Unmanned aerial vehicle-mounted antenna array for unmanned aerial vehicle-mounted satellite chain ground node traceability

Abstract

The invention relates to the technical field of electronic countermeasure load antenna array design, in particular to an unmanned aerial vehicle-mounted antenna array for unmanned aerial vehicle-mounted satellite chain ground node traceability, and the antenna array comprises a substrate, eight antenna units, and low-noise amplification modules connected with the antenna units in a one-to-one correspondence manner. Wherein the working frequency bands of the eight antenna units cover a Ku wave band of uplink communication of a star chain terminal, and the whole antenna adopts a fan-shaped ladder-shaped array structure: every two antenna units form a column, and array elements in the same column are of a vertical coplanar dual-element structure, so that the high consistency of channel response is ensured, and a hardware basis is provided for weak signal detection based on cross-correlation; the space amplitude and phase difference base line is constructed for amplitude-comparison and phase-comparison combined direction finding, meanwhile, light-weight design is combined, the space amplitude and phase difference base line is well matched with an unmanned aerial vehicle platform, and integrated coupling of the interception function and the direction finding function of star chain uplink signals is achieved.

Description

Technical Field

[0001] The embodiments of this application relate to the field of electronic countermeasures payload antenna array design technology, and in particular to a UAV-borne antenna array for UAV-borne satellite link ground node tracing. Background Technology

[0002] In recent years, global low-Earth orbit (LEO) satellite communications, exemplified by the Starlink system, have developed rapidly. Through a global LEO satellite network, it has constructed a multi-purpose platform encompassing reconnaissance, detection, navigation, and communication, empowering and enhancing various applications. Therefore, it has become a key target for countermeasures. Its communication stability and reliability are strong, and numerous examples have verified its extremely strong intelligence support capabilities. Furthermore, the Starlink system is built from a low-cost satellite constellation using a flat, decentralized networking architecture, resulting in high system accuracy and performance that is difficult to jam or destroy, and strong survivability. Faced with the low-cost, high-precision, and highly resistant Starlink communication system, effectively cracking its systematic intelligence support capabilities and taking effective countermeasures has become one of the greatest challenges in countermeasures.

[0003] Currently, using UAVs equipped with reconnaissance payloads to intercept Starlink terminal uplink signals for rapid and accurate reconnaissance and location is a relatively effective way to deal with the Starlink system. However, Starlink communication uplink signals have characteristics such as wide frequency band, multiple beams, narrow main lobe beams, strong directivity, and weak side lobe strength. UAVs cannot directly capture the main lobe beams when patrolling the area, and the side lobe signals are extremely weak or even submerged in noise. Therefore, intercepting Starlink uplink signals places considerable demands on the antenna array design of the reconnaissance payload.

[0004] Traditional antenna design methods have significant drawbacks: For example, the extremely narrow main lobe beam of Starlink ground node antennas (only 2°~3°), rapid and irregular scanning, makes it difficult for reconnaissance platforms to remain stably within the main lobe beam. Simultaneously, their low sidelobe characteristics result in weak signal strength and low signal-to-noise ratio most of the time. Traditional antennas have limited gain, making it difficult to reliably detect such weak signals from environmental noise, thus hindering signal interception. Furthermore, while traditional Ku-band amplitude comparison direction finding systems achieve some sensitivity through multi-antenna splicing of the spatial domain, their direction finding accuracy is limited. Conversely, phase comparison direction finding (interferometer) systems, although more accurate, rely on... Antennas are often required to have a wide beam to ensure phase calculation, which limits the gain of the unit antenna. Furthermore, its wide baseline structure is not conducive to achieving lightweight and omnidirectional instantaneous direction finding. Existing single systems cannot simultaneously achieve high-sensitivity interception and high-precision omnidirectional direction finding under limited loads, thus making it difficult to guarantee direction finding accuracy. Finally, due to the strict constraints on UAV payload space and weight, traditional high-gain antennas or multi-baseline interferometer arrays designed to pursue high performance are often bulky and complex in structure, which cannot meet the UAV's requirements for compact and lightweight payload deployment, restricting tactical flexibility and resulting in poor platform adaptability. Summary of the Invention

[0005] In response to the characteristics of Starlink uplink signals, such as wide frequency band, multiple beams, narrow main lobe beam, strong directivity, and weak side lobe strength, as well as the difficulties in interception, insufficient direction finding accuracy, and poor platform adaptability faced by traditional array antennas when intercepting such signals, this invention proposes an UAV-borne antenna array for UAV-borne Starlink ground node tracing.

