Antenna array calibration method, antenna array calibration system, and related devices

Abstract

The application discloses an antenna array calibration method, an antenna array calibration system and related equipment. The method comprises the following steps: obtaining a to-be-analyzed calibration signal related to a plurality of target antennas in a target antenna array; and obtaining amplitude and phase calibration data of the plurality of target antennas by using phase information of the to-be-analyzed calibration signal, wherein each target antenna corresponds to one calibration antenna, and there is a preset positional relationship between the target antenna and the calibration antenna corresponding to the target antenna, that is, the amplitude and phase calibration of the target antenna can be realized by using the calibration antenna satisfying the preset positional relationship, so that the calibration of the target antenna array is simplified, and the calibration efficiency of the antenna array is improved.

Description

Technical Field

[0001] This application relates to the field of antenna technology, and in particular to an antenna array calibration method, an antenna array calibration system, and related equipment. Background Technology

[0002] When entering public transportation areas, it is necessary to inspect the items carried by pedestrians. Metal gates and metal detectors can be used to detect metal items on pedestrians, but it is difficult to identify different types of metal. Millimeter-wave security imaging systems can image pedestrians, and the images can be used to identify the types of items carried by pedestrians.

[0003] Existing image imaging systems include antenna arrays, which need to be calibrated before imaging. During the long-term research and development process, the applicant of this application found that existing calibration methods require the use of another array with known precise location information, and the location information has a significant impact on calibration. Summary of the Invention

[0004] The main technical problem addressed in this application is to provide an antenna array calibration method, antenna array structure, equipment, and medium that can simplify the antenna array calibration method and reduce the cost of antenna array calibration.

[0005] To solve the above-mentioned technical problems, one technical solution adopted in this application is: providing an antenna array calibration method, the method comprising: acquiring calibration signals to be analyzed related to multiple target antennas in a target antenna array, wherein the multiple target antennas include at least one of target transmitting antennas and target receiving antennas, each target antenna corresponds to a calibration antenna in a calibration antenna array, each target antenna and its corresponding calibration antenna have opposite transmission and reception properties and have a preset positional relationship, the calibration signals to be analyzed include amplitude and phase calibration signals transmitted between the multiple target antennas and the calibration antennas, and are received by the antenna acting as the receiving side among the multiple target antennas and the calibration antennas; and using the phase information of the calibration signals to be analyzed, acquiring amplitude and phase calibration data of the multiple target antennas.

[0006] Among them, multiple target antennas are divided into several target antenna groups, different target antenna groups correspond to different calibration antennas, and each target antenna in the same target antenna group corresponds to the same calibration antenna; and / or, the preset position relationship includes far-field position relationship and zero-degree position relationship.

[0007] The system comprises multiple target antennas divided into several target antenna groups. One target antenna within a target antenna group serves as the reference antenna for that group. Other target antennas within the target antenna group, excluding the reference antenna, are designated as other target antennas within the group. One of the reference antennas is designated as the base antenna, and the remaining reference antennas are designated as other reference antennas. The system utilizes the phase information of the calibration signal to be analyzed to obtain amplitude and phase calibration data for multiple target antennas. This includes: for each target antenna group, using the first phase difference between the target amplitude and phase calibration signals of other target antennas within the target antenna group and the reference amplitude and phase calibration signals, obtaining the intra-group calibration data of the other target antennas relative to the reference antenna. The target amplitude and phase calibration signals of the other target antennas are the amplitude and phase calibration signals transmitted between the other target antennas and their corresponding calibration antennas. The reference amplitude and phase calibration signals are the amplitude and phase calibration signals transmitted between the reference antenna and the reference antenna. The amplitude and phase calibration signals are transmitted between the calibration antennas corresponding to the line; for each other reference antenna, the inter-group calibration data of the other reference antennas relative to the reference antenna are obtained by using the second phase difference between the first amplitude and phase calibration signal of the other reference antenna and the reference amplitude and phase calibration signal of the other reference antenna, and the third phase difference between the reference amplitude and phase calibration signal of the reference antenna and the second amplitude and phase calibration signal of the other reference antenna. The first amplitude and phase calibration signal of the other reference antenna is the amplitude and phase calibration signal transmitted between the reference antenna and the calibration antenna corresponding to the other reference antenna. The reference amplitude and phase calibration signal is the amplitude and phase calibration signal transmitted between the reference antenna and the calibration antenna corresponding to the reference antenna. The second amplitude and phase calibration signal of the other reference antenna is the amplitude and phase calibration signal transmitted between the other reference antenna and the calibration antenna corresponding to the reference antenna. Based on the inter-group calibration data and the intra-group calibration data, the amplitude and phase calibration data of multiple target antennas are obtained.

[0008] The method of obtaining intra-group calibration data of other target antennas relative to the reference antenna by utilizing the first phase difference between the target amplitude-phase calibration signals and the reference amplitude-phase calibration signals of other target antennas in the target antenna group includes: performing spectrum analysis on the amplitude-phase calibration signals received by the first receiving antenna to obtain the first phase information of the target amplitude-phase calibration signals and the second phase information of the reference amplitude-phase calibration signals; the first receiving antenna being the receiving antenna in the target antenna group and the corresponding calibration antenna; determining the phase difference between other target antennas and the reference antenna based on the first phase difference between the first and second phase information, as the intra-group calibration data; and utilizing the second phase difference between the first amplitude-phase calibration signals of other reference antennas and the reference amplitude-phase calibration signals of other reference antennas, as well as the reference amplitude-phase calibration signals and the reference amplitude-phase calibration signals... The third phase difference between the second amplitude-phase calibration signals of other reference antennas is used to obtain inter-group calibration data of other reference antennas relative to the reference antenna. This includes: performing spectrum analysis on the amplitude-phase calibration signals received by the second receiving antenna to obtain the second phase information of the reference amplitude-phase calibration signal, the third phase information of the first amplitude-phase calibration signal, the fourth phase information of the reference amplitude-phase calibration signal, and the fifth phase information of the second amplitude-phase calibration signal. The second receiving antenna is the reference antenna, each of the other reference antennas, the calibration antenna corresponding to the reference antenna, and the antenna serving as the receiving side among the calibration antennas corresponding to the other reference antennas. Based on the second phase difference between the second phase information and the third phase information, and the third phase difference between the fourth phase information and the fifth phase information, the phase difference between the other reference antennas and the reference antenna is determined as inter-group calibration data.

[0009] The method further includes: using one of the multiple target antennas and calibration antennas as the transmitting antenna as the transmitting antenna, and controlling each transmitting antenna to transmit signals.

[0010] The transmitted signals include amplitude and phase calibration signals. Controlling the transmission of signals by each transmitting antenna includes: determining different additional phase sequences for each transmitting antenna according to the additional phase value rules, wherein the additional phase sequence includes a preset number of additional phase values; and using each transmitting antenna to transmit a preset number of pulse signals as amplitude and phase calibration signals, wherein the preset number of pulse signals are phase-added according to the additional phase values ​​contained in the additional phase sequence.

[0011] Specifically, for several preset frequency points, the following steps are performed once at each preset frequency point: control each transmitting antenna to transmit the amplitude and phase calibration signal corresponding to the preset frequency point, obtain the calibration signal to be analyzed at the preset frequency point, and use the phase information of the calibration signal to be analyzed to obtain the amplitude and phase calibration data at the preset frequency point.

[0012] The method further includes: acquiring a coupling calibration signal received by the target receiving antenna in an anechoic chamber environment, wherein the coupling calibration signal is transmitted by the target transmitting antenna in an anechoic chamber environment; and obtaining coupling compensation data of the target antenna array based on the coupling calibration signal received by the target receiving antenna.

[0013] The method further includes: using the detection echo signals received by each target receiving antenna to obtain detection echo data, wherein the detection echo signals are the echo signals of the detection signals transmitted by each target transmitting antenna in a time-division manner; calibrating the detection echo data using detection calibration data to obtain imaging data, wherein the detection calibration data includes amplitude and phase calibration data; and performing imaging using the imaging data to obtain a detection image.

[0014] The detection calibration data also includes real-time calibration data; the target antenna array includes at least one set of reference networks, each of which includes a reference transmitting antenna, a reference receiving antenna, and an attenuation network connected between the reference transmitting antenna and the reference receiving antenna. The reference transmitting antenna and the reference receiving antenna belong to the same area in the target antenna array. Before calibrating the detection echo data using the detection calibration data to obtain the imaging data, the method further includes: using the reference echo signal received by the reference receiving antenna in at least one set of reference networks to obtain real-time calibration data about the target antenna array, wherein the reference echo signal is the echo signal of the reference signal transmitted by the reference transmitting antenna.

