Calibration system in active channel of waveguide array phased array antenna

Abstract

The invention discloses a calibration system in an active channel of a waveguide array phased-array antenna, and relates to the technical field of calibration in the active channel. Comprising a calibration judgment module, a waveguide directional coupling module, an amplitude-phase detection module and a digital domain optimization module, the calibration judgment module realizes intelligent triggering calibration through real-time monitoring of a multi-dimensional environment and performance parameters, and ensures that a calibration process is started only when the system state is deteriorated; the waveguide directional coupling module ensures that the calibration signal is accurately injected into each channel, and realizes cross polarization suppression through a polarization grid filter; the amplitude-phase detection module realizes high-precision measurement of amplitude, phase, group delay and polarization parameters of feedback signals of each channel by using superheterodyne and IQ demodulation technologies; and the digital domain optimization module calculates and updates the complex compensation weight of each channel through real-time digital signal processing and a self-adaptive algorithm, and realizes comprehensive and accurate calibration in combination with temperature-frequency interpolation and nonlinear pre-distortion compensation.

Description

Technical Field

[0001] The present invention relates to the technical field of active in-channel calibration, and in particular to an active in-channel calibration system for a waveguide array phased array antenna. Background Art

[0002] In active phased array antennas, each channel may experience slight mismatches due to factors such as manufacturing, temperature variations, and aging. These minor errors can accumulate and severely impact the beamforming performance of the entire antenna array, such as reduced mainlobe gain, increased sidelobe levels, and weakened beam pointing accuracy. Active in-channel calibration involves real-time or periodic parameter adjustments to the active signal transmission channel (circuit paths containing active components such as amplifiers, filters, and ADCs / DACs) through a built-in calibration mechanism to ensure the accuracy and consistency of its output signal. Therefore, active in-channel calibration is essential.

[0003] The polarization matching between different channels and the calibration loop varies. Poor matching in some channels may result in weak or distorted extracted calibration signals, which in turn leads to unbalanced calibration data and affects the beamforming accuracy of the entire array. This problem is particularly prominent in multi-polarization or wide-angle scanning arrays. Summary of the Invention

[0004] Based on this, it is necessary to provide an active in-channel calibration system for a waveguide array phased array antenna to address the problems mentioned in the above background technology.

[0005] The object of the present invention can be achieved by the following technical solutions: an active in-channel calibration system for a waveguide array phased array antenna, a calibration judgment module;

[0006] The calibration judgment module comprehensively analyzes the factors affecting the waveguide array to determine whether to trigger signal calibration; specifically:

[0007] By integrating digital environmental sensors into the waveguide array substrate, the temperature and humidity are collected in real time and recorded as T and RH respectively, and the temperature change value I in a unit time period is calculated. temp and humidity change value I hum , the specific calculation formula is:

[0008] Where T th is the maximum temperature change threshold allowed by the waveguide array;

[0009] The actual beam pointing is obtained through the GPS / INS system, and compared with the preset pointing to obtain the actual beam error, and the pointing error value I is calculated. beam The specific calculation formula is: where δ this the maximum beam error that can be tolerated in this application scenario;

[0010] The actual radiation pattern is obtained by far-field measurement, and the amplitude difference ΔP between the main lobe and the side lobe is extracted. sidelobe , and normalize it to get the sidelobe level error value I sidelobe , the specific calculation formula is:

[0011] in is the design target sidelobe level, ΔP th The maximum drop allowed in this application scenario;

[0012] The baseband processor calculates the received signal SNR and normalizes it to obtain the signal-to-noise ratio change value I SNR The specific calculation formula is:

[0013] Among them I signal is the received signal power, I noise is the background noise power;

[0014] The temperature change value I temp , humidity change value I hum , pointing error value I beam , sidelobe level error value I sidelobe and signal-to-noise ratio change value I SNR Compare the values ​​with the corresponding preset thresholds respectively. If three or more of them are greater than the corresponding preset thresholds, the calibration requirement meets the trigger condition, triggering signal calibration, turning off the normal radiation / reception functions, and switching the RF switch to the calibration network mode. Otherwise, signal calibration is not triggered and there is no need to update the polarization parameters.