[0006] Analysis of the Starlink terminal uplink signal system reveals that it is typically a special OFDM system, mainly composed of PSS sequences, SSS sequences, OFDM data streams, and frame guard intervals. The PSS and SSS sequences exhibit significant correlation characteristics, allowing for efficient sensing and detection of weak uplink signals using sliding segmented correlation detection technology. Then, a combination of amplitude and phase comparison is employed for high-precision direction finding of the Starlink terminal's uplink signal, enabling accurate source tracing and localization. Therefore, the antenna array design must ensure sufficient spatial beam coverage while supporting efficient signal correlation detection and high-precision amplitude / phase comparison direction finding. Based on this principle, the core of this invention lies in employing a fan-shaped trapezoidal array structure to support efficient correlation processing of signals received from the same array element and high-precision amplitude / phase comparison between array elements. Simultaneously, a lightweight design ensures good compatibility with UAV platforms, achieving integrated coupling of Starlink uplink signal interception and direction finding functions. To achieve the above objectives, embodiments of this application propose a UAV-borne antenna array for UAV-borne Starlink ground node tracing, mounted on the bottom of the UAV, with a total weight of less than 250 grams. The antenna array includes: The substrate, eight microstrip antennas, and low-noise amplifier modules that are connected one-to-one with the antenna units; The eight antenna elements are mounted in four columns on the substrate, with each column containing two antenna elements.

[0007] The system comprises a substrate, eight microstrip antennas, and low-noise amplification modules connected to each antenna element. Each antenna operates at a frequency of 14GHz to 14.5GHz, employs horizontal linear polarization, and has a 3dB beamwidth of ≥25° in both azimuth and elevation directions, with a normal gain ≥12dBi. The antenna array is mounted on the bottom of the UAV in a 2x4 row arrangement, designed to detect uplink signals from ground-based Starlink terminals within a horizontal sector of approximately 120°. The specific design is as follows: Fan-shaped ladder array structure design Antenna element: It adopts a rectangular microstrip patch with a size of 45mm×45mm (length to width ratio 1:1). Array Arrangement: The array consists of 4 columns, each column comprising 2 microstrip antenna elements that are strictly coplanar and tightly stacked in the vertical direction, for a total of 8 elements. The core purpose of this design is to ensure that the two antenna elements within each column have highly consistent spatial response and channel characteristics. When the same signal arrives at this column, the waveform distortion of the signals received by the two antennas is small. This provides optimal conditions for subsequent cross-correlation operations (used to detect PSS / SSS sequences), effectively improving the probability of intercepting weak signals and the detection sensitivity in low signal-to-noise ratio environments.

[0008] Spatial configuration: The centerline angle between two adjacent antenna columns is 150°, and the entire array plane is installed with a downward tilt (pitch angle) of 24.5° relative to the horizontal plane. This configuration achieves dual optimization: it forms a fan-shaped coverage area with an angle of approximately 120° in the horizontal plane, providing a wide range for inter-column amplitude comparison and direction finding; at the same time, the downward tilt installation allows the main beam direction of each antenna column to be better aligned with the direction of incoming waves at low elevation angles, maximizing the received signal power, and providing a stable and differentiated phase information baseline for inter-column phase comparison and direction finding.

[0009] Lightweight design: The overall weight of the array is kept below 250g.

[0010] Low-noise, high-compliance RF link design Channel amplification: Each antenna element is directly connected to an independent low-noise amplifier (LNA) with a noise figure of less than 5dB and a gain of ≥13dB, aiming to minimize the system noise figure and improve receiver sensitivity.

[0011] Power supply network: Each channel is powered by a coaxial cable with a strictly consistent electrical length to minimize phase errors caused by differences in transmission paths and ensure consistency in amplitude and phase response between channels.