[0015] The method of obtaining real-time calibration data for the target antenna array using reference echo signals received by reference receiving antennas in at least one set of reference networks includes: performing phase calculation on the reference echo signals received by reference receiving antennas in each reference network to obtain the sixth phase information of the reference echo signals received by reference receiving antennas in the reference network; and obtaining real-time calibration data for the target antenna array based on the sixth phase information and the seventh phase information corresponding to the attenuation network. The real-time calibration data is used to calibrate the inherent error of the target antenna array during the current detection process.

[0016] Before calibrating the detection echo data using the detection calibration data to obtain the imaging data, the method further includes: preprocessing the detection echo data, which includes filtering and / or weight adjustment, and the weight adjustment is used to set corresponding weights for the target receiving antennas at different locations.

[0017] The process of imaging using the data to be imaged to obtain a detection image includes: gridding the imaging region; calculating the occupancy state and scattering coefficient of each grid in the imaging region based on the data to be imaged; and obtaining the detection image based on the occupancy state and scattering coefficient of each grid in the imaging region.

[0018] The detection signal includes detection signals corresponding to several preset frequency points; and / or, the detection calibration data also includes coupling compensation data.

[0019] To solve the above-mentioned technical problems, one technical solution adopted in this application is: to provide an antenna calibration system, including an antenna array structure and a calibration device, wherein the calibration device is used to perform the antenna array calibration method in any of the preceding claims to calibrate multiple target antennas in the antenna array structure. The antenna array structure is disposed on a plane and includes: multiple receiving antenna groups and multiple transmitting antenna groups. The multiple receiving antenna groups are arranged at a first distance along a first direction. Each receiving antenna group includes multiple receiving antennas arranged along a second direction. The spacing between adjacent receiving antenna pairs near the two ends of the receiving antenna group is smaller than the spacing between adjacent receiving antenna pairs far from the two ends of the receiving antenna group. Multiple transmitting antenna groups are disposed between at least one set of receiving antenna group pairs. The two receiving antenna groups contained in different receiving antenna group pairs are all different. Each set of receiving antenna group pairs has at least two transmitting antenna groups and is arranged at a second distance along the second direction. Each transmitting antenna group includes multiple transmitting antennas spaced apart along the first direction. The second distance is greater than the spacing between adjacent receiving antenna pairs in the receiving antenna group.

[0020] The number of receiving antenna pairs is at least two, and the multiple transmitting antenna pairs are divided into several large antenna groups. Each large antenna group contains a transmitting antenna group between each receiving antenna pair, and the transmitting antenna groups contained in each large antenna group are arranged along the first direction.

[0021] The spacing between adjacent receiving antenna pairs in the receiving antenna group is positively correlated with the distance between adjacent receiving antenna pairs and the two ends of the receiving antenna group.

[0022] The multiple transmitting antenna groups are divided into several large antenna groups. Each large antenna group contains a transmitting antenna group between each pair of receiving antenna groups. The distance between adjacent transmitting antenna groups in the large antenna group is 4mm.

[0023] The first distance is 136mm.

[0024] The second distance is 136mm.

[0025] In this case, the spacing between adjacent receiving antenna pairs in the receiving antenna group is greater than 2 mm.

[0026] To solve the above-mentioned technical problems, another technical solution adopted in this application is to provide an antenna array, which is the antenna array structure included in any of the above-mentioned antenna calibration systems.

[0027] To solve the above-mentioned technical problems, another technical solution adopted in this application is to provide a calibration device, including a memory and a processor coupled to each other, wherein the processor is used to execute program instructions stored in the memory to implement the antenna array calibration method in any of the above claims.

[0028] To solve the above-mentioned technical problems, another technical solution adopted in this application is to provide a computer-readable storage medium storing program instructions thereon, which, when executed by a processor, implement the antenna array calibration method in any of the above-mentioned methods.

[0029] The above scheme acquires calibration signals related to multiple target antennas in the target antenna array, and uses the phase information of the calibration signals to acquire amplitude and phase calibration data of the multiple target antennas. Each target antenna corresponds to a calibration antenna, and there is a preset positional relationship between the corresponding target antenna and the calibration antenna. That is, the amplitude and phase calibration of the target antenna can be achieved by using the calibration antenna that satisfies the preset positional relationship, which simplifies the calibration of the target antenna array and improves the calibration efficiency of the antenna array. Attached Figure Description

[0030] Figure 1 This is a flowchart illustrating an embodiment of the antenna array calibration method of this application;

[0031] Figure 2 This is a flowchart illustrating another embodiment of step S120 of this application;

[0032] Figure 3 This is a schematic diagram of an embodiment of the amplitude and phase calibration signal spectrum of this application;

[0033] Figure 4 This is a schematic diagram of an embodiment of the target antenna array and calibration antenna array in this application;

[0034] Figure 5 This is a flowchart illustrating another embodiment of the antenna array calibration method of this application;

[0035] Figure 6 This is a flowchart illustrating another embodiment of the antenna array calibration method of this application;

[0036] Figure 7 This is a schematic diagram of an embodiment of the image detection method described in this application;

[0037] Figure 8 This is a schematic diagram of the framework of an embodiment of the antenna array of this application;

[0038] Figure 9 This is a schematic diagram of the framework of an embodiment of the antenna calibration system of this application;

[0039] Figure 10 This is a schematic diagram of the framework of an embodiment of the calibration device of this application;

[0040] Figure 11 This is a schematic diagram of a framework of an embodiment of the computer-readable storage medium of this application. Detailed Implementation

[0041] To make the objectives, technical solutions, and effects of this application clearer and more explicit, the following detailed description is provided with reference to the accompanying drawings and embodiments. In the following description, specific details such as particular system structures, interfaces, and technologies are set forth for illustrative purposes rather than for limiting purposes, in order to provide a thorough understanding of this application.

[0042] In this document, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " generally indicates that the preceding and following related objects have an "or" relationship. Furthermore, "many" in this document means two or more. Moreover, the term "at least one" in this document means any combination of at least two of any one or more of a plurality of objects. For example, including at least one of A, B, and C can mean including any one or more elements selected from the set consisting of A, B, and C.

[0043] It should be noted that the antenna array calibration method in this application can be performed by a calibration device, which can be any device with processing capabilities, such as a mobile phone, computer, tablet computer, etc.

[0044] Please see Figure 1 , Figure 1 This is a flowchart illustrating an embodiment of the antenna array calibration method of this application. The antenna array calibration method in this application is used to calibrate a target antenna array. Specifically, the method may include the following steps:

[0045] Step S110: Obtain the calibration signals to be analyzed that are associated with multiple target antennas in the target antenna array.

[0046] From a transmission and reception perspective, the antennas in the target antenna array include two types: transmitting antennas and receiving antennas. Specifically, multiple target antennas include at least one of target transmitting antennas and target receiving antennas. Steps S110 and S120 can be used to perform amplitude and phase calibration on the antennas in the target antenna array.

[0047] Multiple target antennas may include all or part of the antennas in a target antenna array. For example, multiple target antennas may include all the receiving antennas in a target antenna array, or multiple target antennas may include part of the transmitting antennas in a target antenna array, or multiple target antennas may include part of the transmitting antennas and part of the receiving antennas in a target antenna array, and so on.

[0048] If the aforementioned multiple target antennas include both target transmitting antennas and target receiving antennas, then the amplitude and phase calibration of the target transmitting antennas and the amplitude and phase calibration of the target receiving antennas can be performed independently. Obtaining the calibration signals to be analyzed related to the multiple target antennas can include obtaining the corresponding calibration signals to be analyzed for the target transmitting antennas and obtaining the corresponding calibration signals to be analyzed for the target receiving antennas.

[0049] Each target antenna corresponds to a calibration antenna in the calibration antenna array. The transmit / receive properties of each target antenna and its corresponding calibration antenna are opposite and they have a predetermined positional relationship. The calibration antenna corresponding to the target receiving antenna is the transmitting antenna, and the calibration antenna corresponding to the target transmitting antenna is the receiving antenna. For example, multiple target antennas include target transmitting antennas, and each target transmitting antenna corresponds to a receiving antenna in the calibration antenna array. There is a predetermined positional relationship between the corresponding target antennas and calibration antennas.

[0050] The calibration signal to be analyzed includes amplitude and phase calibration signals transmitted between multiple target antennas and calibration antennas, and the amplitude and phase calibration signals are received by the antenna acting as the receiving side among the multiple target antennas and calibration antennas.

[0051] In a specific application scenario, multiple target antennas include target transmitting antennas. The calibration signal to be analyzed for the target transmitting antennas includes amplitude and phase calibration signals transmitted between the target transmitting antennas and the calibration antenna (receiving antenna), and the amplitude and phase calibration signals are received by the calibration antenna.

[0052] In some embodiments, each target antenna corresponds to a different calibration antenna, or in some embodiments, multiple target antennas are divided into several target antenna groups, different target antenna groups correspond to different calibration antennas, and each target antenna in each target antenna group corresponds to the same calibration antenna.