[0015] After the trigger signal is calibrated, the corresponding calibration update period is matched. The specific matching method is:

[0016] Step 1: Change the temperature value I temp , humidity change value I hum , pointing error value I beam , sidelobe level error value I sidelobe and signal-to-noise ratio change value I SNR Recorded as judgment parameters, the judgment parameters are compared with the corresponding preset thresholds. If all judgment parameters are greater than the preset thresholds, the correction update cycle Y1 is matched and the process jumps to step 4; otherwise, step 2 is executed.

[0017] Step 2: When there is a pointing error value I in the judgment parameter beam , sidelobe level error value I sidelobe and signal-to-noise ratio change value I SNRIf both are greater than the corresponding preset threshold, the calibration update period Y2 is matched and the process jumps to step 4; otherwise, the process goes to step 3;

[0018] Step 3: In all other cases, the correction update period Y3 is matched, and step 4 is executed, Y1<Y2<Y3;

[0019] Step 4: Send the calibration update period obtained by matching to the amplitude and phase detection module to control the amplitude and phase detection module to perform polarization parameter re-measurement, thereby realizing dynamic update of the compensation weight by the digital domain optimization module.

[0020] In some embodiments, it further includes a waveguide directional coupling module, an amplitude and phase detection module, and a digital domain optimization module;

[0021] The waveguide directional coupling module is embedded in the feed network of the waveguide array. It is responsible for injecting the standard calibration signal generated by the calibration signal source into each active channel at a predetermined coupling ratio. At the same time, it extracts a portion of the signal from each channel as feedback for subsequent amplitude and phase detection.

[0022] The amplitude and phase detection module uses a superheterodyne receiver and IQ demodulation technology to precisely measure the feedback signal extracted from each active channel;

[0023] The digital domain optimization module implements real-time digital signal processing based on FPGA, combines amplitude, phase, group delay and polarization parameter data, and uses a joint optimization algorithm to calculate the complex compensation weights of each channel.

[0024] In some embodiments, the specific manner of waveguide directional coupling is:

[0025] Step 1: The calibration signal source is set to continuous wave mode, and the frequency range covers the waveguide array operating frequency band; the output power is based on P out =P ref +20dB setting;

[0026] Step 2: The dual-polarization compensation unit receives the FPGA instruction, turns on the corresponding PIN diode, and switches to the vertical polarization path. After the instruction is sent, it takes 5μs for the switch to stabilize, and then the calibration signal is injected. The calibration signal is injected into the target channel through the main channel.

[0027] Step 3: Extract signal power from the coupled port. The algorithm is: P couple =P in -20dB, the signal level after LNA amplification is: P out =P couple -G LNA , where G LNA Represents the gain value of the low noise amplifier, P inThe power of the calibration signal input to the main channel of the waveguide is measured; a bandpass filter is added to the LNA input to suppress out-of-band noise and shield the cavity design;

[0028] Step 4: When the calibration signal is vertically polarized, the horizontally polarized component is reflected by the grid to the load end; the polarization direction of each antenna element is measured and stored as a polarization parameter matrix; the optimal calibration signal polarization mode is selected based on the polarization parameters;

[0029] Step 5: The calibration signal source is injected into the target channel through the main channel of the directional coupler. The coupled port extracts the feedback signal at -20dB and sends it to the amplitude and phase detection module through a low-noise amplifier. The cable delay value is pre-stored and delay alignment is performed in the digital domain. If the feedback signal power is abnormal, it is determined to be a channel failure, an alarm is triggered, and the calibration cycle is skipped. If the calibration fails three times in a row, the system automatically switches to the redundant channel.

[0030] In some embodiments, the precision measurement method of the amplitude and phase detection module is:

[0031] Step 1: Before calibration, inject a known power P ref , record the ADC output code value D ref ;Amplitude measurement, the specific algorithm is: Among them, P meas,k is the actual measured signal power of channel k;

[0032] Step 2: Phase and delay measurements are performed to extract group delay. A Savitzky-Golay filter is used to smooth the phase curve and suppress random jitter.

[0033] Step 3: Polarization parameter extraction.

