattering sectional area of the target to be measured under different angles is calculated, wherein the calculation formula is as follows:
p in the formula r2 To calibrate the power loss parameters of the ball under different angles, P r1 Receiving and transmitting power loss parameters sigma of target to be measured under different angles 2 The radar cross-sectional area after the ball compensation is calibrated.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311515353.0A CN117518106A (en) | 2023-11-14 | 2023-11-14 | External field measurement calibration error compensation system and compensation method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311515353.0A CN117518106A (en) | 2023-11-14 | 2023-11-14 | External field measurement calibration error compensation system and compensation method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117518106A true CN117518106A (en) | 2024-02-06 |
Family
ID=89758120
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311515353.0A Pending CN117518106A (en) | 2023-11-14 | 2023-11-14 | External field measurement calibration error compensation system and compensation method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117518106A (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5140331A (en) * | 1990-11-22 | 1992-08-18 | Tzn Forschungs- Und Entwicklungszentrum Unterluss Gmbh | Radar antenna arrangement |
| CN102998665A (en) * | 2012-11-23 | 2013-03-27 | 北京航空航天大学 | Target radar cross section measuring and calibrating processing method |
| CN109239682A (en) * | 2018-03-23 | 2019-01-18 | 北京遥感设备研究所 | A kind of external calibration system and method for quantitative measurment radar system |
| CN113156388A (en) * | 2021-04-30 | 2021-07-23 | 佛山蓝谱达科技有限公司 | RCS (remote control system) measuring system and method |
| CN114325630A (en) * | 2022-01-04 | 2022-04-12 | 北京环境特性研究所 | Target scattering matrix measurement method based on antenna spatial domain polarization characteristics |
| CN115453214A (en) * | 2022-08-23 | 2022-12-09 | 西安电子科技大学 | Measuring device and measuring method for internal field active interference scattering characteristics |
-
2023
- 2023-11-14 CN CN202311515353.0A patent/CN117518106A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5140331A (en) * | 1990-11-22 | 1992-08-18 | Tzn Forschungs- Und Entwicklungszentrum Unterluss Gmbh | Radar antenna arrangement |
| CN102998665A (en) * | 2012-11-23 | 2013-03-27 | 北京航空航天大学 | Target radar cross section measuring and calibrating processing method |
| CN109239682A (en) * | 2018-03-23 | 2019-01-18 | 北京遥感设备研究所 | A kind of external calibration system and method for quantitative measurment radar system |
| CN113156388A (en) * | 2021-04-30 | 2021-07-23 | 佛山蓝谱达科技有限公司 | RCS (remote control system) measuring system and method |
| CN114325630A (en) * | 2022-01-04 | 2022-04-12 | 北京环境特性研究所 | Target scattering matrix measurement method based on antenna spatial domain polarization characteristics |
| CN115453214A (en) * | 2022-08-23 | 2022-12-09 | 西安电子科技大学 | Measuring device and measuring method for internal field active interference scattering characteristics |
Non-Patent Citations (2)
| Title |
|---|
| AO PENG: "Calibrator Irregularity Error Compensation for Radar Cross Section Measurement", IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, vol. 21, no. 6, 30 June 2022 (2022-06-30), pages 1263 - 1267, XP011909988, DOI: 10.1109/LAWP.2022.3163910 * |
| YANCHUN ZUO: "Position Error Detection and Compensation for Far-Field Radar Cross-Section Measurement", IEEE ANTENNAS AND WIRELESS PROPAGATION LETTERS, vol. 20, no. 8, 31 August 2021 (2021-08-31), pages 1518 - 1522, XP011870223, DOI: 10.1109/LAWP.2021.3089514 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108872985B (en) | Near-field circumference SAR rapid three-dimensional imaging method | |
| CN109239684B (en) | Radar target echo simulation system based on electromagnetic scattering model and simulation method thereof | |
| CN104849712B (en) | A kind of three-dimensional deformation monitoring system based on many base MIMO SAR | |
| CN109633598B (en) | Array radar target detection method based on characteristic analysis | |
| US10101489B2 (en) | System for exploring underground geophysical properties and method for analyzing underground geophysical properties using the same | |
| CN109581078B (en) | Directional diagram measuring system and method suitable for antenna in half-space environment | |
| US4996533A (en) | Single station radar ocean surface current mapper | |
| CN104730503B (en) | Determine methods and compensation method of the high resolution SAR reference target RCS on calibration influence | |
| CN108983208B (en) | Target RCS measurement method based on near-field sparse imaging extrapolation | |
| WO2018196254A1 (en) | Amplitude-phase correction method and system for microwave imaging system | |
| CN109932719A (en) | RCS high-precision measuring method based on SAR imaging | |
| CN107340434B (en) | Satellite-borne synthetic aperture radar antenna direction picture capturing method based on internal calibration data | |
| CN112986946B (en) | Method for inverting undirected sea wave spectrum by using multi-frequency high-frequency radar sea echo | |
| CN106569191A (en) | Method of acquiring target RCS by using high resolution imaging | |
| CN202735513U (en) | Holographic active microwave imaging device | |
| CN107783092A (en) | To rcs measurement system and method behind near field based on Chain relation | |
| CN113253213A (en) | Method and system for measuring ionosphere echo space distribution characteristics of high-frequency ground wave radar | |
| CN102798858B (en) | Holographic active microwave imaging method | |
| CN114415140A (en) | Target RCS (radar cross section) measuring method based on near-field plane scanning three-dimensional wave number domain imaging | |
| CN113625270B (en) | Three-dimensional imaging radar combining MIMO and ArcSAR and imaging method thereof | |
| CN108717188B (en) | Rapid wall body compensation method suitable for MIMO through-wall radar imaging | |
| CN110297237B (en) | Ground penetrating radar diffraction superposition imaging method and system considering antenna directional diagram | |
| CN110389342B (en) | Target and environment coupling analysis method based on near-field vertical SAR imaging | |
| CN107942145A (en) | A kind of angle change sphere triple antenna radiated electromagnetic field measuring system and method | |
| CN117518106A (en) | External field measurement calibration error compensation system and compensation method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |