Near-field amplitude and phase calibration method, system and device for active phased array radar antenna

Abstract

The specification discloses a near-field amplitude and phase calibration method, system and device of an active phased array radar antenna, relates to the technical field of phased array radar antenna calibration, and aims to solve the problem of poor robustness of the prior art in near-field calibration of the phased array radar antenna.The method comprises the following steps: performing plane scanning on each transmission channel one by one to obtain amplitude values and phase values of each transmission channel of the phased array radar antenna; calculating errors of the amplitude values and the phase values, and calibrating each transmission channel based on the errors; judging whether plane scanning needs to be performed again, if not, calculating amplitude values and phase values of a to-be-tested transmission channel; obtaining amplitude values and phase values of a reference array surface corresponding to the to-be-tested transmission channel, calculating errors between the amplitude values and the phase values, and recalibrating the to-be-tested transmission channel based on the errors.The method improves the compensation accuracy and efficiency of the radar antenna directional diagram, and solves the problem of poor robustness of amplitude and phase calibration of the active phased array radar antenna.

Description

Technical Field

[0001] This document relates to the field of phased array radar antenna calibration technology, and in particular to a near-field amplitude and phase calibration method, system, and equipment for an active phased array radar antenna. Background Technology

[0002] Active phased array radar antennas consist of numerous radiating elements. The T / R (transmit / receive) components of each connecting element can independently change the amplitude and phase of the transmitted and received signals, forming multiple directional beams in a very short time. Due to its flexible beam control capabilities, as well as advantages in signal gain, anti-interference, and spatial resolution, it can effectively improve the radar equipment's ability to perform large-area rapid search, high-precision detection, and all-weather operation. With the widespread application of active phased array radars in various fields such as weaponry, meteorological detection, marine surveillance, and civil aviation in my country, the performance evaluation of phased array antennas used for transmitting and receiving radar signals in these systems is becoming increasingly stringent. The antenna pattern is one of the most important performance characteristics of a phased array antenna. By rapidly changing the beam direction of the antenna pattern, the antenna can scan the spatial domain according to a preset pattern, thereby achieving the operational performance of the radar equipment.

[0003] Active phased array radars often suffer from amplitude and phase consistency errors due to various factors such as manufacturing tolerances, assembly errors, component inconsistencies, channel losses, and inter-element coupling. Amplitude and phase consistency error refers to the difference between the actual sampled amplitude and phase parameters and the preset values ​​when the phased array antenna radiates signals in each channel. This error causes radiation pattern distortion, alters beam pointing, and consequently reduces antenna performance, failing to meet performance requirements.

[0004] Therefore, the amplitude and phase consistency of each channel in an active phased array antenna directly determines the final radiation performance of the antenna product. It is necessary to calibrate the amplitude and phase consistency of the active phased array radar antenna to obtain the initial amplitude and phase distributions of the antenna array channels. Based on this, an amplitude and phase compensation table for the array channels is obtained to compensate for the initial amplitude and phase values ​​of the channels, improving the accuracy and efficiency of the antenna pattern. On the one hand, the first step in the performance debugging of each phased array antenna product is the calibration of the channel amplitude and phase. The amplitude and phase data obtained after calibration are used to compensate the antenna, ensuring that the antenna elements operate at the same amplitude and phase to form an equiphase surface. All subsequent antenna pattern synthesis data is based on this equiphase surface. Therefore, the measurement of the antenna amplitude and phase consistency can directly assess whether the antenna has achieved the calibration objective, which is beneficial for achieving excellent overall performance. On the other hand, after long-term storage or use in complex electromagnetic environments, active phased array antennas may develop channel amplitude and phase consistency errors, leading to differences in product performance compared to when they left the factory. This necessitates conducting antenna amplitude and phase consistency calibration again to determine whether the product meets the conditions for continued use.

[0005] In engineering practice, the near-field scanning method is commonly used to calibrate the amplitude and phase consistency of phased array radar antennas. The near-field calibration method has advantages such as low cost, high accuracy, and large information capacity. This method is simple to operate and allows for real-time monitoring of the channel under test via computer. However, the near-field scanning method typically ignores the mutual coupling effect between array elements, making it difficult to accurately correct the amplitude and phase consistency error of the channel.

[0006] To address the aforementioned calibration challenges, this invention proposes a near-field amplitude and phase calibration method for active phased array radar antennas. Summary of the Invention

[0007] This specification provides a near-field amplitude and phase calibration method for an active phased array radar antenna, which solves the problem that the existing technology uses the near-field scanning method to perform near-field calibration of the phased array radar antenna. However, the near-field scanning method usually ignores the mutual coupling effect between array elements, making it difficult to accurately correct the amplitude and phase consistency error of the channel, resulting in poor calibration robustness. The method includes the following steps.

[0008] Step S100: Adjust the phased array radar antenna to be calibrated to work in single-channel mode, and use the microwave probe in the near-field amplitude and phase calibration system of the active phased array radar antenna to perform planar scanning on each transmission channel in turn to obtain the amplitude value and phase value of each transmission channel of the phased array radar antenna as the first amplitude value and the first phase value.

[0009] Step S200: Based on the preset beam control mapping table, calculate the errors between the first amplitude value and the second amplitude value, and between the first phase value and the second phase value, and calibrate each transmission channel based on the errors; the second amplitude value and the second phase value are the preset amplitude value and phase value in the beam control mapping table, respectively.

[0010] Step S300: Determine whether the number of transmission channels whose error between the first amplitude value and the second amplitude value is greater than a set amplitude error threshold is less than a set number threshold and whether the number of transmission channels whose error between the first phase value and the second phase value is greater than a set phase error threshold is less than a set number threshold. If yes, proceed to step S400; otherwise, proceed to step S100.