[0034] In some embodiments, the specific method of extracting the group delay is:

[0035] 201: The calibration signal source sweeps the frequency in the range of 5-40 GHz with a step of 1 MHz, and the dwell time at each frequency point is T dwell ;

[0036] 202: Phase difference calculation, the calculation formula is: Where f is the operating frequency, Q k (f) and I k (f) represents the I / Q quadrature component of the kth channel at frequency f, Δφ k (f) represents the phase error of the kth channel at frequency f; Q ref (f) and I ref (f) represents the known power P ref I / Q quadrature components at frequency f;

[0037] 203: Group delay extraction, Δφk (f) Perform linear fitting, the slope The calculation formula for group delay is:

[0038] In some embodiments, the polarization parameter extraction method is:

[0039] 401: Transmit vertical, horizontal, and left-hand circularly polarized calibration signals in sequence, and the received signals are recorded as

[0040] 402: Constructing a system of equations: Solve the least squares solution J by QR decomposition k ; Among them J k represents the polarization response matrix of the kth channel, Ev and E h represents the vertical and horizontal polarization components received by the kth channel;

[0041] 403: Polarization Matrix J k Perform singular value decomposition (SVD) to obtain the main polarization component σmax and the secondary polarization component σmin. The calculation formulas for the axial ratio and tilt angle are:

[0042]

[0043] In some embodiments, the digital domain optimization module calculates the complex compensation weights of each channel in the following manner:

[0044] Step 1: Use the CORDIC algorithm to support 16-stage pipeline calculation. The calculation process is as follows:

[0045] Where j represents the imaginary unit, satisfying j 2 =-1; input phase error Δφ k and time delay Δτ k , output complex

[0046] Index term

[0047] Step 2: Polarization matrix J k Decompose into orthogonal matrix Q and upper triangular matrix R, then

[0048] Solve by back substitution

[0049] Step 3: Weight synthesis to solve the complex compensation weight W of the kth channel k , the calculation formula is: in For amplitude compensation, For phase compensation, Polarization compensation; the output format is complex weights, which are written to the channel gating device through the SPI interface;

[0050] Step 4: Use the temperature-frequency LUT interpolation formula: W(T,f)=W(T a ,f b )(1-α)(1-β)+W(T a+1 ,f b )α(1-β)+W(T a ,f b+1 )(1-α)β+W(T a+1 ,f b+1 )αβ where α and β are the normalized interpolation coefficients of temperature T and frequency f. And α≥0, β≤1;

[0051] Using nonlinear predistortion, the memory polynomial model is Where Z represents the memory depth, C represents the nonlinear order, Z = 3, C = 5, and n represents the discrete time index, that is, the sequence number of the signal sample point currently being processed; inject the multi-tone signal and collect the amplifier output feedback; solve the coefficient r by the least squares method zc , until the iterative convergence condition is met: NMSE < -40dB; the specific NMSE calculation formula is:

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] 1. By comprehensively considering multiple influencing factors, including environmental factors (temperature and humidity changes), beam pointing error, sidelobe level error, and signal-to-noise ratio changes, a judgment mechanism for triggering calibration was established to ensure calibration when needed, thereby improving system reliability. Furthermore, a calibration update cycle was calculated based on the calibration judgment value to control the amplitude and phase detection modules to perform polarization parameter remeasurement, thereby enabling the digital domain optimization module to dynamically update the compensation weights.

[0054] 2. Through precise signal injection, polarization adaptive switching, and high-quality feedback acquisition, it can inject precise power and polarization state into each channel. At the same time, the acquisition of high-quality feedback signals provides accurate measurement data for the amplitude and phase detection modules, thus laying a solid hardware foundation for the entire internal calibration system and significantly reducing the risk of signal attenuation and distortion caused by polarization mismatch.

[0055] 3. Through high-precision amplitude measurement, precise phase and delay detection, and polarization parameter extraction, the amplitude, phase, delay, and polarization state of each channel's feedback signal can be accurately obtained, providing high-quality, low-noise data support for the digital domain optimization module, thereby ensuring the accuracy and real-time performance of the entire calibration process, and ultimately achieving effective correction of channel polarization mismatch and other errors;

[0056] 4. Through efficient digital signal processing, the compensation weights of each channel are calculated in real time to achieve precise correction of amplitude, phase, delay, and polarization errors. Temperature and frequency adaptive functions ensure that the system can maintain high-precision compensation even in complex environments. The nonlinear pre-distortion algorithm further improves system linearity, thereby significantly enhancing the accuracy and stability of the entire phased array calibration.

