A phase-amplitude calibration method for a millimeter wave human body security instrument

Abstract

The application discloses a kind of millimeter wave human security instrument's amplitude phase calibration method.The amplitude phase calibration method includes the following steps: obtaining metal plate calibration data, air calibration data and human body scanning data;Host computer carries out calibration calculation and imaging processing to the basic calibration data;The quality of human imaging result is judged and handled.The amplitude phase calibration method utilizes the movable characteristics of antenna array scanning, reduces the size of metal calibration plate, and realizes high amplitude phase calibration precision, good imaging effect and strong engineering practicability by adopting the technical scheme of combining metal plate calibration and air calibration.

Description

Technical Field

[0001] This invention relates to an amplitude and phase calibration method for a millimeter-wave human body security scanner, belonging to the field of security inspection technology. Background Technology

[0002] Millimeter-wave body scanners are devices that utilize the penetrating power of electromagnetic waves to conduct security checks on the human body. They are widely used in airports, customs, government departments, large conferences, and other locations requiring body security screening. In millimeter-wave body scanners, a linear array antenna typically scans the imaging scene. Focusing in the range direction is achieved by pulse compression of the echo data from the target scene, while focusing in the antenna array direction requires coherent superposition of all echo signals in that direction. However, in practical applications, amplitude and phase errors often exist in the array antenna's transmit and receive channels, leading to blurred and defocused imaging results, rendering the millimeter-wave body scanner unusable. The main causes of amplitude and phase errors include: inconsistencies in the characteristics of each antenna element in the array antenna; deviations between the positions of the antenna elements from the ideal arrangement; and differences between transmission lines. Phase errors are primarily caused by positional deviations between antenna elements and distance offsets between different paths. Furthermore, with long-term use, component deformation and aging can also cause amplitude and phase errors between channels.

[0003] To ensure image clarity, the amplitude and phase of each channel must remain consistent. Therefore, the amplitude and phase calibration system is an indispensable component for the normal operation of millimeter-wave body scanners. By accurately measuring and calibrating the amplitude and phase errors between channels, the imaging effect and accuracy of body security checks of millimeter-wave body scanners can be significantly improved.

[0004] Chinese invention patent ZL 201310716741.5 discloses a calibration method for a millimeter-wave antenna array. This method uses a calibration metal plate with an external reference to achieve coarse calibration of the antenna array's amplitude and phase. Then, it employs a wavefront reconstruction algorithm using spatial frequency interpolation to reconstruct the three-dimensional space of the calibration metal plate. Finally, it corrects the phase of the antenna array by self-focusing the three-dimensional spatial scattering intensity distribution cross-section to achieve fine phase calibration. This calibration method uses a cylindrical scanning calibration metal plate. Because the length of the metal plate is greater than the length of the antenna array, the metal calibration plate is huge and heavy, resulting in poor calibration repeatability.

[0005] Furthermore, Chinese invention patent ZL 201010608694.9 discloses a near-field real-time calibration method for a human body millimeter-wave imaging security inspection system. This calibration method uses an antenna array to measure a reference signal, an amplitude and phase consistency calibration module to calibrate amplitude and phase consistency, and a relative time delay calibration module to calibrate relative time delay, thus achieving near-field real-time calibration of the human body millimeter-wave imaging security inspection system. However, the mathematical model of this calibration method is relatively simple, highly susceptible to environmental influences, and prone to ignoring error effects, thus its accuracy needs improvement. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an amplitude and phase calibration method for a millimeter-wave human body security scanner.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for amplitude and phase calibration of a millimeter-wave human body security scanner includes the following steps:

[0009] (1) Obtain three basic calibration data; among them,

[0010] A metal calibration plate is used as a reference device, and the antenna array acquires calibration data from the metal plate through static calibration sampling. And then upload the data to the host computer;

[0011] The antenna array acquires air calibration data through dynamic calibration sampling. And then upload the data to the host computer;

[0012] The antenna array acquires human body scanning data through human body scanning sampling. And then upload the data to the host computer;

[0013] Where B, A, and D represent amplitude, θ, ω represents the phase; the subscripts i and j are the number of channels in the two-dimensional acquisition plane, respectively.

