Complete polarization active phased array radar and signal processing method

Abstract

The invention provides a fully-polarized active phased array radar and a signal processing method, and belongs to the technical field of radar signal processing, and the radar comprises a cross dual-polarized antenna array, a dual-polarized transmitting channel, a dual-polarized receiving channel, a beam forming and synthesizing module and a signal processing control module. The dual-polarization transmitting channel is used for generating and outputting two paths of radio-frequency transmitting signals with orthogonal polarization modes and adjustable phase difference between the two paths of radio-frequency transmitting signals; the dual-polarization receiving channel is used for receiving and processing dual-polarization echo signals from the cross dual-polarization antenna array; the beam forming and synthesizing module is used for performing spatial domain beam forming and polarization synthesizing processing on the dual-polarization echo signal; and the signal processing control module is used for sending a control instruction to the dual-polarization transmitting channel, receiving a polarization synthesis signal from the beam forming and synthesis module and carrying out target detection and identification. According to the invention, the overall detection performance, the anti-interference capability and the target identification accuracy of the radar in a complex electromagnetic environment are improved.

Description

Technical Field

[0001] This invention relates to the field of radar signal processing technology, specifically to a fully polarized active phased array radar and its signal processing method. Background Technology

[0002] With the rapid development of modern electronic countermeasures technology, jamming devices and other countermeasure equipment have significantly enhanced their ability to detect and analyze radar signals. They can intercept radar radiation signals, identify and replicate their polarization state, and then release targeted jamming with the same polarization, severely weakening the radar's normal detection performance. Against this backdrop, polarization, as another key physical dimension of electromagnetic waves besides frequency, phase, and amplitude, is increasingly valued for its potential in radar anti-jamming, target enhancement detection, and feature recognition. Polarization technology allows radars to improve their information acquisition capabilities in complex environments by selecting or matching specific electromagnetic wave polarization states. Traditionally, radars have attempted to use simple methods such as polarization filtering to suppress some interference or clutter.

[0003] In the process of developing this invention, the inventors realized that existing methods have at least the following problems: Currently mainstream early warning and surveillance radars, especially widely used active phased array radars, have gradually revealed several inherent defects in practical applications. First, in terms of anti-jamming, fixed transmission polarization patterns are easily detected and imitated. Jammers can emit jamming signals with the same polarization, making it difficult for radar to effectively separate targets from jammers in the polarization domain, resulting in low signal recognition accuracy. Second, in terms of target detection, the radar cross-section (RCS) of a target strongly depends on the polarization of the radar wave illumination. When the radar operates with a single fixed polarization, the echo intensity of the target under that specific polarization may be extremely weak, even below the radar detection threshold, causing the target to be missed. Finally, in terms of target identification and classification, a single polarization channel can only provide limited scattering information of the target under that polarization state, failing to obtain the complete, multi-dimensional polarization scattering matrix or polarization features of the target, severely limiting the accuracy and reliability of fine target classification and identification based on polarization domain features.

[0004] In summary, existing active phased array radars generally suffer from technical problems such as limited anti-jamming capabilities, low detection probability of small, polarization-sensitive targets, and low accuracy due to insufficient target identification feature dimensions. These issues make it difficult to meet the increasingly demanding requirements for the comprehensive detection performance of radar systems in increasingly severe and complex electromagnetic environments. Summary of the Invention

[0005] In view of this, it is necessary to provide a fully polarized active phased array radar and a signal processing method to solve the technical problems of existing active phased array radars, such as limited anti-jamming capability, low detection probability of polarization-sensitive small targets, and low accuracy due to insufficient target recognition feature dimensions.

[0006] To address the aforementioned technical problems, in a first aspect, the present invention provides a fully polarized active phased array radar, comprising a cross-polarized antenna array, a dual-polarized transmit channel, a dual-polarized receive channel, a beamforming and combining module, and a signal processing and control module. The cross-polarized antenna array includes multiple cross-polarized antenna elements; The dual-polarized transmission channel is connected to the cross-dual-polarized antenna array and is used to generate and output two radio frequency transmission signals with orthogonal polarization and adjustable phase difference between them. The dual-polarized receiving channel is connected to the cross-dual-polarized antenna array and is used to receive and process dual-polarized echo signals from the cross-dual-polarized antenna array. The beamforming and combining module is connected to the dual-polarization receiving channel and is used to perform spatial beamforming and polarization combining processing on the dual-polarization echo signal. The signal processing control module is connected to the dual-polarized transmission channel and the beamforming and combining module. It is used to send control commands to the dual-polarized transmission channel to set the phase difference between the two radio frequency transmission signals, control the cross dual-polarized antenna array to radiate a transmission beam with a specific polarization mode, and receive the polarization combined signal from the beamforming and combining module for target detection and identification.

[0007] In one possible implementation, the dual-polarized transmit channel includes a digital T / R component and an analog T / R component; The digital T / R component is used to generate two orthogonal polarization signals of digital baseband based on waveform control parameters and amplitude-phase compensation data from the signal processing control module. The analog T / R component is connected between the digital T / R component and the cross-polarized antenna array, and is used to up-convert and amplify the two orthogonal polarized signals of the digital baseband to form the two radio frequency transmission signals.