[0012] Compared with the prior art, the present invention has the following characteristics: Customized array configuration for signals: The fan-shaped trapezoidal array structure adopted in this invention is a comprehensive design based on the characteristics of Starlink uplink signals and the reconnaissance needs of UAV platforms. Its horizontal fan-shaped layout (120° angle) combined with platform flight can achieve large-area area scanning; the vertical coplanar dual-element structure within the column ensures channel consistency, thereby optimizing the relevant detection performance and improving the probability of intercepting Starlink terminal uplink signals; the fan-shaped tilted unfolding layout between columns directly constructs the airspace sampling structure required for amplitude and phase comparison direction finding.

[0013] Lightweight and highly integrated, with strong platform adaptability: Through a compact array layout and the selection of lightweight materials, the total weight of the eight-element antenna array system is ≤250g, which significantly reduces its load burden on the UAV platform, improves the system's portability and deployment flexibility on different UAV models, and enhances its adaptability to tactical applications.

[0014] A solid hardware foundation: While providing wide-coverage reconnaissance capabilities, the design ensures the quality of received signals through strict channel consistency and low-noise design. This provides a high-fidelity data source for the effective operation of back-end signal processing (signal correlation detection algorithm, amplitude-ratio combined direction finding algorithm), thereby improving the probability of weak signal interception and positioning accuracy at the system level.

[0015] In summary, this invention, through a targeted array design of "intra-column optimized correlation and inter-column service direction finding," effectively improves the sensitivity, interception probability, and direction finding accuracy of Starlink uplink signals, providing a logically clear, novel, and highly efficient antenna array design scheme for UAV-borne Starlink ground node tracing payloads. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies of this application will be briefly introduced below. Obviously, the following drawings are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings described herein are only used to explain this application and are not intended to limit this application.

[0017] Figure 1This is an external view of an unmanned aerial vehicle (UAV) antenna array for Starlink ground node tracing provided in one embodiment of this application; Figure 2 This is a diagram of a fan-shaped volumetric array structure provided in one embodiment of this application; Figure 3 This is an actual installation diagram of an antenna array payload provided in one embodiment of this application; Figure 4 This is a flowchart of a method for tracing ground nodes of a UAV satellite link, provided in another embodiment of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. Those skilled in the art will understand that many technical details have been presented in the embodiments of this application to facilitate better understanding. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments. The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of this application. The following embodiments can be combined with and referenced by each other without contradiction.

[0019] In recent years, global low-Earth orbit (LEO) satellite communications, exemplified by the Starlink system, have developed rapidly. Through a global LEO satellite network, it has constructed a multi-purpose platform encompassing reconnaissance, detection, navigation, and communication, empowering and enhancing various applications. Therefore, it has become a key target for countermeasures. Its communication stability and reliability are strong, and numerous examples have verified its extremely strong intelligence support capabilities. Furthermore, the Starlink system is built from a low-cost satellite constellation using a flat, decentralized networking architecture, resulting in high system accuracy and performance that is difficult to jam or destroy, and strong survivability. Faced with the low-cost, high-precision, and highly resistant Starlink communication system, effectively cracking its systematic intelligence support capabilities and taking effective countermeasures has become one of the greatest challenges in countermeasures.

[0020] Currently, using UAVs equipped with reconnaissance payloads to intercept Starlink terminal uplink signals for rapid and accurate reconnaissance and location is a relatively effective way to deal with the Starlink system. However, Starlink communication uplink signals have characteristics such as wide frequency band, multiple beams, narrow main lobe beams, strong directivity, and weak side lobe strength. UAVs cannot directly capture the main lobe beams when patrolling the area, and the side lobe signals are extremely weak or even submerged in noise. Therefore, intercepting Starlink uplink signals places considerable demands on the antenna array design of the reconnaissance payload.