[0014] (2) The host computer performs calibration calculations and imaging processing on the basic calibration data; wherein...

[0015] The first step involves the host computer processing the air calibration data and the metal plate calibration data, through normalized calibration calculations for each channel, to obtain the first reference data.

[0016] The amplitude normalized calibration data are as follows:

[0017] Among them, B rij The amplitude value is for the reference channel;

[0018] The phase data after conjugate multiplication is as follows:

[0019] The phase-normalized calibration data are as follows:

[0020] Where, φ rij The phase value of the reference channel;

[0021] The first reference data obtained is:

[0022] The second step involves the host computer processing the human body scanning data to remove the phase influence in the air calibration data and performing conjugate multiplication of the phase data to obtain the second reference data.

[0023] The third step is that the host computer uses a three-dimensional wavenumber domain algorithm to input the first reference data and the second reference data into the imaging algorithm, and then obtains a complete SAR image after range dimension pulse compression, interpolation, and azimuth dimension pulse compression.

[0024] (3) Quality judgment and processing of human body imaging results.

[0025] Preferably, when using the metal calibration plate as a reference device for static calibration sampling, the metal calibration plate is first moved to the detection area and placed in the middle of the two antenna arrays, and the verticality and / or horizontality are adjusted and calibrated to ensure that the metal calibration plate is completely parallel to the two antenna arrays; then the two antenna arrays are moved along their respective tracks to the designated position at the bottom, so that the metal calibration plate completely covers the aperture of the two antenna arrays.

[0026] Preferably, during the static calibration sampling process, the two antenna arrays remain stationary at a designated position, and the transmission and reception of millimeter-wave signals are completed using an electrical scanning method.

[0027] Preferably, during the dynamic calibration sampling process, the two antenna arrays move in opposite directions along their respective tracks, using a combination of mechanical and electrical scanning to complete the transmission and reception of millimeter-wave signals.

[0028] Preferably, in step (3), when the quality of the human body imaging result is good, the millimeter-wave human body security inspection instrument will collect three basic calibration data in step (1) for calibration when performing the next calibration work.

[0029] Preferably, the calibration data of the metal plate is stored in the host computer;

[0030] When the millimeter-wave human body security scanner is calibrated under conditions of high traffic volume, only the air calibration data and the human body scanning data are collected in step (1);

[0031] When the host computer performs calibration calculations and imaging processing in step (2), the calibration data of the metal plate is stored data.

[0032] Preferably, in step (3), when the quality of the human body imaging results is good, the millimeter-wave human body security detector will only collect the air calibration data and the human body scanning data in step (1) when it performs the next calibration work.

[0033] When the quality of human body imaging results deteriorates, the millimeter-wave human body security inspection instrument performs calibration work. In step (1), three basic calibration data are collected for calibration, and the calibration data of the metal plate stored in the host computer is updated.

[0034] Preferably, in step (3), the host computer uses a backward projection algorithm or a distance migration algorithm to perform calibration calculations and imaging processing on the basic calibration data.

[0035] Compared with existing technologies, the amplitude and phase calibration method for millimeter-wave human body security scanners provided by this invention utilizes the movable characteristics of antenna array scanning to reduce the size of the metal calibration plate. By adopting a technical solution combining metal plate calibration and air calibration, it achieves the beneficial effects of high amplitude and phase calibration accuracy, good imaging effect, and strong engineering practicality. On the other hand, it can perform double-sided calibration simultaneously, and in applications with high traffic flow, it simplifies the calibration process, shortens calibration time, and increases speed, thereby improving calibration efficiency. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the composition structure of a millimeter-wave human body security scanner in an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram illustrating the installation positions of the antenna array, antenna track, and metal calibration plate in an embodiment of the present invention.