[0057] In summary, the present application realizes the intelligent internal calibration of the waveguide phased array antenna through a closed-loop process of calibration judgment → signal injection → parameter detection → digital optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0059] Figure 1 This is a schematic diagram of module connection of the present invention;

[0060] Figure 2 A schematic diagram of the calibration signal injection path of the invention;

[0061] Figure 3 Schematic diagram of the path of the horizontal polarization component reflected by the grid in the present invention. DETAILED DESCRIPTION

[0062] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0063] like Figure 1 As shown, a waveguide array phased array antenna active channel calibration system includes: a calibration judgment module, a waveguide directional coupling module, an amplitude and phase detection module, and a digital domain optimization module;

[0064] The calibration judgment module comprehensively analyzes the factors affecting the waveguide array to determine whether to trigger signal calibration. Specifically:

[0065] By integrating digital environmental sensors (temperature and humidity sensors) into the waveguide array substrate, the temperature and humidity are collected in real time and recorded as T and RH respectively; the temperature change value I in a unit time period is calculated. temp and humidity change value I hum , the specific calculation formula is:

[0066] Where T th is the maximum temperature change threshold allowed by the waveguide array (for example, those skilled in the art can set it to 5°C / min in this scenario). When the temperature change exceeds 5°C / min, the temperature change value I temp Reach 1; for humidity RH, if RH exceeds 80%, it is considered a sudden change, and a step function or linear mapping is used to map the humidity exceeding 80% to 1 at most, completing the normalization of the impact of temperature and humidity on the waveguide array;

[0067] The actual beam pointing is obtained by GPS / INS and compared with the preset pointing to obtain the actual beam error δ beam , calculate the pointing error value I beam The specific calculation formula is:

[0068] where δ th is the maximum beam error that can be tolerated in this application scenario (for example, those skilled in the art can set it to 0.5° in this scenario). The larger the error, the greater the pointing error I beam The closer to 1;

[0069] The actual radiation pattern is obtained by far-field measurement, and the amplitude difference ΔP between the main lobe and the side lobe is extracted. sidelobe , in decibels (dB), and normalize it to get the sidelobe level error value I sidelobe , the specific calculation formula is:

[0070] in is the design target sidelobe level (for example, those skilled in the art can set it to -30dB in this scenario), ΔP th is the maximum drop allowed in this application scenario (for example, those skilled in the art can set it to 10 dB in this scenario); if the actual sidelobe level is lower than the design target, the indicator approaches 0, otherwise the sidelobe level error value I sidelobe rise;

[0071] The baseband processor calculates the received signal SNR and normalizes it to obtain the signal-to-noise ratio change value I SNR The specific calculation formula is:

[0072] Among them I signal Refers to the received signal power, which reflects the energy of the target signal; I noise is the background noise power, that is, the noise energy in the channel; the higher the SNR, the stronger the signal relative to the noise, which usually means the better the performance of the communication or radar system; the purpose of this normalization formula is to convert the problem of insufficient SNR into an indicator between 0 and 1. When the actual SNR is lower than the threshold, the signal-to-noise ratio change value I SNR When it approaches 1, it indicates poor performance; when the SNR reaches or exceeds the threshold, the signal-to-noise ratio change value I SNR Close to or equal to 0, indicating that no calibration is required;

[0073] The temperature change value I temp , humidity change value I hum , pointing error value I beam , sidelobe level error value I sidelobe and signal-to-noise ratio change value I SNR Compare the values ​​with the corresponding preset thresholds respectively. If three or more of them are greater than the corresponding preset thresholds, the calibration requirement meets the trigger condition, triggering signal calibration, turning off the normal radiation / reception functions, and switching the RF switch to the calibration network mode. Otherwise, signal calibration is not triggered and there is no need to update the polarization parameters.

[0074] After the trigger signal is calibrated, the corresponding calibration update period is matched. The specific matching method is:

[0075] Step 1: Change the temperature value I temp , humidity change value I hum , pointing error value I beam , sidelobe level error value I sidelobe and signal-to-noise ratio change value I SNR Recorded as judgment parameters, the judgment parameters are compared with the corresponding preset thresholds. If all the judgment parameters are greater than the preset thresholds (i.e., all five judgment parameters are greater than the corresponding preset thresholds), the correction update cycle Y1 is matched and the process jumps to step 4; otherwise, step 2 is executed.