[0021] Traditional antenna design methods have significant drawbacks: 1. Difficulty in Signal Acquisition: Due to the Starlink ground node antenna's main lobe beamwidth of only 2-3°, its scanning speed is fast and lacks regularity, making it difficult for the reconnaissance platform to stabilize within the main lobe beam. Simultaneously, its low sidelobe characteristics result in extremely weak signal strength and low signal-to-noise ratio for most of the time. Traditional wide-beam or ordinary array antennas, due to their limited gain, struggle to reliably detect such weak signals from environmental noise, leading to initial acquisition difficulties. 2. Difficulty in Guaranteeing Direction Finding Accuracy: Traditional Ku-band direction finding primarily relies on amplitude and phase comparison. Amplitude comparison direction finding requires multiple antennas to be uniformly arranged at a certain angle. Because multiple antennas are used to stitch together the airspace, the beamwidth of a single antenna can be narrowed, resulting in a certain gain in sensitivity. However, the amplitude comparison direction finding accuracy is relatively limited, making it difficult to meet the precise positioning requirements of Starlink terminals. Phase comparison direction finding offers higher accuracy, but typically requires antennas with wide beams to ensure phase ambiguity resolution. This limits the gain of individual antennas, thus affecting system sensitivity. Furthermore, its wide baseline structure also restricts the system's lightweight design and omnidirectional instantaneous direction finding capabilities. Existing single-system approaches struggle to simultaneously achieve high-sensitivity interception and high-precision omnidirectional direction finding under limited loads.

[0022] 3. Poor platform adaptability: UAVs have limited payload space and weight. Traditional arrays designed to achieve high performance, such as high-gain antennas or multi-baseline interferometer arrays, are often bulky and complex in structure, which cannot meet the UAV's requirements for compact and lightweight payload deployment, thus restricting tactical flexibility.

[0023] In summary, traditional antenna design methods still suffer from problems such as difficulty in signal interception, difficulty in guaranteeing direction finding accuracy, and poor platform adaptability.

[0024] In response to the characteristics of Starlink uplink signals, such as wide frequency band, multiple beams, narrow main lobe beam, strong directivity, and weak side lobe strength, as well as the difficulties in interception, insufficient direction finding accuracy, and poor platform adaptability faced by traditional array antennas when intercepting such signals, this invention proposes an UAV-borne antenna array for UAV-borne Starlink ground node tracing.

[0025] Analysis of the Starlink terminal uplink signal system reveals that it is typically a special OFDM system, mainly composed of PSS sequences, SSS sequences, OFDM data streams, and frame guard intervals. The PSS and SSS sequences exhibit significant correlation characteristics, allowing for efficient sensing and detection of weak uplink signals using sliding segmented correlation detection technology. Then, a combination of amplitude and phase comparison is employed for high-precision direction finding of the Starlink terminal's uplink signal, enabling accurate source tracing and localization. Therefore, the antenna array design must ensure sufficient spatial beam coverage while supporting efficient signal correlation detection and high-precision amplitude / phase comparison direction finding. Based on this principle, the core of this invention lies in employing a fan-shaped trapezoidal array structure to support efficient correlation processing of signals received from the same array element and high-precision amplitude / phase comparison between array elements. Simultaneously, a lightweight design ensures good compatibility with UAV platforms, achieving integrated coupling of Starlink uplink signal interception and direction finding functions. To achieve the above objectives, embodiments of this application propose an UAV-borne antenna array for UAV-borne Starlink ground node tracing, which is installed on the bottom of the UAV. The total weight of the antenna array is less than 250 grams. The antenna array includes: a substrate, eight microstrip antennas, and low-noise amplification modules that are connected one-to-one with the antenna elements. The eight antenna elements are mounted in four columns on the substrate, with each column containing two antenna elements.

[0026] In one possible embodiment, the antenna elements in each column are coplanarly arranged in the vertical direction to form an antenna subarray; the four antenna subarrays are arranged in a fan-shaped trapezoidal pattern in the horizontal plane, and the whole is tilted downward at a preset angle relative to the horizontal plane; the operating frequency band of the antenna array covers the Ku band of Starlink terminal uplink communication, and adopts a horizontal linear polarization method.

[0027] In one possible embodiment, the antenna array is configured as follows: This ensures high consistency of signals received by antenna elements within the same column, supporting Starlink uplink signal detection based on signal cross-correlation; it also enables amplitude and phase differences in signals received by antenna elements in different columns, supporting direction finding of Starlink ground nodes based on a combination of amplitude and phase ratios.