[0038] Figure 3 This is a schematic diagram of the structure of the metal calibration plate in an embodiment of the present invention;

[0039] Figure 4 This is a flowchart of the amplitude and phase calibration method of the millimeter-wave human body security scanner in the first embodiment of the present invention;

[0040] Figure 5 This is a flowchart of the amplitude and phase calibration method of the millimeter-wave human body security scanner in the second embodiment of the present invention;

[0041] Figure 6 This is a schematic diagram of the calibrated imaging effect in the second embodiment of the present invention; Detailed Implementation

[0042] The technical content of the present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0043] To facilitate understanding and explanation, this invention first provides a brief introduction to the millimeter-wave human body security scanner, and then details the specific technical solutions of the embodiments of this invention.

[0044] like Figure 1 As shown, the millimeter-wave human body security scanner involved in this embodiment of the invention includes a first antenna array 1 and a second antenna array 2, a first antenna track 3 and a second antenna track 4, a servo control device 5, a system control device 6 and a host computer 8, and also includes a metal calibration plate 7. Figure 1 (Not shown in the image). The installation positions of the first antenna array 1 and the second antenna array 2, the first antenna track 3 and the second antenna track 4, and the metal calibration plate 7 are as follows: Figure 2 As shown.

[0045] The first antenna array 1 and the second antenna array 2 are used for dual-sided scanning. Each antenna array consists of multiple integrated transmitting antennas and multiple receiving antennas, with the number of transmitting antennas equal to the number of receiving antennas. In this embodiment, it consists of 96 transmitting antennas and 96 receiving antennas, with a center-to-center spacing of 10mm between each antenna, and the antenna array length is approximately 1 meter. Each RF channel includes antennas, switches, transmission lines, etc.

[0046] The first antenna track 3 and the second antenna track 4 are the scanning motion tracks of the first antenna array 1 and the second antenna array 2, respectively. The length of the antenna motion track is usually 2 meters.

[0047] The servo control device 5 is used to drive and control the up-and-down movement of the antenna array on the antenna track. It includes a motion device, a mechanical positioning module, a motor, and a drive module. The motion device may employ methods including, but is not limited to, lead screws, conveyor belts, and pulleys. The mechanical positioning module is responsible for positioning the millimeter-wave transceiver antenna array units and sending drive signals to the system control device 6. Positioning methods include, but are not limited to, optical encoders, magnetic encoders, and controller encoders. The motor and drive module consists of a controller, motor, reducer, and control board.

[0048] The system control unit 6 is used to control the security inspection and calibration of the entire millimeter-wave human body scanner. It includes an instruction module, an intermediate frequency signal acquisition and preprocessing module, and a data and instruction transmission module. Upon receiving a position trigger signal, the instruction module sends an coded instruction to activate the millimeter-wave transceiver antenna array unit. The intermediate frequency signal acquisition and preprocessing module is responsible for acquiring the two IQ signals (i.e., a pair of phase-quadrature modulated signals) transmitted by the millimeter-wave transceiver antenna array unit, performing DDC (digital down-conversion) preprocessing on the received data, and transmitting the preprocessed data to the host computer 8 via gigabit Ethernet for final processing.

[0049] The host computer 8 is used to perform calibration calculations and three-dimensional imaging processing on the basic data obtained from the antenna array scanning, which can be implemented by a computer with built-in algorithm software.

[0050] The metal calibration plate 7 is used as a reference device for amplitude and phase calibration of millimeter-wave human body security scanners, such as... Figure 3 As shown, it consists of a metal plate and a movable support. The width and height of the metal plate are (W+δ) and (H+δ), respectively, where W and H are the width and height of the antenna array, and δ typically ranges from 300 to 400 mm, determined based on the antenna's radiation spread angle. In this embodiment, assuming the antenna array is 1000 mm * 200 mm, the metal plate can be 1800 mm (width).

[0051] *1000mm (height).

[0052] The above provides a brief introduction to the millimeter-wave human body security inspection device involved in the embodiments of the present invention. The following describes in detail the amplitude and phase calibration method of a millimeter-wave human body security inspection device provided by the embodiments of the present invention, focusing on the planar scanning method of antenna array.

