Retroreflector apparatus and method with incoming direction perception and beam self-alignment

Abstract

The application relates to a retroreflector device and method with incoming wave direction sensing and beam self-alignment, wherein the device comprises: an antenna array module for receiving incident radar waves and emitting retroreflected waves; a direction finding module connected to the antenna array module for extracting signals of at least four channels from the antenna array module and calculating the incoming wave direction by amplitude comparison or phase comparison to generate a direction finding signal; a control module connected to the direction finding module for processing the direction finding signal output by the direction finding module to generate a control instruction; and a direction adjusting module connected to the control module for driving the antenna array module to rotate according to the control instruction so that the main beam direction of the antenna array module is aligned with the direction of the incident radar waves. The scheme can automatically sense the incoming wave direction and mechanically align, and effectively realizes the beneficial effect of maintaining high radar scattering cross section (RCS) performance in a wide incident angle range.

Description

Technical Field

[0001] This invention relates to the fields of radar electronic countermeasures and electromagnetic wave reflection technology, and in particular to a retroreflector device and method with incoming wave direction sensing and beam self-alignment. Background Technology

[0002] In the field of modern electronics, retroreflectors play an indispensable role as a special device. Their unique ability to reflect incident electromagnetic waves back along their original path has led to their widespread application in many key areas. For example, in radar target simulation, retroreflectors can simulate the radar reflection characteristics of real targets, providing a reliable reference for the testing and calibration of radar systems; in the field of electronic jamming, they can disrupt the normal operation of enemy radar systems by reflecting jamming signals; and in the fields of communication relay and passive beacons, retroreflectors help achieve effective signal transmission and positioning.

[0003] Among them, the direction-backtracking antenna based on the Van Atta array has attracted much attention and is widely used due to its outstanding advantages. This antenna has a compact structure and can automatically achieve beam backtracking without prior knowledge of the direction of the incoming wave, which greatly simplifies the design and operation process of the system and improves its adaptability in complex and ever-changing environments.

[0004] However, existing Van Atta retroreflectors have an inherent technical bottleneck that is difficult to overcome, namely, their effective retroreflection angle coverage is limited by many factors, mainly in terms of the beamwidth of the antenna element and the array factor.

[0005] First, there's the issue of element gain attenuation. As the incident angle (θ) increases, the signal power received by a single antenna element gradually decreases due to deviation from its normal beam. Taking a common element antenna as an example, if its 3dB beamwidth is 45°, the element gain will drop by approximately 6dB when the incident angle reaches 45°. This means that the echo signal strength (RCS) will significantly decrease, thus affecting the performance of the retroreflector at larger incident angles. For instance, in applications requiring high signal strength, such as long-range radar target simulation, a decrease in signal strength can lead to a significant reduction in the detectability of the simulated target.

[0006] Secondly, there is the issue of array factor degradation. For planar arrays, when the beam scans at large angles, the array factor causes radiation pattern distortion. This distortion further exacerbates RCS attenuation, significantly reducing the reflection effect of retroreflectors at large angles of incidence. For example, in electronic jamming applications, radiation pattern distortion may prevent jamming signals from accurately returning to the enemy radar along their original path, thus reducing jamming effectiveness.

[0007] To improve the performance of existing Van Atta retroreflectors, several methods are commonly employed. One common approach is to increase the antenna element gain, such as by using high-gain elements. However, while this method improves signal strength to some extent, it often results in a narrower beam, sacrificing angular coverage. Another method is to increase the overall gain by increasing the number of array elements. But this undoubtedly increases the system's complexity and cost, requiring higher technical standards and more resources in design and manufacturing, and making system maintenance and management more difficult in practical applications.

[0008] Furthermore, to cover a wider range of incident angles, the current common solution is to deploy multiple reflectors facing different directions. However, this approach not only significantly increases equipment costs and deployment complexity but also reduces system mobility. For example, in scenarios requiring rapid deployment and movement, such as emergency communications, deploying and moving multiple reflectors becomes extremely inconvenient.