[0028] In one possible embodiment, the included angle between the centerlines of two adjacent antenna elements is 150°, and the entire array plane is tilted down 24.5° relative to the horizontal plane, so that the antenna array forms a fan-shaped coverage area with an angle of about 120° in the horizontal plane, thereby providing a wide range for inter-column amplitude comparison and direction finding.

[0029] In one possible embodiment, the antenna array is installed at a preset depression angle of 24.5°, which allows the main beam direction of each column of antennas to be better aligned with the direction of incoming waves at a low elevation angle, maximizing the received signal power and providing a stable and differentiated phase information baseline for inter-column phase direction finding.

[0030] In one possible embodiment, a single antenna element has a length of 45 mm and a width of 45 mm.

[0031] In one possible embodiment, the antenna element is a horizontally polarized microstrip patch antenna with an operating frequency band between 14 GHz and 14.5 GHz and a normal gain of not less than 12 dBi.

[0032] In one possible embodiment, the noise figure of the low-noise amplifier module is less than 5dB, and the gain is not less than 13dB.

[0033] Next, combined Figures 1 to 3 The following is a schematic diagram of an unmanned aerial vehicle (UAV) antenna array for Starlink ground node tracing provided as an embodiment of this application, which will be described in detail below.

[0034] like Figure 1 As shown, this application consists of eight microstrip antennas, a low-noise amplifier module, and corresponding structural components. Each antenna operates at a frequency of 14GHz to 14.5GHz, with horizontal linear polarization. The 3dB beamwidth is ≥25° in both azimuth and elevation directions, and the antenna normal gain is ≥12dBi. The antenna array is arranged in a fan-shaped trapezoidal pattern, with four columns and eight channels. Each column contains two vertically stacked antenna elements, all strictly coplanar. The centerlines of adjacent columns form a 150° angle, and the entire array is tilted at a 24.5° depression angle, forming a fan-shaped coverage area (approximately 120°) in the horizontal plane. The entire array (including structural components) weighs less than 600g. Each channel is connected to an independent low-noise amplifier and a coaxial cable of equal length. The antenna array is mounted on the bottom of the UAV, divided into 2*4 subarrays, capable of detecting the ground within a 120° range, used for detecting uplink communication signals from ground-based Starlink terminals. The processing flow for Starlink terminal uplink signals is coordinated with the antenna design. The specific design is as follows: like Figure 2 As shown, Figure 2 The following describes a sector-shaped trapezoidal array structure used to introduce this application.

[0035] Antenna element: It adopts a rectangular microstrip patch with a size of 45mm×45mm (length to width ratio 1:1). Array Arrangement: The array consists of 4 columns, each column comprising 2 microstrip antenna elements that are strictly coplanar and tightly stacked in the vertical direction, for a total of 8 elements. The core purpose of this design is to ensure that the two antenna elements within each column have highly consistent spatial response and channel characteristics. When the same signal arrives at this column, the waveform distortion of the signals received by the two antennas is small. This provides optimal conditions for subsequent cross-correlation operations (used to detect PSS / SSS sequences), effectively improving the probability of intercepting weak signals and the detection sensitivity in low signal-to-noise ratio environments.

[0036] Spatial configuration: The centerline angle between two adjacent antenna columns is 150°, and the entire array plane is installed with a downward tilt (pitch angle) of 24.5° relative to the horizontal plane. This configuration achieves dual optimization: it forms a fan-shaped coverage area with an angle of approximately 120° in the horizontal plane, providing a wide range for inter-column amplitude comparison and direction finding; at the same time, the downward tilt installation allows the main beam direction of each antenna column to be better aligned with the direction of incoming waves at low elevation angles, maximizing the received signal power, and providing a stable and differentiated phase information baseline for inter-column phase comparison and direction finding.

[0037] Lightweight design: The overall weight of the array is kept below 250g.

[0038] This application also provides a low-noise, high-consistency RF link design, as detailed below.

[0039] Channel amplification: Each antenna element is directly connected to an independent low-noise amplifier (LNA) with a noise figure of less than 5dB and a gain of ≥13dB, aiming to minimize the system noise figure and improve receiver sensitivity.

[0040] Power supply network: Each channel is powered by a coaxial cable with a strictly consistent electrical length to minimize phase errors caused by differences in transmission paths and ensure consistency in amplitude and phase response between channels.

