CN-122017762-A - Active phased array radar calibration method

CN122017762ACN 122017762 ACN122017762 ACN 122017762ACN-122017762-A

Abstract

The invention relates to the field of phased radars, and discloses an active phased array radar calibration method for improving accuracy of measured phase data. The method comprises the steps of calculating theoretical excitation phases of all radiation units according to physical geometric structures of an antenna array and a target beam pointing angle, enabling the antenna to sequentially excite the radiation units in a single-channel mode, collecting coupling signals, analyzing to obtain actual measurement amplitude values, actual phase and phase deviation, generating actual emission phases by integrating the theoretical excitation phases and the phase deviation, constructing a phase compensation lookup table, measuring the actual measurement directional diagram after compensation by the lookup table, and fine tuning if the actual measurement directional diagram is not met. The invention improves the calibration precision and reliability and can meet the high-precision detection requirement of the active phased array radar.

Inventors

ZENG YINGJIE
WANG RUI

Assignees

无锡正弦科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260228

Claims (8)

1. An active phased array radar calibration method, comprising: Calculating to obtain a theoretical excitation phase of each radiation unit according to the physical geometry of the antenna array and the target beam pointing angle; under a single-channel working mode, exciting each radiation unit in sequence by taking a normal direction as a reference standard, collecting coupling signals, analyzing the coupling signals to obtain the actually measured amplitude and the phase of each channel at a target point, and calculating to obtain the phase deviation between the actually measured amplitude and the phase and the theoretical value; Invoking the theoretical excitation phase and the phase deviation, generating an actual emission phase for a radiation unit under each angle through comprehensive calculation, and forming a phase compensation lookup table by the actual emission phase; And compensating the antenna by using the phase compensation lookup table, measuring an actual measurement direction diagram, comparing and analyzing the actual measurement direction diagram with an ideal theoretical direction diagram, judging that the calibration process is finished if the angle precision index meets a preset error, and otherwise, finely adjusting the phase compensation lookup table.
2. The active phased array radar calibration method of claim 1, comprising: establishing a plane rectangular coordinate system of an antenna array, setting the center of the array as a reference origin, and traversing the array structure to obtain space geometric coordinate data of each radiation unit relative to the reference origin; analyzing the target beam pointing angle to determine a spatial propagation direction vector of a beam, and performing projection calculation on the spatial propagation direction vector by utilizing the spatial geometrical coordinate data to obtain wave path difference data of each radiation unit relative to a reference wave front; The wave path difference data are converted into angle values in proportion by combining with the working wavelength corresponding to the radar center frequency, and phase delay data are generated; and performing phase conjugation or inversion operation on the phase delay data, and calculating to obtain a theoretical excitation phase.
3. The active phased array radar calibration method of claim 1, comprising: A reset instruction is sent to a radar beam controller, the beam direction is locked at the normal zero-degree position, and electronic switch logic which polls one channel by one channel is activated to establish a single-channel scanning configuration state; Triggering a single radiation unit to emit a radio frequency signal according to the single channel scanning configuration state, and synchronously capturing electromagnetic wave response at each moment by utilizing a near-field or far-field probe to generate a time sequence coupling sampling signal; Performing vector signal analysis on the time sequence coupling sampling signal to obtain an actual measurement signal characteristic vector comprising real part information and imaginary part information; Analyzing the characteristic vector of the actual measurement signal, calculating the model value and the argument of each channel under a polar coordinate system through coordinate transformation, and determining actual measurement amplitude data and actual measurement phase data; And calling a prestored theoretical standard value, and carrying out point-to-point differential operation on the theoretical standard value and the actually measured phase data to obtain a channel phase error value.
4. An active phased array radar calibration method as claimed in claim 3, further comprising the step of eliminating drift errors of the system over time: Selecting a fixed radiation unit in the array as a reference anchor point, periodically inserting an excitation instruction for the reference anchor point according to a preset time step in a scanning sequence for sequentially exciting the radiation units of the whole array, and acquiring a time-varying signal of a reference channel; extracting phase response values of the reference channel time-varying signals at different moments, and constructing a phase drift trend curve reflecting the fluctuation of a system link along with time by taking time as a horizontal axis; according to the specific time stamp of the coupling signal acquired by each radiation unit, linear index or interpolation calculation is carried out on the phase drift trend curve, and an instantaneous phase drift compensation value is acquired; And carrying out reverse offset operation on the instantaneous phase drift compensation value and the actual measured phase of the corresponding radiation unit to generate phase data after drift correction.
5. An active phased array radar calibration method as claimed in claim 3, comprising: traversing a preset radar beam scanning angle set, carrying out one-to-one correspondence on the theoretical excitation phase and the phase deviation according to the physical address of a radiation unit, and establishing a phase data association pair; Performing reverse compensation operation on the phase data association pair to generate an ideal calibration phase value of a continuous numerical range; Obtaining the minimum phase stepping precision of a radar phase shifter, mapping the ideal calibration phase value to a discrete hardware control level, and converting a continuous numerical value into a digital phase control code adapting to the number of hardware bits through rounding or truncation operation; And packaging the full-array digital phase control code according to a storage protocol by taking the beam pointing angle as an index key value, and constructing a phase compensation lookup table.
6. The active phased array radar calibration method of claim 5, comprising: loading the phase compensation lookup table to a radar beam controller, driving an antenna array to emit a test beam, controlling a scanning system to record signal intensity distribution of a full airspace, and generating actual measurement space radiation data; Performing a wave crest searching algorithm on the actually measured space radiation data, determining an actual space angle corresponding to the maximum radiation intensity, and comparing the actual space angle with a preset target beam pointing angle to generate a beam pointing deviation value; comparing the beam pointing deviation value with a preset angular precision tolerance threshold, outputting a locking instruction to finish the flow if the deviation value is smaller than the threshold, and outputting a correction triggering instruction if the deviation value is larger than the threshold; And responding to the correction triggering instruction, calculating linear phase slope data for correcting the beam inclination according to the beam pointing deviation value, and adding the data into a current phase compensation lookup table to generate a corrected phase compensation lookup table.
7. The active phased array radar calibration method of claim 1, further comprising: sampling a test environment by using a near field or far field scanning system under a silent state that the antenna array does not emit signals, and acquiring background noise vector data comprising environmental clutter and system background noise; in the process of enabling the antenna to perform a single-channel working mode and collecting coupling signals, vector difference operation of a complex domain is performed on the collected original signals and the background noise vector data, and a headroom response signal is generated; and carrying out quadrature demodulation analysis on the headroom response signal to separate a real component and an imaginary component of high fidelity.
8. The active phased array radar calibration method of claim 7, further comprising the step of removing multipath reflection interference: Performing reverse frequency-time conversion processing on the original frequency domain coupled signals acquired by the scanning system, mapping the signals from a frequency axis to a time axis, and analyzing to obtain a time domain impulse response sequence; analyzing the time domain impulse response sequence, identifying the position of a main peak in the time domain impulse response sequence, setting a reserved interval according to the width of the main peak, setting a time period outside the interval as a cut-off area, and generating a time gating window function; Performing time domain convolution or windowing operation on the time gating window function and the time domain impulse response sequence to generate a cut-off time domain net signal; and performing forward time-frequency conversion processing on the time domain net signal, restoring the signal to a frequency domain, and generating a multipath inhibition calibration signal.

