Method for testing the directional diagram of a satellite-borne SAR phased array antenna and related equipment

Abstract

This invention discloses an automated method and related equipment for testing the radiation pattern of a spaceborne SAR phased array antenna, relating to the field of spaceborne SAR active phased array antenna testing technology. The method includes: receiving a position signal from the scanning probe control system; generating a corresponding radio frequency (RF) test excitation signal based on the scanning probe's position signal; controlling the RF test excitation signal to be output via the calibration port or microwave combination port of the SAR central processing unit, and simultaneously controlling the operating state of the spaceborne SAR phased array antenna to transmit or receive mode, thereby forming a self-closed-loop test link between the scanning probe and the spaceborne SAR phased array antenna; acquiring amplitude and phase data of the spaceborne SAR phased array antenna at multiple wavelengths through the self-closed-loop test link; and processing the amplitude and phase data to generate the radiation pattern of the spaceborne SAR phased array antenna. This invention can efficiently generate high-quality radiation patterns.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of satellite-borne SAR active phased array antenna testing, and particularly relates to a method for automatically testing the directional diagram of a satellite-borne SAR phased array antenna and related equipment. BACKGROUND

[0002] During the development and testing of a satellite-borne synthetic aperture radar (SAR) system, it is essential and costly to accurately and efficiently test the radiation performance of the core component, i.e., the satellite-borne SAR phased array antenna. The traditional testing method relies heavily on a large microwave anechoic chamber and a complex external instrument system. This process not only requires a large investment in equipment, but also is complicated and time-consuming, and has become a key link affecting the development progress and cost control of the entire satellite.

[0003] Currently, the existing technical solution commonly used in the industry consists of a microwave shielding anechoic chamber and an antenna near-field testing system. The antenna near-field testing system is a highly integrated automatic measurement system, which specifically includes a mechanical subsystem, a radio frequency subsystem, a control subsystem, antenna measurement software, and system accessories. Its composition principle is as follows: under the unified control of a central computer, a scanning probe is driven to accurately scan and collect data in a three-dimensional space close to the antenna array surface, and then the collected near-field data is converted into far-field radiation characteristics through a specific antenna testing algorithm, so as to identify whether the working performance of the antenna meets the standard. During testing, for the active phased array antenna as the measured object, the directional diagram test needs to be performed separately for the receiving directional diagram and the transmitting directional diagram. The test software needs to coordinate the control of the scanning frame controller, the dedicated beam controller, the vector network analyzer, and other hardware devices to work together. Taking the receiving directional diagram test as an example, the vector network analyzer needs to transmit the parameter measurement state, the 1-port is connected to the scanning probe and transmits a signal, and the 2-port is connected to the TR component of the antenna to receive the signal; the signal radiated by the probe is received by the antenna and returned to the vector network analyzer for measurement. After the scanning frame drives the probe to complete the scanning of the entire antenna array surface, the data logger records the original data, and finally the directional diagram result is generated by the data analysis and processing software of the anechoic chamber. The transmitting directional diagram test needs to interchange the devices connected to the two ports of the vector network analyzer based on the above connection, and rely on the pulse transmission function of the vector network analyzer to simulate the real working mode of the SAR antenna.

[0004] However, this prior art solution has several significant objective shortcomings. First, the hardware and software costs required for testing are extremely high. The core instrument of the entire system is a high-end vector network analyzer with pulse transmission function, which usually costs more than one million yuan; in addition, a special beam controller with a price of hundreds of thousands of yuan is also required, as well as a series of special software for device cooperative control, data acquisition and analysis, and the comprehensive cost burden is heavy. Second, the professional skills of the test personnel are required. The operator must have a deep understanding of the working principle and operation method of complex instruments such as vector network analyzer, and needs long-term professional training and practical exercise to be competent. Third, the software and hardware maintenance and damage repair time is long, and the risk is big. The system involves many devices, which increases the failure probability. Once the precision instrument such as vector network analyzer fails, the manufacturer's repair cycle is usually 10 working days; the fault repair of special software may also cause several days of work stagnation, which will seriously threaten the tight schedule of the whole satellite development.

[0005] Therefore, in view of the problems of high cost, complex operation and test efficiency being subject to external equipment in the existing satellite-borne SAR phased array antenna pattern test method, there is an urgent need for a new method that can utilize the resources of the SAR system itself, significantly reduce the cost and improve the test reliability. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art, and specifically provides an automatic satellite-borne SAR phased array antenna pattern test method and related equipment, as follows: 1) In a first aspect, the present application provides an automatic satellite-borne SAR phased array antenna pattern test method, and the specific technical solution is as follows: Receive the position-to-position signal of the scanning probe from the scanning frame control system; generate the corresponding radio frequency test excitation signal according to the position-to-position signal of the scanning probe; control the radio frequency test excitation signal to be output via the scaling port or the microwave combination port of the SAR central processor, and simultaneously control the working state of the satellite-borne SAR phased array antenna to be in the transmission mode or the receiving mode, so as to form a self-closed loop test link between the scanning probe and the satellite-borne SAR phased array antenna; through the self-closed loop test link, the amplitude and phase data of the satellite-borne SAR phased array antenna at multiple wave positions are collected; the amplitude and phase data are processed to generate the pattern of the satellite-borne SAR phased array antenna.

[0007] The automatic satellite-borne SAR phased array antenna pattern test method provided by the present application has the following beneficial effects: This significantly reduces hardware and software costs for testing. By utilizing the SAR central processing unit to generate RF test excitation signals and constructing a self-closed-loop test link including calibration and microwave combination ports, it completely eliminates reliance on external vector network analyzers and dedicated beam controllers, saving expensive equipment procurement costs. It simplifies the testing process and reduces the professional skills required of personnel. The testing process is synchronously triggered by the scanning probe's position signal, eliminating the need for test personnel to be proficient in operating complex external instruments, reducing training time and difficulty. It improves the reliability and availability of the testing system, reducing the risk of test interruptions due to external equipment failures. Since the core signal generation and acquisition functions are built into the SAR system, reliance on external precision instruments is reduced, thereby lowering the overall system failure rate and maintenance waiting time. It improves the accuracy and efficiency of test results. The RF test excitation signal is generated by the SAR system itself, more closely resembling the actual operating signal; the self-closed-loop test link simultaneously acquires amplitude and phase data of the spaceborne SAR phased array antenna at multiple wavelengths, enabling efficient generation of high-quality radiation patterns.

[0008] Based on the above scheme, the automated spaceborne SAR phased array antenna pattern testing method of the present invention can be further improved as follows.

[0009] Furthermore, before receiving the position signal of the scanning probe from the scanning rig control system, the process also includes: setting the scanning range, scanning step and scanning speed of the scanning probe, and starting the scanning probe to scan the array surface of the spaceborne SAR phased array antenna along a predetermined trajectory.

[0010] The advantages of adopting the above-mentioned further solution are as follows: By precisely setting the scanning range, scanning step, and scanning speed of the scanning probe in advance, and controlling the probe to move along a predetermined trajectory, an accurate physical spatial foundation is laid for the entire automated test. This ensures the uniform distribution and complete coverage of near-field data acquisition points, enabling subsequent amplitude and phase data to accurately reflect the radiation field distribution of the antenna across the entire array. Simultaneously, automated trajectory movement replaces manual adjustment, improving test consistency and repeatability, reducing errors introduced by improper human operation, and providing a prerequisite for the automation and efficient execution of the entire test process.

[0011] Furthermore, through a self-closed-loop test link, amplitude and phase data of the spaceborne SAR phased array antenna at multiple wavelengths are collected, including: as the scanning probe arrives at each scanning position in sequence according to the scanning probe's position signal, for each scanning position, based on the radio frequency test excitation signal, the AD module of the SAR central processor and the data logger synchronously record the signal amplitude and signal phase data of the spaceborne SAR phased array antenna under multiple pre-set different wavelength configurations.

[0012] The beneficial effects of adopting the above-mentioned further scheme are: it enables the synchronous recording of signal amplitude and phase data under multiple pre-set different waveform configurations during a pause at a single scan position. This method makes full use of the settling time of each scan point, completing the data acquisition of multiple logical waveforms with a single physical pause, avoiding the huge time overhead of repeatedly performing mechanical scans for each waveform. This not only improves the efficiency of radiation pattern testing by several times, but also ensures that the data of different waveforms are acquired under exactly the same spatial location and environmental conditions, greatly enhancing the consistency and accuracy of comparative analysis between radiation pattern results of different waveforms.

