A method and system for multi-channel synchronization calibration of a phased array antenna

Abstract

This application relates to the technical field of phased array antenna testing and calibration, and discloses a multi-channel synchronous calibration method and system for phased array antennas. By applying continuous phase modulation at different frequencies to the independent phase shifters corresponding to multiple selected antenna elements, the radio frequency signals of multiple channels are superimposed and radiated synchronously. The superimposed signals are received by the measurement antenna, and after down-conversion and analog-to-digital conversion, a discrete data sequence is obtained. The discrete sequence is then subjected to frequency domain transformation to separate the signals corresponding to each modulation frequency in the spectrum, and the initial amplitude and phase of each channel are extracted to complete the synchronous calibration. This application significantly shortens the calibration time of phased array antennas, reduces mass production testing costs, and can simultaneously complete the health screening of phase shifter chips, making it suitable for mass production calibration of large-scale phased array antennas.

Description

Technical Field

[0001] This application relates to the technical field of phased array antenna testing and calibration, and in particular to a method and system for multi-channel synchronous calibration of phased array antennas. Background Technology

[0002] Phased array antennas achieve flexible beam scanning and shaping by controlling the amplitude and phase of the transmitted signals from each antenna element in the array. They are widely used in radar, satellite communications, 5G / 6G mobile communications, and other fields. The core performance indicators of a phased array antenna, such as beam pointing accuracy and sidelobe level performance, directly depend on the consistency of the amplitude and phase characteristics of each channel. Therefore, precise amplitude and phase calibration of each channel is essential during the production and testing process of phased array antennas.

[0003] Currently, the industry commonly uses a single-channel polling calibration method, where only one antenna channel is activated for measurement at a time, sequentially acquiring the initial amplitude and phase information of each channel to complete the calibration of the entire array. With the development of phased array technology, the number of elements in large-scale phased array antennas has reached hundreds or even thousands. The total time consumption of the traditional single-channel serial calibration method is directly proportional to the number of channels, resulting in extremely long calibration times for a single phased array antenna, becoming a core bottleneck in mass production. Furthermore, excessively long testing times require production lines to be equipped with more expensive equipment such as anechoic chambers and testing fixtures, significantly increasing equipment depreciation costs and product manufacturing costs. In addition, traditional single-channel static testing methods struggle to dynamically assess the operating status of phase shifters under high-speed switching conditions within a short time, and cannot simultaneously complete the rapid screening of faulty phase shifter chips during calibration, requiring additional testing steps and further reducing production efficiency. Summary of the Invention

[0004] To address the aforementioned technical issues, this application provides a method and system for multi-channel synchronous calibration of phased array antennas.

[0005] Firstly, this application provides a method for multi-channel synchronous calibration of a phased array antenna, employing the following technical solution: A method for multi-channel synchronous calibration of a phased array antenna includes the following steps: S1. Select n antenna elements to be calibrated from multiple antenna elements of the phased array antenna, where n≥2, and each antenna element to be calibrated is configured with an independent phase shifter. S2. Assign different modulation frequencies to the phase shifters corresponding to each selected antenna element to be calibrated, and control each phase shifter to continuously phase modulate the transmitted radio frequency signal at the corresponding assigned modulation frequency to generate a phase modulation sequence of corresponding length. S3. Control all selected antenna elements to be calibrated to transmit phase-modulated radio frequency signals synchronously, so that the radio frequency signals are superimposed in space to form a sum signal; S4. Receive the summed signal through a measuring antenna, perform down-conversion processing on the summed signal to obtain an intermediate frequency signal, and perform analog-to-digital conversion on the intermediate frequency signal to obtain a discrete data sequence; S5. Perform frequency domain transformation on the discrete data sequence to obtain the corresponding spectrum data. Based on the correspondence between each modulation frequency and the antenna element to be calibrated, extract the amplitude and phase information corresponding to each antenna element to be calibrated from the spectrum data to complete the synchronous calibration of multiple channels.

[0006] Optionally, the value of n is adjusted according to the phase accuracy of the phase shifter, and the possible values ​​of n include 2, 4, 8, 16, and 32.

[0007] Optionally, in step S2, a phase modulation sequence is generated based on a preset sampling rate, and the length of the phase modulation sequence is m points, where m is a positive integer.

[0008] Optionally, in step S4, the sampling frequency of the analog-to-digital conversion is greater than twice the sampling rate, and the length of the acquired discrete data sequence is greater than 2m.