[0053] In one embodiment of the present invention, the amplitude and phase calibration method of the millimeter-wave human body security scanner includes the following steps:

[0054] S1: Obtain basic calibration data.

[0055] The antenna array acquires metal plate calibration data b through static calibration sampling; the antenna array acquires air calibration data a through dynamic calibration sampling; the antenna array acquires human body scan data d through human body scan sampling.

[0056] S2: The host computer performs calibration calculations and imaging processing on the basic calibration data.

[0057] The host computer performs amplitude and phase calibration calculations based on the data air calibration (a), metal plate calibration data (b), and human body scan data (d), and reconstructs the human body millimeter-wave three-dimensional image to obtain the final human body imaging result.

[0058] S3: To judge and process the results of human body imaging.

[0059] The implementation steps of the above-described amplitude and phase calibration method will be described in detail below through two specific embodiments.

[0060] like Figure 4 As shown, in the first embodiment of the present invention, the amplitude and phase calibration method of the millimeter-wave human body security scanner includes the following steps:

[0061] S11: Perform static calibration sampling to obtain the metal plate calibration data of the first antenna array and the second antenna array, and upload it to the host computer.

[0062] First, the metal calibration plate is moved to the detection area and placed in the middle of the two antenna arrays. In this embodiment of the invention, the distance between the metal calibration plate and the antenna arrays on both sides is 300mm. Then, a spirit level is used to adjust the verticality of the calibration plate and / or the horizontality of the support platform by adjusting the anchor bolts on the metal calibration plate bracket, so as to ensure that the metal calibration plate is completely parallel to the two antenna arrays.

[0063] During static calibration sampling, the first and second antenna arrays, under the control of the servo control device, move along their respective antenna tracks to designated positions at the bottom, ensuring that the metal calibration plate completely covers the aperture (i.e., external dimensions) of the antenna arrays and that the projection of the antenna array edges is centered on the metal calibration plate. Upon receiving instructions from the system control device 6, millimeter-wave signal transmission is initiated, and the signal receiving channel is opened. Following a specific electronic switch switching sequence, the transmission and reception of millimeter-wave signals in the electrical scanning dimension are completed. The metal plate is scanned 500 times while the antenna arrays are stationary, thereby acquiring calibration data b1 and b2 for both sides of the metal plate. This is static calibration sampling, simulating the transmission and reception during antenna array movement.

[0064] Each antenna array consists of 96 antennas that perform 500 scans, collecting data b1 and b2, each with a count of 192*500. Each data point is in the format of... Where B represents amplitude and θ represents phase; the subscripts i and j are the number of channels in the two-dimensional acquisition plane, i = 1,...,192, j = 1,...,500.

[0065] S12: Perform dynamic calibration sampling, obtain air calibration data of the first antenna array and the second antenna array, and upload them to the host computer.

[0066] During dynamic calibration sampling, the detection area is empty. Under the control of the servo control device, the first and second antenna arrays move in opposite directions along their respective antenna tracks to scan the air background vertically. For example, the first antenna array moves from the top to the bottom of the antenna track, while the second antenna array moves from the bottom to the top of the antenna track. The travel distance of the antenna arrays is 2 meters. The dynamic calibration sampling process combines mechanical scanning and electrical scanning to obtain the raw data a1 and a2 collected under the double-sided empty background. This raw data is called air calibration data.

[0067] Within a 2-meter travel distance on the antenna array track, the antenna array performs 500 reception and transmission operations. The servo control device 5 records the movement position of the antenna array and sends pulse signals to the system control device 6 every 4mm to initiate millimeter-wave signal transmission, switch the network on / off, and acquire intermediate frequency signals. The acquired data a1 and a2 are both 192*500, and each data point is in [format missing]. Where A represents amplitude, The subscripts i and j represent the number of channels in the two-dimensional acquisition plane, i = 1, ..., 192, j = 1, ..., 500.