[0008] In one possible implementation, the fully polarized active phased array radar further includes a sidelobe antenna and a sidelobe receiving and processing channel; The sidelobe antenna adopts a cross-dual polarization design; The sidelobe receiving and processing channel is connected to the sidelobe antenna and the signal processing control module. It is used to receive interference signals and send the processed interference signals to the signal processing control module for polarization analysis. The signal processing control module generates the control command based on the polarization mode of the interference signals obtained from the analysis.

[0009] In one possible implementation, the beamforming and combining module includes a digital beamformer; The digital beamformer is used to weight and synthesize multiple digital echo signals from the dual-polarized receiving channel to form multiple receiving beams in the azimuth and elevation dimensions, wherein each receiving beam contains two orthogonal polarized signals; and to perform polarization synthesis operations on the two orthogonal polarized signals in each receiving beam.

[0010] In one possible implementation, the signal processing control module includes a storage unit that pre-stores a target polarization feature library, which contains feature data of different types of targets under different polarization modes. The signal processing control module controls the beamforming and synthesis module to switch between different polarization synthesis modes, obtains the echo characteristics of the target under different polarization states, and matches and identifies them with the target polarization feature library to obtain the target identification result.

[0011] On the other hand, the present invention also provides a signal processing method for a fully polarized active phased array radar, comprising: Generate launch scheduling instructions based on radar mission requirements; According to the transmission scheduling command, the dual-polarized transmission channel is controlled to generate two radio frequency excitation signals with orthogonal polarization and adjustable phase difference, and the transmission beam containing the first polarization is radiated through the cross dual-polarized antenna array. The target echo signal is received through the cross-polarized antenna array; The target echo signal is received and digitized to obtain dual-channel digital echo data; Beamforming and polarization combining processes are performed on the dual-channel digital echo data to obtain a composite signal containing a second polarization mode; The synthesized signal is detected, and the target parameters are estimated and identified based on the detection results to obtain the target identification result.

[0012] In one possible implementation, when the radar mission requirement is anti-jamming, the step of generating a launch scheduling instruction based on the radar mission requirement includes: The system receives spatial interference signals via a sidelobe antenna, performs polarization analysis on the interference signals, and extracts the polarization patterns as interference polarization information. Based on the interference polarization information, the transmission scheduling command is generated. The transmission scheduling command includes a phase difference control parameter to make the first polarization mode orthogonal to the interference polarization mode.

[0013] In one possible implementation, the beamforming and polarization combining process performed on the dual-channel digital echo data to obtain a synthesized signal containing a second polarization includes: Calculate the signal quality metric values ​​of the dual-channel digital echo data under different polarization synthesis coefficients; The polarization combining coefficient corresponding to the largest signal quality metric value is selected as the reference combining coefficient. Using the reference synthesis coefficients, the dual-channel digital echo data is synthesized to obtain a synthesized signal containing a second polarization mode.

[0014] In one possible implementation, the signal quality metric is the signal-to-noise ratio (SNR) or signal-to-noise ratio (SNR).

[0015] In one possible implementation, the step of estimating and identifying target parameters based on the detection results to obtain target identification results includes: During multiple radar detections, the beamforming and combining module is controlled to sequentially observe the same target area using various different second polarization modes to obtain observation characteristics. From the observed features, micro-motion features or scattering features under each second polarization mode are extracted sequentially to form a multi-polarization feature vector; The multipolar feature vector is matched with a pre-stored target polarization feature library, and the target type is determined based on the matching result, which is then used as the target recognition result.

[0016] The beneficial effects of this invention are as follows: The fully polarized active phased array radar provided by this invention is composed of a cross-polarized antenna array, a dual-polarized transmit channel, a dual-polarized receive channel, a beamforming and combining module, and a signal processing and control module. The antenna array serves as the physical foundation, providing dual-polarized radiation and reception capabilities; the dual-polarized transmit and receive channels are respectively responsible for generating dual-path radio frequency signals with flexible adjustable phase difference and preprocessing the dual-polarized echo; the beamforming and combining module performs spatial filtering and polarization domain optimization synthesis on the echo; and the signal processing and control module, as the control center, coordinates and regulates the polarization state of the transmitted signal and processes the received signal to complete information extraction. By dynamically controlling the phase difference of the two signals at the transmitting end to synthesize any desired transmit polarization beam, and by performing joint spatial and polarization domain processing on the dual-polarization echo at the receiving end to adaptively select the optimal receive polarization state, the radar system can achieve active matching and adaptive optimization in the polarization domain according to the interference environment, target characteristics and mission requirements. This simultaneously and significantly improves the radar's anti-jamming capability, the detection probability of polarization-sensitive targets, and the target recognition accuracy based on multi-polarization features at the mechanism level. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of an embodiment of the fully polarized active phased array radar provided by the present invention; Figure 2 A schematic diagram of an embodiment of the dual-polarization transmission channel provided by the present invention; Figure 3 A schematic diagram of another embodiment of the fully polarized active phased array radar provided by the present invention; Figure 4 A schematic flowchart of an embodiment of the signal processing method for a fully polarized active phased array radar provided by the present invention; Figure 5 For the present invention Figure 4 A schematic diagram of an embodiment of S401; Figure 6 For the present invention Figure 4 A schematic diagram of an embodiment of S405; Figure 7 For the present invention Figure 4 A schematic diagram of an embodiment of S406. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] In the description of the embodiments of the present invention, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0021] The terms "first," "second," etc., used in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a technical feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] Before demonstrating the embodiments, the following terms will be explained.