[0013] Furthermore, the amplitude and phase data are processed to generate the radiation pattern of the spaceborne SAR phased array antenna, including: performing a near-field data to far-field radiation pattern transformation calculation on the signal amplitude data and signal phase data at multiple acquired wavelengths, and generating the amplitude radiation pattern of the spaceborne SAR phased array antenna based on the transformation calculation results.

[0014] The beneficial effects of adopting the above-mentioned further scheme are as follows: by performing rigorous mathematical transformation calculations from near-field data to far-field radiation patterns, the directly acquired near-field amplitude and phase data are transformed into an intuitive far-field amplitude radiation pattern that conforms to engineering standards. This process is based on mature electromagnetic field transformation theories such as plane wave spectrum expansion, ensuring the accuracy and reliability of the derivation from near-field sampling values ​​to far-field radiation characteristics. The final generated amplitude radiation pattern is output in a standardized graphical or data format, providing a direct basis for directly evaluating key radiation performance indicators such as the main lobe width and sidelobe level of the antenna, completing the closed-loop processing from raw data to final usable conclusions.

[0015] 2) In a second aspect, the present invention also provides an automated spaceborne SAR phased array antenna pattern testing system, the specific technical solution of which is as follows: It includes a signal receiving module, a signal generation module, a control module, an acquisition module, and a radiation pattern generation module. The signal receiving module is used to receive the position signal of the scanning probe from the scanning gantry control system. The signal generation module is used to generate the corresponding radio frequency test excitation signal based on the position signal of the scanning probe. The control module is used to control the output of the radio frequency test excitation signal through the calibration port or microwave combination port of the SAR central processor, and simultaneously control the working state of the spaceborne SAR phased array antenna to transmit mode or receive mode, so as to form a self-closed-loop test link between the scanning probe and the spaceborne SAR phased array antenna. The acquisition module is used to acquire the amplitude and phase data of the spaceborne SAR phased array antenna at multiple spectral positions through the self-closed-loop test link. The radiation pattern generation module is used to process the amplitude and phase data and generate the radiation pattern of the spaceborne SAR phased array antenna.

[0016] Based on the above scheme, the automated spaceborne SAR phased array antenna pattern testing method of the present invention can be further improved as follows.

[0017] Furthermore, it also includes a setting module, which is used to: set the scanning range, scanning step and scanning speed of the scanning probe before receiving the position signal of the scanning probe from the scanning rig control system, and start the scanning probe to scan the array surface of the spaceborne SAR phased array antenna along a predetermined trajectory.

[0018] Furthermore, the acquisition module is specifically used to: during the process of the scanning probe arriving at each scanning position in sequence according to the scanning probe's position signal, for each scanning position, based on the radio frequency test excitation signal, through the AD module of the SAR central processor and the data logger, synchronously record the signal amplitude data and signal phase data of the spaceborne SAR phased array antenna under multiple pre-set different wave position configurations.

[0019] Furthermore, the radiation pattern generation module is specifically used to: perform near-field data to far-field radiation pattern transformation calculations on the signal amplitude data and signal phase data collected at multiple wave positions, and generate the amplitude radiation pattern of the spaceborne SAR phased array antenna based on the transformation calculation results.

[0020] 3) In a third aspect, the present invention also provides an electronic device, the electronic device including a processor coupled to a memory, the memory storing at least one computer program, the at least one computer program being loaded and executed by the processor, so as to enable the electronic device to implement any of the above-mentioned automated spaceborne SAR phased array antenna pattern testing methods.

[0021] 4) In a fourth aspect, the present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements any of the above-described automated spaceborne SAR phased array antenna pattern testing methods.

[0022] It should be noted that the beneficial effects of the technical solutions of the second to fourth aspects of the present invention and their corresponding possible implementations can be found in the above description of the technical effects of the first aspect and its corresponding possible implementations, and will not be repeated here. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below: Figure 1 This is a flowchart illustrating an automated spaceborne SAR phased array antenna pattern testing method according to an embodiment of the present invention. Figure 2 This is one of the structural schematic diagrams of an automated spaceborne SAR phased array antenna pattern testing system according to an embodiment of the present invention; Figure 3This is a schematic diagram of the antenna transmission pattern testing process; Figure 4 This is a schematic diagram of the antenna reception pattern testing process; Figure 5 A schematic diagram of data acquisition in self-closed-loop transmission mode; Figure 6 A schematic diagram of data acquisition in self-closed-loop receiving mode; Figure 7 This is a schematic diagram of the amplitude distribution of multi-wavelength transmission. Figure 8 This is a schematic diagram of the amplitude distribution of multi-wavelength receivers; Figure 9 This is the second schematic diagram of an automated spaceborne SAR phased array antenna pattern testing system according to an embodiment of the present invention. Detailed Implementation

[0024] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0025] The technical solution of the present invention and how the technical solution of the present invention solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0026] like Figure 1 As shown in the figure, an automated method for testing the radiation pattern of a spaceborne SAR phased array antenna according to an embodiment of the present invention includes the following steps: S1. Receive the position signal of the scanning probe from the scanning gantry control system; The scanning gantry control system is a mechatronic system used to drive and control the scanning probe to move precisely and automatically within a microwave anechoic chamber. This system is a key actuator in planar near-field testing, its core function being to move the scanning probe precisely and smoothly to a series of specified spatial coordinate points according to a preset scanning trajectory and parameters. The scanning gantry control system typically consists of the following sub-components working together: a high-precision multi-axis mechanical structure, such as a precision guide rail and slide consisting of X, Y, Z axes and a rotary axis; servo motors or stepper motors and their matching drivers to provide motion power; a motion control card or programmable logic controller (PLC), serving as the control core, responsible for receiving commands from the host computer, executing motion planning algorithms, and driving the motors; and position feedback sensors, such as grating rulers or encoders, for real-time, high-precision measurement of the actual position of each axis and forming closed-loop control. During testing, the scanning gantry control system receives scanning parameter commands from the host computer software and controls the scanning probe to move along a specific trajectory, such as a serpentine trajectory, covering the surface of the tested satellite-borne SAR phased array antenna at a set speed and step distance, providing a spatial position basis for subsequent data acquisition.

[0027] The scanning probe's position arrival signal is a specific digital level signal generated and output by the scanning gantry control system. Physically, this signal signifies that after completing a step movement, the scanning probe has actually reached the pre-calculated target scanning position, mechanical vibration has attenuated, and the probe is in a stable state, ready to begin transmitting or receiving radio frequency signals at that point. This signal is a crucial timing handshake signal for synchronization between the motion control logic within the scanning gantry control system and the external SAR test system. Its generation mechanism relies on the processing of real-time feedback data from high-precision position sensors within the scanning gantry control system. When the system determines that the deviation between the probe's actual position and the commanded target position is less than a preset, extremely small tolerance threshold, it considers the position "in place." At this point, the control system outputs a pulse signal that transitions from low to high or from high to low as the scanning probe's position arrival signal through a dedicated digital input / output interface. This signal ensures a strict correspondence between the radio frequency data acquisition action and the probe's spatial position, a necessary condition for guaranteeing the accuracy of the sampling points in the near-field scanning test space.

[0028] The specific implementation process of S1 is as follows: S10. Before the test begins, the operator uses the host computer software of the scanning gantry control system to set the scanning parameters for the specific spaceborne SAR phased array antenna. These parameters include the scanning range, which is determined by the physical dimensions of the antenna array and the angle of the beam under test; and the scanning step distance. For example, setting it to 2 cm determines the density of spatial sampling points; and the scanning speed. After the settings are complete, start the scanning program. The motion controller inside the scanning gantry control system calculates the coordinates of the next target point of the scanning probe in real time based on these parameters and the pre-stored serpentine trajectory algorithm. And drive the servo motor to move the probe toward that point.