[0068] S13: Perform human body scanning sampling, obtain human body scanning data from the first antenna array and the second antenna array, and upload it to the host computer.

[0069] During human body scanning sampling, after the subject enters the detection area carrying the items to be inspected and stands stably, the system control device 6 sends a scan start command to the servo control device 5. The servo control device 5 drives the first antenna array and the second antenna array to move from their initial positions along their respective antenna array tracks in opposite directions. Simultaneously, the servo control device 5 sends a command to start millimeter-wave signal transmission and opens the signal receiving channel, thereby acquiring human body scan data d1 and d2 from both sides.

[0070] Within a 2-meter travel distance of the antenna array track, the antenna array performed 500 receive and transmit operations, one every 4mm. The number of data points collected, d1 and d2, were both 192*500, and each data point was in [format missing]. Where D represents amplitude and ω represents phase; the subscripts i and j are the number of channels in the two-dimensional acquisition plane, i = 1,...,192, j = 1,...,500.

[0071] The order of steps S11, S12 and S13 can be arbitrarily changed, that is, the order in which static calibration sampling, dynamic calibration sampling and human body scanning sampling are performed can be arbitrarily changed.

[0072] S14: The host computer uses algorithm software to perform amplitude and phase calibration calculations based on air calibration data a1 and a2, metal plate calibration data b1 and b2, and human body scan data d1 and d2, and realizes the reconstruction of the human body millimeter-wave three-dimensional image to obtain the final human body imaging result.

[0073] The first step is that the host computer calculates and processes the air calibration data a1 and a2, as well as the metal plate calibration data b1 and b2, to obtain the first reference data c1 and c2 after removing the background influence.

[0074] The normalized calibration data for each channel are calculated as follows:

[0075] Since the amplitude values ​​of the air calibration data are negligible, the amplitude-normalized calibration data can be expressed as:

[0076]

[0077] Among them, B rij This is the amplitude value of the reference channel.

[0078] The phase data after conjugate multiplication is Then, phase data normalization is performed using the phase of the reference channel. The phase-normalized calibration data can be expressed as:

[0079]

[0080] Where, φ rij This is the phase value of the reference channel.

[0081] After amplitude and phase normalization, the first reference data c is obtained as follows:

[0082]

[0083] The second step involves the host computer processing the air calibration data a1 and a2 and the human body scan data d1 and d2 to remove the phase influence from data a1 and a2, and then performing conjugate multiplication of the phase data to obtain the second reference data.

[0084] The third step is to use a three-dimensional wavenumber domain (WK) algorithm to reconstruct a three-dimensional millimeter-wave image of the human body.

[0085] The first reference data c1 and c2, along with the processed data d1 and d2 (i.e., the second reference data), are input into the imaging algorithm. The calibrated amplitude value is: The calibrated phase value is: Then, through range pulse compression, interpolation, and azimuth pulse compression, a complete SAR (Synthetic Aperture Radar) image is finally obtained.

[0086] The algorithm described above for reconstructing 3D millimeter-wave images of the human body can also employ other similar algorithms, such as back projection algorithms and distance migration algorithms, to obtain the final human body security inspection imaging results. Furthermore, the imaging results are then used for AI-powered intelligent image analysis to identify the types and locations of dangerous items and display or label them on the software interface.

[0087] S15: The imaging results of the human body and the inspected items are of good quality. This calibration is now complete.

[0088] Generally, millimeter-wave body scanners can obtain good, clear, and distinguishable imaging results after calibration using the above-mentioned amplitude and phase calibration methods. However, if the amplitude and phase errors between channels cannot be directly calibrated using these methods due to age or accidental damage, the equipment must be stopped, the cause of the malfunction investigated, and measures taken such as adjusting hardware component wiring and / or software parameter settings. Then, amplitude and phase calibration should be performed again following the above procedure.

[0089] In the first embodiment, each calibration of the millimeter-wave human body security scanner is performed according to the above-described process, steps S11 to S15.