[0011] Step S400: Adjust the transmission channel of the phased array radar antenna to be in multi-channel operation, change the phase of the transmission channel under test by the phase shifter of the phased array radar antenna and measure the amplitude change value of the signal, calculate the amplitude value and phase value of the transmission channel under test based on the amplitude change value, and use them as the third amplitude value and the third phase value.

[0012] Step S500: Obtain the amplitude and phase values ​​of the reference array corresponding to the transmission channel under test, and use them as the fourth amplitude and fourth phase values. Calculate the errors between the fourth amplitude value and the third amplitude value, and between the fourth phase value and the third phase value, and recalibrate the transmission channel under test based on the errors.

[0013] In some preferred embodiments, the beam control mapping table includes the amplitude value, phase value, sub-board number, power-on number, DA number, channel number, and coordinates of the transmission channel.

[0014] In some preferred embodiments, a process of calibrating the microwave probe in the near-field amplitude and phase calibration system of the active phased array radar antenna is included before step S100:

[0015] Acquire the laser measurement device, the microwave probe to be calibrated, and the reference antenna; wherein the reference antenna is a 1GHz to 18GHz reference antenna;

[0016] The laser measuring device measures the three-dimensional coordinate data of the reference antenna and the microwave probe, and corrects the relative position of the scanning frame and the reference antenna, thereby completing the spatial position calibration of the scanning frame and the reference antenna; the scanning frame is used to mount the microwave probe.

[0017] After calibration, the microwave probe scans the reference antenna according to the preset scanning trajectory, and the microwave probe is calibrated based on the scanning data.

[0018] In some preferred embodiments, the phase of the transmission channel under test is changed by a phase shifter of the phased array radar antenna, and the amplitude change value of the signal is measured. The amplitude value and phase value of the transmission channel under test are calculated based on the amplitude change value. The method is as follows:

[0019] According to the rotating vector method, the final vector transformation of all antenna elements of a phased array radar antenna is: If the phase of the transmission channel under test changes by Δ, then... Change to

[0020]

[0021] in, This represents the vector change of the nth antenna element;

[0022] Define the relative amplitude k and relative phase X of the array element as follows:

[0023]

[0024]

[0025] electric field vector and The power ratings are as follows:

[0026]

[0027] Where, Y2=(cosX-k)2+sin2X、 As Δ changes, the electric field vector and The power ratio function exhibits both maximum and minimum values:

[0028]

[0029]

[0030] Where γ is the power ratio of the maximum signal to the minimum signal;

[0031] Based on the power ratio of the maximum and minimum signals, the relative amplitude k and relative phase X are obtained, and then the amplitude and phase values ​​of the current antenna element are calculated.

[0032] In some preferred embodiments, when the power ratio of the maximum signal to the minimum signal is positive, the relative amplitude k and the relative phase X are obtained as follows:

[0033]

[0034]

[0035]

[0036] In some preferred embodiments, when the power ratio of the maximum signal to the minimum signal is negative, the relative amplitude k and the relative phase X are obtained as follows:

[0037]

[0038]

[0039] The second aspect of this specification proposes a near-field amplitude and phase calibration system for an active phased array radar antenna. The near-field amplitude and phase calibration system is installed in a semi-anechoic chamber and includes: an amplitude and phase calibration hardware system, a high-precision near-field scanning system, a turntable control system, and a phased array antenna measurement and control system; the amplitude and phase calibration hardware system, the high-precision near-field scanning system, the turntable control system, and the phased array antenna measurement and control system are connected via a communication link.

[0040] The amplitude and phase calibration hardware system includes a vector network analyzer and a microwave probe; the microwave probe is positioned opposite to the phased array radar antenna to be calibrated; the vector network analyzer is connected to both the microwave probe and the phased array radar antenna to be calibrated.

[0041] The amplitude and phase calibration hardware system is used to transmit, receive, and measure radio frequency signals during the calibration process.

[0042] The high-precision near-field scanning system includes a high-precision scanning frame and a near-field scanning control device; the microwave probe is mounted on the high-precision scanning frame; the near-field scanning control device is connected to the high-precision scanning frame.

[0043] The high-precision near-field scanning system is used to move the high-precision scanning frame according to the set scanning trajectory through the near-field scanning control device, and to perform planar near-field scanning of each transmission channel of the phased array radar antenna to be calibrated through a microwave probe.

[0044] The turntable control system comprises a three-dimensional turntable and a turntable control device; the phased array radar antenna to be calibrated is placed on the three-dimensional turntable.

[0045] The turntable control system is used to rotate the three-dimensional turntable through the turntable control device to realize the angle rotation measurement of the phased array radar antenna transmission channel.

[0046] The phased array antenna measurement and control system includes an industrial control computer and an antenna unit control device; the industrial control computer is connected to the antenna unit control device, the near-field scanning control device, and the vector network analyzer.

[0047] The phased array antenna measurement and control system is used to control the movement of the high-precision scanning frame and the scanning of the microwave probe, control the phase shifter to change the phase of the transmission channel to be measured, control the phased array radar antenna to be calibrated to operate in single-channel or multi-channel mode, and obtain the amplitude and phase values ​​of each transmission channel of the phased array radar antenna, thereby realizing the secondary calibration of the phased array radar antenna.

[0048] In some preferred embodiments, the positioning accuracy of the high-precision scanning frame is below λ / 50, where λ represents the wavelength of the phased array radar antenna radiated signal.

[0049] A third aspect of this specification provides an electronic device, comprising at least one processor, and a memory communicatively connected to at least one of the processors, wherein the memory stores instructions executable by the processor to implement the aforementioned near-field amplitude and phase calibration method for an active phased array radar antenna.

[0050] In a fourth aspect of this specification, a computer-readable storage medium is provided, the computer-readable storage medium storing computer instructions for execution by the computer to implement the above-described near-field amplitude and phase calibration method for an active phased array radar antenna.