[0029] S11. During the probe's movement, the scanning frame control system continuously reads the probe's actual spatial coordinates through its integrated high-precision grating ruler. The control system calculates the Euclidean distance deviation between the actual position and the target position. The system has a preset minimum position error threshold. Typically on the order of micrometers. When the probe approaches the target point, the servo system enters the fine positioning phase. Once the system detects the condition... Established and lasted for a short period of time For example, after 50 milliseconds to confirm that the mechanical vibration has subsided and the probe has stabilized, the motion control card or programmable logic controller of the scanning gantry control system will trigger one of its digital output channels to generate a scanning probe position signal. This signal is typically a transition from a low level to a high level, and its level standard may be TTL or differential signal.

[0030] S12. The position signal of the scanning probe generated from the digital output port of the scanning gantry control system is transmitted via cable. Depending on the electrical interface, a signal conversion step may be required. For example, if the output is a differential signal, it needs to be converted to a single-ended TTL level signal through a differential receiver circuit. This conversion function is usually integrated into an interface adapter device called a SAR ground test fixture. The converted single-ended position signal of the scanning probe is directly connected to a specific digital input interface board of the SAR central processing unit via cable. The input circuit on the SAR central processing unit's interface board electrically isolates and shapes the signal before sending it to the general-purpose input / output pins or dedicated interrupt pins of its main control unit, such as the Atmel SAM V71 chip. At this point, the SAR system has completed a reliable reception of the position signal of the scanning probe from the scanning gantry control system. This signal will serve as a precise synchronization clock reference to trigger the SAR system to begin RF excitation and data acquisition at that scanning point.

[0031] S2. Based on the position signal of the scanning probe, generate the corresponding RF test excitation signal. The specific implementation process is as follows: The interface board of the S20 SAR central processing unit continuously monitors the level status of its dedicated digital input pins. When a valid transition occurs in the position signal of the scanning probe relayed from the SAR ground test fixture, the level detection circuit on the interface board immediately captures this event. This signal transition is converted into an interrupt request or a high-priority event and sent to the main control unit of the SAR central processing unit. The main control unit, which can be an Atmel SAM V71 chip, responds to this interrupt and reads the context information associated with the interrupt, including whether the current test mode is a transmit pattern test or a receive pattern test, and the pre-loaded set of spectral configuration parameters corresponding to the current scan point.

[0032] S21. Based on the waveform configuration parameters corresponding to the interrupt trigger time, the main control unit commands its internal digital signal processor or dedicated waveform generation logic to calculate the corresponding digital baseband signal sequence. The digital baseband signal sequence is a discrete-time sequence, denoted as... , where index , representing discrete time points, This is the total number of sampling points within one pulse period. (Sequence) The values ​​include the pulse envelope shape, phase encoding, and amplitude and phase weighting information applied to a specific antenna element. Waveform configuration parameters include the range scan angle. Azimuth scanning angle Distance-weighted coefficients and azimuth weighting coefficient ,in and The antenna subarrays or elements are indexed separately in the range and azimuth directions. The generation of the digital baseband signal sequence can be represented by a functional relationship: ,function The specific design is determined by the radar signal waveform. The calculated sequence... It is written at high speed into the cache of the data converter interface.

[0033] S22, Digital Baseband Signal Sequence It is fed into the high-speed digital-to-analog converter module. The digital-to-analog converter operates at a constant clock frequency. Run, to process discrete numerical sequences Converted into a time-continuous analog baseband signal The conversion process can be represented as: ,in, It is the clock cycle of the digital-to-analog converter. The function reflects the effect of the reconstruction filter inside the digital-to-analog converter. Analog baseband signal. It is usually a low-frequency signal with its spectrum concentrated near zero frequency.

[0034] S23, Analog baseband signal The signal is fed into the modulator or upconverter at the RF front end. The upconverter modulates the baseband signal onto a stable intermediate frequency (IF) local oscillator (LOO) signal. The IF OSO signal is... ,in, It is the intermediate frequency. This is the initial phase. The modulated signal becomes... This intermediate frequency signal The frequency is then boosted by cascading one or more frequency multipliers. If the frequency multiplier has a multiplication factor of 1... Then the carrier frequency of the output signal becomes The frequency multiplication process also amplifies the phase noise of the signal, therefore a low-phase-noise initial oscillation source needs to be selected. After frequency multiplication and bandpass filtering, the radio frequency signal is obtained. Its center frequency is Bandwidth and original baseband signal It is directly proportional to the bandwidth.

[0035] S24, Radio frequency signal The power level is relatively low and needs to be amplified by a power amplifier. The power amplifier provides power gain. (Usually expressed in decibels), and operates in the linear region to avoid signal distortion. The amplified signal is the final RF test excitation signal, denoted as... Meanwhile, the main control unit controls an RF switch matrix according to the current test mode. If the system is performing a transmit pattern test, the RF switch matrix will apply the RF test excitation signal. Connect to the microwave combination port of the SAR central processing unit. If the system is performing a receive pattern test, the RF switch matrix will transmit the RF test excitation signal. Connect to the calibration port of the SAR central processing unit. Port switching and signal generation are synchronized and coordinated.

[0036] Throughout the process, from receiving the position signal of the scanning probe to the RF test excitation signal... Stable output is achieved at the designated port. All steps are completed in a pipeline under strict timing control, with fixed and known delay times, ensuring precise synchronization between signal transmission or reception and the spatial position of the scanning probe. The RF test excitation signal corresponding to each scanning point may vary depending on the waveform configuration, thus enabling the acquisition of multiple waveform data in a single scan.

[0037] The radio frequency (RF) test excitation signal refers to a specific RF signal generated and output by the internal circuitry of the SAR central processing unit (CPU) during the pattern testing of a spaceborne SAR phased array antenna. This signal is used in a closed-loop test link to simulate the electromagnetic wave excitation transmitted or received by a synthetic aperture radar (SAR) system under actual operating conditions. The RF test excitation signal has strictly defined frequency, bandwidth, pulse width, modulation form, and power level, which are preset according to the technical specifications of the antenna under test and the test wave configuration. During testing, this signal is output through the microwave combination port or calibration port of the SAR CPU and connected to the antenna array or scanning probe via an RF coaxial cable to form the radiation or reception conditions required for the test. The characteristics of the RF test excitation signal, such as its phase noise, spectral purity, and amplitude stability, directly affect the accuracy and reliability of the pattern test results. Generating the RF test excitation signal is a key step in the method of this invention, replacing the traditional vector network analyzer in providing test signals.

[0038] S3. The RF test excitation signal is output through the calibration port or microwave combination port of the SAR central processing unit, and the operating state of the spaceborne SAR phased array antenna is simultaneously controlled to transmit mode or receive mode, so as to form a self-closed-loop test link between the scanning probe and the spaceborne SAR phased array antenna. The specific implementation process is as follows: After entering the pattern test cycle, the main control unit of the S30 and SAR central processing unit continuously queries the current global test mode flag. This flag is set by the operator through the host computer software of the SAR ground test fixture during the test initialization phase, with a value of "transmit pattern test" or "receive pattern test". When the scanning probe's position signal triggers a new test cycle, the main control unit first reads this flag. Simultaneously, the main control unit loads the current scan point number from the pre-stored scan point-wavelength mapping table. (in, , Configure parameters for all waveforms associated with the total number of scan points. These parameters include not only those used to generate the waveform. It also includes an antenna operating status control word. and an RF path control word .

[0039] S31, The main control unit controls the signal based on the test mode flag and antenna operating status. This generates a specific sequence of control commands. If the global test mode is set to "Transmit Pattern Test," the command sequence configures the spaceborne SAR phased array antenna to transmit mode. Control commands are sent via the control bus to the beam control unit on the antenna array. These commands precisely control each TR component: turning on the power supply and power amplifier of the transmit channel, turning off the low-noise amplifier of the receive channel, and setting the phase value of the phase shifter to... ,in, This function identifies the row and column positions of antenna elements on the array surface. The formula for calculating the phase required for beamforming is described. If the flag is "Receive Pattern Test," the command sequence configures the antenna to receive mode, commands the TR component to shut down the transmit channel, open the receive channel, and sets the phase shifter phase value according to the requirements of receive beamforming. The transmission and execution of control commands have a defined delay. .