[0009] Therefore, effectively expanding the angular coverage of a single retroreflector without significantly increasing system size and cost has become a key technical problem urgently needing to be solved in this field. Solving this problem is of great significance for improving the performance and adaptability of retroreflectors in various application areas and promoting the development of related technologies. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to provide a retroreflector device and method with incoming wave direction sensing and beam self-alignment, overcoming the defect of narrow angle coverage of existing retroreflectors.

[0011] To achieve the above-mentioned objectives, the present invention provides a retroreflector device with incoming wave direction sensing and beam self-alignment, comprising: Antenna array module, used to receive incident radar waves and transmit back-reflected waves; The direction-finding module, connected to the antenna array module, is used to extract signals from at least four channels of the antenna array module, calculate the incoming wave direction using the amplitude comparison method or the phase comparison method, and generate a direction-finding signal. The control module, connected to the direction finding module, is used to process the direction finding signals output by the direction finding module and generate control commands; The orientation adjustment module, connected to the control module, is used to drive the antenna array module to rotate according to control commands, so that the main beam direction of the antenna array module is aligned with the direction of the incident radar wave.

[0012] According to one aspect of the present invention, the antenna array module includes: a receiving antenna array for receiving incident radar waves, a transmitting antenna array for transmitting back-reflected waves, and an amplifier module; The elements of the receiving antenna array and the elements of the transmitting antenna array are arranged in a geometrically symmetrical manner. The receiving elements and transmitting elements in symmetrical positions form corresponding element pairs through a unidirectional transmission link. The amplifier module is connected to the unidirectional transmission link of each array element pair to compensate for link loss and enhance the radar cross-section.

[0013] According to one aspect of the invention, the antenna array module employs a Van Atta array.

[0014] According to one aspect of the present invention, the direction-finding module includes: a directional coupler, a detector, an analog-to-digital converter, and a signal processor; The directional coupler is coupled to the output terminal of the array element of the receiving antenna array, wherein the directional coupler is coupled to the output terminal of the array element at at least four different positions on the receiving antenna array to form at least four channels of radio frequency signals. The detector performs envelope detection on the radio frequency signals of each channel to obtain the signal amplitude value corresponding to the radio frequency signal; The analog-to-digital converter digitizes the signal amplitude value and transmits it to the signal processor; The signal processor calculates the left-right amplitude difference and the up-down amplitude difference based on the output of the analog-to-digital converter, and obtains the azimuth and elevation angles of the incident radar wave according to a pre-established amplitude difference-angle mapping table.

[0015] According to one aspect of the invention, the directional coupler is coupled to the output terminals of four array elements at four different positions: upper left, upper right, lower left, and lower right of the receiving antenna array, to form an upper left channel radio frequency signal, an upper right channel radio frequency signal, a lower left channel radio frequency signal, and a lower right channel radio frequency signal. The difference in amplitude in the left and right directions is expressed as: , The vertical amplitude difference is expressed as: , in, This represents the signal amplitude value obtained from the radio frequency signal in the upper left channel. This represents the signal amplitude value obtained from the radio frequency signal in the upper right channel. This represents the signal amplitude value obtained from the lower left channel radio frequency signal. This indicates the signal amplitude value obtained from the radio frequency signal in the lower right channel.

[0016] According to one aspect of the present invention, the direction adjustment module includes: a two-dimensional electric turntable and a drive motor; The antenna array module is fixedly mounted on a two-dimensional electric turntable; The drive motor is used to drive the rotation of the two-dimensional electric turntable to align the main beam direction of the antenna array module with the direction of the incident radar wave.