[0053] Step S120: Use the phase information of the calibration signal to be analyzed to obtain amplitude and phase calibration data of multiple target antennas.

[0054] It should be noted that if multiple target antennas include target transmitting antennas and target receiving antennas, the target transmitting antennas and target receiving antennas can be processed separately. For example, for the target transmitting antenna, the amplitude and phase calibration data of the target transmitting antenna can be obtained using the phase information of the amplitude and phase calibration signal transmitted between it and the corresponding calibration antenna (receiving antenna). For the target receiving antenna, the amplitude and phase calibration data of the target receiving antenna can be obtained using the phase information of the amplitude and phase calibration signal transmitted between it and the corresponding calibration antenna (transmitting antenna).

[0055] Target antenna arrays can be used to detect objects, such as in security checks in public places. For example, by emitting detection signals and receiving detection echo signals, an image is created of the object to be detected. This image can then be used by the user to determine whether the object contains prohibited items. Amplitude and phase calibration aims to eliminate amplitude and phase differences between all target receiving antennas and all target transmitting antennas in the target antenna array. This prevents differences between target receiving antennas and target transmitting antennas from affecting the detection imaging process during the detection using the target antenna array.

[0056] In order to calibrate multiple target antennas, the phase information of the calibration signal transmitted between the multiple target antennas and the calibration antenna can reflect the phase information of each target antenna. Based on the phase information of the calibration signal, the amplitude and phase calibration data of multiple target antennas can be obtained. The amplitude and phase calibration data can be used to adjust the phase of multiple target antennas to be consistent, that is, it can be used to achieve amplitude and phase calibration.

[0057] The above scheme acquires calibration signals related to multiple target antennas in the target antenna array, and uses the phase information of the calibration signals to obtain amplitude and phase calibration data for the multiple target antennas. Each target antenna corresponds to a calibration antenna, and there is a preset positional relationship between the corresponding target and calibration antennas. Since the calibration and target antennas satisfy this preset positional relationship, amplitude and phase calibration data can be obtained using only the phase information of the calibration signals without needing the specific positional information between the calibration and target antennas. This simplifies the calibration of the target antenna array and improves the calibration efficiency.

[0058] Please see Figure 2 , Figure 2 This is a flowchart illustrating another embodiment of step S120 of this application.

[0059] It should be noted that the multiple target antennas in the target antenna array can be divided into several target antenna groups. Different target antenna groups correspond to different calibration antennas, and each target antenna in the same target antenna group corresponds to the same calibration antenna. There is a preset positional relationship between each target antenna in the same target antenna group and its corresponding calibration antenna.

[0060] In some embodiments, the preset positional relationship includes a far-field positional relationship and a zero-degree positional relationship.

[0061] In this context, the echo from one of the antennas with a predetermined positional relationship can be considered a parallel wave to the other. This assumption holds only when the perpendicular distance between the two antennas, D >> 2*d*d / lambda, is the size of the same target antenna group and lambda is the wavelength of the transmitted carrier wave. At this point, the two antennas are considered to satisfy the far-field condition. The zero-degree positional relationship in the predetermined positional relationship refers to the fact that, under far-field conditions, the projection of the calibration antenna corresponding to the same target antenna group along its perpendicular direction falls within the region of the same target antenna group.

[0062] Furthermore, one target antenna in the target antenna group serves as the reference antenna for that group, while the other target antennas in the group (excluding the reference antenna) are considered other target antennas within the group. The reference antenna can be used as a calibration reference for the other target antennas in the target antenna group. One of all reference antennas is the base antenna, and the others are considered other reference antennas. The base antenna can be used as a calibration reference for all target antennas. Specifically, after intra-group calibration is completed using the reference antennas of each group, the target antennas within the target antenna group can be considered to have completed calibration with the reference antenna of that group. Then, inter-group calibration is performed using the base antenna as a calibration reference for the other reference antennas, thus ensuring that all target antennas are calibrated with the base antenna as the calibration reference.

[0063] The calibration device in this application can control the antennas of the target antenna array and the calibration antenna array, for example, controlling the target transmitting antenna to transmit signals. Specifically, step S120 may include the following steps:

[0064] Step S221: Using the first phase difference between the target amplitude and phase calibration signals of other target antennas in the target antenna group and the reference amplitude and phase calibration signals, obtain the intra-group calibration data of other target antennas in the target antenna group relative to the reference antenna.

[0065] Among them, the target amplitude and phase calibration signal refers to the amplitude and phase calibration signal transmitted between the target antenna and the calibration antenna corresponding to the target antenna, and the reference amplitude and phase calibration signal refers to the amplitude and phase calibration signal transmitted between the reference antenna and the calibration antenna corresponding to the reference antenna.

[0066] A target antenna group corresponds to an identical calibration antenna. The phase information of the target amplitude and phase calibration signals of other target antennas in the group reflects the phase information of those other target antennas, and the phase information of the reference amplitude and phase calibration signal reflects the phase information of the reference antenna in the group. Therefore, the first phase difference between the target amplitude and phase calibration signals of other target antennas and the reference amplitude and phase calibration signals reflects the phase difference between those other target antennas and the reference antenna, thus allowing us to obtain the intra-group calibration data of other target antennas relative to the reference antenna. This intra-group calibration data can be used to calibrate other target antennas within the target antenna group using the reference antenna as a calibration reference.

[0067] It should be noted that among multiple target antennas and calibration antennas, the antennas acting as transmitters are referred to as transmitter antennas. The calibration equipment can control each transmitter antenna to transmit signals, which may include amplitude and phase calibration signals. During an amplitude and phase calibration process, the calibration equipment can control all transmitter antennas to transmit amplitude and phase calibration signals simultaneously, or control all transmitter antennas to transmit amplitude and phase calibration signals within a short time interval. This short time interval can be considered equivalent to simultaneous transmission. The aforementioned simultaneous transmission is achieved under ideal conditions. In practical applications, there may be a sequence of signal transmission among the transmitter antennas. Controlling all transmitter antennas to transmit within a short time interval can be considered equivalent to simultaneous transmission.

[0068] In a specific application scenario, multiple target antennas, including target transmitting antennas, are involved. The calibration equipment can control all target transmitting antennas to transmit amplitude and phase calibration signals simultaneously.

[0069] In a specific application scenario, multiple target antennas, including target receiving antennas, are involved. The calibration equipment can control all calibration antennas (transmitting antennas) to simultaneously transmit amplitude and phase calibration signals.

[0070] In a specific application scenario, multiple target antennas, including target receiving antennas and target transmitting antennas, can transmit amplitude and phase calibration signals independently. For the target receiving antennas, all calibration antennas (transmitting antennas) transmit amplitude and phase calibration signals simultaneously; for the target transmitting antennas, all target transmitting antennas transmit amplitude and phase calibration signals simultaneously.

[0071] Taking the target antenna as the transmitting antenna as an example, a target antenna group contains six target transmitting antennas, numbered 1-6. This target antenna group corresponds to the same calibration antenna, where target transmitting antenna 1 serves as the reference antenna. For target transmitting antenna 2, target amplitude and phase calibration signals are transmitted between target transmitting antenna 2 and its corresponding calibration antenna, while reference calibration signals are transmitted between target transmitting antenna 1 (the reference antenna) and its corresponding calibration antenna. The intra-group calibration data for target transmitting antenna 2 can be determined using the first phase difference between its target amplitude and phase calibration signal and the reference calibration signal. This intra-group calibration data is used to perform amplitude and phase calibration on target transmitting antenna 2 with target transmitting antenna 1 (the reference antenna) as the calibration reference. The same logic applies to target transmitting antennas 3-6. In this example, when all transmitting antennas (including target transmitting antennas 1 and 2) transmit simultaneously, and when there is a preset positional relationship between the corresponding target transmitting antennas and calibration antennas, the target amplitude and phase calibration signals and the reference calibration signals are received by the same calibration antenna for both target transmitting antenna 1 (the reference antenna) and target transmitting antenna 2. The first phase difference between the phase information of the target amplitude and phase calibration signal and the phase information of the reference calibration signal can reflect the difference between the phase information of the target transmitting antenna 2 and the phase information of the reference antenna. Therefore, the intra-group calibration data can be obtained based on this, which can be used to perform amplitude and phase calibration of the target transmitting antenna 2 with the reference antenna as the calibration reference.