[0040] S32. Synchronizing with the issued antenna command, the main control unit, based on the test mode flag and RF path control word, performs the following actions: This drives the RF switch matrix inside the SAR central processing unit. The RF switch matrix consists of a series of single-pole double-throw or multi-throw RF switches, and its topology ensures that signals can be routed to the correct ports. Define a two-port RF network whose input ports are connected to the RF test excitation signal. The two output ports are respectively connected to the microwave combination port (denoted as port). ) and calibration port (denoted as port) The state of the switch matrix is ​​determined by a Boolean variable. Indicates. When When, it indicates that the switch is in state A; when When this occurs, it indicates that the switch is in state B. The main control unit executes the following logic: if it is a transmission pattern test, then set... ,make Connected to At the same time, ensure Connect the downconverter input to the internal receiver link. For receiver pattern testing, set... ,make Connected to At the same time, ensure The downconverter input is connected to the internal receive link. The switching action is completed within microseconds and generates an "RF path ready" feedback signal.

[0041] S33. The main control unit awaits two key feedback signals: one is the "Antenna Status Ready" signal from the antenna beam control unit, confirming that all TR components have completed mode switching as instructed; the other is the "RF Path Ready" signal from the RF switch matrix. Only when both signals are valid does the main control unit determine that the self-closed-loop test link has been established. At this time, the physical structure of the link is as follows: After confirming the link establishment, the main control unit sends a "link ready" trigger to the data acquisition subsystem, preparing the system to receive the upcoming echo signal data. This completes all control operations in step S3 and lays the foundation for data acquisition in step S4. The entire control process ensures a strict match between the signal path and the antenna operating mode, which is a necessary condition for effective self-closed-loop testing.

[0042] The calibration port of the SAR central processing unit is a dedicated radio frequency (RF) signal port on the synthetic aperture radar (SAR) central processing unit (CPU) board. In normal operating mode of the SAR system, this port is connected to the calibration port of the SAR phased array antenna TR assembly via an RF coaxial cable to receive coupled samples of the transmitted signal from the antenna array for internal amplitude and phase calibration. The calibration port's function is multiplexed. During receive pattern testing, the calibration port acts as the transmit port for the RF test excitation signal, feeding the signal to the scanning probe. During transmit pattern testing, the calibration port acts as the receive port, receiving the electromagnetic wave signal returned from the scanning probe, radiated by the SAR antenna, and propagated through space. The calibration port typically has known and stable impedance characteristics and frequency response, making it a key physical interface for constructing a self-closed-loop test link.

[0043] The microwave combination port is another core radio frequency (RF) signal port on the SAR central processing unit (CPU) board. During normal imaging operation of the SAR system, the microwave combination port serves as the main signal transceiver port, directly connected to the junction port of the SAR phased array antenna TR assembly via an RF coaxial cable, completing the transmission of radar signals and the reception of echo signals. In the test method of this invention, the role of the microwave combination port is reconfigured. During transmit pattern testing, the microwave combination port acts as the transmit port for the RF test excitation signal, feeding the signal to the SAR phased array antenna to radiate electromagnetic waves. During receive pattern testing, the microwave combination port acts as the receive port, receiving electromagnetic wave signals acquired from space by the SAR phased array antenna from the scanning probe. The microwave combination port typically possesses higher power handling capabilities and a wider frequency range.

[0044] The transmit mode refers to the operational state of the spaceborne SAR phased array antenna during testing, configured to actively radiate electromagnetic wave signals into space. In this mode, multiple transmit channels (TRs) of the SAR phased array antenna are controlled to transmit, their internal transmit channel amplifiers are activated, and phase shifters are set to specific phase values ​​to form a beam pointing in a specific direction. The antenna array converts the RF test excitation signal from the SAR central processing unit's microwave port into radiated electromagnetic waves into space. The transmit mode can be further subdivided into full-array transmit mode, where all antenna elements operate simultaneously; or single-TR transmit mode, where only one designated antenna element is controlled at a time for diagnosing its radiation characteristics.

[0045] The receiving mode refers to the operational state of the spaceborne SAR phased array antenna during testing, configured to passively receive electromagnetic wave signals from space. In this mode, multiple TR components of the SAR phased array antenna are controlled in a receiving state, the low-noise amplifiers of its internal receiving channels are activated, and the phase shifters are set to specific phase values ​​to achieve weighted reception of signals from specific directions. The antenna array captures the electromagnetic wave signals propagating from space and converts them into radio frequency electrical signals, which are then transmitted to the microwave combination port of the SAR central processing unit via radio frequency coaxial cable. The receiving mode can also be further subdivided into full-array receiving mode or single-TR receiving mode.

[0046] A self-closed-loop test link refers to a closed-loop path within the test system that utilizes the SAR system's own hardware resources to generate, radiate, propagate, receive, and acquire signals, without relying on external signal sources and analysis instruments (such as vector network analyzers). The link begins with the radio frequency (RF) test excitation signal generated within the SAR central processing unit (CPU). Depending on the test type, this signal is output through a calibration port or a microwave combination port. After propagating through the RF cable, scanning probe, or SAR phased array antenna, and the free space between them, the signal is captured by the system's receiving section through another port and ultimately returns to the signal processing and data acquisition module within the SAR CPU. This closed loop achieves "self-transmission and self-reception" of the signal, entirely within the controllable range of the SAR system, thus replacing the open links in traditional testing that rely on expensive external instruments.

[0047] S4. Through a self-closed-loop test link, acquire amplitude and phase data of the spaceborne SAR phased array antenna at multiple wavelengths, specifically including: S40. As the scanning probe arrives at each scanning position sequentially according to the scanning probe's position signal, for each scanning position, based on the radio frequency test excitation signal, the AD module of the SAR central processing unit and the data logger synchronously record the signal amplitude and signal phase data of the spaceborne SAR phased array antenna under multiple pre-set different wave position configurations. The specific implementation process is as follows: S400, when the Once the position signal of each scanning probe is captured and processed by the main control unit of the SAR central processing unit, and the self-closed-loop test link established in step S3 is ready, the main control unit initiates a data acquisition cycle. This cycle corresponds to the scanning probe stabilizing at the current scanning position. The time window. The main control unit sends a global synchronization pulse to the waveform generation, RF switch, antenna beam control, and data acquisition subsystems, marking the start of data acquisition for a new scan point.

[0048] S401. Within a data acquisition cycle, the system needs to traverse sequentially. Multiple pre-defined different waveform configurations. The main control unit sets a waveform index. The initial value is 1. For each wave position Perform the following steps: ①The main control unit will... Parameter set for each wave position configuration Loading to the waveform generator and antenna beam controller. ② Transmit excitation and antenna configuration: System generation and beam position. Corresponding RF test excitation signal The system then controls the antenna to switch to the corresponding transmit or receive mode for that wavelength. This process reuses the logic of steps S2 and S3, but is repeated rapidly within a single scan point. ③ The signal is transmitted through the established self-closed-loop test link and captured by the receiver after propagation through space. ④ The signal received by the receiver (either the calibration port or the microwave combination port, depending on the test mode). It enters the downconversion link and is converted to an intermediate frequency analog signal. We are preparing to digitize it.

[0049] S402, intermediate frequency analog signal The data is fed into the analog-to-digital converter (ADC) of the SAR central processing unit. The ADC operates at a predetermined high sampling rate. The signal is sampled. The sampling process can be represented as follows: ,in, It is the sampling interval. This is the number of sampling points acquired in this transaction, determined by the pulse width and sampling rate. This represents the quantization function. It is a complex sequence (usually obtained through I / Q quadrature downconversion, or through digital quadrature demodulation after sampling a real signal), whose real and imaginary parts contain the amplitude and phase information of the signal, respectively.

[0050] S403, Digital Sampling Sequence The signal is fed into a digital signal processor or a dedicated amplitude-phase extraction logic circuit. This processing typically includes digital filtering, pulse compression, and peak detection. For each waveform... At each scan point The goal of processing the data is to extract a complex value representing the channel transmission characteristics at that point. : ,in, It is the extracted signal amplitude data. It is the extracted signal phase data. This represents the aforementioned digital signal processing algorithm, such as taking the complex envelope of the signal pulse peak.