[0024] A cross-polarized antenna array is an antenna system consisting of multiple antenna elements, each of which can simultaneously radiate or receive electromagnetic waves with two orthogonal polarization directions (such as horizontal polarization and vertical polarization). It is the basic hardware for realizing full polarization.

[0025] A dual-polarization transmit channel refers to the circuitry and processing links used to generate and output two radio frequency signals. The polarization of these two signals is orthogonal, and the relative phase difference between them can be controlled and adjusted to synthesize any desired polarization beam in the air.

[0026] A dual-polarization receive channel refers to the circuitry and processing links used to receive and preprocess dual-polarized echo signals from an antenna. It typically includes functions such as low-noise amplification, down-conversion, and analog-to-digital conversion of the two orthogonally polarized signals.

[0027] A beamforming and synthesis module is a signal processing unit that first performs spatial weighting on multi-channel signals to form a directional beam (digital beamforming, DBF), and then combines the dual-polarized signals within the beam (polarization synthesis) to optimize signal quality or form a specific receiving polarization.

[0028] The Signal Processing and Control Module (SCM) is the core processing and control unit of the radar system. It is responsible for generating transmission control commands, processing received radar data, executing target detection, parameter estimation and identification algorithms, and coordinating the work of various subsystems.

[0029] A digital T / R module is a digital processing unit that integrates transmission and reception functions. It typically generates programmable transmission waveforms digitally in baseband or intermediate frequency and performs digital sampling and preprocessing on the received signal.

[0030] An analog T / R module is a radio frequency circuit unit located between a digital T / R module and an antenna. It is mainly responsible for up-converting digital baseband signals to radio frequency and amplifying their power for transmission, as well as amplifying and down-converting received radio frequency signals with low noise.

[0031] A sidelobe antenna is an antenna specifically designed to receive signals from the sidelobes of a radar main beam. It is typically used for reconnaissance or to counter interference signals entering from the sidelobes.

[0032] Transmission Scheduling Command refers to the set of commands generated by the control module to control the operation of the transmitter, including waveform parameters, pulse repetition frequency, and key polarization control parameters (such as phase difference setting).

[0033] The phase difference control parameter is a numerical parameter used to precisely control the relative phase between two orthogonal signals in a dual-polarized transmit channel. It is a key variable for regulating the final polarization state of the radiated beam.

[0034] Polarization synthesis coefficients refer to a set of complex weights (including amplitude and phase) used to linearly combine two orthogonally polarized received signals. Different combinations of coefficients can synthesize different equivalent receiving polarization modes.

[0035] Signal quality metric refers to an indicator used to quantify the quality of radar echo signals. In this invention, it specifically refers to the signal quality after being synthesized with different polarizations. Signal-to-noise ratio (SNR) or signal-to-clutter ratio (SCR) are commonly used as the metric.

[0036] The Target Polarization Signature Database is a pre-generated database that stores feature data (such as scattering matrix, micro-motion features, etc.) of various types of targets under different polarization radar wave illumination, which is used for pattern matching during target identification.

[0037] Micro-motion feature refers to the periodic modulation information generated by the minute vibrations or rotational motions of a target or its components (such as rotors or engines) on radar echoes. In the frequency domain, it manifests as characteristic micro-Doppler spectral lines and can be used for target classification and identification.

[0038] This invention provides a fully polarized active phased array radar and a signal processing method for it. The technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0039] Figure 1 This is a schematic diagram of an embodiment of the fully polarized active phased array radar provided by the present invention, as shown below. Figure 1 As shown, the fully polarized active phased array radar includes a cross dual-polarized antenna array 101, a dual-polarized transmit channel 102, a dual-polarized receive channel 103, a beamforming and combining module 104, and a signal processing and control module 105. The cross-polarized antenna array 101 includes multiple cross-polarized antenna elements; The dual-polarized transmit channel 102 is connected to the cross dual-polarized antenna array 101, and is used to generate and output two radio frequency transmit signals with orthogonal polarization and adjustable phase difference between them; The dual-polarized receiving channel 103 is connected to the cross-dual-polarized antenna array 101 and is used to receive and process the dual-polarized echo signal from the cross-dual-polarized antenna array 101. The beamforming and combining module 104 is connected to the dual-polarization receiving channel 103 and is used to perform spatial beamforming and polarization combining processing on the dual-polarization echo signal. The signal processing control module 105 is connected to the dual-polarized transmission channel 102 and the beamforming and combining module 104. It is used to send control commands to the dual-polarized transmission channel 102 to set the phase difference between the two radio frequency transmission signals, control the cross dual-polarized antenna array 101 to radiate a transmission beam with a specific polarization mode, and receive the polarization combined signal from the beamforming and combining module 104 for target detection and recognition.

[0040] The cross-polarized antenna array 101 is the front-end radiating and receiving unit of the entire system. Physically, it consists of a large number of cross-polarized antenna elements arranged in a specific manner (such as triangles). Each antenna element has the ability to simultaneously radiate and receive two orthogonally polarized electromagnetic waves (such as horizontal polarization and vertical polarization).