[0051] The above-described at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0052] This invention improves the accuracy and efficiency of radar antenna pattern compensation and solves the problem of poor amplitude and phase calibration robustness of active phased array radar antennas.

[0053] 1) This invention achieves the calibration of the amplitude and phase consistency of phased array antenna channels by constructing a near-field calibration system in a microwave anechoic chamber to measure the phased array antenna. Based on the amplitude and phase consistency calibration requirements of each element of the phased array radar antenna, and the advantages and characteristics of the near-field calibration method, an active phased array antenna near-field amplitude and phase calibration system is constructed to achieve rapid and accurate calibration of the amplitude and phase consistency error of the phased array radar. A high-precision near-field scanning platform is used for measurement. The amplitude and phase of the electromagnetic wave radiation are changed using the antenna element measurement and control system. Then, the amplitude and phase parameters of each channel, i.e., the amplitude and phase distribution of the entire array, are obtained through a decoupling algorithm. Measurement errors during the calibration process are analyzed and compensated, ultimately achieving calibration of the array surface and improving calibration robustness.

[0054] 2) This invention employs a near-field scanning method and a rotating vector method to perform two calibrations on the phased array antenna, improving the compensation accuracy and efficiency of the radar antenna pattern, thereby solving the amplitude and phase calibration problem of active phased array radar antennas. Furthermore, in the near-field planar scanning calibration method, a scanning frame device is designed to ensure precise trajectory movement. A laser measurement system is used to calibrate the spatial positions of the scanning frame and the antenna under test. A beam control mapping table in the calibration system is set to determine the power-on sequence of the TR module channels and the movement position of the scanning frame, further improving calibration efficiency. Attached Figure Description

[0055] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0056] Figure 1 This is a flowchart illustrating a near-field amplitude and phase calibration method for an active phased array radar antenna provided in one embodiment of this specification.

[0057] Figure 2 A schematic diagram of the framework of a near-field amplitude and phase calibration system for an active phased array radar antenna provided in one embodiment of this specification;

[0058] Figure 3 A schematic diagram illustrating the principle of the rotation vector method provided in one embodiment of this specification;

[0059] Figure 4 A schematic diagram of the curve of the combined power as a function of phase Δ provided in one embodiment of this specification;

[0060] Figure 5 This is a schematic diagram of the structure of a computer system suitable for implementing an electronic device according to an embodiment of this specification. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0062] The technical solutions provided by various embodiments of this application are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0063] This invention provides a near-field amplitude and phase calibration method for an active phased array radar antenna, such as... Figure 1 As shown, the method includes the following steps;

[0064] Step S100: Adjust the phased array radar antenna to be calibrated to work in single-channel mode, and use the microwave probe in the near-field amplitude and phase calibration system of the active phased array radar antenna to perform planar scanning on each transmission channel in turn to obtain the amplitude value and phase value of each transmission channel of the phased array radar antenna as the first amplitude value and the first phase value.

[0065] Step S200: Based on the preset beam control mapping table, calculate the errors between the first amplitude value and the second amplitude value, and between the first phase value and the second phase value, and calibrate each transmission channel based on the errors; the second amplitude value and the second phase value are the preset amplitude value and phase value in the beam control mapping table, respectively.

[0066] Step S300: Determine whether the number of transmission channels whose error between the first amplitude value and the second amplitude value is greater than a set amplitude error threshold is less than a set number threshold and whether the number of transmission channels whose error between the first phase value and the second phase value is greater than a set phase error threshold is less than a set number threshold. If yes, proceed to step S400; otherwise, proceed to step S100.

[0067] Step S400: Adjust the transmission channel of the phased array radar antenna to be in multi-channel operation, change the phase of the transmission channel under test by the phase shifter of the phased array radar antenna and measure the amplitude change value of the signal, calculate the amplitude value and phase value of the transmission channel under test based on the amplitude change value, and use them as the third amplitude value and the third phase value.

[0068] Step S500: Obtain the amplitude and phase values ​​of the reference array corresponding to the transmission channel under test, and use them as the fourth amplitude and fourth phase values. Calculate the errors between the fourth amplitude value and the third amplitude value, and between the fourth phase value and the third phase value, and recalibrate the transmission channel under test based on the errors.

[0069] To more clearly illustrate the near-field amplitude and phase calibration method for the active phased array radar antenna of the present invention, the steps of one embodiment of the method of the present invention will be described in detail below with reference to the accompanying drawings.

[0070] In the following embodiments, the near-field amplitude and phase calibration system of the active phased array radar antenna is first described in detail, and then the near-field amplitude and phase calibration method of the active phased array radar antenna is described in detail.

[0071] A near-field amplitude and phase calibration system for an active phased array radar antenna according to a first embodiment of the present invention:

[0072] This invention establishes a near-field amplitude and phase calibration system for active phased array antennas, achieving rapid and accurate calibration of amplitude and phase consistency errors in phased array radars. A high-precision near-field scanning platform is used for measurement. The amplitude and phase of electromagnetic wave radiation are altered using an antenna element measurement and control system. Then, the amplitude and phase parameters of each channel, i.e., the amplitude and phase distribution of the entire array, are obtained through a decoupling calibration method. Measurement errors during the calibration process are analyzed and compensated, ultimately achieving array calibration. The product under test is a phased array radar antenna, preferably with an 8×8 array size, an element spacing of 10mm, and an array size of 120mm×120mm. Figure 2 As shown. Specifically:

[0073] The near-field amplitude and phase calibration system is set up in a semi-anechoic chamber and includes: an amplitude and phase calibration hardware system, a high-precision near-field scanning system, a turntable control system, and a phased array antenna measurement and control system; the amplitude and phase calibration hardware system, the high-precision near-field scanning system, the turntable control system, and the phased array antenna measurement and control system are connected through a communication link;

[0074] The amplitude and phase calibration hardware system includes a vector network analyzer and a microwave probe; the microwave probe is positioned opposite to the phased array radar antenna to be calibrated; the vector network analyzer is connected to both the microwave probe and the phased array radar antenna to be calibrated.