[0041] Compared with the prior art, the present invention has the following characteristics: 1. Customized array configuration for signals: The fan-shaped trapezoidal array structure adopted in this invention is a comprehensive design based on the characteristics of Starlink uplink signals and the reconnaissance needs of UAV platforms. Its horizontal fan-shaped layout (120° angle) combined with platform flight can achieve large-area area scanning; the vertical coplanar dual-element structure within the column ensures channel consistency, thereby optimizing the relevant detection performance and improving the probability of intercepting Starlink terminal uplink signals; the fan-shaped tilted unfolding layout between columns directly constructs the airspace sampling structure required for amplitude and phase comparison direction finding.

[0042] 2. Lightweight and highly integrated, with strong platform adaptability: Through a compact array layout and the selection of lightweight materials, the total weight of the eight-element antenna array system is ≤250g, which significantly reduces its load burden on the UAV platform, improves the system's portability and deployment flexibility on different UAV models, and enhances its adaptability to tactical applications.

[0043] 3. Strong hardware foundation: While providing wide coverage reconnaissance capabilities, this design ensures the quality of received signals through strict channel consistency and low noise design. This provides a high-fidelity data source for the effective operation of back-end signal processing (signal correlation detection algorithm, amplitude-ratio combined direction finding algorithm), thereby improving the probability of weak signal interception and positioning accuracy at the system level.

[0044] In summary, this application, through a targeted array design of "intra-column optimized correlation and inter-column service direction finding", effectively improves the sensitivity, interception probability and direction finding accuracy of Starlink uplink signals, providing a logically clear, novel and efficient antenna array design scheme for UAV-borne Starlink ground node tracing payloads.

[0045] The specific process of the method for tracing ground nodes of a UAV satellite link proposed in the embodiment can be as follows: Figure 4 As shown, it includes: Step 101: Receive radio frequency signals from the ground area during the flight of the UAV using the antenna elements in the onboard antenna array.

[0046] For example, a drone can cover a ground area with a horizontal fan-shaped range of 120° using an antenna array.

[0047] For example, a drone equipped with the aforementioned antenna array can be dispatched to patrol over a target area. During flight, the antenna array continuously receives radio frequency signals from the ground area below it. Due to the array's fan-shaped layout and downward tilt design, it can effectively receive signals from low elevation angles.

[0048] Step 102: Perform cross-correlation calculation on the radio frequency signals from different antenna elements in the same antenna subarray to obtain the cross-correlation processing result, and detect the Starlink terminal uplink signal based on the cross-correlation processing result.

[0049] For example, cross-correlation is performed on the two radio frequency (RF) signals received by each antenna subarray (i.e., two vertically coplanar antenna elements) in the antenna array. Specifically, the RF signals received by the upper and lower antenna elements in the same column are denoted as follows: and .

[0050] The cross-correlation operation is performed on the signals received by the upper and lower antenna elements within each subarray, specifically using the following formula: ; in, Indicates the result of cross-correlation processing; and They represent the first The signals received by the upper and lower antenna elements in the array antenna subarray; * indicates taking the conjugate. Indicates time delay; The uplink signal of the Starlink terminal is detected by detecting the peak value of the cross-correlation processing result.

[0051] For example, the Starlink terminal uplink signal adopts a special OFDM system, whose frame structure includes a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) with significant autocorrelation and cross-correlation characteristics. Therefore, by performing sliding segmentation on the radio frequency signal and executing the above cross-correlation operation, weak Starlink uplink signals can be identified by detecting the peak value of the cross-correlation function in low signal-to-noise ratio environments. The strict coplanar design of the antenna elements within the array ensures that the two signals have highly consistent spatial response and channel characteristics, thereby making the correlation peak values ​​of the PSS / SSS sequences sharper and more obvious, greatly improving the interception probability and detection sensitivity of weak signals.

[0052] Step 103: After confirming the uplink signal of the Starlink terminal, calculate the ground azimuth of the Starlink terminal based on the radio frequency signals received by the antenna elements in different columns of antenna subarrays.