[0076] Step 2: When there is a pointing error value I in the judgment parameter beam , sidelobe level error value I sidelobe and signal-to-noise ratio change value I SNR If both are greater than the corresponding preset threshold, the calibration update period Y2 is matched and the process jumps to step 4; otherwise, the process goes to step 3;

[0077] Step 3: In all other cases, the calibration update period Y3 is matched and step 4 is executed;

[0078] Step 4: Send the matched calibration update period to the amplitude and phase detection module to control it to remeasure the polarization parameters, thereby enabling the digital domain optimization module to dynamically update the compensation weights. It should be noted that the larger the calibration judgment value, the greater the calibration demand, and the smaller the calibration update period and the more frequent the updates, to ensure that the polarity parameters of each channel are updated in a timely manner. By accurately measuring and compensating these parameters, signal attenuation, distortion, and beamforming errors caused by polarization mismatch between channels can be effectively resolved, providing key protection for high-precision phased array systems.

[0079] It should be noted that Y1<Y2<Y3;

[0080] By comprehensively considering multiple influencing factors such as environmental factors (temperature and humidity changes), beam pointing errors, sidelobe level errors and signal-to-noise ratio changes, a judgment mechanism for triggering calibration was established to ensure calibration when needed and improve system reliability.

[0081] The waveguide directional coupling module is embedded in the feed network of the waveguide array. It is responsible for injecting the standard calibration signal generated by the calibration signal source into each active channel at a predetermined coupling ratio (for example, -20dB). At the same time, it extracts a portion of the signal from each channel as feedback for subsequent amplitude and phase detection. Specifically:

[0082] Step 1: The calibration signal source is set to continuous wave mode, and the frequency range covers the waveguide array operating frequency band; the output power is based on P out =P ref +20dB setting (compensates for the coupler -20dB loss, P ref is the rated input power of the channel);

[0083] Step 2: The dual-polarization compensation unit receives the FPGA instruction, turns on the corresponding PIN diode, and switches to the vertical polarization path; Switching timing: After the instruction is sent, it takes 5μs for the switch to stabilize, and then the calibration signal is injected; Switching path: Figure 2 As shown, the calibration signal is injected into the target channel through the main channel (Port1→Port2);

[0084] Step 3: Extract signal power at the coupled port (Port3). The algorithm is: P couple =P in -20dB, the signal level after LNA amplification is: P out =P couple -G LNA , where G LNA Indicates the gain value of the low noise amplifier (LNA), specifically G LNA =20dB, P inThe calibration signal power is input to the main waveguide channel (Port 1). A bandpass filter (25-40 GHz) is added to the LNA input to suppress out-of-band noise (such as 5G base station interference). The shielded cavity design (made of aluminum, 3 mm thick) ensures that external electromagnetic interference (EMI) is less than -80 dBm.

[0085] Step 4: If Figure 3 As shown in Figure 1, when the calibration signal is vertically polarized, the horizontally polarized component is reflected by the grid to the load end (matching load VSWR < 1.2); the polarization direction (axial ratio, tilt angle) of each antenna element is measured and stored as the polarization parameter matrix [θ k ,AR k ], where θ is the polarization tilt, AR is the axial ratio, and k represents the kth antenna element or channel in the antenna array; for example, in a 64-channel phased array antenna, k = 1 corresponds to the first element in the upper left corner, and k = 64 corresponds to the last element in the lower right corner; the optimal calibration signal polarization mode is selected according to the polarization parameters: linear polarization element (AR> 3dB): select the linear polarization signal with matching tilt (e.g., 45° linear polarization is used for θ = 45° element); circular polarization element (AR< 3dB): select left-hand / right-hand circularly polarized signal (LHCP / RHCP);

[0086] Step 5: The calibration signal source is injected into the target channel through the directional coupler main channel (Port1→Port2). The coupled port (Port3) extracts the feedback signal at -20dB and sends it to the amplitude and phase detection module through the low noise amplifier (LNA). The cable delay value is pre-stored and the delay alignment is performed in the digital domain. If the feedback signal power is abnormal (such as P couple <-50dBm), it is determined as a channel failure, triggering an alarm and skipping the calibration cycle; if the calibration fails three times in a row, the system automatically switches to the redundant channel;

[0087] Through precise signal injection, polarization adaptive switching, and high-quality feedback acquisition, it is possible to inject precise power and polarization state into each channel. At the same time, the acquisition of high-quality feedback signals provides accurate measurement data for the amplitude and phase detection modules, thus laying a solid hardware foundation for the entire internal calibration system and significantly reducing the risk of signal attenuation and distortion caused by polarization mismatch.