[0075] The amplitude and phase calibration hardware system is used to transmit, receive, and measure radio frequency signals during the calibration process.

[0076] In this embodiment, an existing vector network analyzer is used as a signal transceiver. The scanning probe (i.e., microwave probe) is connected to the signal receiving device, and the phased array radar antenna under test is connected to the antenna unit measurement and control device. The amplitude and phase information between the scanning probe and the phased array radar antenna under test are measured and calculated.

[0077] The high-precision near-field scanning system includes a high-precision scanning frame and a near-field scanning control device; the microwave probe is mounted on the high-precision scanning frame; the near-field scanning control device is connected to the high-precision scanning frame.

[0078] The high-precision near-field scanning system is used to move the high-precision scanning frame according to the set scanning trajectory through the near-field scanning control device, and to perform planar near-field scanning of each transmission channel of the phased array radar antenna to be calibrated through a microwave probe.

[0079] In this embodiment, testing the phased array radar antenna under test requires a precision scanning frame carrying a microwave probe to scan each array element individually. In engineering practice, this necessitates the construction of a high-precision planar scanning device. Accurate positioning and measurement are its two primary functions. The most significant factor affecting test accuracy is the positioning accuracy of the probe during the scanning process. A high-precision scanning frame is needed to improve calibration accuracy. In this invention, the positioning accuracy of the high-precision scanning frame is preferably set to below λ / 50, where λ represents the wavelength of the radiated signal from the phased array radar antenna.

[0080] To ensure precise trajectory movement of the scanning gantry, a miniaturized, high-precision on-site scanning device (i.e., a high-precision scanning gantry) is employed. This device meets the requirements for on-site installation space and scanning stroke range calibration. The scanning device performs two-dimensional scanning motion, primarily along the horizontal X-axis and vertical Y-axis. Each axis is controlled by its own drive controller. During operation, each axis can work simultaneously or independently under its respective control system. The planned horizontal X-axis stroke is 0.6m, and the planned vertical Y-axis stroke is 0.6m. The straightness of the probe's trajectory facing the incoming wave direction is better than 0.03mm, with a positioning accuracy of 0.03mm. The polarization axis rotates continuously for 360° with a positioning accuracy of 0.1°. Both the horizontal X-axis and vertical Y-axis consist of a welded base, linear guides, ball screws, nuts, planetary reducers, linear magnetic scales, AC servo motors, cable chains, and adjustment mechanisms. They feature simple configuration, high rigidity, and high cost-effectiveness. Each axis is machined integrally to ensure the required flatness, straightness, and other precision indicators for installation. The horizontal motion components initially use HSR20A ball linear guides as the motion support components; the vertical motion also uses HSR20A ball linear guides as the motion support components. The horizontal and vertical motion ball screw pairs are ground ball screws (precision grade C1). The planetary reducers, linear magnetic scales, AC servo motors, and cable chains are all sourced from internationally renowned manufacturers, ensuring reliable quality. During operation, the motor drives the planetary reducer, which in turn drives the gears to push the rack and pinion to achieve linear motion. Simultaneously, the linear magnetic scale attached to the base acts as a feedback element to achieve a fully closed loop, ensuring positioning accuracy. The overall structure is leveled using feet, ensuring that the probe antenna mounting surface moves within a sufficient range of flatness accuracy.

[0081] The near-field scanning control device can establish the scanning coordinate system for each array element and simultaneously control the spatial trajectory scanning. Intelligent software guides the probe to complete the near-field scan along a preset trajectory, and then error correction is performed based on the measured results.

[0082] The turntable control system comprises a three-dimensional turntable and a turntable control device; the phased array radar antenna to be calibrated is placed on the three-dimensional turntable.

[0083] The turntable control system is used to rotate the three-dimensional turntable through the turntable control device to realize the angle rotation measurement of the phased array radar antenna transmission channel.

[0084] In this embodiment, the turntable control system can realize the pitch adjustment and channel alignment of the phased array radar antenna array. When calibrating and decoupling the phased array antenna based on the near-field scanning method and the rotating vector method, the turntable is required to support the phased array radar antenna under test and control the spatial position of the antenna in order to obtain the amplitude and phase information of the antenna elements.

[0085] The phased array antenna measurement and control system includes an industrial control computer and an antenna unit control device; the industrial control computer is connected to the antenna unit control device, the near-field scanning control device, and the vector network analyzer.

[0086] The phased array antenna measurement and control system is used to control the movement of the high-precision scanning frame and the scanning of the microwave probe, control the phase shifter to change the phase of the transmission channel to be measured, control the phased array radar antenna to be calibrated to operate in single-channel or multi-channel mode, and obtain the amplitude and phase values ​​of each transmission channel of the phased array radar antenna, thereby realizing the secondary calibration of the phased array radar antenna.

[0087] In this embodiment, the phased array antenna measurement and control system is the control center of the phased array antenna. Its main functions are to execute commands sent by the signal processor, calculate and distribute antenna element amplitude and phase values, and issue power-on control signals, thereby achieving antenna element calibration, antenna beamforming, and transmit / receive control. The measurement and control system implements product functions through the control, communication, and beamforming calculation interfaces of the programmable logic device (FPGA) with the signal processor and TR components. It features high control accuracy, fast beam switching time, and short response time, meeting various application requirements. The main functions of the phased array antenna measurement and control system are as follows:

[0088] 1) Serial communication function with signal processor: Receive commands from signal processor such as beam pointing control, phased array power-on / off, version query, and temperature query, and send commands such as temperature feedback and version feedback.