[0053] For example, once the uplink signal of the Starlink terminal is determined, the direction finding can be performed using the radio frequency signals received by different arrays of antennas to determine the azimuth of the signal source (i.e., the ground location of the Starlink terminal). This embodiment uses a direction finding system that combines amplitude comparison and phase comparison methods, as detailed in the following embodiment.

[0054] For example, based on the signal amplitude of the radio frequency signals from two adjacent antenna subarrays, the coarse direction finding azimuth of the Starlink terminal is calculated using the sum-difference amplitude ratio method; based on the phase difference of the radio frequency signals from two adjacent antenna subarrays and the coarse direction finding azimuth, the fine direction finding azimuth of the Starlink terminal is calculated, and thus the ground azimuth of the Starlink terminal is obtained.

[0055] Among them, the radio frequency signals in each antenna subarray are the synthesized signals of the antenna elements within the array; For example, the radio frequency signal in each antenna subarray is a composite signal of the signals received by all antenna elements within that subarray. For instance, the signals of two vertically coplanar antenna elements in each column can be in-phase synthesized to improve the signal-to-noise ratio and directivity.

[0056] The synthesized radio frequency signals of the two antenna subarrays are denoted as follows: and Through processing via a dedicated feed network, a sum signal and a difference signal are generated from these two signals, specifically: ; ; in, The difference signal representing the radio frequency signal. This represents the sum of radio frequency signals.

[0057] Subsequently, using the amplitude ratio of the sum and difference signals, combined with the known geometric configuration of the antenna array, the coarse azimuth angle of the Starlink terminal is calculated using the sum-difference amplitude ratio method.

[0058] For example, known geometric configurations may include column spacing (i.e., the spacing between two adjacent columns of antenna subarrays) and signal wavelength.

[0059] In one possible embodiment of this application, the coarse azimuth angle is determined. The calculation formula is: ; in, This indicates the spacing between two adjacent antenna subarrays. Indicates the signal wavelength.

[0060] Understandably, by calculating the coarse lateral azimuth angle, a target can be initially oriented over a large airspace, with a direction finding accuracy of about 10 degrees, thereby determining the approximate directional range of the signal source.

[0061] After obtaining the coarse azimuth angle, the fine direction finding stage can begin. This stage is based on the synthesized radio frequency signals from two adjacent antenna subarrays of the same type. and The phase difference between the two sides is calculated. For example, in an interferometer direction finding system, the coarse direction finding result can be used to help determine the integer ambiguity number of the phase difference, thereby solving for the phase difference. Finally, using the principle of phase interferometer, the fine direction finding azimuth of the Starlink terminal is calculated.

[0062] In one possible embodiment of this application, the precise azimuth angle is measured. The calculation formula is: ; in, This indicates a phase take operation. express and The phase difference between them.

[0063] It is understood that this precise azimuth angle is a high-precision estimate of the Starlink terminal's ground azimuth. Through this collaborative process of first comparing amplitude coarse measurements and then comparing phases fine measurements, the method provided by the embodiments of this application achieves high-precision positioning of the Starlink terminal while ensuring a large instantaneous reconnaissance airspace.

[0064] This application proposes a method for tracing the ground node of a UAV-borne Starlink satellite. This method utilizes antenna elements in the UAV's antenna array to receive radio frequency (RF) signals from the ground region during UAV flight. Cross-correlation calculations are performed on the RF signals from different antenna elements in the same antenna subarray to obtain the cross-correlation processing results. The uplink signal of the Starlink terminal is detected based on these results. If the uplink signal is confirmed, the ground azimuth of the Starlink terminal is calculated based on the RF signals received by the antenna elements in different antenna subarrays. This solution overcomes the technical problems of low interception probability, insufficient direction finding accuracy, and difficulty in adapting to lightweight UAV platforms faced by traditional antenna arrays when intercepting Starlink uplink signals. This achieves a higher interception probability, more accurate direction finding, and a lighter antenna array design for Starlink terminal uplink signals.

[0065] The steps described above are for clarity only. In implementation, they can be combined into one step, or some steps can be broken down into multiple steps, as long as they involve the same logical relationship, they are all within the scope of protection of this application. Adding insignificant modifications or introducing insignificant designs to the algorithm or process, without changing the core design of the algorithm and process, are also within the scope of protection of this application.