[0090] In the second embodiment of the present invention, in order to ensure the normal operation of the millimeter-wave human body security scanner when there is a large flow of people, and to reduce the complexity and time required for calibration, such as... Figure 5 As shown, the following amplitude and phase calibration procedure can also be used for real-time calibration:

[0091] S21: Perform static calibration sampling to obtain the metal plate calibration data b1 and b2 of the first antenna array and the second antenna array, and upload them to the host computer for storage.

[0092] Step S21 is performed once during non-working hours or off-peak hours of the millimeter-wave body scanner, with the aim of not affecting normal security checks during working hours or when there is a large flow of people. The specific operation process of step S21 is the same as the corresponding part of the first embodiment described above.

[0093] S22: Perform dynamic calibration sampling, obtain air calibration data a1 and a2 of the first antenna array and the second antenna array, and upload them to the host computer.

[0094] S23: Perform human body scanning sampling, obtain human body scanning data d1 and d2 from the first antenna array and the second antenna array, and upload them to the host computer.

[0095] Steps S22 and S23 are performed once during the operation of the millimeter-wave body scanner when calibration is required. The air calibration and body scanning operations require relatively short time and do not significantly affect normal security checks during working hours or when there is a large flow of people. The specific operation process of each step is the same as the corresponding part of the first embodiment described above.

[0096] S24: The host computer uses algorithm software to perform amplitude and phase consistency processing based on air calibration data a1 and a2, metal plate calibration data b1 and b2, and human body scan data d1 and d2, and realizes the reconstruction of the human body millimeter wave three-dimensional image to obtain the final human body imaging result.

[0097] The specific process of the host computer processing is the same as the corresponding part of the first embodiment mentioned above. In each calibration process, before the metal plate calibration data b1 and b2 are re-scanned and updated, the metal plate calibration data stored in the host computer are used. The other processes are exactly the same, so they will not be described again here.

[0098] S25: Judge the imaging results in step S24; if the imaging results are clear and of good quality, proceed to step S26, and repeat steps S22 to S25 for the next calibration; if the imaging results are blurry and of poor quality, proceed to step S21, update the metal plate calibration data b1 and b2, upload them to the host computer for storage, and then repeat steps S22 to S25 for the calibration.

[0099] S26: This calibration is now complete.

[0100] Calibration imaging results as follows Figure 6 As shown, the left figure is a schematic diagram of good imaging quality; the right figure is a schematic diagram of deteriorated imaging quality, which requires returning to step S21 to update the metal plate calibration data and to perform recalibration.

[0101] In the two embodiments described above, the millimeter-wave body scanner is equipped with two antenna arrays for front and back dual-sided scanning. In other embodiments of the present invention, the above amplitude and phase calibration method is also applicable to the case where the millimeter-wave body scanner is equipped with a single antenna array. That is, the above amplitude and phase calibration method is used to calibrate the millimeter-wave body scanner equipped with a single antenna array. The difference is that the amount of data collected is reduced. The specific workflow of each step will not be described in detail here.

[0102] In summary, compared with existing technologies, the amplitude and phase calibration method for millimeter-wave human body security scanners provided by this invention utilizes the movable characteristics of antenna array scanning to reduce the size of the metal calibration plate. By employing a technical solution combining metal plate calibration and air calibration, it achieves the beneficial effects of high amplitude and phase calibration accuracy, good imaging effect, and strong engineering practicality. Furthermore, it allows for simultaneous double-sided calibration, simplifies the calibration process in high-traffic environments, and reduces calibration time and speed, thereby improving calibration efficiency.

[0103] It should be noted that the above two embodiments are merely examples, and the technical solutions of each embodiment can be combined, all of which are within the protection scope of this invention.

[0104] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0105] The amplitude and phase calibration method for the millimeter-wave human body security scanner provided by this invention has been described in detail above. Any obvious modifications made by those skilled in the art without departing from the essence of this invention will constitute an infringement of the patent rights of this invention and will incur corresponding legal liability.