[0072] Similarly, when the target antenna is a receiving antenna, a target antenna group contains 10 target receiving antennas, numbered 1-10. This target antenna group corresponds to the same calibration antenna. Target receiving antenna 1 serves as the reference antenna. For target receiving antenna 2, a target amplitude and phase calibration signal is transmitted between target receiving antenna 2 and its corresponding calibration antenna, while a reference calibration signal is transmitted between target receiving antenna 1 (the reference antenna) and its corresponding calibration antenna. The intra-group calibration data for target receiving antenna 2 can be determined using the first phase difference between its target amplitude and phase calibration signal and the reference calibration signal. This intra-group calibration data is used to perform amplitude and phase calibration on target receiving antenna 2 with target receiving antenna 1 (the reference antenna) as the calibration reference. The same principle applies to target receiving antennas 3-10. Using the above example as an illustration, the target receiving antenna in the target antenna group receives the signal emitted by the same calibration antenna. When there is a preset positional relationship between the corresponding target receiving antenna and the calibration antenna, the first phase difference between the phase information of the target amplitude and phase calibration signal and the phase information of the reference calibration signal can reflect the phase difference between the phase information of the target receiving antenna 2 and the phase information of the reference antenna. Therefore, the calibration data within the group can be obtained based on this, which is used to perform amplitude and phase calibration on the target receiving antenna 2 with the reference antenna as the calibration reference.

[0073] Step S221 is performed for each target antenna group to achieve intra-group amplitude and phase calibration for all target antenna groups.

[0074] Step S222: Using the second phase difference between the first amplitude and phase calibration signal of other reference antennas and the reference amplitude and phase calibration signal of other reference antennas, and the third phase difference between the reference amplitude and phase calibration signal and the second amplitude and phase calibration signal of other reference antennas, the inter-group calibration data of other reference antennas relative to the reference antenna are obtained.

[0075] Among them, the reference amplitude-phase calibration signal is the amplitude-phase calibration signal transmitted between the reference antenna and the corresponding calibration antenna, and the standard amplitude-phase calibration signal is the amplitude-phase calibration signal transmitted between the reference antenna and the corresponding calibration antenna. The first amplitude-phase calibration signal of other reference antennas is the amplitude-phase calibration signal transmitted between the reference antenna and the corresponding calibration antenna of other reference antennas, and the second amplitude-phase calibration signal of other reference antennas is the amplitude-phase calibration signal transmitted between the other reference antennas and the corresponding calibration antenna of the reference antenna.

[0076] Understandably, during an amplitude and phase calibration process, the calibration equipment can control all transmitting antennas to simultaneously transmit amplitude and phase calibration signals.

[0077] Taking the target antennas, including the target transmitting antennas, as an example, there are 18 target transmitting antennas (denoted as Tx1-Tx18), which are divided into 3 target antenna groups in sequence, corresponding to calibration antennas 1-3 (denoted as Rx1-Rx3). Amplitude and phase calibration is performed on multiple target transmitting antennas simultaneously; therefore, all target transmitting antennas 1-18 transmit amplitude and phase calibration signals simultaneously, while calibration antennas 1-3 receive amplitude and phase calibration signals. Tx1-Tx6 form a target antenna group, with Tx1 as the reference antenna. Similarly, Tx7 and Tx13 are the reference antennas for Tx7-Tx12 and Tx13-Tx18, respectively. Step S221 is executed, using Tx2-Tx6 with Tx1 as the calibration reference to obtain the intra-group calibration data for the target antenna group; using Tx8-Tx12 with Tx7 as the calibration reference to obtain the intra-group calibration data for the target antenna group; and using Tx14-Tx18 with Tx13 as the calibration reference to obtain the intra-group calibration data for the target antenna group. Then, step S222 is executed to use Tx7 and Tx13 with Tx1 as the calibration reference to obtain intergroup calibration data.

[0078] It should be noted that the phase information of the amplitude-phase calibration signal can be obtained through spectrum analysis, and the difference between the two amplitude-phase calibration signals can be obtained by comparing the phase information of the two amplitude-phase calibration signals.

[0079] Step S221 can then be achieved through the following steps: Perform spectrum analysis on the amplitude-phase calibration signal received by the first receiving antenna to obtain the first phase information of the target amplitude-phase calibration signal and the second phase information of the reference amplitude-phase calibration signal. Based on the first phase difference between the first and second phase information, determine the phase difference between other target antennas and the reference antenna, which will serve as the intra-group calibration data. Here, the first receiving antenna is the antenna serving as the receiving side in the target antenna group and the corresponding calibration antenna.

[0080] Step S222 can be achieved through the following steps: performing spectrum analysis on the amplitude and phase calibration signal received by the second receiving antenna to obtain the second phase information of the reference amplitude and phase calibration signal, the third phase information of the first amplitude and phase calibration signal, the fourth phase information of the reference amplitude and phase calibration signal, and the fifth phase information of the second amplitude and phase calibration signal. Based on the second phase difference between the second phase information and the third phase information, and the third phase difference between the fourth phase information and the fifth phase information, the phase difference between other reference antennas and the reference antenna is determined as inter-group calibration data.

[0081] In the above scheme, the calibration antenna and the target antenna meet a preset positional relationship. When acquiring amplitude and phase calibration data, the phase information of the amplitude and phase calibration signal is utilized, without needing the specific positional information of the calibration antenna and the target antenna (specific positional information is used to reflect the phase change of signal transmission between the calibration antenna and the target antenna). Furthermore, in the above scheme, all transmitting antennas transmit simultaneously during amplitude and phase calibration. Meeting the preset positional relationship requires less precision in the calibration antenna's position than using specific positional information for calculations, simplifying the target antenna calibration steps and improving calibration efficiency. It effectively avoids the influence of inaccurate array antenna positional information, reducing the impact of deviations in the specific positional relationship on the amplitude and phase calibration data, thus improving the accuracy of the amplitude and phase calibration data.

[0082] Please see Figure 3 , Figure 3 This is a schematic diagram of an embodiment of the amplitude and phase calibration signal spectrum of this application.

[0083] In this embodiment, there are 18 target transmitting antennas (denoted as Tx1-Tx18), which are divided into 3 target antenna groups in sequence, corresponding to calibration antennas 1-3 (denoted as Rx1-Rx3). Amplitude and phase calibration is performed on multiple target transmitting antennas simultaneously; therefore, all target transmitting antennas 1-18 transmit amplitude and phase calibration signals simultaneously, while calibration antennas 1-3 receive the amplitude and phase calibration signals. Tx1-Tx6 form one target antenna group, with Tx1 serving as the reference antenna. Similarly, Tx7 and Tx13 are the reference antennas for Tx7-Tx12 and Tx13-Tx18, respectively.

[0084] For Tx1-Tx6, the depth distance from Rx1 to Tx1-Tx6 is much greater than 2D. 2 / lamba, D is the lateral distance of Tx1-Tx6, lambba is the carrier wavelength, that is, it can be assumed that Tx1-Tx6 and Rx1 have a far-field position relationship, and Rx1 is located at the zero degree position of Tx1-Tx6. Combined with digital beamforming, the phase deviation of Tx2-Tx6 relative to Tx1 is obtained.

[0085] Figure (a) shows the spectrum of the amplitude and phase calibration signal received by Rx1. Figure 3 (b) is the spectrum of the amplitude and phase calibration signal received by Rx2. Figure 3 (c) shows the spectrum of the amplitude-phase calibration signal received by Rx3, with the horizontal axis representing frequency. Each calibration antenna can receive the amplitude-phase calibration signals transmitted by Tx1-Tx18 respectively, and each target transmitting antenna transmits amplitude-phase calibration signals with different phase information. For example, based on the first phase information of the target amplitude-phase calibration signals between Tx2 and Rx1 and the second phase information of the reference amplitude-phase calibration signal between Tx1 and Rx1, the intra-group calibration data for Tx2 can be obtained; the same applies to Tx3-Tx6. Furthermore, similar processing can be performed on Tx7-Tx12 and Tx13-Tx18 to obtain the corresponding intra-group calibration data.

[0086] Taking the inter-group calibration between Tx1 and Tx7 as an example, the phase of the amplitude and phase calibration signals satisfies the following relationship:

[0087] φTiRj=φTi+φRj+φTiRj_delay

[0088] φT1R1=φT1+φR1+φT1R1_delay

[0089] φT1R2=φT1+φR2+φT1R2_delay

[0090] φT7R1=φT7+φR1+φT7R1_delay

[0091] φT7R2=φT7+φR2+φT7R2_delay

[0092]

[0093]

[0094] Where φTiRj represents the phase of the amplitude-phase calibration signal transmitted between transmitting antenna i and receiving antenna j, φTi represents the phase of transmitting antenna i, φRj represents the phase of receiving antenna j, and φTiRj_delay represents the phase of transmitting antenna i and receiving antenna j due to distance.