[0089] 2) Communication with TR component: When the measurement and control system controls the amplitude, phase and power-on of the TR component, it generates the transmission clock, serial control code, enable signal and latch signal required by the communication protocol and transmits them to the TR component to realize the phase shift attenuation control and power-on / off control of the TR component.

[0090] 3) Command parsing function: After the measurement and control system correctly receives a command frame, it parses the command code of the command according to the command protocol with the signal processor, generates the enable signal of the corresponding functional module, such as angle command enable, power-on enable, temperature query enable, mode switching control enable, etc., and sends the corresponding information in the command to the corresponding processing module.

[0091] 4) Angle calculation function: After receiving the angle command sent by the signal processor through the synchronous serial port, the measurement and control system performs angle calculation to obtain the calculated phase of each channel of the entire array. The phase is quantized according to the phase accuracy of the TR component and sent to the TR component to realize the beam pointing control of the entire array.

[0092] 5) Power control function: After receiving the power-on / power-off command sent by the signal processing, the measurement and control system software will power on / off the corresponding channel of the TR component.

[0093] 6) Temperature Query Function: The measurement and control system cyclically reads and stores the temperature chip data according to the communication protocol of the temperature chip. Upon receiving a temperature query command, the system sends the read data to the signal processor according to the communication protocol with the signal processor.

[0094] 7) Version query function: After receiving the version query command sent by the signal processor, perform version return operation.

[0095] It should be noted that the near-field amplitude and phase calibration system for the active phased array radar antenna provided in the above embodiments is only an example of the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the modules or steps in the embodiments of the present invention can be further decomposed or combined. For example, the modules in the above embodiments can be merged into one module, or further divided into multiple sub-modules to complete all or part of the functions described above. The names of the modules and steps involved in the embodiments of the present invention are only for distinguishing the various modules or steps and are not considered as an improper limitation of the present invention.

[0096] A near-field amplitude and phase calibration method for an active phased array radar antenna according to a second embodiment of the present invention:

[0097] The antenna is a core component of an active phased array radar system. The antenna pattern is one of the most important performance characteristics of a phased array antenna. By rapidly changing the beam direction of the antenna pattern, the antenna can scan the spatial domain according to a preset pattern, thereby achieving the operational performance of the radar equipment. Amplitude and phase inconsistencies in radar antenna elements, TR components, and radar transceiver channels can cause radiation pattern distortion, altering the beam direction and consequently reducing antenna performance, making it unable to meet performance requirements.

[0098] Planar near-field scanning measurement technology obtains amplitude and phase information at various points within a plane range by scanning the antenna at a specific distance from the antenna under test. Near-field calibration uses a scanning frame to scan the antenna array, and then obtains the amplitude and phase parameters of each channel, i.e., the amplitude and phase distribution of the entire array, through a decoupling algorithm, thereby achieving array calibration. The main advantage of the near-field calibration system is its small measurement distance and low requirement for test space. This invention considers that phased array antennas operate with multiple channels simultaneously, and that single-channel amplitude and phase calibration methods easily overlook coupling interference between channels. To analyze and reduce the impact of mutual coupling effects between array elements on the amplitude and phase characteristics calibration of the antenna array, a secondary calibration of the antenna transmitting channel is required based on the near-field scanning method. The antenna is adjusted to operate under multi-channel conditions, and the operation of a single array element of the phased array antenna is analyzed, as follows:

[0099] Step S100: Adjust the phased array radar antenna to be calibrated to work in single-channel mode, and use the microwave probe in the near-field amplitude and phase calibration system of the active phased array radar antenna to perform planar scanning on each transmission channel in turn to obtain the amplitude value and phase value of each transmission channel of the phased array radar antenna as the first amplitude value and the first phase value.

[0100] In this embodiment, the amplitude and phase parameters of each channel are first measured and compensated sequentially using the near-field scanning method. During the calibration process, only the independent effect of each array element is considered, and the antenna channels are calibrated sequentially using the antenna near-field measurement equipment.

[0101] Before calibration, the beam control mapping table of the calibration system must be set up, as shown in Table 1. The data row and data list indicate the row and column in the beam control mapping table where the data in that row is located. The sub-board number, power-on number, DA number, and channel number define the power-on sequence of the TR module channels, determined by the phased array antenna array and the TR module definition. The X and Y coordinates determine the movement position of the scanning frame, determined by the antenna array distribution. The beam control mapping table also includes amplitude and phase values, but these are not shown in the table below.

[0102] Table 1

[0103]

[0104] Connect the vector network analyzer, scanning frame, and waveguide. After successful connection, configure the parameters of the scanning frame and vector network analyzer. Vector network analyzer configuration parameters include frequency, power, intermediate frequency bandwidth, number of scan frequencies, and S-parameters. Define the calibration origin according to the waveguide mapping table and perform origin positioning to ensure the distance from the antenna array under test to the waveguide aperture is 3–5 wavelengths. During calibration, the scanning frame automatically scans according to the waveguide mapping table (coordinates X, Y). The near-field calibration system measures, records, and calculates the error between the actual sampling angle and the preset value.

[0105] Then, the spatial position measurement of the alignment between the antenna under test and the probe's geometric center is performed. Using the spatial coordinates of the laser measurement device, the measuring probe, and the antenna under test, the relative position and attitude of the scanning frame and antenna are corrected using the three-dimensional orientation data (i.e., three-dimensional coordinate data) of the antenna and probe from the laser measurement system, thus completing the motion trajectory for planar near-field scanning. Before scanning, the laser measurement system calibrates the spatial positions of the scanning frame and the antenna under test, establishes a coordinate system through data analysis, presets the scanning trajectory according to the measurement method, and finally completes the scanning trajectory. Before testing, the scanning probe needs to be calibrated using a 1GHz–18GHz reference antenna to ensure measurement accuracy.