[0088] The amplitude and phase detection module uses a superheterodyne receiver and IQ demodulation technology to precisely measure the feedback signals extracted from each active channel. The specific parameter measurement algorithm is as follows:

[0089] Step 1: Before calibration, inject a known power P ref , record the ADC output code value D ref ;Amplitude measurement, the specific algorithm is: Among them, P meas,kis the actual measured signal power of channel k;

[0090] Step 2: Phase and delay measurement:

[0091] 201: The calibration signal source sweeps the frequency in the range of 5-40 GHz with a step of 1 MHz, and the dwell time at each frequency point is T dwell , which is set by those skilled in the art as T dwell =10μs;

[0092] 202: Phase difference calculation, the calculation formula is: Where f is the operating frequency, Q k (f) and I k (f) represents the I / Q quadrature component of the kth channel at frequency f, Δφ k (f) represents the phase error of the kth channel at frequency f; Q ref (f) and I ref (f) represents the known power P ref I / Q quadrature components at frequency f;

[0093] 203: Group delay extraction, Δφ k (f) Perform linear fitting, the slope The calculation formula for group delay is: Savitzky-Golay filter is used to smooth the phase curve and suppress random jitter;

[0094] Step 3: Polarization parameter extraction:

[0095] 401: Transmit vertical (V), horizontal (H), and left-hand circular polarization (LHCP) calibration signals in sequence, and the received signal is recorded as

[0096] 402: Constructing a system of equations: Solve the least squares solution J by QR decomposition k ; Among them J k represents the polarization response matrix of the kth channel, Ev and E h represents the vertical and horizontal polarization components received by the kth channel;

[0097] 403: Polarization Matrix J k Perform singular value decomposition (SVD) to obtain the main polarization component σmax and the secondary polarization component σmin. The calculation formulas for the axial ratio and tilt angle are:

[0098]

[0099] Through high-precision amplitude measurement, precise phase and delay detection, and polarization parameter extraction, the amplitude, phase, delay, and polarization state of each channel's feedback signal can be accurately acquired, providing high-quality, low-noise data support for the digital domain optimization module, thereby ensuring the accuracy and real-time performance of the entire calibration process, and ultimately achieving effective correction of channel polarization mismatch and other errors.

[0100] The digital domain optimization module implements real-time digital signal processing based on FPGA. It combines amplitude, phase, group delay, and polarization parameter data and uses a joint optimization algorithm to calculate the complex compensation weights of each channel. Specifically,

[0101] Step 1: Use the CORDIC algorithm to support 16-stage pipeline calculation. The calculation process is as follows: Where j represents the imaginary unit, satisfying j 2 =-1; input phase error Δφ k and time delay Δτ k , output the complex exponential term through the operation process (32-bit fixed point, 16 bits for real and imaginary parts respectively);

[0102] Step 2: Polarization matrix J k Decompose into orthogonal matrix Q and upper triangular matrix R, and then solve by back substitution method Adopts Q2.14 format (16 bits, 2 integers + 14 decimals) to ensure numerical stability when the matrix condition number is less than 100; each channel has an independent QR decomposition unit, and the calculation time is 1.2μs (2D matrix);

[0103] Step 3: Weight synthesis to solve the complex compensation weight (including amplitude, phase, delay, and polarization compensation) W of the kth channel k , the calculation formula is: in For amplitude compensation, For phase compensation, Polarization compensation; the output format is complex weight (real part + imaginary part 16 bits each), which is written to the channel gating device through the SPI interface;

[0104] Step 4: Use the temperature-frequency LUT to interpolate. The formula is: Where α and β are the normalized interpolation coefficients (linear scale) of temperature T and frequency f, and have no units. And α≥0, β≤1;

[0105] Using nonlinear predistortion (DPD), the memory polynomial model is Where Z represents the memory depth (i.e., the number of past signal samples considered by the model), C represents the nonlinear order, Z = 3, C = 5, and n represents the discrete time index, i.e., the sequence number of the signal sample point currently being processed; inject the multi-tone signal and collect the amplifier output feedback; solve the coefficient r by the least squares method zc (nonlinear predistortion coefficient) until the iterative convergence condition is met: NMSE (normalized mean square error) < -40dB; the specific NMSE calculation formula is: When NMSE < -40dB, it means that the predistortion coefficient has reached convergence;

[0106] Through efficient digital signal processing, compensation weights for each channel are calculated in real time, enabling precise correction of amplitude, phase, delay, and polarization errors. Temperature and frequency adaptation ensures high-precision compensation even in complex environments, while a nonlinear pre-distortion algorithm further improves system linearity, significantly enhancing the accuracy and stability of the entire phased array calibration.