[0009] Optionally, in step S5, the frequency domain transformation is a discrete Fourier transform or a fast Fourier transform; based on the harmonic components, noise floor, and peak state information in the spectrum data, the working state of the phase shifter in the corresponding channel is determined, and the health screening of the phase shifter is completed.

[0010] Secondly, this application provides a multi-channel synchronous calibration system for a phased array antenna, employing the following technical solution: A phased array antenna multi-channel synchronous calibration system includes a phased array antenna, a measurement antenna, a down-conversion module, an analog-to-digital conversion module, and a digital signal processing module; The phased array antenna includes an antenna controller and multiple antenna elements. Each antenna element is configured with an independent phase shifter. The antenna controller is used to select n antenna elements to be calibrated, assign different modulation frequencies to the phase shifters corresponding to each antenna element to be calibrated, control the phase shifters to complete phase modulation, and control each antenna element to be calibrated to transmit radio frequency signals synchronously, where n≥2. The measuring antenna is used to receive the sum of the radio frequency signals emitted by each antenna unit to be calibrated, which are spatially superimposed to form the signal. The down-conversion module is used to perform down-conversion processing on the summed signal to obtain an intermediate frequency signal; The analog-to-digital conversion module is used to perform analog-to-digital conversion on the intermediate frequency signal to obtain a discrete data sequence; The digital signal processing module is used to perform frequency domain transformation on the discrete data sequence to obtain the corresponding spectrum data. Based on the correspondence between each modulation frequency and the antenna element to be calibrated, the module extracts the amplitude and phase information corresponding to each antenna element to be calibrated from the spectrum data to complete the synchronous calibration of multiple channels.

[0011] In summary, this application includes at least one of the following beneficial technical effects: This application assigns different modulation frequencies to the phase shifters of multiple channels to be calibrated, performing differentiated continuous phase modulation on the transmitted signals of each channel. This results in orthogonal separation of signals from multiple channels in the frequency domain. With only one signal acquisition and frequency domain transformation, the amplitude and phase information of multiple channels can be extracted simultaneously, achieving synchronous calibration of multiple channels. This significantly shortens the calibration time of the entire phased array antenna, effectively improves the efficiency of mass production testing, reduces the number of testing equipment required on the production line, and lowers the manufacturing cost of the product. At the same time, based on the spectrum data obtained from the frequency domain transformation, the working status of each channel's phase shifter can be directly evaluated, and faulty chips can be quickly screened during calibration without adding extra testing procedures. This simplifies the production and testing process of phased array antennas and improves the overall efficiency of the mass production process. The solution of this application can flexibly adjust the number of parallel calibration channels according to the channel scale of the phased array antenna and the performance of the phase shifters. It has strong adaptability and can be widely used in mass production calibration scenarios of various phased array antennas with independent phase shifters. Attached Figure Description

[0012] Figure 1 This is a flowchart illustrating the multi-channel synchronous calibration method for phased array antennas in this application; Figure 2 This is a block diagram of the architecture of the phased array antenna multi-channel synchronous calibration system in this application; Figure 3 This is a schematic diagram of the spectrum corresponding to the phase modulation of multiple channels at different frequencies in this application. Detailed Implementation

[0013] The embodiments of this application are described in detail below, and examples of the embodiments are shown in the accompanying drawings.

[0014] In the description of this specification, the references to "certain embodiments," "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples" refer to specific features, structures, materials, or characteristics described in connection with the described embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0015] The phased array antenna multi-channel synchronous calibration method and system described in this invention are applicable to phased array antennas containing multiple antenna elements, each of which is equipped with an independent phase shifter, and are particularly suitable for mass production calibration scenarios of large-scale phased array antennas.

[0016] First, the calibration method of the present invention will be described in detail. This application discloses a multi-channel synchronous calibration method for a phased array antenna, referring to… Figure 1 It includes the following basic steps: S1. Select n antenna elements to be calibrated from multiple antenna elements of the phased array antenna, where n≥2, and each antenna element to be calibrated is configured with an independent phase shifter. S2. Assign different modulation frequencies to the phase shifters corresponding to each selected antenna element to be calibrated, and control each phase shifter to continuously phase modulate the transmitted radio frequency signal at the corresponding assigned modulation frequency to generate a phase modulation sequence of corresponding length. S3. Control all selected antenna elements to be calibrated to transmit phase-modulated radio frequency signals synchronously, so that the radio frequency signals are superimposed in space to form a sum signal; S4. Receive the summed signal through a measuring antenna, perform down-conversion processing on the summed signal to obtain an intermediate frequency signal, and perform analog-to-digital conversion on the intermediate frequency signal to obtain a discrete data sequence; S5. Perform frequency domain transformation on the discrete data sequence to obtain the corresponding spectrum data. Based on the correspondence between each modulation frequency and the antenna element to be calibrated, extract the amplitude and phase information corresponding to each antenna element to be calibrated from the spectrum data to complete the synchronous calibration of multiple channels.