[0095] Based on the above relationship, we can conclude that:

[0096]

[0097]

[0098] Tx1 is the reference antenna. A reference amplitude and phase calibration signal is transmitted between Tx1 and its corresponding calibration antenna Rx1. The fourth phase information of the reference amplitude and phase calibration signal can be represented as φT1R1. Tx7 is another reference antenna. A reference amplitude and phase calibration signal is transmitted between Tx7 and its corresponding calibration antenna Rx2. The second phase information of the reference amplitude and phase calibration signal can be represented as φT7R2. The third phase information of the first amplitude and phase calibration signal can be represented as φT1R2, and the fifth phase information of the second amplitude and phase calibration signal can be represented as φT7R1.

[0099] Based on the second phase difference between the second phase information φT7R2 and the third phase information φT1R2, and the third phase difference between the fourth phase information φT1R1 and the fifth phase information φT7R1, the phase difference between other reference antennas Tx7 and the reference antenna Tx1 is determined as inter-group calibration data.

[0100] Similarly, the phase difference between all other reference antennas and the reference antenna can be obtained to obtain inter-group calibration data. Furthermore, if the target antenna is the target receiving antenna, the inter-group calibration data can be determined in the same way.

[0101] Furthermore, controlling the transmission signals of each transmitting antenna includes: determining different additional phase sequences for each transmitting antenna according to the additional phase value rules, and using each transmitting antenna to transmit a preset number of pulse signals as amplitude and phase calibration signals. The additional phase sequence includes a preset number of additional phase values, and the preset number of pulse signals are phase-added according to the additional phase values ​​contained in the additional phase sequence.

[0102] It should be noted that all pulse signals are at a certain preset frequency point. Different additional phase values ​​will bring additional frequency differences, causing the signals received by the receiving antenna from different transmitting antennas to be separated at the preset frequency point. Therefore, phase information about different transmitting antennas can only be obtained based on the spectrum analysis of the receiving antenna.

[0103] Taking target transmitting antenna 2 as an example, target transmitting antenna 2 transmits a total of N pulse signals. These N pulse signals are respectively phase-added according to N additional phase values ​​in the additional phase sequence corresponding to target transmitting antenna 2. For example, the additional phases can be 0.5π, π, 1.5π, ... . For the reference transmitting antenna, the additional phases of its N pulse signals can all be 0. For other target transmitting antennas, the additional phase sequence can include N additional phase values ​​that change according to a certain pattern. The same applies to the calibration transmitting antenna.

[0104] With each transmitted pulse, the additional phase of each transmitting antenna is also different. Taking the i-th transmitting antenna as an example, its additional phase is 2*pi*i*k / M, where i is the transmitting antenna index, k is the pulse index, and M is the number of phase sets supported by the phase shifter. If the phase shifter is 6-bit, then M = 2. 6 =64.

[0105] In a specific application scenario, transmitting antennas 1-3 transmit two pulse signals respectively, with the following additional phase values: Pulse 1: T1: 0, T2: 0.5π, T3: 1.5π; Pulse 2: T1: 0, T2: π, T3: 3π.

[0106] Step S223: Based on the inter-group calibration data and intra-group calibration data, obtain the amplitude and phase calibration data of multiple target antennas.

[0107] Inter-group calibration data can be used to calibrate other target antennas in a target antenna group to be consistent with the reference antenna, while intra-group calibration data can be used to calibrate other reference antennas to be consistent with the reference antenna. Thus, based on the inter-group calibration data and intra-group calibration data, the amplitude and phase calibration data of each target antenna can be obtained.

[0108] The above steps are performed at a specific frequency. In some embodiments, during detection, the detection signal includes detection signals at several preset frequency points. Therefore, for several preset frequency points, the process can be performed once at each preset frequency point: controlling each transmitting antenna to transmit the amplitude and phase calibration signal corresponding to the preset frequency point, obtaining the calibration signal to be analyzed at the preset frequency point, and using the phase information of the calibration signal to be analyzed, obtaining the amplitude and phase calibration data at the preset frequency point, thereby obtaining the amplitude and phase calibration data at each frequency point. The operation at each preset frequency point can be the same.

[0109] In a specific application scenario, multiple target antennas, including target receiving antennas, comprise several target antenna groups. Each target antenna group corresponds to a calibration transmitting antenna, and there is a preset positional relationship between any two corresponding antennas. All target antennas simultaneously transmit N pulses as amplitude and phase calibration signals. Using DDMA, spectral analysis is performed on each target receiving antenna along (N pulses), revealing peak values ​​corresponding to the calibration transmitting antennas in the spectrum of each target receiving antenna.

[0110] The above scheme can achieve calibration of the target transmitting antenna relative to the reference transmitting antenna and calibration of the target receiving antenna relative to the reference receiving antenna at different frequency points.

[0111] Please see Figure 4 , Figure 4 This is a schematic diagram of an embodiment of the target antenna array and calibration antenna array in this application.

[0112] Figure 4 The document describes a "U"-shaped target antenna array, with the target antenna array and calibration antenna array positioned opposite each other. The target antenna array includes three target transmit antenna groups (Tx1_Group, Tx2_Group, and Tx3_Group) and two target receive antenna groups (Rx1_Group and Rx2_Group). The target antenna array also includes dummy antennas used to align the target receive antennas with the target transmit antennas. The calibration antenna array includes receive antenna 1, receive antenna 2, receive antenna 3, transmit antenna 1, and transmit antenna 2. Specifically, receive antenna 1 is the calibration antenna corresponding to Tx1_Group, receive antenna 2 is the calibration antenna corresponding to Tx2_Group, receive antenna 3 is the calibration antenna corresponding to Tx3_Group, transmit antenna 1 is the calibration antenna corresponding to Rx1_Group, and transmit antenna 2 is the calibration antenna corresponding to Rx2_Group.

[0113] Please see Figure 5 , Figure 5 This is a flowchart illustrating another embodiment of the antenna array calibration method of this application. Specifically, the method may further include the following steps:

[0114] Step S510: Obtain the coupling calibration signal received by the target receiving antenna in an anechoic environment.

[0115] Based on any of the foregoing embodiments, the antenna array calibration method may further include steps S510 and S520. Steps S510-S520 can be performed at any step before detection using the target antenna array.

[0116] The system includes multiple target antennas, including at least one target transmitting antenna and at least one target receiving antenna. The coupling calibration signal is transmitted by the target transmitting antenna in an anechoic chamber environment. The calibration equipment can also control the target transmitting antenna to transmit the coupling calibration signal. The anechoic chamber environment can be considered as one in which the signal emitted by the target transmitting antenna is absorbed upon contact with the anechoic chamber environment, without being reflected or refracted to generate an echo signal that is then received by the target receiving antenna.

[0117] In a specific application scenario, an anechoic chamber is a special room constructed with absorbing materials and metal shielding. When the coupled calibration signal emitted by the target transmitting antenna comes into contact with the walls, ceiling, floor, etc. of the anechoic chamber, it is completely absorbed.

[0118] Step S520: Obtain the coupling compensation data of the target antenna array based on the coupling calibration signal received by the target receiving antenna.

[0119] The coupling calibration signal received by the target receiving antenna can reflect the signal transmission between the target receiving antenna and the target transmitting antenna in the target antenna array.

[0120] It is understandable that some of the coupling calibration signals emitted by the target transmitting antenna are not absorbed by the anechoic chamber environment but are received by the target receiving antenna. When using the target antenna array to detect and image the object under test, imaging is performed based on the detection echo signal received by the receiving antenna in the target antenna array. If the detection signal emitted by the transmitting antenna is directly received by the receiving antenna, it will affect the imaging of the detection echo signal. Therefore, the coupling compensation data obtained from the coupling calibration signal directly received by the target receiving antenna can be used to eliminate the influence of the directly received detection signal on the imaging.

[0121] The above steps are performed at a specific frequency. In some embodiments, during detection, the detection signal includes detection signals at several preset frequency points. Therefore, for several preset frequency points, the above steps can be performed once at each preset frequency point, and the operation for each preset frequency point can be the same.

[0122] Understandably, the transmitting antenna is represented as N. T The receiving antenna is represented as N. R The frequency point is represented as N. F A total of N T *N R *N F The combinations used in the detection process may introduce inconsistent phases due to channel inconsistencies, inter-channel coupling, or other reasons, leading to unfocused imaging. For each of these possibilities, amplitude-phase calibration / coupling calibration is required, generating amplitude-phase calibration data / coupling compensation data of size N. T *NR *N F .

[0123] In a specific application scenario, the obtained coupling compensation data is a three-dimensional table MutualComp[TxNum][RxNum][Frequency Num], where the three dimensions represent the transmitting antenna, receiving antenna, and transmitting frequency point, respectively. The obtained three-dimensional table can be corrected; for example, values ​​below a certain threshold can be directly set to zero.

[0124] Please see Figure 6 , Figure 6 This is a flowchart illustrating another embodiment of the antenna array calibration method of this application. Specifically, the method may further include the following steps:

[0125] Step S610: Obtain detection echo data using the detection echo signals received by each target receiving antenna.