[0041] The dual-polarized transmit channel 102 is electrically connected to the antenna array 101. According to instructions from the signal processing control module 105, the dual-polarized transmit channel 102 generates two mutually orthogonal radio frequency transmit signals with a precisely adjustable relative phase difference. By adjusting this phase difference and through the coordinated radiation of each element in the antenna array 101, a transmit beam with any desired polarization (e.g., left-hand circular polarization, right-hand circular polarization, or linear polarization at any angle) can be synthesized in a specified spatial domain. The dual-polarized receive channel 103 is also connected to the antenna array 101 and is responsible for preprocessing the dual-polarized echo signal containing target information received by the antenna array 101, including low-noise amplification, filtering, and down-conversion.

[0042] The beamforming and combining module 104 is connected after the dual-polarized receiving channel 103. The beamforming and combining module 104 first performs spatial beamforming processing on the digital signals from multiple receiving channels, and simultaneously forms multiple high-gain, low-sidelobe receiving beams in the azimuth and elevation dimensions through digital weighting, thereby achieving spatial filtering and interference suppression.

[0043] It is worth mentioning that the beamforming and combining module 104 also performs real-time polarization combining operations on the two orthogonal polarization signals contained in each receiving beam, so as to dynamically select or combine the receiving polarization state that is most sensitive to the current target or has the best effect on suppressing clutter / interference at the receiving end.

[0044] The signal processing control module 105 is connected to both the dual-polarized transmission channel 102 and the beamforming and combining module 104. On one hand, the signal processing control module 105 sends control commands containing key parameters such as phase difference to the transmission channel 102 to dynamically shape the polarization characteristics of the transmitted beam. On the other hand, it receives echo signals from the beamforming and combining module 104 that have undergone spatial and polarization domain optimization processing, and performs final information extraction tasks such as target detection, parameter estimation (e.g., ranging, angle measurement), and classification. For example, in an adversarial scenario, the signal processing control module 105 can command the transmission channel 102 to generate polarized waves orthogonal to the interference to improve the signal-to-interference ratio (SNR). When detecting weak targets, it can command the receiver to scan in multiple preset polarization states and select the polarization synthesis result with the highest SNR for detection, thereby increasing the detection probability.

[0045] This embodiment integrates flexible polarization-adjustable transmission and reception hardware channels, and combines them with a digital signal processing flow that performs joint optimization in the airspace and polarization domains. This enables the radar system to have active adaptability in the polarization dimension. For different mission scenarios (such as anti-jamming, weak target detection, and target recognition), it adaptively selects the optimal combination of transmission and reception polarization, thereby greatly improving the radar's overall detection performance, anti-jamming capability, and target recognition accuracy in complex electromagnetic environments.

[0046] In some embodiments of the present invention, such as Figure 2 As shown, the dual-polarized transmit channel 102 includes a digital T / R component and an analog T / R component; The digital T / R component 201 is used to generate two orthogonal polarization signals of digital baseband based on waveform control parameters and amplitude and phase compensation data from the signal processing control module 105. The analog T / R component 202 is connected between the digital T / R component and the cross-polarized antenna array 101. It is used to upconvert and amplify the two orthogonal polarized signals of the digital baseband to form two radio frequency transmission signals.

[0047] Specifically, the digital T / R component 201 receives waveform control parameters, amplitude and phase compensation data, and the system reference clock from the signal processing control module 105. Based on these inputs, the digital T / R component 201 generates two mutually orthogonal baseband polarization signals in the digital domain according to a preset synchronization sequence. The analog T / R component 202 is connected between the digital T / R component 201 and the cross-polarized antenna array 101 in the RF link. It is used to up-convert the aforementioned two baseband signals to the operating frequency band and perform multi-stage power amplification, ultimately forming two RF transmission signals with sufficient radiated power and orthogonal polarization. By precisely controlling the initial phase of one or both baseband signals digitally, flexible control of the relative phase difference between the two RF transmission signals can be achieved. For example, when it is necessary to generate a left-hand circularly polarized wave, the two orthogonal signals can be set to have a fixed phase difference of 90 degrees through the digital T / R component 201; if it is necessary to generate a linearly polarized wave at a specific angle, the phase difference can be adjusted to 0 degrees or 180 degrees, and then combined with amplitude weighting to achieve the desired result.

[0048] This embodiment employs a digital T / R component 201 to generate the signal and control its initial amplitude and phase in the baseband, ensuring the digital programmability of the polarization state. This allows the radar to quickly and accurately switch or synthesize any desired transmission polarization. The analog T / R component 202 focuses on the efficient amplification and radiation of the radio frequency signal, ensuring the radar's detection power. This division of labor and cooperation allows the fully polarized phased array radar to not only match target characteristics with the optimal polarization to improve detection performance, but also dynamically adjust the transmission polarization in adversarial environments to mismatch it with the interference polarization. This effectively enhances anti-jamming capabilities and target detection accuracy from the signal transmission source.

[0049] In some embodiments of the present invention, such as Figure 3 As shown, the fully polarized active phased array radar also includes a sidelobe antenna 301 and a sidelobe receiving and processing channel 302. The sidelobe antenna 301 adopts a cross-polarization design; The sidelobe receiving and processing channel 302 connects the sidelobe antenna 301 and the signal processing control module 105. It is used to receive interference signals and send the processed interference signals to the signal processing control module 105 for polarization analysis. The signal processing control module 105 generates control commands based on the polarization mode of the interference signals obtained from the analysis.

[0050] The sidelobe antenna 301 employs a cross-polarization design, with its orientation corresponding to the sidelobe region of the main antenna array, for receiving interference signals from the sidelobe direction in space. The sidelobe receiving and processing channel 302 connects the sidelobe antenna 301 to the signal processing and control module 105.