[0017] To achieve the aforementioned objective, this invention provides an alignment method for the aforementioned retroreflector device with incoming wave direction sensing and beam self-alignment, comprising the following steps: S1. Receive incident radar waves with unknown incident direction through the antenna array module; S2. Use the direction finding module to extract signals from at least four channels, calculate the incoming wave direction using the amplitude comparison method or the phase comparison method, and generate a direction finding signal; S3. The control module processes the direction finding signal output by the direction finding module and generates control commands; S4. The direction adjustment module drives the antenna array module to rotate according to the control command, so that the main beam direction of the antenna array module is aligned with the direction of the incident radar wave; S5. Repeat steps S1 to S4 to achieve closed-loop tracking and alignment of the incident radar wave.

[0018] According to one aspect of the present invention, in step S2, in the step of extracting signals from at least four channels using a direction-finding module, calculating the direction of arrival of the wave using an amplitude comparison method or a phase comparison method, and generating a direction-finding signal, the calculated direction of arrival of the wave ensures that the main beam of the antenna array module is within the -3dB beamwidth of the incident radar wave.

[0019] According to one aspect of the present invention, this approach can automatically sense the direction of incoming waves and perform mechanical alignment, effectively achieving the beneficial effect of maintaining high radar cross section (RCS) performance over a wide incident angle range.

[0020] According to one aspect of the present invention, this approach calculates and estimates the direction of the incoming wave and uses a mechanical beam self-alignment method to ensure that the incoming wave is always within the coverage area of ​​the array's main lobe. This overcomes the problem of limited effective working angle of traditional fixed Van Atta retroreflectors and achieves retroreflection with a high radar cross section (RCS) over a wide angle range.

[0021] According to one aspect of the present invention, this aspect achieves the effect of significantly widening the angular coverage range. By introducing a mechanical rotation mechanism, the static coverage range originally determined by the beamwidth of the antenna element is transformed into a dynamic coverage range (e.g., ±90° or even larger) determined by the mechanical rotation angle, thereby enabling a single device to effectively respond to wide-angle incident signals.

[0022] According to one aspect of the present invention, this aspect fully maintains the high radar cross section (RCS) performance. Since the system can actively align the main beam with the direction of incoming wave, the incident angle is always kept within a small range (such as close to normal incidence), thereby avoiding the decrease in unit gain and the deterioration of array factor caused by large-angle incidence, and maintaining a higher radar cross section (RCS).

[0023] According to one aspect of the present invention, the direction-finding system does not require extremely high accuracy (such as the milliradian level required for radar tracking radar). It only needs to determine whether the outgoing wave direction is outside the effective width of the current beam of the retroreflector. As long as the direction-finding error is less than the antenna beamwidth, the radar cross section (RCS) can be significantly improved through coarse alignment. This allows the present invention to significantly reduce the performance requirements and cost of the direction-finding module, while also making the present invention more flexible in its application prospects.

[0024] According to one aspect of the present invention, this solution effectively improves system integration and cost-effectiveness. Compared with deploying multiple fixed reflectors to cover different angles, it only requires a single device to achieve the equivalent function. It has the advantages of low power consumption, miniaturization, lightweight, portability and rapid deployment, and is particularly suitable for resource-constrained scenarios such as portable deployment.

[0025] According to one aspect of the present invention, the performance optimization objective of the retroreflector is shifted from "precise angle estimation" to "main beam coverage determination." It is sufficient to ensure that the incoming wave enters the main lobe coverage area; high-precision direction finding and control are not required to achieve near-maximum RCS reflection performance. By combining low-precision direction finding with mechanical coarse alignment, high RCS maintenance in the wide-angle domain is achieved, thereby significantly reducing system complexity and cost.

[0026] According to one aspect of the present invention, compared to conventional fixed VanAtta retroreflectors whose effective angular coverage is limited by the antenna element beamwidth (typically ≤±45°) and whose RCS attenuation exceeds 10dB at large angles, this approach extends the coverage to dynamic omnidirectional coverage (±90° to ±180°) through mechanical rotation, and maintains a near-normal incidence state throughout the entire dynamic range, enabling effective recovery of the radar cross section (RCS).