[0106] The process of calibrating the microwave probe in the near-field amplitude and phase calibration system of an active phased array radar antenna includes:

[0107] Acquire the laser measurement device, the microwave probe to be calibrated, and the reference antenna; wherein the reference antenna is a 1GHz to 18GHz reference antenna;

[0108] The laser measuring device measures the three-dimensional coordinate data of the reference antenna and the microwave probe, and corrects the relative position of the scanning frame and the reference antenna, thereby completing the spatial position calibration of the scanning frame and the reference antenna; the scanning frame is used to mount the microwave probe.

[0109] After calibration, the microwave probe scans the reference antenna according to the preset scanning trajectory, and the microwave probe is calibrated based on the scanning data.

[0110] Step S200: Based on the preset beam control mapping table, calculate the errors between the first amplitude value and the second amplitude value, and between the first phase value and the second phase value, and calibrate each transmission channel based on the errors; the second amplitude value and the second phase value are the preset amplitude value and phase value in the beam control mapping table, respectively.

[0111] In this embodiment, abnormal channels are screened and compensated by measuring the amplitude and phase differences from the beam control to the antenna in the transmission channel. Preset amplitude values ​​a0 and phase values ​​q0 are assigned to 64 channels using a beam control mapping table for measurement. Channels 1 through 64 of the transmitter are sequentially turned on, with other channels turned off while testing each channel, resulting in 64 sets of amplitude and phase test data a. i q i (i = 1, 2, 3... 64). The amplitude difference and phase difference of each channel are calculated sequentially, and the calculation formula is as follows:

[0112] ΔP i =a i -a0 (1)

[0114] Δφ i =qi -q0 (2)

[0116] Where, ΔP i , Δφ i These represent the errors between the first amplitude value and the second amplitude value, and between the first phase value and the second phase value of the i-th channel, respectively.

[0117] Step S300: Determine whether the number of transmission channels whose error between the first amplitude value and the second amplitude value is greater than a set amplitude error threshold is less than a set number threshold and whether the number of transmission channels whose error between the first phase value and the second phase value is greater than a set phase error threshold is less than a set number threshold. If yes, proceed to step S400; otherwise, proceed to step S100.

[0118] In this embodiment, if all channels under test meet the amplitude and phase consistency requirements in Table 2, the next step of inter-channel amplitude and phase consistency measurement can be performed; otherwise, the channel is deemed to have an abnormal calibration, and the amplitude or phase difference is compensated in the wave control table of that channel. The test is then repeated until all channels under test meet the requirements. Six different preset amplitude and phase values ​​are selected to ensure that all channels under test meet the amplitude and phase consistency requirements.

[0119] Table 2

[0120] Serial Number Amplitude consistency requirements Phase consistency requirements 1 Amplitude difference ≤ 0.5dB Phase difference ≤ 5° 2 Number of abnormal channels <2% Number of abnormal channels <2%

[0121] Step S400: Adjust the transmission channel of the phased array radar antenna to be in multi-channel operation, change the phase of the transmission channel under test by the phase shifter of the phased array radar antenna and measure the amplitude change value of the signal, calculate the amplitude value and phase value of the transmission channel under test based on the amplitude change value, and use them as the third amplitude value and the third phase value.

[0122] In this embodiment, considering that the phased array antenna operates with multiple channels simultaneously, the single-channel amplitude and phase calibration method easily overlooks the coupling interference between channels. To analyze and reduce the impact of mutual coupling effects between array elements on the amplitude and phase characteristics calibration of the antenna array, a secondary calibration of the antenna transmitting channel is required based on the near-field scanning method. This adjusts the antenna to operate under multi-channel conditions, allowing for analysis of the operation of a single array element. The rotating vector method is used for the secondary calibration of the antenna transmitting channel. The principle of the rotating vector method is as follows: Figure 3 As shown. Specifically:

[0123] The rotating vector method alters the phase of the channel under test (DUT) using a phase shifter, and then calculates the actual amplitude and phase of the DUT by measuring the signal amplitude change. To ensure the actual operating state of the DUT, the antenna elements surrounding it also remain operational. According to the rotating vector method, the final vector change synthesized by all antenna elements of the phased array radar antenna is: If the phase of the transmission channel under test changes by Δ, then... Change to

[0124]

[0125] in, This represents the vector change of the nth antenna element;

[0126] Define the relative amplitude k and relative phase X of the array element as follows:

[0127]

[0128]

[0129] electric field vector and The power ratings are as follows:

[0130]

[0131] Where, Y2=(cosX-k)2+sin2X、 As can be seen from the expression for the electric field vector power ratio, its power satisfies the cosine function, such as... Figure 4 As shown.

[0132] As Δ changes, the electric field vector and The power ratio function exhibits both maximum and minimum values:

[0133]

[0134]

[0135] Wherein, γ is the power ratio of the maximum signal to the minimum signal, and its result can be obtained directly through testing, and the value of γ is greater than 1;

[0136] Based on the power ratio of the maximum and minimum signals, the relative amplitude k and relative phase X are obtained, and then the amplitude and phase values ​​of the current antenna element are calculated.

[0137] When the power ratio of the maximum signal to the minimum signal is positive, the relative amplitude k and the relative phase X are obtained as follows:

[0138]

[0139]

[0140]

[0141] When the power ratio of the maximum signal to the minimum signal is negative, the relative amplitude k and the relative phase X are obtained as follows:

[0142]

[0143]

[0144] The initial amplitude and phase of the antenna element are calculated using the relative amplitude k and relative phase X. The phase of the next element is then changed, and the initial amplitude and phase are calculated based on the signal received by the microwave probe. This process is repeated until all elements are calibrated, and calibration data is loaded to compensate for the amplitude and phase parameters. Three phase parameter change values ​​Δ are selected based on the number of phase shifters for calibration. The measurement data is processed to calibrate its amplitude and phase to match the reference array surface. In summary, two calibration methods are proposed to correct the amplitude and phase consistency error between array elements. A secondary calibration technique using the rotating vector method is investigated to reduce the impact of mutual coupling on the array.