[0051] Specifically, the interference signal received by the sidelobe antenna 301 is first preprocessed by the sidelobe receiving and processing channel 302, including low-noise amplification, filtering, and down-conversion, to form two orthogonal interference intermediate frequency or baseband signals. Subsequently, these signals are sent to the signal processing control module 105 for polarization analysis.

[0052] In the signal processing control module 105, by extracting and calculating the amplitude and phase of the two orthogonal interference signals, the specific polarization mode adopted by the interference signal during spatial propagation can be determined, such as left-hand circular polarization, right-hand circular polarization, or linear polarization at a specific angle. This result is defined as interference polarization information. Based on this interference polarization information, the signal processing control module 105 generates corresponding control commands. These commands are sent to the dual-polarization transmission channel 102 to dynamically adjust the phase difference between the two orthogonal radio frequency transmission signals it generates. The adjustment aims to ensure that the polarization mode of the transmission beam ultimately radiated by the radar main antenna remains orthogonal to the polarization mode of the detected interference signal in the polarization domain. For example, if the analysis reveals that the interference signal is vertically polarized, the radar is controlled to transmit a horizontally polarized wave; if the interference is right-hand circularly polarized, a left-hand circularly polarized wave is transmitted.

[0053] This embodiment adds an independent sidelobe listening and polarization analysis path, enabling the radar to actively detect and identify the polarization state of interference. Then, by emitting polarized waves orthogonal to it, the energy of the interference signal entering the radar's main receiving channel is greatly reduced, thereby improving the system's signal-to-interference ratio and survivability in complex electromagnetic environments.

[0054] In some embodiments of the present invention, the beamforming and combining module 104 includes a digital beamformer; the digital beamformer is used to weight and combine multiple digital echo signals from the dual-polarized receiving channel 103 to form multiple receiving beams in the azimuth and elevation dimensions, wherein each receiving beam contains two orthogonal polarized signals; and to perform polarization combining operations on the two orthogonal polarized signals in each receiving beam.

[0055] The digital beamformer receives multiple digital echo signals from the dual-polarized receiving channel 103 and performs spatial adaptive weighting and synthesis operations on these signals in the digital domain.

[0056] Specifically, it uses preset or adaptively calculated complex weighting coefficients to adjust the amplitude and phase of the signals from each receiving channel distributed on the array and superimpose them in phase, thereby simultaneously forming multiple receiving beams with high gain and low sidelobes at a specified azimuth and elevation angle. Each formed receiving beam contains two signals at the signal level, corresponding to a pair of orthogonal polarization components received by the cross-polarized antenna array 101, such as the signals from the horizontal polarization (H) and vertical polarization (V) channels.

[0057] Furthermore, the digital beamformer can perform polarization synthesis operations on the two orthogonally polarized signals within each beam. Based on mission requirements or optimization criteria (such as maximum signal-to-noise ratio), a set of polarization synthesis coefficients (including amplitude ratio and phase difference) are calculated and applied in real time to linearly combine the two orthogonally polarized signals, thereby synthesizing a scalar signal with a new polarization state in the polarization domain.

[0058] In this embodiment, the digital beamformer suppresses interference and clutter from non-main lobe directions through spatial processing, improving spatial resolution and anti-interference capability. The subsequent polarization synthesis operation adaptively selects the polarization receiving state most sensitive to the target or least sensitive to interference within each beam direction. This enables the radar system to not only accurately point to the target in space but also align with the target in the polarization dimension, significantly improving the radar's detection probability and measurement accuracy for weak targets in complex scenarios.

[0059] In some embodiments of the present invention, the signal processing control module 105 includes a storage unit, which pre-stores a target polarization feature library, which contains feature data of different types of targets under different polarization modes; The signal processing control module 105 controls the beamforming and synthesis module 104 to switch different polarization synthesis modes, obtains the echo characteristics of the target under different polarization states, and matches and identifies them with the target polarization feature library to obtain the target identification result.

[0060] The target polarization feature library is constructed by conducting extensive full polarization measurements and data accumulation on various typical targets (such as different types of aircraft, ships, vehicles, etc.). It includes feature data of various targets under different radar frequency bands, different observation angles, and different polarization transceiver combinations. These features may include, but are not limited to, the polarization scattering matrix elements, polarization entropy, polarization synthetic aperture radar features, and micro-Doppler-based polarization modulation features.

[0061] In practical applications, the signal processing control module 105 sends commands to the beamforming and synthesis module 104 to control it to sequentially switch between different polarization synthesis coefficients (i.e., change the receiving polarization mode), thereby acquiring the echo sequence of the same target under illumination in multiple different polarization states. Subsequently, the dynamic or static polarization features of the target are extracted from these multi-polarization echo data to form a set of multi-dimensional feature vectors. Finally, this feature vector is compared with the target polarization feature library in the storage unit for pattern matching and similarity calculation. Based on the optimal matching result, the type and attributes of the target are determined, and the target recognition result is output. For example, by comparing the difference in the micro-Doppler spectrum of the target under left-hand circular polarization and right-hand circular polarization reception, it is possible to effectively distinguish between rotary-wing UAVs and fixed-wing aircraft.