[0027] According to one aspect of the present invention, the direction-finding module employs a threshold detection mechanism, which only initiates angle estimation and adjustment when the direction of the incoming wave exceeds the effective range of the current beam. In the absence of an incoming wave or when the direction of the incoming wave remains unchanged for an extended period, the direction-finding module and the direction adjustment module can be in a dormant or standby state, significantly reducing overall power consumption and exhibiting superior energy-saving characteristics, thereby effectively extending the runtime. Furthermore, the direction-finding and adjustment process of this solution is not continuous, greatly reducing its electromagnetic radiation characteristics and lowering the probability of detection by the enemy's electronic reconnaissance system, thus enhancing the survivability of this solution. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the retroreflector device with incoming wave direction sensing and beam self-alignment according to the present invention. Detailed Implementation

[0029] In describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" express orientations or positional relationships based on the orientations or positional relationships shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on the present invention.

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0031] like Figure 1 As shown, according to one embodiment of the present invention, a retroreflector device with incoming wave direction sensing and beam self-alignment includes: an antenna array module 1, a direction-finding module 2 connected to the antenna array module 1, a control module 3 connected to the direction-finding module 2, and a direction adjustment module 4 connected to the control module 3 and the antenna array module 1 respectively. In this embodiment, the antenna array module 1 is used to receive incident radar waves and transmit retroreflected waves; the direction-finding module 2 is connected to the antenna array module 1 and is used to extract signals from at least four channels of the antenna array module 1, calculate the incoming wave direction using amplitude comparison or phase comparison, and generate a direction-finding signal; the control module 3 is connected to the direction-finding module 2 and is used to process the direction-finding signal output by the direction-finding module 2 and generate control commands; the direction adjustment module 4 is connected to the control module 3 and is used to drive the antenna array module 1 to rotate according to the control commands, so that the main beam direction of the antenna array module 1 is aligned with the direction of the incident radar wave.

[0032] like Figure 1As shown, according to one embodiment of the present invention, the antenna array module 1 includes: a receiving antenna array 11 for receiving incident radar waves, a transmitting antenna array 12 for transmitting back-reflected waves, and an amplifier module 13; in this embodiment, the antenna array module 1 may be a Van Atta array; specifically, the elements of the receiving antenna array 11 and the elements of the transmitting antenna array 12 are arranged in a geometrically symmetrical manner, wherein the receiving elements and transmitting elements in symmetrical positions form corresponding element pairs through a unidirectional transmission link; the amplifier module is connected to the unidirectional transmission link of each element pair to compensate for link loss and enhance the radar cross section.

[0033] like Figure 1 As shown, according to one embodiment of the present invention, the direction-finding module 2 includes: a directional coupler 21, a detector, an analog-to-digital converter (ADC), and a signal processor 22. In this embodiment, the directional coupler 21 is coupled to the output terminals of the array elements of the receiving antenna array 11, wherein the directional coupler 21 is coupled to the output terminals of at least four array elements at different positions on the receiving antenna array 11 to form at least four channels of radio frequency (RF) signals. The detector performs envelope detection on the RF signals of each channel to obtain the signal amplitude value corresponding to the RF signal. The detector employs a threshold detection mechanism. The ADC digitizes the signal amplitude value and transmits it to the signal processor. The signal processor calculates the left-right amplitude difference and the up-down amplitude difference based on the output of the ADC, and obtains the azimuth and elevation angles of the incident radar wave according to a pre-established amplitude difference-angle mapping table.

[0034] In this embodiment, the direction finding module first determines whether the direction of the incoming wave exceeds the preset effective beam range based on the signal amplitude value. If it does not exceed the effective beam range, the current beam pointing remains unchanged. Only when the direction of the incoming wave exceeds the effective beam range will the angle estimation and direction adjustment process be initiated.