[0145] Step S500: Obtain the amplitude and phase values ​​of the reference array corresponding to the transmission channel under test, and use them as the fourth amplitude and fourth phase values. Calculate the errors between the fourth amplitude value and the third amplitude value, and between the fourth phase value and the third phase value, and recalibrate the transmission channel under test based on the errors.

[0146] In this embodiment, the rotating vector method changes the phase of the channel under test by a phase shifter, and then calculates the amplitude and phase of the channel under test by measuring the signal amplitude change. To ensure the actual working state of the channel under test, the antenna elements around the antenna element under test also remain in working state. The reference array is an equiphase surface of the plane where the microwave probe is located, obtained from preset values, calibrating the signals of all channels to the same plane to form the same phase.

[0147] The inter-channel amplitude and phase consistency error of the phased array antenna surface after secondary calibration was measured. Amplitude values ​​a0 and phase values ​​q0 were preset for 64 channels using a waveguide mapping table. The transmitter channels 1 through 64 were turned on sequentially for testing, with other channels turned off during the test of each channel, resulting in 64 sets of amplitude and phase test data a. i q i (i = 1, 2, 3...64). Taking channel 1 as the reference channel, the amplitude difference and phase difference of channels 2, 3, 4...64 relative to the reference channel are calculated in sequence. The amplitude consistency error and phase consistency error between channels are calculated as follows.

[0148] The amplitude consistency error of the i-th channel:

[0149] ΔP i =|a i -a1| (14)

[0150] Where i = 2, 3, 4, ..., 64.

[0151] Phase consistency error of the i-th channel:

[0152] Δφ i =|q i -q1| (15)

[0153] Where i = 2, 3, 4, ..., 64.

[0154] The amplitude consistency error and phase consistency error of the remaining channels after calibration are calculated sequentially using the method described above, and the maximum amplitude and phase consistency error between channels is calculated using the following formula.

[0155] Antenna array amplitude consistency error:

[0156] ΔP=max{ΔPi} (16)

[0157] Where i = 2, 3, 4, ..., 64.

[0158] Antenna array phase consistency error:

[0159] Δφ=max{Δφi} (17)

[0160] Where i = 2, 3, 4, ..., 64.

[0161] A third embodiment of the present invention provides an electronic device comprising at least one processor and a memory communicatively connected to at least one of the processors, wherein the memory stores instructions executable by the processor for implementing the above-described near-field amplitude and phase calibration method for an active phased array radar antenna.

[0162] A computer-readable storage medium according to a fourth embodiment of the present invention stores computer instructions, which are executed by the computer to implement the above-described near-field amplitude and phase calibration method for an active phased array radar antenna.

[0163] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process and related descriptions of the electronic devices and computer-readable storage media described above can be referred to the corresponding processes in the foregoing method examples, and will not be repeated here.

[0164] The following is for reference. Figure 5 It shows a schematic diagram of the structure of a computer system suitable for implementing the system embodiments of this application. Figure 5 The server shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0165] like Figure 5 As shown, the computer system includes a Central Processing Unit (CPU) 501, which can perform various appropriate actions and processes based on programs stored in Read Only Memory (ROM) 502 or programs loaded from storage section 508 into Random Access Memory (RAM) 503. RAM 503 also stores various programs and data required for system operation. The CPU 501, ROM 502, and RAM 503 are interconnected via bus 504. Input / output (I / O) interface 505 is also connected to bus 504.

[0166] The following components are connected to I / O interface 505: an input section 506 including a keyboard, mouse, etc.; an output section 507 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and speakers, etc.; a storage section 508 including a hard disk, etc.; and a communication section 509 including a network interface card such as a LAN (Local Area Network) card, modem, etc. The communication section 509 performs communication processing via a network such as the Internet. A drive 510 is also connected to I / O interface 505 as needed. Removable media 511, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., are installed on drive 510 as needed so that computer programs read from them can be installed into storage section 508 as needed.

[0167] Specifically, according to embodiments of this disclosure, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this disclosure include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 509, and / or installed from removable medium 511. When the computer program is executed by central processing unit (CPU) 501, it performs the functions defined in the methods of this application. It should be noted that the computer-readable medium described above in this application can be a computer-readable signal medium or a computer-readable storage medium, or any combination of the two. A computer-readable storage medium can be, for example—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in connection with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium can also be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on a computer-readable medium can be transmitted using any suitable medium, including but not limited to: wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0168] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0169] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0170] The terms “first”, “second”, etc., are used to distinguish similar objects, not to describe or indicate a specific order or sequence.

[0171] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0172] The technical solution of the present invention has now been described in conjunction with the preferred embodiments shown in the accompanying drawings.

[0173] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A near-field amplitude and phase calibration method for an active phased array radar antenna, applied to a near-field amplitude and phase calibration system for an active phased array radar antenna, characterized in that, The method includes the following steps: Step S100: Adjust the phased array radar antenna to be calibrated to work in single-channel mode, and use the microwave probe in the near-field amplitude and phase calibration system of the active phased array radar antenna to perform planar scanning on each transmission channel in turn to obtain the amplitude value and phase value of each transmission channel of the phased array radar antenna as the first amplitude value and the first phase value. Step S200: Based on the preset beam control mapping table, calculate the errors between the first amplitude value and the second amplitude value, and between the first phase value and the second phase value, and calibrate each transmission channel based on the errors; the second amplitude value and the second phase value are the preset amplitude value and phase value in the beam control mapping table, respectively. Step S300: Determine whether the number of transmission channels whose error between the first amplitude value and the second amplitude value is greater than a set amplitude error threshold is less than a set number threshold and whether the number of transmission channels whose error between the first phase value and the second phase value is greater than a set phase error threshold is less than a set number threshold. If yes, proceed to step S400; otherwise, proceed to step S100. Step S400: Adjust the transmission channel of the phased array radar antenna to be in multi-channel operation, change the phase of the transmission channel under test by the phase shifter of the phased array radar antenna and measure the amplitude change value of the signal, calculate the amplitude value and phase value of the transmission channel under test based on the amplitude change value, and use them as the third amplitude value and the third phase value. Step S500: Obtain the amplitude and phase values ​​of the reference array corresponding to the transmission channel under test, and use them as the fourth amplitude and fourth phase values. Calculate the errors between the fourth amplitude value and the third amplitude value, and between the fourth phase value and the third phase value, and recalibrate the transmission channel under test based on the errors.