[0062] This embodiment significantly improves the accuracy and confidence of classification and recognition, and reduces false alarms and misjudgments by acquiring the characteristic fingerprints of the target under multiple polarization states and comparing them with a prior knowledge base.

[0063] Figure 4 This is a schematic flowchart of an embodiment of the signal processing method for a fully polarized active phased array radar provided by the present invention, as shown below. Figure 4 As shown, the signal processing method of this fully polarized active phased array radar includes: S401. Generate launch scheduling instructions based on radar mission requirements; S402. According to the transmission scheduling command, control the dual-polarized transmission channel to generate two radio frequency excitation signals with orthogonal polarization and adjustable phase difference, and radiate the transmission beam containing the first polarization through the cross dual-polarized antenna array. S403: Receive target echo signals via a cross-polarized antenna array; S404. Perform dual-polarization reception and digitization processing on the target echo signal to obtain dual-channel digital echo data; S405. Perform beamforming and polarization synthesis processing on the dual-channel digital echo data to obtain a synthesized signal containing a second polarization mode; S406. Detect the synthesized signal, and estimate and identify the target parameters based on the detection results to obtain the target identification result.

[0064] In step S401, the main control computer generates corresponding launch scheduling instructions based on the upper-level radar mission requirements (such as search, tracking, anti-jamming, or identification). These instructions define basic parameters such as waveform, pulse width, and repetition frequency, and specifically include key control parameters for polarization synthesis.

[0065] In step S402, the transmit scheduling command is issued to the dual-polarized transmit channel. Specifically, the digital T / R component generates two baseband signals that are orthogonal in the digital domain and whose relative phase difference can be precisely adjusted, based on the waveform control parameters and amplitude-phase compensation data in the command. After up-conversion and power amplification by the analog T / R component, these signals form two radio frequency excitation signals. These two signals are radiated through a cross-polarized antenna array and combined in space into a transmit beam with a specific polarization, which is defined as the first polarization. By changing the phase difference between the two baseband signals, the first polarization can be flexibly controlled, allowing it to be linear, circular, or arbitrary elliptical polarization.

[0066] Steps S403 and S404 involve signal reception and digitization. The cross-polarized antenna array receives the echo signal containing target information, which naturally contains two orthogonal polarization components. The dual-polarized receiving channel performs low-noise amplification, filtering, down-conversion, and other processing on these signals, and finally digitizes them to output synchronized dual-channel digital echo data.

[0067] Step S405 performs digital beamforming on the dual-channel digital echo data to form a high-gain beam in the spatial domain to suppress spatial interference. Subsequently, polarization combining is performed: multiple polarization combining coefficients (i.e., different amplitude and phase combinations of the two signals) are used to calculate the signal quality metric (such as signal-to-noise ratio) for each combining result, and the combining coefficient that optimizes this metric is automatically selected, ultimately generating a combined signal with the optimal second polarization mode.

[0068] Finally, in step S406, the optimized synthetic signal is subjected to detection, parameter estimation (such as distance, angle, and velocity), and target recognition. The recognition process makes particular use of full polarization capability, which can obtain the multidimensional polarization features of the target by switching different "second polarization modes" and comparing them with the database to improve recognition accuracy.

[0069] This embodiment maximizes the signal-to-interference ratio and signal-to-noise ratio from a physical principle perspective by shaping the optimal illumination polarization at the transmitting end and selecting the optimal receiving polarization at the receiving end. This simultaneously and significantly improves the radar's anti-jamming capability, the probability of detecting weak targets, and the accuracy of target classification and recognition.

[0070] In some embodiments of the present invention, such as Figure 5 As shown, step S401, when the radar mission requirement is anti-jamming, generates a launch scheduling command based on the radar mission requirement, including: S501. Receive spatial interference signals through a sidelobe antenna, perform polarization analysis on the interference signals, and extract the polarization mode as interference polarization information. S502. Based on the interference polarization information, generate a transmission scheduling command. The transmission scheduling command includes a phase difference control parameter to make the first polarization mode orthogonal to the interference polarization mode.

[0071] In this embodiment, when the radar mission requires anti-jamming, the process of generating launch scheduling commands involves an active sensing and dynamic suppression loop for jamming signals. Specifically, this embodiment uses a sidelobe antenna with cross-polarization to receive spatial jamming signals entering from the sidelobes of the radar main beam. The jamming signal is then sent to a processing unit for real-time, precise polarization analysis. This analysis process extracts a complete polarization state description, i.e., jamming polarization information, by performing amplitude and phase calculations on the two orthogonal polarization components of the jamming signal. This information clearly characterizes the specific polarization mode of the jamming signal, such as left-hand circular polarization, right-hand circular polarization, or linear polarization with a specific orientation.

[0072] After acquiring precise interference polarization information, the signal processing and control module generates a transmission scheduling command. This command contains a specific set of phase difference control parameters, the values ​​of which are calculated to precisely set the relative phase of the two orthogonal transmitted signals in the dual-polarization transmission channel. This setting ensures that the transmitted beam radiated by the radar's main antenna, containing the first polarization, maintains an orthogonal relationship in the polarization domain with the detected interference polarization. For example, if the analysis determines that the interference signal uses vertical polarization, the radar is controlled to transmit a horizontally polarized wave; if the interference is right-hand circularly polarized, left-hand circularly polarized waves are transmitted.