[0035] In this embodiment, the angle mapping table can be a partitioned mapping table, constructed by establishing a correspondence between amplitude difference intervals and direction regions, for example: left and right amplitude difference. When the value is in the range of 0 to 0.2, the mapping angle of the direction region corresponds to 0°; the difference in amplitude between the left and right sides... When the value is in the range of 0.2 to 0.5, the corresponding mapping angle for the direction region is 15°; the difference in amplitude between the left and right sides... When the value is in the range of 0.5 to 0.8, the mapping angle of the direction region corresponds to 30°; the difference in amplitude between the left and right sides... When the value is greater than 0.8, the mapping angle of the orientation region corresponds to 45°. This setting significantly reduces the computational load of the alignment process and substantially lowers computational resource consumption, particularly by controlling the continuous amplitude difference variable. Discretization is performed into a finite number of intervals, and angle mapping can be completed through simple conditional judgments (if-else or switch-case). The entire mapping process requires no multiplication, division, or transcendental function operations, only comparison operations and constant assignments. Taking four intervals as an example, a single mapping requires at most three comparisons, and the computation time is typically on the order of tens of nanoseconds (depending on the clock frequency). Compared with traditional continuous models, this reduces computational overhead by more than 80%, thus significantly improving the alignment timeliness of this scheme.

[0036] Through the above settings, this scheme introduces quantization tolerance by dividing the range, thus reducing the difference in amplitude between the left and right sides. The output angle remains constant when the amplitude varies within a certain range. For example, when the left and right amplitudes differ... When fluctuating arbitrarily within the range of 0 to 0.2, the angle is always locked at 0°, and will not be erroneously offset due to noise interference. This "hard decision" characteristic makes the coarse alignment method of this scheme inherently have a jitter reduction function, applying an equivalent nonlinear filter to the angle domain, enabling this scheme to maintain a stable directional output even in noisy environments, greatly improving the smoothness and reliability of tracking.

[0037] In another implementation, if the phase comparison method is used to calculate the direction of arrival (DOA), the direction-finding module is implemented using a phase comparison interferometer. This interferometer accurately calculates the DOA by measuring the phase difference between the received signals from adjacent antenna elements, thus achieving the calculation of the DOA. In this implementation, when using the phase comparison method, hardware requirements can be appropriately reduced (e.g., reducing the baseline length or the ADC sampling rate), aiming only at achieving a "rough alignment" (i.e., the calculated DOA ensures that the main beam of the antenna array module is within the -3dB beamwidth of the incident radar wave), thereby reducing costs.

[0038] like Figure 1 As shown, according to one embodiment of the present invention, a directional coupler is coupled to the output terminals of four array elements at four different positions: upper left, upper right, lower left, and lower right, to form upper left channel RF signals, upper right channel RF signals, lower left channel RF signals, and lower right channel RF signals; in this embodiment, the amplitude difference in the left and right directions is expressed as: , The difference in amplitude in the vertical direction is expressed as: , in, This represents the signal amplitude value obtained from the radio frequency signal in the upper left channel. This represents the signal amplitude value obtained from the radio frequency signal in the upper right channel. This represents the signal amplitude value obtained from the lower left channel radio frequency signal. This indicates the signal amplitude value obtained from the radio frequency signal in the lower right channel.

[0039] With the above settings, this scheme can significantly improve the stability of direction finding and reduce the impact of single-channel fluctuations on the direction finding results by accumulating the amplitudes of the two sampling channels on the same side and then performing differential calculations.

[0040] like Figure 1 As shown, according to one embodiment of the present invention, the direction adjustment module includes: a two-dimensional electric turntable and a drive motor; in this embodiment, the antenna array module is fixedly mounted on the two-dimensional electric turntable; the drive motor is used to drive the rotation of the two-dimensional electric turntable to align the main beam direction of the antenna array module with the direction of the incident radar wave; wherein, the drive motor may be a servo motor.

[0041] In this embodiment, the speed of the two-dimensional electric turntable is set according to the dwell time of the incident radar wave or the pulse repetition frequency to ensure that alignment is completed within the radar illumination cycle.