[0051] S404, Extracted amount of compound standard (or separated) and ) along with its metadata (scan point index) Wave position index Data (such as timestamps) is immediately sent to the data logger of the SAR central processing unit. With the assistance of the direct memory access controller, the data logger writes this data in a structured format to a non-volatile storage medium, such as... Figure 5 and Figure 6 The table shown is in tabular form. Complete the wave position. After the data is recorded, the main control unit will index the wave position. Increment, repeat the above steps until... That is, complete the current scanning position. All Data acquisition for each wave position.

[0052] S405, when scanning position corresponding Once all wavefront data has been recorded, the main control unit of the SAR central processing unit sends a "data acquisition complete at this point" response signal to the scanning gantry control system. The scanning gantry control system then drives the scanning probe to move to the next scanning position. Once the probe stabilizes again and sends a signal indicating the next scanning probe is in position, a new data acquisition cycle begins. The above steps are repeated until the entire area is covered. Each scan position. Through this rigorous synchronization and looping, a complete sequence containing... A collection of amplitude and phase data from a spaceborne SAR phased array antenna at multiple wavelengths.

[0053] The analog-to-digital converter (ADC) module of the SAR central processing unit is a key hardware unit within the synthetic aperture radar (SAR) central processing unit responsible for converting analog radio frequency (RF) signals into digital signals. This module receives the down-converted analog intermediate frequency (IF) signal returned from the end of the self-closed-loop test link. At its core is a high-speed, high-precision ADC chip that discretizes and quantizes the input continuous analog voltage signal in the time domain at a fixed sampling frequency, generating a sequence of discrete digital sample values. These digital sample values ​​accurately reflect the amplitude and phase information of the original analog signal. The performance parameters of the ADC module, such as sampling rate, resolution (bit depth), and effective bit depth, directly affect the acquisition accuracy and fidelity of amplitude and phase data from the spaceborne SAR phased array antenna at multiple wavelengths.

[0054] The data logger of the SAR central processing unit (CPU) is a massive storage and caching subsystem within or tightly coupled to the CPU. Its function is to receive and store the digital sampled value stream output from the analog-to-digital converter (ADC) in real time and in an orderly manner, forming raw data files for subsequent processing. The data logger typically consists of a high-speed cache, a direct memory access controller, a large-capacity non-volatile storage medium, and corresponding control logic. During pattern testing, the data logger records the complete sequence of digital signals at each scan point and each wave position, following the order of the scan points. For example... Figure 5 and Figure 6 As shown, the recorded data is organized in the form of a matrix or table, with each row or column associated with a specific scan position and waveform configuration, containing information such as signal amplitude, signal phase, and possible time delay.

[0055] The pre-set multiple different beam configurations refer to a set of parameters that are loaded and stored in the SAR central processing unit's memory by the SAR test system's control software before the test begins. Each beam configuration defines a specific antenna beam state. A beam configuration typically includes the following parameters: range scanning angle. Azimuth scanning angle Distance-to-amplitude weighting coefficient Azimuth amplitude weighting coefficient Range-phase weighting coefficients Azimuth phase weighting coefficient etc., where superscript Indicates the first Each wave position configuration , Configure the total number of wave positions. and Index antenna elements. These configurations simulate the beam pointing and shape of the SAR antenna under different operating scenarios. In step S40, the system needs to quickly apply these multiple different beam configurations sequentially or concurrently within a single scan position, based on the same RF test excitation signal transmission and reception cycle, thereby acquiring multiple sets of radiation pattern data in a single physical scan, greatly improving test efficiency.

[0056] Among them, the amplitude and phase data of the spaceborne SAR phased array antenna at multiple wavelengths refers to a set of measurement results acquired through a self-closed-loop test link. For each spatial scanning position (corresponding to the first) The position signal of each scanning probe), and the first of multiple pre-set different wave position configurations. Each configuration records a pair of values ​​in the data logger: signal amplitude data. and signal phase data Amplitude data This reflects the signal strength or attenuation in the self-closed-loop test link at that scan position and wavelength configuration, typically expressed in volts, milliwatts, or decibels. Phase data It reflects the relative phase delay of the signal, usually measured in radians or degrees. It includes information such as the phase distribution of the antenna array's radiation field, the spatial propagation path difference, and the inherent delay of the circuit. All of these... and The set of (where) , This constitutes the original near-field complex sampling data, i.e., amplitude and phase data, used to reconstruct the far-field radiation pattern of the antenna.

[0057] S5. Process amplitude and phase data to generate the radiation pattern of the spaceborne SAR phased array antenna. Specifically, perform near-field data to far-field radiation pattern transformation calculations on the signal amplitude data and signal phase data at multiple wave positions acquired. Based on the transformation calculation results, generate the amplitude radiation pattern of the spaceborne SAR phased array antenna. The specific implementation process is as follows: S50. First, read the amplitude and phase data of all spaceborne SAR phased array antennas at multiple spectral positions recorded in step S40 from the file stored in the data logger of the SAR central processing unit. The data is organized in matrix or array form. Define a three-dimensional complex array. ,in, , indicates the index of the scan point in the X-axis direction. This indicates the index of the scan point in the Y-axis direction (for planar rectangular raster scanning, the total number of scan points). ), , representing the index of the wave position configuration. Each element of the array is a complex number: ,in, It is signal amplitude data. It is signal phase data. It is the imaginary unit.

[0058] S51. To eliminate errors introduced by the test system itself, the raw near-field complex data needs to be calibrated. This includes removing known system responses, such as the transmission loss of the RF cable, the directivity coefficient of the scanning probe, and the inherent amplitude and phase differences between the calibration port and the microwave combination port. Define a system error function. It is a function of the scan position and frequency. The calibration process is accomplished by dividing the measurement data by (or subtracting from) the systematic error function in the complex domain: ,in, It is a scan point Cartesian coordinates, It is the first Each wave position is configured with a corresponding center frequency. Furthermore, probe position error compensation is required. Based on feedback data from the actual position of the scanning frame, the theoretical coordinates of each scanning point are corrected to ensure the accuracy of the near-field sampling plane.

[0059] S52. Perform the transformation calculation from near-field data to far-field radiation pattern. Specifically, a Fourier transform method based on plane wave spectrum theory is used. Specifically, for each wave position configuration... Process the calibrated near-field complex data matrix (fixed The first sub-step is a two-dimensional discrete Fourier transform. This transforms the data located in the plane... Tangential near-field distribution (proportional to) Transforming to the spatial frequency domain yields the plane wave spectrum. : in, This represents the two-dimensional discrete Fourier transform operator. and It is a spatial frequency variable. and This involves scanning steps in the X and Y directions. The second sub-step is the mapping from the spectral domain to the angular domain. According to electromagnetic wave theory, spatial frequency and far-field observation angle... The relationship is: ,in, It is the operating wavelength. It is the pitch angle (measured from the direction of the normal). It is the azimuth angle.

[0060] Simultaneously, the propagation factor needs to be considered to calculate the far-field electric field from the plane wave spectrum. : ,in, It is the free space wavenumber. It is the distance from the observation point to the antenna origin. It is the tilt factor.

[0061] S53, For each wave position Amplitude pattern function of far-field radiation It is calculated from the amplitude of the far-field electric field. The magnitude of the electric field strength is usually taken as the value. To facilitate analysis and comparison, the amplitude pattern was normalized. Maximum value in the entire corner domain Calculate the normalized amplitude pattern (in decibels): .

[0062] S54, based on the calculation Numerical matrices can be used to generate two-dimensional or three-dimensional graphics. For example, it can generate cross-sections with specific azimuth angles (such as...). The amplitude radiation pattern curve of the upper half of the space can be generated, or a two-dimensional chromaticity map of the entire upper half of the space can be produced. The graph should clearly label key information such as coordinate axes, scales, main lobe width, and side lobe levels. For example... Figure 7 and Figure 8 As shown, these figures visually demonstrate the radiation characteristics of a spaceborne SAR phased array antenna under different wave configurations, thus completing the entire generation process from raw near-field amplitude and phase data to the final amplitude pattern of the spaceborne SAR phased array antenna that can be used for performance evaluation.