[0073] The anti-interference method provided in this embodiment achieves a qualitative change from passively enduring interference to actively avoiding interference, maximizing the difficulty of interference signals entering the radar's main receiving channel, improving the radar's signal-to-interference ratio in complex electronic warfare environments, and enhancing the radar's survivability and continuous detection accuracy under strong interference conditions.

[0074] In some embodiments of the present invention, such as Figure 6 As shown, step S405 performs beamforming and polarization combining processing on the dual-channel digital echo data to obtain a combined signal containing a second polarization mode, including: S601. Calculate the signal quality metric of dual-channel digital echo data under different polarization synthesis coefficients; S602. Select the polarization synthesis coefficient corresponding to the largest signal quality metric value as the reference synthesis coefficient; S603. Using reference synthesis coefficients, the dual-channel digital echo data is synthesized to obtain a synthesized signal containing the second polarization mode.

[0075] In some embodiments of the present invention, the signal quality metric is the signal-to-noise ratio (SNR) or signal-to-noise ratio (SNR).

[0076] Specifically, in this embodiment, a series of preset or dynamically generated polarization combining coefficients are first applied to the dual-channel data (i.e., two orthogonally polarized signals) in the digital domain. These polarization combining coefficients define how to perform amplitude weighting and phase combination of the two signals. For each set of coefficients, a signal quality metric for the synthesized signal is calculated. This metric is typically selected as the signal-to-noise ratio (SNR) or signal-to-noise ratio (SCR) as an objective evaluation standard.

[0077] Specifically, the signal-to-noise ratio (SNR) directly reflects the strength of the target signal relative to the system noise, while the signal-to-clutter ratio (SCR) characterizes the degree to which the target signal is submerged in environmental clutter (such as ground features, ocean waves, and weather echoes).

[0078] Subsequently, all calculated signal quality metrics are compared, and the set of polarization combining coefficients corresponding to the maximum value is identified and selected as the reference combining coefficients. Finally, using this set of reference combining coefficients, the original dual-channel digital echo data undergoes final polarization combining operations, resulting in a single-channel synthesized signal with a second polarization mode. The second polarization mode is the specific polarization reception state defined by this set of optimal coefficients that achieves the best signal quality.

[0079] The adaptive polarization synthesis processing method in this embodiment realizes real-time automatic optimal matching between the received polarization state and the current detection environment and target characteristics, which significantly improves the detection probability and measurement accuracy of radar for small targets (such as UAVs and stealth aircraft) in strong clutter background.

[0080] In some embodiments of the present invention, such as Figure 7 As shown, step S406 estimates and identifies target parameters based on the detection results to obtain target identification results, including: S701. During multiple radar detections, the beamforming and combining module is controlled to sequentially observe the same target area using various different second polarization methods to obtain observation characteristics. S702. From the observed features, extract the micro-motion features or scattering features under each second polarization mode in sequence to form a multi-polarization feature vector; S703. Match the multi-polarization feature vector with the pre-stored target polarization feature library, determine the target type based on the matching result, and use it as the target recognition result.

[0081] Specifically, during multiple consecutive detection cycles of the radar targeting the same target area, the signal processing control module controls the beamforming and synthesizing module to switch sequentially and repeatedly observe the area using various different second polarization modes according to a preset order. Each observation acquires echo data of the target under that specific receiving polarization state; these data are collectively referred to as observation features. Subsequently, physical quantities characterizing the target's properties are extracted from these observation features differentiated by polarization mode. These physical quantities can be micro-motion characteristics reflecting the motion of target components (such as rotor rotation and engine vibration) (e.g., spectral lines and modulation sidebands of the micro-Doppler spectrum), or scattering characteristics reflecting the target's geometry and material (e.g., scattering intensity, polarization scattering matrix elements, and polarization entropy). Combining these feature values ​​extracted from different polarization modes constitutes a multi-dimensional, multi-polarization feature vector, which comprehensively describes the target's response characteristics to electromagnetic waves of various polarization modes.

[0082] To complete the identification, the multi-polarization feature vector is matched against a pre-existing target polarization feature library in a database. This feature library contains feature data of various typical targets (such as different types of aircraft, ships, and vehicles) under multi-polarization observation, obtained through prior measurements or simulations. The matching process is achieved by calculating the similarity between the feature vector and various target templates in the library. Finally, the target type corresponding to the template with the highest similarity or exceeding a preset threshold is determined as the identification result of the currently observed target.

[0083] For example, when distinguishing between a rotorcraft drone and a bird, the radar can be controlled to receive echoes sequentially in left-hand circular polarization, right-hand circular polarization, etc. The metal blades of the rotor exhibit significantly different modulation effects to the two circular polarizations, and their micro-Doppler spectra possess a unique harmonic structure; while the scattering from a bird's body is not sensitive to this. By extracting and comparing the micro-motion characteristics under these two polarizations, effective differentiation can be achieved.

[0084] This embodiment actively manipulates and utilizes the diversity of polarization dimensions to obtain a series of physical response fingerprints of the target that are closely related to its polarization state. These features originate from the target's own geometry, material, and motion properties, making them difficult to disguise, thus improving the accuracy of radar target identification.

