Method and system for dielectric antenna design for mmwave imaging security screening devices
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- BEIJING ZHONGCHENG KANGFU TECH CO LTD
- Filing Date
- 2026-03-03
- Publication Date
- 2026-05-26
Smart Images
Figure CN121765983B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of millimeter-wave imaging technology, and more specifically, to a method and system for designing dielectric antennas for millimeter-wave imaging security inspection devices. Background Technology
[0002] In the field of modern public security, millimeter-wave imaging security inspection devices are widely used in airports, subways, customs, and other locations for detecting contraband due to their advantages such as non-contact operation, no radiation, strong penetration, and high resolution. As a core component of this type of security inspection equipment, the performance of the antenna system directly determines the imaging quality, resolution, and target identification accuracy of the imaging system. Especially in millimeter-wave array antenna systems composed of multiple array elements, the antenna's beamforming capability, pattern accuracy, and scanning response efficiency all have a significant impact on the overall system performance.
[0003] Currently, millimeter-wave imaging systems are trending towards high resolution, rapid scanning, and intelligent control, placing higher demands on array antennas. On the one hand, antenna arrays need to possess flexible beam scanning capabilities to cover the target detection area and achieve synergistic optimization of spatial resolution and image quality. On the other hand, due to the mutual coupling effect between array antenna elements, and the fact that antennas are installed in multi-layer dielectric structures in practical applications, their radiation patterns are affected by the electromagnetic environment, resulting in non-ideal characteristics and leading to problems such as beam distortion and sidelobe rise. Therefore, effectively obtaining the true radiation pattern characteristics of antenna elements, considering mutual coupling interference, and establishing a high-precision excitation model have become crucial for optimizing antenna design.
[0004] Furthermore, the millimeter-wave band features high frequencies, small antenna sizes, and extremely narrow beams, thus demanding even more stringent requirements for pattern accuracy. Failure to effectively control the main lobe width, sidelobe level, and pointing accuracy can easily lead to false alarms or missed detections, reducing the system's reliability and practicality. Therefore, developing an antenna design method that can adapt to complex scanning tasks and possesses high-precision beam reconstruction and dynamic adjustment capabilities is of great significance for improving the imaging clarity, recognition accuracy, and environmental adaptability of millimeter-wave imaging security inspection systems.
[0005] For example, US Patent Publication No. 9967081B2 discloses a method for performing beamforming. The method includes initiating a first signal transmitted from a target second device for reception by a first device having an antenna array. The first device generates a first beamforming weight matrix that automatically corrects for amplitude and phase errors of the antenna array and maximizes the antenna gain toward the target second device using a covariance matrix derived from the received first signal. The first device then generates an enhanced second beamforming weight matrix using a mask window or a joint optimization algorithm to further suppress interference with other active second devices. This enhancement is calculated and applied based on the distribution of multiple active second devices.
[0006] For example, US Patent No. 11031980B2 discloses a method and apparatus for forming an efficient hybrid digital-analog beam in a multi-antenna system. The method includes the following steps: First, a mathematical model is performed on the beamforming design to construct a beamforming optimization problem to minimize ripple in the main lobe and side lobes. The original optimization problem is transformed into a constrained separable optimization problem using a penalty function method. Finally, the block coordinate descent method is used for iterative solution. The beam designed in this invention has a low peak-to-average power ratio, high power amplification efficiency of the power amplifier, and considers the finite resolution characteristics of the phase shifter.
[0007] The above-disclosed technical solutions have at least the following technical problems:
[0008] Traditional array antenna designs often rely on idealized, uncoupled models for excitation calculations, failing to adequately consider the mutual coupling effects between array elements. This leads to deviations between the actual beam pattern and the desired pattern, affecting imaging accuracy and directional resolution. Furthermore, traditional beamforming methods struggle to effectively suppress sidelobes while ensuring main lobe focusing, resulting in high imaging noise and increased false alarm rates, particularly in complex environments. To address these issues, this invention proposes a solution. Summary of the Invention
[0009] To overcome the aforementioned deficiencies of existing technologies, embodiments of the present invention provide a dielectric antenna design method and system for millimeter-wave imaging security inspection devices. By combining vector network analysis with HFSS simulation, the antenna pattern and mutual coupling characteristics are extracted to construct an accurate initial excitation matrix. Combined with dynamic commands from the beam scanning controller, a multi-task priority scheduling table is generated to achieve flexible configuration of the beam scanning path. Based on a beam reconstruction algorithm, a pattern error cost function is constructed to solve for the optimal excitation weight vector. Finally, real-time control and adaptive correction of the millimeter-wave beam are achieved through the issuance of amplitude and phase digital control words. This method effectively solves problems such as poor beamforming accuracy, slow direction switching response, and severe mutual coupling interference in existing security inspection systems, significantly improving the resolution and imaging stability of millimeter-wave imaging systems in complex security inspection environments.
[0010] To achieve the above objectives, the present invention provides the following technical solution:
[0011] A method for designing a dielectric antenna for a millimeter-wave imaging security inspection device includes: acquiring the radiation pattern and mutual coupling characteristics of each dielectric antenna element and establishing an initial excitation matrix; acquiring the dynamic scanning command of the beam scanning controller and generating a beam scanning task schedule table; outputting the optimal excitation weight vector corresponding to the current frame based on the beam reconstruction algorithm according to the initial excitation matrix and the beam scanning task schedule table; and dynamically adjusting the millimeter-wave beam according to the optimal excitation weight vector.