[0107] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0108] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A waveguide array phased array antenna active in-channel calibration system, characterized in that: including a calibration judgment module; The calibration judgment module comprehensively analyzes the factors affecting the waveguide array to determine whether to trigger signal calibration, generates a calibration update cycle, and controls the update of the polarization parameters of each channel. Specifically: By integrating digital environmental sensors into the waveguide array substrate, real-time temperature and humidity are collected and recorded as T and RH respectively, and the temperature change and humidity change values ​​within a unit time period are calculated. The actual beam pointing is obtained through the GPS / INS system, and the actual beam error is obtained by comparing it with the preset pointing, and the pointing error value is calculated; The actual radiation pattern is obtained by far-field measurement, the amplitude difference between the main lobe and the side lobe is extracted, and the side lobe level error value is calculated. The baseband processor calculates the received signal and calculates the signal-to-noise ratio change value; The temperature change value, humidity change value, pointing error value, sidelobe level error value and signal-to-noise ratio change value are compared with the corresponding preset thresholds respectively. If three or more of them are greater than the corresponding preset thresholds, the calibration requirement meets the trigger condition, triggering signal calibration, turning off the normal radiation / reception function, and switching the RF switch to the calibration network mode; After the trigger signal is calibrated, the corresponding calibration update period is matched and the calibration update period is sent to the amplitude and phase detection module.

2. The active in-channel calibration system for a waveguide array phased array antenna according to claim 1, characterized in that: The method to match the corresponding calibration update period is: Step 1: Record the temperature change value, humidity change value, pointing error value, sidelobe level error value, and signal-to-noise ratio change value as judgment parameters, and compare the judgment parameters with the corresponding preset thresholds. If all the judgment parameters are greater than the preset thresholds, the correction update period Y1 is matched and the process jumps to step 4; otherwise, execute step 2. Step 2: When the pointing error value, sidelobe level error value, and signal-to-noise ratio change value in the judgment parameters are all greater than the corresponding preset thresholds, the correction update period Y2 is matched and the process jumps to step 4; Otherwise, proceed to step 3; Step 3: In all other cases, the calibration update period Y3 is matched and step 4 is executed; Step 4: Send the matched calibration update period to the amplitude and phase detection module.

3. The active in-channel calibration system for a waveguide array phased array antenna according to claim 2, characterized in that: It also includes a waveguide directional coupling module, an amplitude and phase detection module, and a digital domain optimization module; The waveguide directional coupling module is embedded in the feed network of the waveguide array. It is responsible for injecting the standard calibration signal generated by the calibration signal source into each active channel at a predetermined coupling ratio. At the same time, it extracts a portion of the signal from each channel as feedback for subsequent amplitude and phase detection. The amplitude and phase detection module uses a superheterodyne receiver and IQ demodulation technology to precisely measure the feedback signal extracted from each active channel; The digital domain optimization module implements real-time digital signal processing based on FPGA, combines amplitude, phase, group delay and polarization parameter data, and uses a joint optimization algorithm to calculate the complex compensation weights of each channel.