[0066] It is worth mentioning that all modules and units involved in this embodiment are logical modules. In practical applications, a logical unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. Furthermore, to highlight the innovative aspects of this application, this embodiment does not introduce units that are not closely related to solving the technical problems proposed in this application; however, this does not mean that other units do not exist in this embodiment.

[0067] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

Claims

1. A UAV-borne antenna array for Starlink ground node tracing, mounted on the bottom of a UAV, wherein the total weight of the antenna array is less than or equal to 250 grams, characterized in that, The antenna array includes: The substrate, eight microstrip antennas, and low-noise amplifier modules that are connected one-to-one with the antenna units; The eight antenna elements are mounted in four columns on the substrate, with each column containing two antenna elements.

2. The antenna array according to claim 1, characterized in that: Each column of antenna elements is coplanar in the vertical direction, forming a column of antenna subarrays; the four columns of antenna subarrays are arranged in a fan-shaped trapezoidal pattern in the horizontal plane, and the whole is tilted downward at a preset angle relative to the horizontal plane. The antenna array operates in the Ku band of Starlink terminal uplink communication and uses horizontal polarization.

3. The antenna array according to claim 1, characterized in that, The antenna array configuration is as follows: This ensures high consistency of signals received by antenna elements within the same column, supporting Starlink uplink signal detection based on signal cross-correlation. The signals received by antenna elements in different columns are made to have amplitude and phase differences, so as to support direction finding of Starlink ground nodes based on a combination of amplitude and phase ratio.

4. The antenna array according to claim 1, characterized in that, The angle between the centerlines of two adjacent antenna elements is 150°, and the entire array plane is tilted 24.5° downward relative to the horizontal plane, so that the antenna array forms a fan-shaped coverage area with an angle of about 120° in the horizontal plane, thus providing a wide range for inter-column amplitude comparison and direction finding.

5. The antenna array according to claim 1, characterized in that, The antenna array is installed at a preset downward angle; the preset downward angle is 24.5°, which makes the main beam direction of each column of antennas better aligned with the direction of incoming waves at low elevation angle, maximizes the received signal power, and provides a stable and differentiated phase information baseline for inter-column phase comparison and direction finding.

6. The antenna array according to claim 1, characterized in that, Each antenna element measures 45 mm in length and 45 mm in width.

7. The antenna array according to claim 1, characterized in that, The antenna element is a horizontally polarized microstrip patch antenna, operating in the frequency band between 14 GHz and 14.5 GHz, with a normal gain of not less than 12 dBi.

8. The antenna array according to claim 1, characterized in that, The noise figure of the low-noise amplifier module is less than 5dB, and the gain is not less than 13dB.

9. A method for tracing the ground nodes of a UAV-borne satellite link, characterized in that, The method, applied to an unmanned aerial vehicle (UAV) onboard antenna array as described in any one of claims 1 to 8, comprises: By utilizing the antenna elements in the onboard antenna array of the drone, radio frequency signals from the ground area can be received during the drone's flight. Cross-correlation calculations are performed on radio frequency signals from different antenna elements in the same antenna subarray to obtain cross-correlation processing results. The uplink signal of the Starlink terminal is detected based on the cross-correlation processing results. Once the uplink signal of the Starlink terminal is confirmed, the ground azimuth of the Starlink terminal is calculated based on the radio frequency signals received by the antenna elements in different columns of antenna subarrays.

10. The method according to claim 9, characterized in that, The step of calculating the ground azimuth of the Starlink terminal based on the radio frequency signals received by the antenna elements in different columns of the antenna subarray, after confirming the uplink signal of the Starlink terminal, includes: Once the uplink signal of the Starlink terminal is confirmed, the coarse direction-finding azimuth angle of the Starlink terminal is calculated using the sum-difference amplitude ratio method based on the radio frequency signals received by the antenna elements in different antenna subarrays; wherein, the radio frequency signals in each antenna subarray are the composite signals of the antenna elements within the array; Based on the phase difference and coarse direction finding azimuth angle of the radio frequency signals from two adjacent antenna subarrays, the fine direction finding azimuth angle of the Starlink terminal is calculated by phase interferometry, and then the ground azimuth of the Starlink terminal is obtained.

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