[0126] Based on any of the foregoing embodiments, the antenna array calibration method may further include steps S610-S630.

[0127] The calibration device in this application can control the transmission signals of each target transmitting antenna, for example, controlling each target transmitting antenna to transmit detection signals in a time-division manner. The detection signals include pulse signals at several preset frequency points, and each target transmitting antenna transmits them in a time-division manner, with no additional phase in the detection signals. The detection echo signal is the echo signal of the detection signal. The detection signal is used to detect the object to be detected. The object to be detected will reflect, refract, etc., the detection signal, thereby forming the detection echo signal.

[0128] Specifically, the detection echo signal can be converted from analog to digital to obtain detection echo data. The detection echo data can be used to image the object to be detected, so that users can determine whether there is a target to be detected, such as security checks for prohibited items.

[0129] Step S620: Use calibration data to calibrate the detected echo data to obtain the imaging data.

[0130] The calibration data may include amplitude and phase calibration data. This calibration data is used to calibrate the target antenna array to ensure accurate imaging of the object being detected.

[0131] In some embodiments, the calibration data may also include coupling compensation data.

[0132] In some embodiments, prior to step S620, the method may further include: obtaining real-time calibration data about the target antenna array using reference echo signals received by reference receiving antennas in at least one set of reference networks, wherein the reference echo signals are received by the reference receiving antennas and are reference signals transmitted by the reference transmitting antennas and transmitted to the reference receiving antennas via an attenuation network. The calibration data may then include the aforementioned real-time calibration data.

[0133] The reference network includes a reference transmitting antenna, a reference receiving antenna, and an attenuation network connecting the reference transmitting antenna and the reference receiving antenna. The target antenna array can be divided into several regions, and the reference transmitting antenna and the reference receiving antenna can belong to the same region.

[0134] In a specific application scenario, the target antenna array is divided into several regions according to the receiving aperture it forms. The reference transmitting antenna and the reference receiving antenna in a reference network can belong to the same aperture region.

[0135] In this system, any receiving antenna in the target antenna array can serve as a reference receiving antenna. Furthermore, the target receiving antenna used as a reference antenna during amplitude and phase calibration can also be selected as the reference receiving antenna. Similarly, any transmitting antenna in the target antenna array can serve as a reference transmitting antenna. Furthermore, the target transmitting antenna used as a reference antenna during amplitude and phase calibration can also be selected as the reference transmitting antenna. The reference transmitting antenna and reference receiving antenna in a reference network are selected within the same region.

[0136] It should be noted that if multiple reference networks are selected, each reference network is processed separately, and a reference echo signal for the target antenna array is obtained based on the reference echo signals obtained from each reference network. Furthermore, the multiple reference networks can all belong to different regions within the target antenna array, or at least some of the reference networks can belong to the same region. For example, the target antenna array includes four regions (A, D), and four reference networks are formed by selecting a reference transmitting antenna and a reference receiving antenna from each region, with the four reference networks belonging to different regions.

[0137] It should be noted that the reference receiving antenna and reference transmitting antenna in the reference network do not participate in the transmission and reception of the detection signal during the detection process. The transmission and reception of the reference signal are also completed during the detection process.

[0138] Specifically, for each reference network, the phase of the reference echo signal received by the reference receiving antenna is calculated to obtain the sixth phase information of the reference echo signal received by the reference receiving antenna in the reference network. Based on the sixth phase information and the seventh phase information corresponding to the attenuation network, real-time calibration data for the target antenna array is obtained. The real-time calibration data is used to calibrate the inherent error of the target antenna array during the current detection process. The seventh phase information corresponding to the attenuation network represents the phase of the reference signal due to time delay in the attenuation network, which is an inherent property of the attenuation network.

[0139] It should be noted that calibration data includes two types: one is fixed and unchanging, such as coupling compensation data and amplitude-phase calibration data, which are inherent properties of the target antenna array; the other is variable and changes with each test, such as real-time calibration data, which changes during each test. Therefore, for the first type, it only needs to be calculated once and can be used in each subsequent test. For the second type, the calibration data for each test needs to be calculated.

[0140] In a specific application scenario, let φ1 be the phase difference generated from the RF source to the transmit channel, φ2 be the phase difference generated from the local oscillator to the receive channel, and φ3 be the phase difference caused by the attenuation network due to time delay. The phase of the ADC signal received by the reference receiving antenna is calculated and denoted as φ. Then, φ1 + φ2 = φ - φ3. φ1 + φ2 can represent the phase difference generated from the RF source to the transmit channel and the phase difference generated from the local oscillator to the receive channel, which is the inherent error of the target antenna array in the current detection process.

[0141] In a specific application scenario, the detection calibration data includes amplitude and phase calibration data, coupling compensation data, and real-time calibration data. The detection echo data is calibrated using the detection calibration data to obtain the imaging data.

[0142] In some embodiments, the method may further include preprocessing the detection echo data before calibrating it using the detection calibration data. This preprocessing may include filtering and / or weight adjustment.

[0143] Specifically, the detected echo data (ADC data, analog-to-digital conversion data) is filtered using filters, such as FIR filters (Finite Impulse Response filters, non-recursive filters, also known as finite-length unit impulse response filters). Filtering reduces the impact of interfering targets on the imaging results.

[0144] Specifically, weight adjustment is used to set corresponding weights for receiving antennas at different locations in the target antenna array. Weight adjustment can suppress the effects of specular reflection, resulting in more uniform illumination.

[0145] Step S630: Use the data to be imaged to perform imaging to obtain the detection image.

[0146] The detected image can be viewed by the user to determine whether the object to be detected contains the target.

[0147] In a specific application scenario, different types of metal objects appear differently in the detection images. Security personnel can use the detection images to determine whether people passing through the security check area are carrying prohibited items, and what types of prohibited items they are carrying.

[0148] Furthermore, using the data to be imaged to obtain a detection image can include: gridding the imaging region, calculating the occupancy state and scattering coefficient of each grid in the imaging region based on the data to be imaged, and obtaining the detection image based on the occupancy state and scattering coefficient of each grid in the imaging region.

[0149] In a specific application scenario, the imaging area is gridded, and the occupancy state of each grid and the scattering coefficient of the target in the grid are solved by the back-projection method. That is, the scattering coefficient δxyz in the spatial grid is ∑∑∑s(T,R,F)*h(T,R,F,x,y,z), where s is the original data after calibration, T, R, and F represent the three dimensions of transmitting antenna, receiving antenna, and transmitting frequency, respectively, h is the corresponding matched filter function, and x, y, and z represent the coordinates of the grid.

[0150] Using a time-division multiplexing method facilitates the orthogonality of the detection signals in the time dimension. Simultaneous reception by all receiving antennas allows for higher SNR (signal-noise ratio) and a wider dynamic response range. Specifically, each transmitting antenna transmits a signal sequentially, and then all receiving antennas simultaneously receive the data, with a data size of N. T *N R *N F *N sample , where N T N represents the number of transmitting antennas. R N represents the number of receiving antennas. F N represents the number of frequency points. sample This represents the number of samples per frequency point.

[0151] Please see Figure 7 , Figure 7 This is a schematic diagram of an embodiment of the image detection method described in this application.

[0152] in, Figure 7 Image (a) shows the simulated imaging result of the detected image. Figure 7 (b) is the detected image.

[0153] In a specific application scenario, the target antenna array is used to transmit millimeter-wave signals, which can then be used for security inspection imaging. The detected images are displayed to users to help them determine whether the person being inspected in the security area is carrying controlled items. Different types of items appear differently in the detected images, so users can also determine the type of controlled items based on the detected images.

[0154] Please see Figure 8 , Figure 8 This is a schematic diagram of the framework of an embodiment of the antenna array of this application.

[0155] In this embodiment, the antenna array 80 is disposed on a plane, and each point in the figure represents an antenna. The antenna array 80 includes multiple receiving antenna groups 81 and multiple transmitting antenna groups 82.

[0156] The plurality of receiving antenna groups 81 are arranged at a first distance along a first direction. Each receiving antenna group 81 includes a plurality of receiving antennas 811 arranged along a second direction. The plurality of receiving antennas 811 are non-uniformly arranged. The spacing between adjacent receiving antenna pairs near the two ends of the receiving antenna group 81 is smaller than the spacing between adjacent receiving antenna pairs far from the two ends of the receiving antenna group 81.

[0157] In this configuration, multiple receiving antenna groups 81 are disposed between at least one pair of receiving antenna groups. The two receiving antenna groups 81 contained in different pairs of receiving antenna groups are all different. There are at least two transmitting antenna groups 82 between each pair of receiving antenna groups, which are arranged at a second distance along a second direction. The transmitting antenna group 82 includes multiple transmitting antennas arranged at intervals along a first direction. The second distance is greater than the interval between adjacent receiving antenna pairs in the receiving antenna group 81.