[0017] The following is a further detailed explanation of the above steps: The first step is parameter initialization and channel grouping. From all the antenna elements of the phased array antenna, select n antenna elements to be calibrated, where n is not less than 2. Each antenna element to be calibrated is configured with an independent phase shifter, and the phase state of the phase shifter can be independently controlled by the antenna controller. In practical applications, the value of n can be flexibly adjusted according to the phase accuracy of the phase shifter. Selectable values ​​include 2, 4, 8, 16, 32, etc. Under the premise of ensuring the frequency domain separation effect, an appropriate number of parallel channels should be selected to obtain the optimal calibration efficiency. For phased array antennas with a large number of channels, all channels can be divided into multiple groups, each containing n channels, and the calibration of the entire array can be completed by calibrating each group one by one.

[0018] The second step involves assigning a unique modulation frequency to the phase shifter corresponding to each selected antenna element to be calibrated. This ensures that the modulation frequency for each channel is unique, preventing crosstalk during subsequent frequency domain separation. The antenna controller generates a phase modulation sequence corresponding to the modulation frequency for each phase shifter, based on a preset sampling rate. It then controls each phase shifter to continuously modulate the RF signal transmitted by the corresponding channel according to the generated phase modulation sequence. The length of the phase modulation sequence is m points, where m is a positive integer and can be adjusted according to the required calibration accuracy.

[0019] The third step involves filling all selected channels to be calibrated with phase modulation sequences. Then, the antenna controller controls all selected antenna elements to be calibrated to synchronously transmit phase-modulated radio frequency signals. The radio frequency signals transmitted by each antenna element propagate and superimpose in the space of the test field to form a sum signal. The test field can be a conventional phased array test environment such as an anechoic chamber or a near-field test rack.

[0020] The fourth step involves receiving the summation signal in the space via a measurement antenna set up in the test field. This received summation signal is then transmitted to a down-conversion module. The down-conversion module uses a local oscillator signal to down-convert the RF-format summation signal to an intermediate frequency (IF) signal. The IF signal is then transmitted to an analog-to-digital (ADC) converter. The ADC samples the IF signal, converting the analog IF signal into a discrete data sequence in digital format. To satisfy the Nyquist sampling theorem and improve the resolution of the frequency domain transformation, the sampling frequency of the ADC is set to be greater than twice the reference sampling rate of the phase modulation sequence. The length of the acquired discrete data sequence is greater than twice the length *m* of the phase modulation sequence to ensure the accuracy of the frequency domain transformation.

[0021] The fifth step involves transmitting the discrete data sequence to the digital signal processing module. This module performs a frequency domain transformation on the discrete data sequence to obtain the corresponding spectral data. This frequency domain transformation can employ either Discrete Fourier Transform (DFT) or Fast Fourier Transform (FFT). Since each channel has a different modulation frequency, the signals from each channel will appear at different frequency positions in the spectrum, forming mutually separated peaks. Based on the pre-set one-to-one correspondence between the modulation frequency and the antenna element to be calibrated, the amplitude and phase information corresponding to each antenna element to be calibrated can be extracted from the peaks at the corresponding frequency positions in the spectral data. This amplitude and phase information constitutes the initial amplitude and phase calibration coefficients for the corresponding channel, thus completing the synchronous calibration of multiple channels. Simultaneously, the digital signal processing module can also determine whether the phase shifter of the corresponding channel is functioning correctly based on information such as harmonic components, noise floor, peak integrity, and distortion in the spectral data. If a peak that meets the requirements does not appear at a position corresponding to a certain modulation frequency, or if the peak spuriousness is too high or the signal-to-noise ratio is insufficient, a fault in the phase shifter of the corresponding channel can be identified, completing the health screening of the phase shifter without requiring additional testing procedures.