4. The active in-channel calibration system for a waveguide array phased array antenna according to claim 3, characterized in that: The specific method of waveguide directional coupling is: Step 1: Set the calibration signal source to continuous wave mode, with a frequency range covering the waveguide array operating frequency band; set the output power; Step 2: The dual-polarization compensation unit receives the FPGA instruction, turns on the corresponding PIN diode, and switches to the vertical polarization path. After the instruction is sent, it takes 5μs for the switch to stabilize, and then the calibration signal is injected. The calibration signal is injected into the target channel through the main channel. Step 3: The coupled port extracts the signal power. After LNA amplification, the signal level is: P out =P couple -G LNA , where G LNA Represents the gain value of the low noise amplifier, P in The power of the calibration signal input to the main channel of the waveguide is measured; a bandpass filter is added to the LNA input to suppress out-of-band noise and shield the cavity design; Step 4: When the calibration signal is vertically polarized, the horizontally polarized component is reflected by the grid to the load end; the polarization direction of each antenna element is measured and stored as a polarization parameter matrix; the optimal calibration signal polarization mode is selected based on the polarization parameters; Step 5: The calibration signal source is injected into the target channel through the main channel of the directional coupler. The coupled port extracts the feedback signal at -20dB and sends it to the amplitude and phase detection module through the low-noise amplifier. Pre-store cable delay values ​​and perform delay alignment in the digital domain; If the feedback signal power is abnormal, it is determined to be a channel failure, an alarm is triggered and the calibration cycle is skipped; If calibration fails three times in a row, it will automatically switch to the redundant channel.

5. The active in-channel calibration system for a waveguide array phased array antenna according to claim 4, characterized in that: The precise measurement method of the amplitude and phase detection module is: Step 1: Before calibration, inject a known power P ref , record the ADC output code value D ref ;Amplitude measurement, the specific algorithm is: Among them, P meas,k is the actual measured signal power of channel k; Step 2: Phase and delay measurements are performed to extract group delay. A Savitzky-Golay filter is used to smooth the phase curve and suppress random jitter. Step 3: Polarization parameter extraction.

6. The active in-channel calibration system for a waveguide array phased array antenna according to claim 5, characterized in that: The specific method of extracting group delay is: 201: The calibration signal source sweeps the frequency in the range of 5-40 GHz with a step of 1 MHz, and the dwell time at each frequency point is T dwell ; 202: Phase difference calculation, the calculation formula is: Where f is the operating frequency, Q k (f) and I k (f) represents the I / Q quadrature component of the kth channel at frequency f, Δφ k (f) represents the phase error of the kth channel at frequency f; Q ref (f) and I ref (f) represents the known power P ref I / Q quadrature components at frequency f; 203: Group delay extraction, Δφ k (f) Perform linear fitting, the slope The calculation formula for group delay is:

7. The active in-channel calibration system for a waveguide array phased array antenna according to claim 6, characterized in that: The polarization parameter extraction method is: 401: Transmit vertical, horizontal, and left-hand circularly polarized calibration signals in sequence, and the received signals are recorded as 402: Constructing a system of equations: Solve the least squares solution J by QR decomposition k ; Among them J k represents the polarization response matrix of the kth channel, Ev and E h represents the vertical and horizontal polarization components received by the kth channel; 403: Polarization Matrix J k Perform singular value decomposition (SVD) to obtain the main polarization component σmax and the secondary polarization component σmin. The calculation formulas for the axial ratio and tilt angle are:

8. The active in-channel calibration system for a waveguide array phased array antenna according to claim 7, characterized in that: The digital domain optimization module calculates the complex compensation weights of each channel in the following way: Step 1: Use the CORDIC algorithm to support 16-stage pipeline calculation. The calculation process is as follows: Where j represents the imaginary unit, satisfying j 2 =-1; input phase error Δφ k and time delay Δτ k , output the complex exponential term through the operation process Step 2: Polarization matrix J k Decompose into orthogonal matrix Q and upper triangular matrix R, and then solve by back substitution method Step 3: Weight synthesis to solve the complex compensation weight W of the kth channel k , the calculation formula is: in For amplitude compensation, For phase compensation, Polarization compensation; the output format is complex weights, which are written to the channel gating device through the SPI interface; Step 4: Use the temperature-frequency LUT to interpolate. The formula is: W(T,f)=W(T a ,f b )(1-α)(1-β)+W(T a+1 ,f b )α(1-β)+W(T a ,f b+1 )(1-α)β+W(T a+1 ,f b+1 )αβ where α and β are the normalized interpolation coefficients of temperature T and frequency f. And α≥0, β≤1; Using nonlinear predistortion, the memory polynomial model is Where Z represents the memory depth, C represents the nonlinear order, Z = 3, C = 5, and n represents the discrete time index, that is, the sequence number of the signal sample point currently being processed; inject the multi-tone signal and collect the amplifier output feedback; solve the coefficient r by the least squares method zc , until the iterative convergence condition is met: NMSE<-40dB.

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