[0158] In the diagram, the antennas in columns 1-4 are receiving antennas 811, and each column of receiving antennas 811 forms a receiving antenna group 81. The antennas in rows 5-8 are transmitting antennas 821, and each row of receiving antenna groups consists of transmitting antennas 821 forming a transmitting antenna group 82. In the diagram, d1 represents the first distance, and d2 represents the second distance. Figure 8 As shown, there are a total of 8 transmitting antenna groups, denoted as Tx_Line1-Tx_Line8.

[0159] In some embodiments, the number of receiving antenna pairs is at least two, and the plurality of transmitting antenna pairs 82 are divided into several antenna groups 83. Each antenna group contains a transmitting antenna pair 82 between each receiving antenna pair, and the transmitting antenna pairs 82 contained in each antenna group 83 are arranged along a first direction.

[0160] Each antenna group 83 may include two or more transmitting antenna groups 82, which can be adjusted according to the number of receiving antenna pairs.

[0161] In some embodiments, the spacing between adjacent receiving antenna pairs in receiving antenna group 81 is positively correlated with the distance between adjacent receiving antenna pairs and the two ends of receiving antenna group 81.

[0162] In some embodiments, multiple transmit antenna groups 82 are divided into several antenna groups 83, each antenna group 83 containing a transmit antenna group 82 between each pair of receive antenna groups, and the distance between adjacent transmit antennas 821 in the antenna group 83 is 4mm.

[0163] In some embodiments, the first distance is 136 mm.

[0164] In some embodiments, the second distance is 136 mm.

[0165] In some embodiments, the first direction and the second direction may be at a certain angle, and further, they may be perpendicular.

[0166] In some embodiments, the spacing between adjacent receiving antenna pairs in receiving antenna group 81 is greater than 2 mm.

[0167] like Figure 8As shown, each group of transmitting antennas 82 is uniformly arranged, with a horizontal spacing of 4mm between adjacent transmitting antennas 821. This 4mm spacing prevents severe image aliasing in the X direction. The horizontal length of the gap between each group is 136mm, resulting in a horizontal aperture of 408mm for the transmitting antennas, achieving good spatial resolution. Specifically, the transmitting antennas corresponding to Tx_Line1 have X-direction positions ranging from 0.006m to 0.13m and Y-direction positions of 0.048m; those corresponding to Tx_Line2 have X-direction positions ranging from 0.278m to 0.402m and Y-direction positions of 0.048m; and those corresponding to Tx_Line3 have X-direction positions ranging from 0.006m to 0.13m. The X-axis position of the transmitting antenna corresponding to Tx_Line4 is 0.278m to 0.402m, and the Y-axis position is 0.184m. The X-axis position of the transmitting antenna corresponding to Tx_Line5 is 0.006m to 0.13m, and the Y-axis position is 0.32m. The X-axis position of the transmitting antenna corresponding to Tx_Line6 is 0.278m to 0.402m, and the Y-axis position is 0.32m. The X-axis position of the transmitting antenna corresponding to Tx_Line7 is 0.006m to 0.13m, and the Y-axis position is 0.456m. The X-axis position of the transmitting antenna corresponding to Tx_Line8 is 0.278m to 0.402m, and the Y-axis position is 0.456m. These values ​​may vary with the initial coordinate position, but the relative relationships remain constant.

[0168] The receiving antennas are sparsely arranged to achieve a large aperture in the vertical direction and suppress vertical imaging aliasing. The intervals between each pair are arranged in an arithmetic progression, which effectively suppresses imaging aliasing in simulations. The arrangement is as follows: the X position of the first column is 0mm, the X position of the second column is 0.136m, the X position of the third column is 0.272m, and the X position of the fourth column is 0.408m. Each group of receiving antennas 81 is distributed along the Y-axis according to the following rules: when 1<=i and i<=31, Y(i+1)=Y(i)+i, Y(1)=0, where i is the index of the receiving antenna; otherwise, let m=i-31, YM(m+1)=YM(m)–m, YM(1)=496. Multiply the calculated Y(i) and YM(m) by 1mm to obtain their corresponding spatial positions. If the distance between the two receiving antennas is less than 2mm, the spacing between the receiving antennas should be appropriately increased to be greater than 2mm, or the two receiving antennas should be combined. The above values ​​may vary with the initial coordinate position, but the relative relationship remains unchanged.

[0169] By introducing the sparse antenna array design described above, a larger antenna aperture can be obtained than that of a uniform array with the same number of antennas, thus improving spatial resolution. Furthermore, the presence of closely spaced receiving antenna pairs in the sparse antenna array can increase the wavenumber K. x K y This solves the problem of blurry imaging at large field of view. Furthermore, the sparse array antenna layout described above allows for better 3D reconstruction of spatial objects.

[0170] Please see Figure 9 , Figure 9 This is a schematic diagram of the framework of an embodiment of the antenna calibration system of this application.

[0171] In this embodiment, the antenna calibration system 90 includes an antenna array structure 91 and a calibration device 92. The calibration device 92 is used to perform the antenna array calibration method in any of the above embodiments to calibrate multiple target antennas in the antenna array structure 91. The antenna array structure 91 can be any antenna array as described in the foregoing embodiments.

[0172] Please see Figure 10 , Figure 10 This is a schematic diagram of the framework of an embodiment of the calibration device of this application.

[0173] In this embodiment, the calibration device 100 includes a memory 101 and a processor 102, wherein the memory 101 is coupled to the processor 102. Specifically, the various components of the calibration device 100 can be coupled together via a bus, or the processor 102 of the calibration device 100 can be connected to each other component individually. The calibration device 100 can be any device with processing capabilities, such as a computer, tablet computer, mobile phone, etc.

[0174] The memory 101 is used to store program data executed by the processor 102 and data generated by the processor 102 during processing. For example, first phase information, second phase information, etc. The memory 101 includes a non-volatile storage portion for storing the aforementioned program data.

[0175] Processor 102 controls the operation of calibration device 100. Processor 102 can also be referred to as CPU (Central Processing Unit). Processor 102 may be an integrated circuit chip with signal processing capabilities. Processor 102 can also be a general-purpose processor, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component. The general-purpose processor can be a microprocessor or any conventional processor. In addition, processor 102 can be implemented by multiple integrated circuit chips.

[0176] The processor 102 executes instructions to implement any of the above-mentioned antenna array calibration methods by calling the program data stored in the memory 101.

[0177] Please see Figure 11 , Figure 11 This is a schematic diagram of a framework of an embodiment of the computer-readable storage medium of this application.

[0178] In this embodiment, the computer-readable storage medium 110 stores processor-executable program data 111, which can be executed to implement any of the above-described antenna array calibration methods.

[0179] The computer-readable storage medium 110 can be a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, or it can be a server that stores the program data. The server can send the stored program data to other devices for execution, or it can run the stored program data itself.

[0180] In some embodiments, the computer-readable storage medium 110 may also be such as Figure 10 The memory shown.

[0181] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An antenna array calibration method, characterized in that, The method includes: Acquire calibration signals to be analyzed related to multiple target antennas in a target antenna array, wherein the multiple target antennas include at least one of a target transmitting antenna and a target receiving antenna, each target antenna corresponds to a calibration antenna in a calibration antenna array, each target antenna and its corresponding calibration antenna have opposite transmission and reception properties and a preset positional relationship, and the calibration signals to be analyzed include amplitude and phase calibration signals transmitted between the multiple target antennas and the calibration antenna, and are received by the antenna that serves as the receiving side among the multiple target antennas and the calibration antenna; Using the phase information of the calibration signal to be analyzed, amplitude and phase calibration data of the multiple target antennas are obtained; the multiple target antennas are divided into several target antenna groups, one of the target antennas in the target antenna group is the reference antenna corresponding to the target antenna group, the target antennas in the target antenna group other than the reference antenna are the other target antennas in the target antenna group, one of all the reference antennas is the reference antenna, and the reference antennas other than the reference antenna are the other reference antennas; The amplitude and phase calibration data are obtained based on intra-group calibration data and inter-group calibration data. The intra-group calibration data is obtained by using the amplitude and phase calibration signals transmitted between other target antennas and their corresponding calibration antennas in the target antenna group, and the first phase difference between the reference amplitude and phase calibration signals. The reference amplitude and phase calibration signal is the amplitude and phase calibration signal transmitted between the reference antenna and its corresponding calibration antenna. The inter-group calibration data is obtained by using the second phase difference between the first amplitude and phase calibration signals of the other reference antennas and the reference amplitude and phase calibration signals of the other reference antennas, and the third phase difference between the reference amplitude and phase calibration signals of the other reference antennas and the second amplitude and phase calibration signals of the other reference antennas. The first amplitude and phase calibration signal of the other reference antennas is the amplitude and phase calibration signal transmitted between the reference antenna and its corresponding calibration antenna. The reference amplitude and phase calibration signal is the amplitude and phase calibration signal transmitted between the reference antenna and its corresponding calibration antenna. The second amplitude and phase calibration signal of the other reference antennas is the amplitude and phase calibration signal transmitted between the other reference antennas and its corresponding calibration antenna.