2. The near-field amplitude and phase calibration method for an active phased array radar antenna according to claim 1, characterized in that, The beam control mapping table includes the amplitude value, phase value, sub-board number, power-on number, DA number, channel number, and coordinates of the transmitting channel.

3. The near-field amplitude and phase calibration method for an active phased array radar antenna according to claim 1, characterized in that, Before step S100, the process also includes calibrating the microwave probe in the near-field amplitude and phase calibration system of the active phased array radar antenna: Acquire the laser measurement device, the microwave probe to be calibrated, and the reference antenna; wherein the reference antenna is a 1GHz to 18GHz reference antenna; The laser measuring device measures the three-dimensional coordinate data of the reference antenna and the microwave probe, and corrects the relative position of the scanning frame and the reference antenna, thereby completing the spatial position calibration of the scanning frame and the reference antenna; the scanning frame is used to mount the microwave probe. After calibration, the microwave probe scans the reference antenna according to the preset scanning trajectory, and the microwave probe is calibrated based on the scanning data.

4. The near-field amplitude and phase calibration method for an active phased array radar antenna according to claim 1, characterized in that, The phase of the transmitted channel under test is changed by a phase shifter in a phased array radar antenna, and the amplitude change of the signal is measured. The amplitude and phase values ​​of the transmitted channel under test are then calculated based on the amplitude change. The method is as follows: According to the rotating vector method, the final vector transformation of all antenna elements of a phased array radar antenna is: If the phase of the transmission channel under test changes by Δ, then Change to in, This represents the vector change of the nth antenna element; Define the relative amplitude k and relative phase X of the array element as follows: electric field vector and The power ratings are as follows: in, , As Δ changes, the electric field vector and The power ratio function exhibits both maximum and minimum values: Where γ is the power ratio of the maximum signal to the minimum signal; Based on the power ratio of the maximum and minimum signals, the relative amplitude k and relative phase X are obtained, and then the amplitude and phase values ​​of the current antenna element are calculated.

5. The near-field amplitude and phase calibration method for an active phased array radar antenna according to claim 4, characterized in that, When the power ratio of the maximum signal to the minimum signal is positive, the relative amplitude k and the relative phase X are obtained as follows: 。 6. The near-field amplitude and phase calibration method for an active phased array radar antenna according to claim 5, characterized in that, When the power ratio of the maximum signal to the minimum signal is negative, the relative amplitude k and relative phase X are obtained as follows: 。 7. A near-field amplitude and phase calibration system for an active phased array radar antenna for implementing the method of any one of claims 1-6, characterized in that, The near-field amplitude and phase calibration system is set up in a semi-anechoic chamber and includes: an amplitude and phase calibration hardware system, a high-precision near-field scanning system, a turntable control system, and a phased array antenna measurement and control system; the amplitude and phase calibration hardware system, the high-precision near-field scanning system, the turntable control system, and the phased array antenna measurement and control system are connected through a communication link; The amplitude and phase calibration hardware system includes a vector network analyzer and a microwave probe; the microwave probe is positioned opposite to the phased array radar antenna to be calibrated; the vector network analyzer is connected to both the microwave probe and the phased array radar antenna to be calibrated. The amplitude and phase calibration hardware system is used to transmit, receive, and measure radio frequency signals during the calibration process. The high-precision near-field scanning system includes a high-precision scanning frame and a near-field scanning control device; the microwave probe is mounted on the high-precision scanning frame; the near-field scanning control device is connected to the high-precision scanning frame. The high-precision near-field scanning system is used to move the high-precision scanning frame according to the set scanning trajectory through the near-field scanning control device, and to perform planar near-field scanning of each transmission channel of the phased array radar antenna to be calibrated through a microwave probe. The turntable control system comprises a three-dimensional turntable and a turntable control device; the phased array radar antenna to be calibrated is placed on the three-dimensional turntable. The turntable control system is used to rotate the three-dimensional turntable through the turntable control device to realize the angle rotation measurement of the phased array radar antenna transmission channel. The phased array antenna measurement and control system includes an industrial control computer and an antenna unit control device; the industrial control computer is connected to the antenna unit control device, the near-field scanning control device, and the vector network analyzer. The phased array antenna measurement and control system is used to control the movement of the high-precision scanning frame and the scanning of the microwave probe, control the phase shifter to change the phase of the transmission channel to be measured, control the phased array radar antenna to be calibrated to operate in single-channel or multi-channel mode, and obtain the amplitude and phase values ​​of each transmission channel of the phased array radar antenna, thereby realizing the secondary calibration of the phased array radar antenna.

8. The near-field amplitude and phase calibration system for an active phased array radar antenna according to claim 7, characterized in that, The positioning accuracy of the high-precision scanning frame is below λ / 50, where λ represents the wavelength of the phased array radar antenna radiated signal.

9. An electronic device, characterized in that, include: At least one processor; and a memory communicatively connected to at least one of the processors; The memory stores instructions that can be executed by the processor to implement the near-field amplitude and phase calibration method for the active phased array radar antenna according to any one of claims 1-6.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that are executed by the computer to implement the near-field amplitude and phase calibration method for the active phased array radar antenna according to any one of claims 1-6.

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