Description

Active phased array radar calibration method Technical Field The invention relates to the field of phased radars, in particular to an active phased array radar calibration method. Background The active phased array radar has been widely used in a plurality of key fields such as military defense, aerospace and meteorological monitoring by virtue of the remarkable advantages of rapid beam scanning, multi-target tracking, high-precision detection and the like. The core principle is that the flexible direction and shape modeling of the wave beam are realized by precisely controlling the excitation phase of each radiation unit in the antenna array, thereby meeting the detection requirements in different scenes. In practical applications, the performance of active phased array radars is highly dependent on the accuracy of the excitation phase of each radiating element in the antenna array. However, due to factors such as manufacturing process deviation, environmental factors, and drift of the system itself over time, there is often a deviation between the actual excitation phase of each radiating element in the antenna array and the theoretical design value. The phase deviation can cause the problems of inaccurate radar beam pointing, raised side lobe level, widened main lobe and the like, and further seriously influences the detection precision, resolution and anti-interference capability of the radar. In order to ensure that the active phased array radar operates stably and reliably and fully takes advantage of its performance, the antenna array must be accurately calibrated to eliminate phase deviations between the radiating elements. Conventional calibration methods typically employ external reference sources or far field test-based methods that, while capable of achieving calibration purposes to some extent, have a number of limitations. The external reference source method requires additional complex equipment, thereby increasing the system cost and the test difficulty; the far field test method has strict requirements on the test site, and the test process is time-consuming and labor-consuming, so that the real-time calibration requirement is difficult to meet; the traditional method often ignores the influence of factors such as drift of the system along with time, multipath reflection interference and the like on a calibration result, so that the calibration precision is difficult to further improve. Therefore, we propose an active phased array radar calibration method to solve the above problems. Disclosure of Invention The invention provides an active phased array radar calibration method which is used for improving the accuracy of measured phase data. The first aspect of the invention provides an active phased array radar calibration method, which comprises the steps of calculating a theoretical excitation phase of each radiating unit according to a physical geometric structure of an antenna array and a target beam pointing angle, sequentially exciting each radiating unit by an antenna in a single-channel working mode by taking a normal direction as a reference standard, collecting coupling signals, obtaining actual measurement amplitude and phase of each channel at a target point through analyzing the coupling signals, calculating to obtain phase deviation between the actual measurement amplitude and the phase and the theoretical value, calling the theoretical excitation phase and the phase deviation, generating an actual emission phase for the radiating units under each angle through comprehensive calculation, forming a phase compensation lookup table by the actual emission phase, compensating the antenna by using the phase compensation lookup table, measuring the actual measurement directional diagram, comparing and analyzing the actual measurement directional diagram with an ideal theoretical directional diagram, judging that a calibration process is completed if an angle precision index meets a preset error, and otherwise, performing fine adjustment on the phase compensation lookup table. Optionally, in a first implementation manner of the first aspect of the present invention, the method includes establishing a planar rectangular coordinate system of an antenna array and setting an array center as a reference origin, traversing an array structure to obtain spatial geometrical coordinate data of each radiating element relative to the reference origin, analyzing a target beam pointing angle to determine a spatial propagation direction vector of a beam, performing projection calculation on the spatial propagation direction vector by using the spatial geometrical coordinate data to obtain wave path difference data of each radiating element relative to a reference wavefront, combining an operating wavelength corresponding to a radar center frequency, converting the wave path difference data into angle values in proportion, generating phase delay data, and performing phase conjugation or negation oper