[0063] The amplitude pattern of a spaceborne SAR phased array antenna is a graphical representation or dataset used to describe the intensity of the antenna's radiated energy distribution in different spatial directions. It characterizes the functional relationship between the electromagnetic power density or field strength amplitude radiated by the antenna and the spatial angle at a specific frequency and polarization. The amplitude pattern is typically plotted in polar or rectangular coordinates, with the horizontal axis representing the azimuth or elevation angle and the vertical axis representing the normalized radiation intensity (expressed in decibels). The amplitude pattern allows for the evaluation of key antenna performance indicators such as main lobe width, sidelobe level, beam pointing accuracy, and gain. The amplitude pattern is the final result obtained through rigorous mathematical transformations of the acquired near-field amplitude and phase data, used to determine whether the performance of the spaceborne SAR phased array antenna meets the required standards.

[0064] Optionally, in the above technical solution, before receiving the position signal of the scanning probe from the scanning gantry control system, the following steps are also included: S01. Set the scanning range, scanning step, and scanning speed of the scanning probe, and start the scanning probe to scan the array surface of the spaceborne SAR phased array antenna along the predetermined trajectory. The specific implementation process is as follows: S010. Before the test begins, the operator needs to start the dedicated control software running on the control computer of the scanning gantry control system. The graphical user interface of this software contains an input area for setting scanning parameters. The operator manually inputs three key parameters based on the physical dimensions of the satellite-borne SAR phased array antenna under test and the test requirements. The scanning range is a rectangular area, and its total length in the X-axis direction needs to be entered. and the total width in the Y-axis direction For example, for a 1m x 4m antenna array, considering the beam angle, it may be necessary to set... , The scan stepping requires inputting the stepping distance in the X-axis direction. Step distance in the Y-axis direction It is usually set to about 2 centimeters, that is... The scanning speed requires inputting the constant speed value of the probe during the scanning process. The unit is usually meters per second or millimeters per second, and this value needs to be determined by a trade-off between the safe speed allowed by the scanning gantry mechanical system and the software data processing capability.

[0065] S011. When the operator clicks the "Parameter Confirmation" button or a similar button, the host computer software of the scanning frame control system will receive the parameters. As input, the software first calculates the number of sampling points in the X and Y axes. and : ,in, This represents the floor function; adding 1 ensures coverage of the boundary. This defines a boundary on the scan plane that includes... A rectangular grid of points is used. Then, the motion planning algorithm generates a predetermined serpentine trajectory based on these grid points. Assume the starting point is the bottom left corner of the rectangle. The probe first moves along the positive X-axis, passing through points in sequence. ,in After reaching the end of the line, the probe moves one step along the positive Y-axis. Reach the starting point of the second line Then move along the negative X-axis, passing through points in sequence. Repeat this process until all areas are covered. Okay. The sequence of coordinates of points on the trajectory. ,in It is then calculated and stored in the memory of the controlling computer.

[0066] S012. After calculating the trajectory point sequence, the control software will perform a series of checks, such as checking whether the calculated total stroke exceeds the physical limits of the scanning carriage mechanical system, and checking the speed. Check if it's within the allowable range of the motor driver. After verification, the operator clicks the "Start Scan" button on the software. The host computer software transmits the trajectory point sequence via a communication interface (such as Ethernet, PCIe, or a dedicated motion control bus). Scanning speed The motion contour parameters, such as acceleration and jerk, are packaged into specific instruction frames and sent to the motion control card or programmable logic controller at the bottom layer of the scanning frame control system.

[0067] After receiving instructions from the host computer, the motion control card or programmable logic controller (PLC) activates its internal trajectory interpolator. Based on the received discrete trajectory point sequence and velocity parameters, the interpolator calculates the precise position, velocity, and acceleration setpoints of the scanning probe at each moment in real time; this process is called trajectory interpolation. For serpentine trajectories on straight segments, linear interpolation is typically used. The controller's servo drive module calculates and outputs drive current to the X-axis and Y-axis servo motors using a closed-loop control algorithm (such as PID control) based on these setpoints. The servo motors drive ball screws or linear motors, which in turn drive the slide table equipped with the scanning probe, starting from its initial position (usually requiring a "return to zero" or "move to the scanning start point" operation) along the calculated predetermined trajectory.

[0068] S014. During the movement of the scanning probe, the motion controller continuously reads the actual position through position sensors such as grating rulers or encoders. and the set position generated by the interpolator Comparisons are made to achieve closed-loop position control. When the control system determines that the scanning probe has stably reached the next predetermined sampling point in the trajectory sequence... When (i.e., the deviation between the actual position and the target position is less than the threshold) And remain stable for a period of time The scanner will then generate a position signal for the scanning probe via its digital output interface. This signal marks the start of data acquisition at that point and triggers the subsequent SAR testing process. The scanning probe moves point by point along the predetermined trajectory until all points in the trajectory sequence have been traversed. This allows for scanning and coverage of the entire spaceborne SAR phased array antenna surface by using a single point.

[0069] A predetermined trajectory refers to the pre-planned spatial path followed by the scanning probe during near-field scanning within a microwave anechoic chamber. For planar near-field testing, the most common predetermined trajectory is a serpentine trajectory covering a rectangular area directly in front of the tested spaceborne SAR phased array antenna. This trajectory lies on a plane parallel to the antenna array, within which the scanning probe moves along a series of parallel straight line segments, connecting smoothly or in a zigzag manner at the beginning and end of adjacent segments, thus continuously and without omission traversing all predetermined sampling points. The purpose of using a serpentine trajectory is to minimize the idle travel time of the scanning gantry mechanical system while ensuring a uniform distribution of sampling points, thereby improving overall scanning efficiency. The specific shape of the trajectory is uniquely determined by parameters such as the scanning range and scanning step, and is calculated and generated by the motion planning algorithm within the scanning gantry control system before scanning begins.

[0070] In existing SAR system testing, the Atmel SAM V71 chip is used as the main control chip in the SAR central processing unit to control the SAR system for imaging and other tasks in normal operating mode. Now, to facilitate testing, the system needs to be modified to operate in a self-transmitting and receiving mode. The modified system can acquire both received and transmitted SAR antenna pattern data. This new testing system eliminates the need for external instruments such as vector network analyzers and beam controllers, as well as the data acquisition and analysis software required for the microwave anechoic chamber. This design saves on hardware and software costs and reduces the risk of test downtime due to damage to external hardware or software or maintenance.

[0071] Based on the existing SAR system control logic, the control logic on the main control board needs to be added and modified. The modified logic enables it to accurately receive the position signal of the scanning probe from the scanning gantry control system through the SAR ground test fixture, thereby determining the precise spatial position of the scanning probe. Based on this position information, the main control system can accurately control the TR components at the corresponding positions on the SAR phased array antenna surface to open or close the receiving or transmitting state, thus completing the self-closed-loop single TR or multiple TR data acquisition. The first step in achieving this function is to add necessary signal conditioning functions to the SAR ground test fixture. This fixture needs to be able to identify the position signal of the scanning probe from the quadcopter driver. This signal is usually physically represented as a differential signal. The circuit on the SAR ground test fixture converts this differential signal into a single-ended TTL level signal, which is then transmitted to the main control system of the SAR central processing unit via cable. In this way, the SAR central processing unit can clearly receive the level signal from the microwave anechoic chamber scanning gantry indicating that the mechanical probe has stably reached the predetermined position. The SAR central processing unit's main control system uses this signal as a key trigger condition to start the radio frequency excitation and data acquisition process, ensuring that the corresponding TR component is opened for receiving or transmitting only after the scanning gantry probe has reached each corresponding position.

[0072] Figure 2The diagram shown illustrates the working principle of the modified SAR system acquiring pattern data in a self-closed-loop manner. Compared to the traditional approach, the new approach eliminates the two external instruments—the vector network analyzer and the beam controller—and instead fully utilizes the system's internal SAR central processing unit (CPU) and newly added SAR ground testing fixtures. The CPU has two key RF ports: a microwave port and a calibration port. During normal imaging operation, the microwave port is connected to the collection port of the SAR phased array antenna's TR assembly via an RF coaxial cable, serving as the primary signal transceiver port. The calibration port is connected to the calibration port of the SAR phased array antenna's TR assembly via another RF coaxial cable. The signal from the calibration port is obtained through signal coupling from the TR assembly port and is typically used to acquire closed-loop calibration data during internal calibration mode testing within the SAR system.