[0022] This application also discloses a multi-channel synchronous calibration system for phased array antennas, such as... Figure 2 As shown, it includes a phased array antenna, a measurement antenna, a down-conversion module (converting radio frequency to intermediate frequency), an analog-to-digital converter (ADC), and a digital signal processing module (for DFT / FFT operations). The phased array antenna, the device to be calibrated, includes an antenna controller and multiple antenna elements. Each antenna element is equipped with an independent phase shifter. The antenna controller is communicatively connected to each phase shifter and can independently control the phase state of each phase shifter. The functions of the antenna controller include: selecting n antenna elements to be calibrated from all antenna elements, where n is not less than 2 and can be flexibly adjusted according to the phase accuracy of the phase shifter, with selectable values ​​including 2, 4, 8, 16, 32, etc.; assigning different modulation frequencies to the phase shifter corresponding to each selected antenna element to be calibrated, generating a phase modulation sequence corresponding to the modulation frequency and feeding it into the corresponding phase shifter, controlling the phase shifter to complete continuous phase modulation of the transmitted signal; and controlling all selected antenna elements to be calibrated to synchronously transmit the phase-modulated radio frequency signal.

[0023] The measurement antenna is set in the test field of the phased array antenna and is used to receive the sum signal formed by the spatial superposition of the radio frequency signals emitted by each antenna element to be calibrated, and transmit the sum signal to the down-conversion module.

[0024] The input terminal of the downconversion module is connected to the output terminal of the measurement antenna. It is used to receive the sum signal transmitted by the measurement antenna, downconvert the RF format sum signal to an intermediate frequency signal through the local oscillator signal, and transmit the intermediate frequency signal to the analog-to-digital conversion module.

[0025] The input of the analog-to-digital converter (ADC) module is connected to the output of the down-conversion module. It receives the intermediate frequency (IF) signal, samples and performs analog-to-digital conversion on the IF signal, converting the analog IF signal into a discrete data sequence in digital format. This discrete data sequence is then transmitted to the digital signal processing module. The sampling frequency of the ADC module is set to be greater than twice the reference sampling rate of the phase modulation sequence, and the length of the acquired discrete data sequence is greater than twice the length of the phase modulation sequence to ensure the accuracy of subsequent frequency domain transformation.

[0026] The input of the digital signal processing module is connected to the output of the analog-to-digital converter module. It receives discrete data sequences, performs frequency domain transformation on these sequences to obtain corresponding spectral data, and extracts the amplitude and phase information of each antenna element from the spectral data based on a pre-defined one-to-one correspondence between the modulation frequency and the antenna elements to be calibrated, thus completing the synchronous calibration of multiple channels. Simultaneously, the digital signal processing module can also determine the operating status of the phase shifter in the corresponding channel based on information such as harmonic components, noise floor, and peak state in the spectral data, completing the health screening of the phase shifter. The digital signal processing module can be implemented using DSP, FPGA, or PC-based processing software, allowing for flexible selection based on the requirements of the test scenario.

[0027] In actual mass production testing, after calibrating one set of channels, the antenna controller can switch to the next set of channels to be calibrated, repeating the above calibration process until all channels of the phased array antenna are calibrated.

[0028] The following is the testing and calibration process for a phased array antenna with 1024 channels: Parameter initialization and channel grouping: For a phased array antenna with 1024 channels, set the number of parallel calibration channels n=16. Divide all channels into 64 groups. Set the phase shifter modulation rate reference fs=1MHz, and assign different modulation frequency steps to each channel (e.g., f1, f2, ..., f16 are all at baseband orthogonal frequencies).

[0029] Phase sequence injection: The antenna controller injects pre-calculated phase modulation state sequences of different frequencies into the 16 phase shifters in the first group (since they are 6-bit phase shifters, the phase changes continuously in steps of 5.625° between 0 and 360°). The sequence length is set to m = 512 points.

[0030] Concurrent transmission and spatial synthesis: 16 channels transmit radio frequency signals simultaneously, and the spatial electromagnetic waves are superimposed at the far-field or near-field probe. The probe / measurement antenna receives the summed signal.

[0031] Down-conversion and oversampling: The received RF total signal is converted to an intermediate frequency signal by a mixer and a local oscillator (LO). The ADC operates according to fADC>2MHz (i.e., >2). Sampling is performed at a sampling rate of fs, obtaining N=1024 points (greater than 2). (m) digital baseband / intermediate frequency sequence.