[0042] According to one embodiment of the present invention, the present invention provides an alignment method for the aforementioned retroreflector device with incoming wave direction sensing and beam self-alignment, comprising the following steps: S1. Receive incident radar waves with unknown incident direction through the antenna array module; S2. Use the direction finding module to extract signals from at least four channels, calculate the incoming wave direction using the amplitude comparison method or the phase comparison method, and generate a direction finding signal; S3. The control module processes the direction finding signal output by the direction finding module and generates control commands; S4. The direction adjustment module drives the antenna array module to rotate according to the control command, so that the main beam direction of the antenna array module is aligned with the direction of the incident radar wave; S5. Repeat steps S1 to S4 to achieve closed-loop tracking and alignment of the incident radar wave.

[0043] According to one embodiment of the present invention, in step S2, the direction-finding module extracts signals from at least four channels, calculates the direction of arrival of the wave using the amplitude comparison method or the phase comparison method, and generates a direction-finding signal. The calculated direction of arrival of the wave ensures that the main beam of the antenna array module is within the -3dB beamwidth of the incident radar wave.

[0044] To further illustrate this plan, further examples will be provided.

[0045] When the incident radar wave is incident at any angle (e.g., 60° azimuth and 30° elevation), the antenna array module passively receives the incident radar wave based on the receiving antenna array. The directional coupler extracts the radio frequency signals from four channels (e.g., upper left, upper right, lower left, and lower right) from the receiving antenna array and sends them to the detector. The detector performs envelope detection on the radio frequency signals of each channel to obtain the signal amplitude value corresponding to the radio frequency signal; The analog-to-digital converter digitizes the signal amplitude value and transmits it to the signal processor; The signal processing unit employs an amplitude comparison method. By comparing the amplitude differences of the radio frequency signals from the four channels, it calculates the amplitude differences in the left-right and up-down directions, thereby identifying the direction of strongest signal. This allows for a rough estimation of the incoming direction of the incident radar wave (e.g., an azimuth angle of 58° and an elevation angle of 28°), and generates a corresponding direction-finding signal. In this embodiment, the calculated incoming direction ensures that the main beam of the antenna array module is within the -3dB beamwidth of the incident radar wave. Assuming the -3dB beamwidth of the antenna array module in the normal direction is 30°, by ensuring the calculated incoming direction places the main beam of the antenna array module within the -3dB beamwidth of the incident radar wave, the error of the direction-finding module is less than 15°. This fully satisfies the requirement that the incident radar wave falls within the main lobe coverage area of ​​the antenna array module after position adjustment, overcoming the limitation of the effective working angle of traditional fixed Van Atta retroreflectors and achieving high RCS retroreflection over a wide angle range. After receiving the direction finding signal, the controller calculates the difference between the current position of the two-dimensional electric turntable (assumed to be 0°, 0°) and the target position (58°, 28°), and drives the two-dimensional electric turntable to rotate by the corresponding angle. After rotation, the incident radar wave is now in a near-normal incident state relative to the antenna array module (the actual incident angle is only an estimated error, assumed to be 2°). The antenna array module operates in this state, and its radar cross section (RCS) reaches its maximum value (avoiding attenuation of more than 10dB that may occur when incident at a large angle of 60°).

[0046] By periodically performing the above direction finding and adjustment process, dynamic tracking of dynamically changing incident radar waves can be achieved.

[0047] The above description is merely an example of a specific solution of the present invention. For any devices and structures not described in detail herein, it should be understood that they are implemented using common devices and methods already available in the art.

[0048] The above description is merely one embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A retroreflector device with incoming wave direction sensing and beam self-alignment, characterized in that, include: Antenna array module, used to receive incident radar waves and transmit back-reflected waves; The direction-finding module, connected to the antenna array module, is used to extract signals from at least four channels of the antenna array module, calculate the incoming wave direction using the amplitude comparison method or the phase comparison method, and generate a direction-finding signal. The control module, connected to the direction finding module, is used to process the direction finding signals output by the direction finding module and generate control commands; The orientation adjustment module, connected to the control module, is used to drive the antenna array module to rotate according to control commands, so that the main beam direction of the antenna array module is aligned with the direction of the incident radar wave.