Claims

1. A method for amplitude and phase calibration of a millimeter-wave human body security scanner, characterized in that... Includes the following steps: (1) Obtain three basic calibration data; among them, A metal calibration plate is used as a reference device, and the antenna array acquires calibration data from the metal plate through static calibration sampling. The data is then uploaded to the host computer. During static calibration sampling, the metal calibration plate is first moved to the detection area and placed in the middle of the two antenna arrays. The verticality and / or horizontality are adjusted and calibrated to ensure that the metal calibration plate is completely parallel to the two antenna arrays. Then, the two antenna arrays are moved along their respective tracks to the designated position at the bottom so that the metal calibration plate completely covers the aperture of the two antenna arrays. The antenna array acquires air calibration data through dynamic calibration sampling. And upload the data to the host computer; The antenna array acquires human body scanning data through human body scanning sampling. And upload the data to the host computer; Where B, A, and D represent amplitudes, , , Represents phase; subscripts i and j are the number of channels in the two-dimensional acquisition plane, respectively; (2) The host computer performs calibration calculations and imaging processing on the basic calibration data; wherein, The first step involves the host computer processing the air calibration data and the metal plate calibration data, through normalized calibration calculations for each channel, to obtain the first reference data. The amplitude normalized calibration data are as follows: in, The amplitude value is for the reference channel; The phase data after conjugate multiplication is as follows: The phase-normalized calibration data are as follows: in, The phase value of the reference channel; The first reference data obtained is: The second step involves the host computer processing the human body scanning data to remove the phase influence in the air calibration data and performing conjugate multiplication of the phase data to obtain the second reference data. The third step involves the host computer employing a three-dimensional wavenumber domain algorithm to input the first and second reference data into the imaging algorithm. Then, through range-dimensional pulse compression, interpolation, and azimuth-dimensional pulse compression, a complete SAR image is finally obtained.

2. The amplitude and phase calibration method for the millimeter-wave human body security scanner as described in claim 1, characterized in that: During the static calibration sampling process, the two antenna arrays remain stationary at a designated position, and the transmission and reception of millimeter-wave signals are completed using an electrical scanning method.

3. The amplitude and phase calibration method for the millimeter-wave human body security scanner as described in claim 1, characterized in that: During the dynamic calibration sampling process, the two antenna arrays move in opposite directions along their respective tracks, using a combination of mechanical and electrical scanning to complete the transmission and reception of millimeter-wave signals.

4. The amplitude and phase calibration method for the millimeter-wave human body security scanner as described in claim 1, characterized in that... The calibration data of the metal plate is stored in the host computer; When the millimeter-wave human body security scanner is calibrated under conditions of high traffic volume, only the air calibration data and the human body scanning data are collected in step (1); When the host computer performs calibration calculations and imaging processing in step (2), the calibration data of the metal plate is stored data.

5. The amplitude and phase calibration method for the millimeter-wave human body security scanner as described in claim 1, characterized in that... It also includes step (3): quality assessment and processing of human body imaging results.

6. The amplitude and phase calibration method for the millimeter-wave human body security scanner as described in claim 5, characterized in that: When the quality of the human body imaging results is good, the millimeter-wave human body security inspection instrument will collect three basic calibration data in step (1) for calibration during the next calibration.

7. The amplitude and phase calibration method for the millimeter-wave human body security scanner as described in claim 5, characterized in that: When the quality of the human body imaging results is good, the millimeter-wave human body security scanner will only collect the air calibration data and the human body scanning data in step (1) during the next calibration.

8. The amplitude and phase calibration method for the millimeter-wave human body security scanner as described in claim 5, characterized in that: When the quality of human body imaging results deteriorates, the millimeter-wave human body security inspection instrument performs calibration work. In step (1), three basic calibration data are collected for calibration, and the calibration data of the metal plate stored in the host computer is updated.

9. The amplitude and phase calibration method for the millimeter-wave human body security scanner as described in claim 5, characterized in that: The host computer uses a backward projection algorithm or a distance migration algorithm to perform calibration calculations and imaging processing on the basic calibration data.

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