2. The method according to claim 1, characterized in that, The plurality of target antennas are divided into several target antenna groups, different target antenna groups correspond to different calibration antennas, and each target antenna in the same target antenna group corresponds to the same calibration antenna; and / or, the preset position relationship includes far-field position relationship and zero-degree position relationship.

3. The method according to claim 1 or 2, characterized in that, The step of obtaining intra-group calibration data of other target antennas in the target antenna group relative to the reference antenna by utilizing the first phase difference between the target amplitude and phase calibration signals of other target antennas in the target antenna group and the reference amplitude and phase calibration signal includes: Spectral analysis is performed on the amplitude and phase calibration signal received by the first receiving antenna to obtain the first phase information of the target amplitude and phase calibration signal and the second phase information of the reference amplitude and phase calibration signal. The first receiving antenna is the antenna that serves as the receiving side in the target antenna group and the corresponding calibration antenna. Based on the first phase difference between the first phase information and the second phase information, the phase difference between the other target antenna and the reference antenna is determined as the group calibration data; The step of obtaining inter-group calibration data of the other reference antenna relative to the reference antenna by utilizing the second phase difference between the first amplitude-phase calibration signal of the other reference antenna and the reference amplitude-phase calibration signal of the other reference antenna, and the third phase difference between the reference amplitude-phase calibration signal and the second amplitude-phase calibration signal of the other reference antenna, includes: Spectral analysis is performed on the amplitude and phase calibration signal received by the second receiving antenna to obtain the second phase information of the reference amplitude and phase calibration signal, the third phase information of the first amplitude and phase calibration signal, the fourth phase information of the reference amplitude and phase calibration signal, and the fifth phase information of the second amplitude and phase calibration signal. The second receiving antenna is the antenna that serves as the receiving side among the reference antenna, each of the other reference antennas, the calibration antenna corresponding to the reference antenna, and the calibration antenna corresponding to the other reference antennas. Based on the second phase difference between the second phase information and the third phase information, and the third phase difference between the fourth phase information and the fifth phase information, the phase difference between the other reference antenna and the reference antenna is determined as the inter-group calibration data.

4. The method according to claim 1, characterized in that, The method further includes: The antennas that serve as the transmitting side among the plurality of target antennas and the calibration antennas are used as transmitting side antennas, and each of the transmitting side antennas is controlled to transmit signals.

5. The method according to claim 4, characterized in that, The transmitted signal includes the amplitude and phase calibration signal, and the control of the transmitted signals of each of the transmitting antennas includes: According to the additional phase value rules, different additional phase sequences are determined for each of the transmitting antennas, and the additional phase sequence includes a preset number of additional phase values; Each of the transmitting antennas transmits a preset number of pulse signals as the amplitude and phase calibration signals, and the preset number of pulse signals are phase-added according to the additional phase values ​​contained in the additional phase sequence; And / or, for a number of preset frequency points, perform the following once at each preset frequency point: control each transmitting antenna to transmit the amplitude and phase calibration signal corresponding to the preset frequency point, obtain the calibration signal to be analyzed at the preset frequency point, and use the phase information of the calibration signal to be analyzed to obtain the amplitude and phase calibration data at the preset frequency point.

6. The method according to claim 1, characterized in that, The plurality of target antennas includes at least one target transmitting antenna and at least one target receiving antenna, and the method further includes: The coupling calibration signal received by the target receiving antenna in an anechoic environment is obtained, and the coupling calibration signal is transmitted by the target transmitting antenna in an anechoic environment. The coupling compensation data of the target antenna array is obtained based on the coupling calibration signal received by the target receiving antenna.

7. The method according to claim 1, characterized in that, The plurality of target antennas includes at least one target transmitting antenna and at least one target receiving antenna, and the method further includes: Detection echo data is obtained by using the detection echo signals received by each of the target receiving antennas, wherein the detection echo signals are the echo signals of the detection signals transmitted by each of the target transmitting antennas in a time-division manner; The detection echo data is calibrated using the detection calibration data to obtain the imaging data, wherein the detection calibration data includes the amplitude and phase calibration data; The image is obtained by imaging using the data to be imaged.

8. The method according to claim 7, characterized in that, The detection calibration data further includes real-time calibration data; the target antenna array includes at least one set of reference networks, the reference network including a reference transmitting antenna, a reference receiving antenna, and an attenuation network connected between the reference transmitting antenna and the reference receiving antenna, the reference transmitting antenna and the reference receiving antenna belonging to the same region in the target antenna array, and before calibrating the detection echo data using the detection calibration data to obtain the imaging data, the method further includes: The real-time calibration data for the target antenna array is obtained by using reference echo signals received by the reference receiving antennas in at least one set of the reference network, wherein the reference echo signals are the echo signals of the reference signals transmitted by the reference transmitting antennas.

9. The method according to claim 8, characterized in that, The step of obtaining the real-time calibration data about the target antenna array using reference echo signals received by at least one set of reference receiving antennas in the reference network includes: For each of the reference networks, the phase of the reference echo signal received by the reference receiving antenna is calculated to obtain the sixth phase information of the reference echo signal received by the reference receiving antenna in the reference network. Based on the sixth phase information and the seventh phase information corresponding to the attenuation network, the real-time calibration data for the target antenna array is obtained. The real-time calibration data is used to calibrate the inherent error of the target antenna array during the current detection process.

10. The method according to claim 7, characterized in that, Before calibrating the detection echo data using the detection calibration data to obtain the imaging data, the method further includes: The detected echo data is preprocessed, including filtering and / or weight adjustment, wherein the weight adjustment is used to set corresponding weights for the target receiving antenna at different locations; and / or, The process of using the data to be imaged to obtain the detection image includes: The imaging area is gridded; The occupancy state and scattering coefficient of each grid in the imaging region are calculated based on the imaging data. The detection image is obtained based on the occupancy state and scattering coefficient of each grid in the imaging region.

11. The method according to claim 7, characterized in that, The detection signal includes detection signals corresponding to several preset frequency points; and / or, the detection calibration data also includes coupling compensation data.

12. An antenna calibration system, characterized in that, The antenna array includes an antenna array structure and a calibration device, wherein the calibration device is used to perform the antenna array calibration method according to any one of claims 1-11 to calibrate a plurality of target antennas in the antenna array structure, the antenna array structure being disposed on a plane, and the antenna array structure comprising: Multiple receiving antenna groups are arranged at a first distance along a first direction. Each receiving antenna group includes multiple receiving antennas arranged along a second direction. The spacing between adjacent receiving antenna pairs near the two ends of the receiving antenna group is smaller than the spacing between adjacent receiving antenna pairs far from the two ends of the receiving antenna group. Multiple transmitting antenna groups are arranged between at least one pair of receiving antenna groups. The two receiving antenna groups included in different pairs of receiving antenna groups are all different. There are at least two transmitting antenna groups between each pair of receiving antenna groups and they are arranged at a second distance along the second direction. Each transmitting antenna group includes multiple transmitting antennas arranged at intervals along the first direction. The second distance is greater than the interval between adjacent receiving antenna pairs in the receiving antenna group.

13. The system according to claim 12, characterized in that, The number of receiving antenna pairs is at least two, and the plurality of transmitting antenna pairs are divided into several antenna groups. Each antenna group contains a transmitting antenna group between each of the receiving antenna pairs, and the transmitting antenna groups contained in each antenna group are arranged along the first direction. And / or, the spacing between adjacent receiving antenna pairs in the receiving antenna group is positively correlated with the distance between the adjacent receiving antenna pairs and the two ends of the receiving antenna group.

14. The system according to claim 12, characterized in that, The plurality of transmitting antenna groups are divided into several antenna groups, each antenna group containing one transmitting antenna group between each pair of receiving antenna groups, and the distance between adjacent transmitting antenna groups in the antenna group is 4mm; And / or, the first distance is 136 mm; And / or, the second distance is 136 mm; And / or, the spacing between adjacent receiving antenna pairs in the receiving antenna group is greater than 2 mm.

15. An antenna array, characterized in that, The antenna array is the antenna array structure included in the system according to any one of claims 12-14.

16. A calibration device, characterized in that, The method includes a memory and a processor coupled to each other, the processor being used to execute program instructions stored in the memory to implement the antenna array calibration method according to any one of claims 1-11.

17. A computer-readable storage medium having program instructions stored thereon, characterized in that, When the program instructions are executed by the processor, they implement the antenna array calibration method according to any one of claims 1-11.

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