[0073] exist Figure 2 In the operating mode shown, for transmit pattern testing, the microwave port on the SAR central processing unit outputs an RF test excitation signal. This signal is connected to the SAR phased array antenna via a transmit coaxial cable, driving the antenna to radiate electromagnetic waves outward. At this time, the SAR system can be configured to operate in full-array transmit mode or single-TR transmit mode. The scanning probe on the scanning gantry is in receiving mode, receiving the electromagnetic wave signal radiated by the SAR antenna, and returning the received signal to the calibration port of the SAR central processing unit via a receive coaxial cable, thus forming a complete self-transmitting, self-receiving, and self-closing loop test link. Specifically: The entire system is built within a microwave anechoic chamber. The core of the system is the SAR central processing unit (CPU), which replaces the vector network analyzer in traditional testing solutions. It is responsible for generating RF test excitation signals and processing echo signals. Two key RF ports are extended from the CPU panel: a microwave combination port and a calibration port. During transmit pattern testing, the RF test excitation signal is output from the microwave combination port and connected via a transmit coaxial line to the onboard array antenna (SAR phased array antenna) of the device under test (DUT). This antenna is fixed to the DUT mounting bracket and adjustment mechanism to align with the scanning plane. After radiating the signal into space, it is received by the scanning probe mounted on the scanning rig. The received signal is then transmitted back to the SAR CPU's calibration port via a receive coaxial line. For receive pattern testing, the signal path is reversed: the RF test excitation signal is output from the calibration port, fed to the scanning probe via the coaxial line, radiated, received by the array antenna, and then returned to the microwave combination port via the coaxial line. The scanning gantry and its precision mechanical structure are driven by a four-axis scanning gantry driver via motor cables, which in turn is controlled by the scanning gantry control system. The scanning gantry control system is connected to the main control computer via a local area network (LAN) to receive scanning parameters and upload status information. The key synchronization element for automated testing is implemented by the SAR ground test fixture: it receives the differential scanning probe's position signal from the four-axis scanning gantry driver, indicating that the probe has stably reached the preset position. This signal is converted into a single-ended level signal and then sent to the SAR central processing unit (CPU) via cable. This signal precisely triggers each RF signal transmission and data acquisition action. The SAR CPU, scanning gantry control system, and the host computer running the SAR data acquisition software are interconnected via a LAN hub to exchange control commands and status information. Finally, during the process of the scanning probe completing the coverage scan of the entire antenna array along the predetermined trajectory according to the instructions of the scanning frame control system, the analog-to-digital conversion module and data logger inside the SAR central processing unit synchronously collect and record the amplitude and phase data of the antenna at multiple wavelengths at each probe position based on the triggering of the scanning probe's position signal, thus forming a complete self-transmitting and self-receiving test loop that does not rely on expensive external instruments.

[0074] Figure 3This document details the closed-loop workflow for testing the transmit pattern of a spaceborne SAR phased array antenna. This workflow primarily consists of a scanning gantry control system and a SAR testing system working together. During the initial test phase, the operator first aligns the scanning probe with the two-dimensional geometric center of the spaceborne SAR phased array antenna plane. The scanning gantry control system then sets the scanning range, step size, and scanning speed of the probe. For example, for a 1m × 4m antenna array, the scanning range is determined based on the beam angle, the step size is set to 2cm, and the scanning speed is set according to software processing capabilities and mechanical limitations. After these settings are completed, the SAR testing system is configured. It receives the probe's position signal (trigger) from the four-axis scanning gantry driver via a SAR ground testing fixture. This differential signal is converted and forwarded to the interface board of the SAR central processing unit. Simultaneously, multiple antenna scanning wave positions for this test are preset, and the scanning begins... The SAR data recorder is set to recording mode. When the operator clicks "Start Transmission" on the SAR test system interface and waits for the scanning probe to reach its position, the scanning gantry control system drives the scanning probe to move along a serpentine trajectory. Inside the SAR central processing unit, the digital baseband signal corresponding to the current wave position is generated by the DA module. After up-conversion and frequency multiplication, the signal is output from the microwave port and connected to the antenna RF interface of the spaceborne SAR phased array antenna via the transmit coaxial line, driving the antenna to radiate electromagnetic waves. At this time, the scanning probe located at a specific scanning position receives the space electromagnetic wave signal and sends it to the calibration port of the SAR central processing unit via the receive coaxial line. After down-conversion and processing, the signal is converted into a digital signal by the AD module and finally recorded by the SAR data recorder. This process is repeated at each scanning point until the entire array is traversed, completing the acquisition of the transmission pattern data.

[0075] exist Figure 2 In another operating mode, the calibration port on the SAR central processing unit transmits an RF test excitation signal to the scanning probe via an RF coaxial cable. The scanning probe radiates this signal outward, forming a space electromagnetic wave signal. At this time, the spaceborne SAR phased array antenna is set to receive mode, which can operate in full-array receiving mode or single-TR receiving mode to receive the electromagnetic wave signal radiated from the scanning probe. The electromagnetic wave signal received by the antenna is converted into an RF electrical signal and transmitted through another RF coaxial cable to the microwave combination port of the SAR central processing unit, thus completing the signal reception stage of the receive pattern test.

[0076] Figure 4This document details the closed-loop workflow for testing the receiving pattern of a spaceborne SAR phased array antenna. This workflow primarily consists of the coordinated operation of the scanning gantry control system and the SAR testing system. Before starting the antenna pattern scan, the scanning probe must be aligned with the two-dimensional geometric center of the spaceborne SAR phased array antenna plane. The scanning range, step size, and scanning speed of the scanning probe are then set via the scanning gantry control system. After completing these near-field scanning system settings in the microwave anechoic chamber, the SAR testing system is configured. This involves receiving the scanning probe's position signal from the four-axis scanning gantry driver via the SAR ground testing fixture. This signal is then converted, processed, and forwarded to the interface board of the SAR central processing unit. Simultaneously, the scanning wave positions of multiple antennas for this test are set, and the SAR data recorder is set to recording mode before scanning begins. When the operator... When the SAR test system interface is clicked to start receiving and the scanning probe is in position signal is waited for, the scanning gantry control system begins to drive the scanning probe to move along a serpentine trajectory. Inside the SAR central processing unit, the digital baseband signal corresponding to the current wave position is generated by the DA module. After up-conversion and frequency multiplication, the signal reaches the calibration port of the SAR central processing unit and radiates electromagnetic wave signals into space through the scanning probe. At this time, the spaceborne SAR phased array antenna is set to receive mode and receives electromagnetic wave signals from the scanning probe through its antenna RF interface. The received signal is returned to the microwave interface of the SAR central processing unit. After down-conversion and processing, it is converted into a digital signal by the AD module and finally recorded by the SAR data recorder. This process is repeated at each scanning point until the entire array is traversed, completing the acquisition of the received radiation pattern data.

[0077] The self-closed-loop test link formed by the spaceborne SAR phased array antenna test system now uses a self-transmitting and self-receiving method to acquire radiation pattern data from the spaceborne SAR phased array antenna. It can simultaneously acquire signals under multiple pre-set different azimuth configurations. Specifically, the system can synchronously acquire data from azimuth configurations including different range-weighted, azimuth-weighted, azimuth scan angle, range scan angle, and two-dimensional scan angle parameters. For example... Figure 5 As shown, Figure 5 In the diagram, the header row includes AMP (signal amplitude), PHASE (signal phase), and SHIYAN (signal time delay), with each column corresponding to signal data from a specific scan point and wavelength. The figure shows four sets of signal data columns with identical structures because the tested spaceborne SAR phased array antenna consists of four antenna sub-boards. After processing the raw amplitude and phase data of the spaceborne SAR phased array antenna at multiple wavelengths using a Matlab program, a near-field amplitude distribution map in the transmission mode can be generated, such as... Figure 7As shown in the figure. From the collected data and processed results, the test results of this invention achieve the same effect as those using a traditional vector network analyzer. This proves that the automated microwave anechoic chamber testing of spaceborne SAR phased array antenna patterns achieved by this invention no longer relies on a vector network analyzer and beam controller, and can achieve the same effect as conventional anechoic chamber testing patterns, making it more convenient and faster. Compared with existing testing technologies, the operation process of the testing method of this invention is basically the same as that of an actual SAR system in operation, saving the time required for additional equipment and software configuration, and reducing the possibility of errors due to increased variables during testing. Figure 6 and Figure 8 These are the raw data measured in receiving mode and the corresponding amplitude distribution results, respectively.