2. The retroreflector device with incoming wave direction sensing and beam self-alignment according to claim 1, characterized in that, The antenna array module includes: a receiving antenna array for receiving incident radar waves, a transmitting antenna array for transmitting back-reflected waves, and an amplifier module. The elements of the receiving antenna array and the elements of the transmitting antenna array are arranged in a geometrically symmetrical manner. The receiving elements and transmitting elements in symmetrical positions form corresponding element pairs through a unidirectional transmission link. The amplifier module is connected to the unidirectional transmission link of each array element pair to compensate for link loss and enhance the radar cross-section.

3. The retroreflector device with incoming wave direction sensing and beam self-alignment according to claim 2, characterized in that, The antenna array module uses a Van Atta array.

4. The retroreflector device with incoming wave direction sensing and beam self-alignment according to any one of claims 1 to 3, characterized in that, The direction finding module includes: a directional coupler, a detector, an analog-to-digital converter, and a signal processor; The directional coupler is coupled to the output terminal of the array element of the receiving antenna array, wherein the directional coupler is coupled to the output terminal of the array element at at least four different positions on the receiving antenna array to form at least four channels of radio frequency signals. The detector performs envelope detection on the radio frequency signals of each channel to obtain the signal amplitude value corresponding to the radio frequency signal; The analog-to-digital converter digitizes the signal amplitude value and transmits it to the signal processor; The signal processor calculates the left-right amplitude difference and the up-down amplitude difference based on the output of the analog-to-digital converter, and obtains the azimuth and elevation angles of the incident radar wave according to a pre-established amplitude difference-angle mapping table.

5. The retroreflector device with incoming wave direction sensing and beam self-alignment according to claim 4, characterized in that, The directional coupler is coupled to the output terminals of the array elements at four different positions: upper left, upper right, lower left, and lower right of the receiving antenna array, to form the upper left channel RF signal, the upper right channel RF signal, the lower left channel RF signal, and the lower right channel RF signal. The difference in amplitude in the left and right directions is expressed as: ， The vertical amplitude difference is expressed as: ， in, This represents the signal amplitude value obtained from the radio frequency signal in the upper left channel. This represents the signal amplitude value obtained from the radio frequency signal in the upper right channel. This represents the signal amplitude value obtained from the lower left channel radio frequency signal. This indicates the signal amplitude value obtained from the radio frequency signal in the lower right channel.

6. The retroreflector device with incoming wave direction sensing and beam self-alignment according to claim 5, characterized in that, The direction adjustment module includes: a two-dimensional electric turntable and a drive motor; The antenna array module is fixedly mounted on a two-dimensional electric turntable; The drive motor is used to drive the rotation of the two-dimensional electric turntable to align the main beam direction of the antenna array module with the direction of the incident radar wave.

7. An alignment method for a retroreflector device with incoming wave direction sensing and beam self-alignment as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Receive incident radar waves with unknown incident direction through the antenna array module; S2. Use the direction finding module to extract signals from at least four channels, calculate the incoming wave direction using the amplitude comparison method or the phase comparison method, and generate a direction finding signal; S3. The control module processes the direction finding signal output by the direction finding module and generates control commands; S4. The direction adjustment module drives the antenna array module to rotate according to the control command, so that the main beam direction of the antenna array module is aligned with the direction of the incident radar wave; S5. Repeat steps S1 to S4 to achieve closed-loop tracking and alignment of the incident radar wave.

8. The alignment method according to claim 7, characterized in that, In step S2, the direction-finding module extracts signals from at least four channels, calculates the direction of arrival using the amplitude comparison method or the phase comparison method, and generates a direction-finding signal. The calculated direction of arrival ensures that the main beam of the antenna array module is within the -3dB beamwidth of the incident radar wave.

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