[0032] FFT Calculation and Coefficient Extraction: The DSP / FPGA performs an FFT operation on the 1024-point sequence. The complex peak values ​​corresponding to the 16 frequency points f1 to f16 are located in the spectrum. The amplitude (magnitude) and phase (argument) of these peak values ​​are calculated and recorded as the initial calibration coefficients for these 16 channels at this RF frequency. Figure 3 The spectrum diagrams shown are of phase modulation at different frequencies for multiple channels (at different frequency points). (A schematic diagram of the frequency domain peaks). Each peak represents a modulation frequency and also a channel.

[0033] Chip screening and judgment: Check the signal-to-noise ratio (SNR) and main-to-side lobe ratio at f1 to f16 in the spectrum. If the peak value at a certain frequency point is lower than the set threshold, the system will immediately mark in the log that the phase shifter chip of that channel may be damaged or poorly soldered.

[0034] Traversing the entire array: The calibration and calculation for these 16 channels takes only 1ms. The system then immediately switches to the next group of 16 channels and repeats steps 2-6. The single-frequency calibration of the entire 1024 array elements will be completed within tens of milliseconds.

[0035] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for multi-channel simultaneous calibration of a phased array antenna, characterized in that, Includes the following steps: S1. Select n antenna elements to be calibrated from multiple antenna elements of the phased array antenna, where n≥2, and each antenna element to be calibrated is configured with an independent phase shifter. S2. Assign different modulation frequencies to the phase shifters corresponding to each selected antenna element to be calibrated, and control each phase shifter to continuously phase modulate the transmitted radio frequency signal at the corresponding assigned modulation frequency to generate a phase modulation sequence of corresponding length. S3. Control all selected antenna elements to be calibrated to transmit phase-modulated radio frequency signals synchronously, so that the radio frequency signals are superimposed in space to form a sum signal; S4. Receive the summed signal through a measuring antenna, perform down-conversion processing on the summed signal to obtain an intermediate frequency signal, and perform analog-to-digital conversion on the intermediate frequency signal to obtain a discrete data sequence; S5. Perform frequency domain transformation on the discrete data sequence to obtain the corresponding spectrum data. Based on the correspondence between each modulation frequency and the antenna element to be calibrated, extract the amplitude and phase information corresponding to each antenna element to be calibrated from the spectrum data to complete the synchronous calibration of multiple channels.

2. The phased array antenna multi-channel simultaneous calibration method of claim 1, wherein, The value of n is adjusted according to the phase accuracy of the phase shifter, and the possible values ​​of n include 2, 4, 8, 16, and 32.

3. The phased array antenna multi-channel simultaneous calibration method of claim 1, wherein, In step S2, a phase modulation sequence is generated based on a preset sampling rate. The length of the phase modulation sequence is m points, where m is a positive integer.

4. The method of claim 3, wherein, In step S4, the sampling frequency of the analog-to-digital conversion is greater than twice the sampling rate, and the length of the acquired discrete data sequence is greater than 2m.

5. The phased array antenna multichannel simultaneous calibration method of claim 1, wherein, In step S5, the frequency domain transformation is either a discrete Fourier transform or a fast Fourier transform; based on the harmonic components, noise floor, and peak state information in the spectrum data, the operating state of the phase shifter in the corresponding channel is determined, and the health screening of the phase shifter is completed.

6. A phased array antenna multi-channel simultaneous calibration system, employing the phased array antenna multi-channel simultaneous calibration method according to any one of claims 1-8, characterized in that, It includes a phased array antenna, a measurement antenna, a down-conversion module, an analog-to-digital conversion module, and a digital signal processing module; The phased array antenna includes an antenna controller and multiple antenna elements. Each antenna element is configured with an independent phase shifter. The antenna controller is used to select n antenna elements to be calibrated, assign different modulation frequencies to the phase shifters corresponding to each antenna element to be calibrated, control the phase shifters to complete phase modulation, and control each antenna element to be calibrated to transmit radio frequency signals synchronously, where n≥2. The measuring antenna is used to receive the sum of the radio frequency signals emitted by each antenna unit to be calibrated, which are spatially superimposed to form the signal. The down-conversion module is used to perform down-conversion processing on the summed signal to obtain an intermediate frequency signal; The analog-to-digital conversion module is used to perform analog-to-digital conversion on the intermediate frequency signal to obtain a discrete data sequence; The digital signal processing module is used to perform frequency domain transformation on the discrete data sequence to obtain the corresponding spectrum data. Based on the correspondence between each modulation frequency and the antenna element to be calibrated, the module extracts the amplitude and phase information corresponding to each antenna element to be calibrated from the spectrum data to complete the synchronous calibration of multiple channels.

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