[0085] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware (such as a processor, controller, etc.), and the computer program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0086] The above provides a detailed description of the fully polarized active phased array radar and its signal processing method provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, those skilled in the art will recognize that there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A fully polarized active phased array radar, characterized in that, It includes a cross-polarized antenna array, a dual-polarized transmit channel, a dual-polarized receive channel, a beamforming and combining module, and a signal processing and control module; The cross-polarized antenna array includes multiple cross-polarized antenna elements; The dual-polarized transmission channel is connected to the cross-dual-polarized antenna array and is used to generate and output two radio frequency transmission signals with orthogonal polarization and adjustable phase difference between them. The dual-polarized receiving channel is connected to the cross-dual-polarized antenna array and is used to receive and process dual-polarized echo signals from the cross-dual-polarized antenna array. The beamforming and combining module is connected to the dual-polarization receiving channel and is used to perform spatial beamforming and polarization combining processing on the dual-polarization echo signal. The signal processing control module is connected to the dual-polarized transmission channel and the beamforming and combining module. It is used to send control commands to the dual-polarized transmission channel to set the phase difference between the two radio frequency transmission signals, control the cross dual-polarized antenna array to radiate a transmission beam containing a specific polarization mode, and receive the polarization combined signal from the beamforming and combining module for target detection and identification.

2. The fully polarized active phased array radar according to claim 1, characterized in that, The dual-polarized transmit channel includes a digital T / R component and an analog T / R component; The digital T / R component is used to generate two orthogonal polarization signals of digital baseband based on waveform control parameters and amplitude-phase compensation data from the signal processing control module. The analog T / R component is connected between the digital T / R component and the cross-polarized antenna array, and is used to up-convert and amplify the two orthogonal polarized signals of the digital baseband to form the two radio frequency transmission signals.

3. The fully polarized active phased array radar according to claim 1, characterized in that, The fully polarized active phased array radar also includes a sidelobe antenna and a sidelobe receiving and processing channel. The sidelobe antenna adopts a cross-dual polarization design; The sidelobe receiving and processing channel is connected to the sidelobe antenna and the signal processing control module. It is used to receive interference signals and send the processed interference signals to the signal processing control module for polarization analysis. The signal processing control module generates the control command based on the polarization mode of the interference signals obtained from the analysis.

4. The fully polarized active phased array radar according to claim 1, characterized in that, The beamforming and combining module includes a digital beamformer; The digital beamformer is used to weight and synthesize multiple digital echo signals from the dual-polarized receiving channel to form multiple receiving beams in the azimuth and elevation dimensions, wherein each receiving beam contains two orthogonal polarized signals; and to perform polarization synthesis operations on the two orthogonal polarized signals in each receiving beam.

5. The fully polarized active phased array radar according to claim 1, characterized in that, The signal processing control module includes a storage unit, which pre-stores a target polarization feature library, which contains feature data of different types of targets under different polarization modes; The signal processing control module controls the beamforming and synthesis module to switch between different polarization synthesis modes, obtains the echo characteristics of the target under different polarization states, and matches and identifies them with the target polarization feature library to obtain the target identification result.

6. A signal processing method for a fully polarized active phased array radar, characterized in that, The signal processing method for the fully polarized active phased array radar according to any one of claims 1 to 5 includes: Generate launch scheduling instructions based on radar mission requirements; According to the transmission scheduling command, the dual-polarized transmission channel is controlled to generate two radio frequency excitation signals with orthogonal polarization and adjustable phase difference, and the transmission beam containing the first polarization is radiated through the cross dual-polarized antenna array. The target echo signal is received through the cross-polarized antenna array; The target echo signal is received and digitized to obtain dual-channel digital echo data; Beamforming and polarization combining processes are performed on the dual-channel digital echo data to obtain a composite signal containing a second polarization mode; The synthesized signal is detected, and the target parameters are estimated and identified based on the detection results to obtain the target identification result.

7. The signal processing method for a fully polarized active phased array radar according to claim 6, characterized in that, When the radar mission requirement is anti-jamming, the step of generating a launch scheduling command based on the radar mission requirement includes: The system receives spatial interference signals via a sidelobe antenna, performs polarization analysis on the interference signals, and extracts the polarization patterns as interference polarization information. Based on the interference polarization information, the transmission scheduling command is generated. The transmission scheduling command includes a phase difference control parameter to make the first polarization mode orthogonal to the interference polarization mode.

8. The signal processing method for a fully polarized active phased array radar according to claim 6, characterized in that, The beamforming and polarization combining process performed on the dual-channel digital echo data to obtain a synthesized signal containing a second polarization mode includes: Calculate the signal quality metric values ​​of the dual-channel digital echo data under different polarization synthesis coefficients; The polarization combining coefficient corresponding to the largest signal quality metric value is selected as the reference combining coefficient. Using the reference synthesis coefficients, the dual-channel digital echo data is synthesized to obtain a synthesized signal containing a second polarization mode.

9. The signal processing method for a fully polarized active phased array radar according to claim 8, characterized in that, The signal quality metric is the signal-to-noise ratio (SNR) or signal-to-noise ratio (SNR).

10. The signal processing method for a fully polarized active phased array radar according to claim 6, characterized in that, The step of estimating and identifying target parameters based on the detection results to obtain target identification results includes: During multiple radar detections, the beamforming and combining module is controlled to sequentially observe the same target area using various different second polarization modes to obtain observation characteristics. From the observed features, micro-motion features or scattering features under each second polarization mode are extracted sequentially to form a multi-polarization feature vector; The multipolar feature vector is matched with a pre-stored target polarization feature library, and the target type is determined based on the matching result, which is then used as the target recognition result.

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