[0078] In this invention, the RF test excitation signal is generated internally by the SAR central processing unit, rather than by an external vector network analyzer. This signal is essentially the same as the signal used in actual system operation, making the test results closer to real-world usage and facilitating the analysis of the amplitude and phase characteristics of each TR component channel. Furthermore, it allows for the acquisition of data from multiple wave positions in a single scan, significantly improving the efficiency and quality of pattern testing.

[0079] In the above embodiments, although the steps are numbered S1, S2, etc., they are only specific embodiments given by the present invention. Those skilled in the art can adjust the execution order of S1, S2, etc. according to the actual situation. The scheme after adjusting the order is also within the protection scope of the present invention. It can be understood that in some embodiments, some or all of the above embodiments may be included.

[0080] like Figure 9 As shown, an automated spaceborne SAR phased array antenna pattern testing system 200 according to an embodiment of the present invention includes a signal receiving module 201, a signal generation module 202, a control module 203, an acquisition module 204, and a pattern generation module 205. The signal receiving module 201 is used to: receive the position signal of the scanning probe from the scanning gantry control system; The signal generation module 202 is used to generate a corresponding radio frequency test excitation signal based on the position signal of the scanning probe. The control module 203 is used to: control the output of the radio frequency test excitation signal through the calibration port or microwave combination port of the SAR central processor, and synchronously control the working state of the spaceborne SAR phased array antenna to transmit mode or receive mode, so as to form a self-closed loop test link between the scanning probe and the spaceborne SAR phased array antenna. The acquisition module 204 is used to: acquire amplitude and phase data of the spaceborne SAR phased array antenna at multiple wavelengths through a self-closed-loop test link; The radiation pattern generation module 205 is used to process amplitude and phase data and generate radiation patterns for spaceborne SAR phased array antennas.

[0081] Optionally, the above technical solution also includes a setting module, which is used for: Before receiving the position signal of the scanning probe from the scanning rig control system, the scanning range, scanning step and scanning speed of the scanning probe are set, and the scanning probe is started to scan the array surface of the spaceborne SAR phased array antenna along the predetermined trajectory.

[0082] Optionally, in the above technical solution, the acquisition module 204 is specifically used for: As the scanning probe arrives at each scanning position sequentially according to the scanning probe's position signal, for each scanning position, based on the radio frequency test excitation signal, the AD module of the SAR central processor and the data logger synchronously record the signal amplitude data and signal phase data of the spaceborne SAR phased array antenna under multiple pre-set different wave position configurations.

[0083] Optionally, in the above technical solution, the radiation pattern generation module 205 is specifically used to: perform near-field data to far-field radiation pattern transformation calculation on the signal amplitude data and signal phase data under multiple acquired wave positions, and generate the amplitude radiation pattern of the spaceborne SAR phased array antenna based on the transformation calculation result.

[0084] It should be noted that the beneficial effects of the automated spaceborne SAR phased array antenna pattern testing system 200 provided in the above embodiments are the same as those of the automated spaceborne SAR phased array antenna pattern testing method described above, and will not be repeated here. Furthermore, the system provided in the above embodiments is only illustrated by 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 system can be divided into different functional modules according to the actual situation to complete all or part of the functions described above. In addition, the system and method embodiments provided in the above embodiments belong to the same concept, and their specific implementation process is detailed in the method embodiments, and will not be repeated here.

[0085] An electronic device according to an embodiment of the present invention includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements any of the above-described automated spaceborne SAR phased array antenna pattern testing methods.

[0086] An embodiment of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements any of the above-described automated spaceborne SAR phased array antenna pattern testing methods.

[0087] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this invention is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-disclosed concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this invention.

[0088] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An automated method for testing the radiation pattern of a spaceborne SAR phased array antenna, characterized in that, include: Receive the position signal of the scanning probe from the scanning gantry control system; Based on the position signal of the scanning probe, a corresponding radio frequency test excitation signal is generated; The radio frequency test excitation signal is controlled to be output through the calibration port or microwave combination port of the SAR central processing unit, and the working state of the spaceborne SAR phased array antenna is controlled to be either transmit mode or receive mode, so as to form a self-closed loop test link between the scanning probe and the spaceborne SAR phased array antenna. The self-closed-loop test link is used to collect amplitude and phase data of the spaceborne SAR phased array antenna at multiple wavelengths. The amplitude and phase data are processed to generate the radiation pattern of the spaceborne SAR phased array antenna.

2. The automated method for testing the radiation pattern of a spaceborne SAR phased array antenna according to claim 1, characterized in that, Before receiving the position signal of the scanning probe from the scanning gantry control system, the following steps are also included: Set the scanning range, scanning step, and scanning speed of the scanning probe, and start the scanning probe to scan the array surface of the spaceborne SAR phased array antenna along a predetermined trajectory.

3. The automated method for testing the radiation pattern of a spaceborne SAR phased array antenna according to claim 1, characterized in that, Through the self-closed-loop test link, amplitude and phase data of the spaceborne SAR phased array antenna at multiple wavelengths are collected, including: As the scanning probe arrives at each scanning position sequentially according to the scanning probe's position signal, for each scanning position, based on the radio frequency test excitation signal, the AD module and data logger of the SAR central processing unit synchronously record the signal amplitude and signal phase data of the spaceborne SAR phased array antenna under multiple pre-set different wave position configurations.

4. The automated method for testing the radiation pattern of a spaceborne SAR phased array antenna according to claim 3, characterized in that, Processing the amplitude and phase data to generate the radiation pattern of the spaceborne SAR phased array antenna includes: The near-field data to far-field radiation pattern transformation calculation is performed on the signal amplitude data and signal phase data collected at multiple wave positions, and the amplitude radiation pattern of the spaceborne SAR phased array antenna is generated based on the transformation calculation result.

5. An automated spaceborne SAR phased array antenna pattern testing system, characterized in that, It includes a signal receiving module, a signal generating module, a control module, a data acquisition module, and a radiation pattern generation module; The signal receiving module is used to: receive the position signal of the scanning probe from the scanning gantry control system; The signal generation module is used to generate a corresponding radio frequency test excitation signal based on the position signal of the scanning probe. The control module is used to: control the output of the radio frequency test excitation signal through the calibration port or microwave combination port of the SAR central processor, and synchronously control the working state of the spaceborne SAR phased array antenna to transmit mode or receive mode, so as to form a self-closed loop test link between the scanning probe and the spaceborne SAR phased array antenna. The acquisition module is used to: acquire amplitude and phase data of the spaceborne SAR phased array antenna at multiple wavelengths through the self-closed-loop test link; The radiation pattern generation module is used to process the amplitude and phase data and generate the radiation pattern of the spaceborne SAR phased array antenna.

6. The automated spaceborne SAR phased array antenna pattern testing system according to claim 5, characterized in that, It also includes a settings module, which is used for: Before receiving the position signal of the scanning probe from the scanning rig control system, the scanning range, scanning step and scanning speed of the scanning probe are set, and the scanning probe is started to scan the array surface of the spaceborne SAR phased array antenna along a predetermined trajectory.

7. The automated spaceborne SAR phased array antenna pattern testing system according to claim 5, characterized in that, The acquisition module is specifically used for: As the scanning probe arrives at each scanning position sequentially according to the scanning probe's position signal, for each scanning position, based on the radio frequency test excitation signal, the AD module and data logger of the SAR central processing unit synchronously record the signal amplitude and signal phase data of the spaceborne SAR phased array antenna under multiple pre-set different wave position configurations.

8. The automated spaceborne SAR phased array antenna pattern testing system according to claim 7, characterized in that, The radiation pattern generation module is specifically used to: perform near-field data to far-field radiation pattern transformation calculation on the signal amplitude data and signal phase data at multiple acquired wavelengths, and generate the amplitude radiation pattern of the spaceborne SAR phased array antenna based on the transformation calculation result.

9. An electronic device, characterized in that, The method includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the automated spaceborne SAR phased array antenna pattern testing method according to any one of claims 1 to 4.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the automated spaceborne SAR phased array antenna pattern testing method according to any one of claims 1 to 4.

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