[0012] In a preferred embodiment, the acquisition of the radiation pattern and mutual coupling characteristics of each dielectric antenna element is specifically as follows: The dielectric antenna elements in the array under test are acquired, and a vector network analyzer is used for actual measurement in an uncoupled environment to obtain the free-space radiation pattern of the antenna elements; based on HFSS electromagnetic simulation software, a simulation model of the antenna elements is established in a multilayer dielectric model to obtain its simulation radiation pattern; based on the free-space radiation pattern and the simulation radiation pattern, a radiation pattern is generated using a weighted average fusion method; under full array excitation conditions, the mutual coupling signal between any two antenna elements in the array is measured using a vector network analyzer to obtain the mutual coupling characteristics.
[0013] In a preferred embodiment, the establishment of the initial excitation matrix is specifically as follows: The mutual coupling characteristics are converted into complex numbers to form a mutual coupling matrix; multiple standard beam directions are set according to the array antenna arrangement and the preset target detection direction; for each standard beam direction and the preset operating frequency, the ideal excitation vector corresponding to each direction is output using the array element phase center method, and all excitation vectors are combined to form an initial ideal excitation matrix; based on the pattern gain corresponding to each antenna element, the initial ideal excitation vector is weighted by direction sensitivity to obtain a pattern correction excitation vector; for each target direction operating frequency and its corresponding mutual coupling matrix, the ideal excitation vector is multiplied by the inverse of the mutual coupling matrix to obtain a compensation excitation vector; all compensation excitation vectors are merged column-wise to form a compensation excitation matrix, i.e., the initial excitation matrix.
[0014] In a preferred embodiment, the step of performing direction sensitivity weighting on the initial ideal excitation vector to obtain the pattern-corrected excitation vector is as follows: extract the pattern gain of each antenna element in each target direction according to the pattern to obtain the pattern gain column vector; based on the pattern gain vector, perform element-wise multiplication on the initial ideal excitation vector to obtain the pattern-corrected excitation vector.
[0015] In a preferred embodiment, the step of obtaining the dynamic scanning command from the beam scanning controller and generating a beam scanning task schedule table is as follows: The beam scanning controller receives the dynamic scanning command from the upper control system and generates a two-dimensional scanning grid within the target area by discretization with specified steps; if a preset beam direction sequence exists, the beam direction sequence is preferentially matched and mapped to the scanning grid, and its corresponding position and scanning priority in the grid are marked; an initial beam scanning task schedule table is generated based on the scanning grid and direction priority.
[0016] In a preferred embodiment, the step of outputting the optimal excitation weight vector corresponding to the current frame based on the beam reconstruction algorithm according to the initial excitation matrix and the beam scanning task scheduling table is as follows: extracting the task data corresponding to the current frame from the beam scanning task scheduling table; constructing a target radiation pattern function based on the main lobe pointing of the current frame and the task data, and performing error modeling based on the beam reconstruction algorithm with the actual radiation pattern corresponding to the current excitation to construct a cost function; and solving for the optimal excitation weight vector corresponding to the current scanning frame based on the cost function.
[0017] In a preferred embodiment, the step of constructing the target radiation pattern function based on the main lobe pointing of the current frame and task data is as follows: Parse the main lobe pointing vector of the current frame in the scan schedule table and convert it into polar coordinates, i.e., the azimuth and elevation angles of the main lobe center; determine the angular width range of the main lobe coverage area according to the angular resolution specified in the current frame task; extract the sidelobe level constraint according to the task schedule table and set the sidelobe suppression level of the area outside the main lobe; construct the target radiation pattern function based on an adjustable cosine window function according to the azimuth and elevation angles of the main lobe center, the angular width range of the main lobe coverage area, and the sidelobe suppression level; construct an angular grid within the scan area and discretize the target radiation pattern function into a two-dimensional function matrix.
[0018] In a preferred embodiment, the dynamic adjustment of the millimeter-wave beam based on the optimal excitation weight vector is specifically as follows: the complex excitation weights in the optimal excitation weight vector are converted into amplitude-phase form and amplitude normalized; corresponding amplitude control values and phase control values are generated for each antenna element in the array based on the normalized excitation weight vector and stored in the form of digital control words; the digital control words are sent to the array beamforming module to drive the amplitude controller and phase shifter of each antenna element in real time to complete the directional adjustment of the beam in the current frame; after the antenna actually outputs the beam, the beamforming effect is fed back and detected by the built-in and external beam sensing modules, and the error is compared with the preset radiation pattern; if the error exceeds the threshold, an adaptive fine-tuning mechanism is triggered to quickly correct and iterate the excitation weights.
[0019] The dielectric antenna design system for millimeter-wave imaging security inspection devices includes an initial excitation matrix module, a form module, a reconstruction module, and a control module, with interconnections between the modules. The initial excitation matrix module is used to acquire the radiation pattern and mutual coupling characteristics of each dielectric antenna element and establish the initial excitation matrix. The form module is used to acquire the dynamic scanning instructions from the beam scanning controller and generate a beam scanning task schedule table. The reconstruction module is used to output the optimal excitation weight vector corresponding to the current frame based on the initial excitation matrix and the beam scanning task schedule table, using a beam reconstruction algorithm. The control module is used to dynamically control the millimeter-wave beam according to the optimal excitation weight vector.
[0020] The technical effects and advantages of the dielectric antenna design method and system for millimeter-wave imaging security inspection devices of the present invention are as follows:
[0021] 1. This invention effectively improves the realism and stability of the radiation pattern modeling by weighted fusion of the free-space radiation pattern of the dielectric antenna element and the simulated radiation pattern under a multi-layer dielectric environment. Simultaneously, a vector network analyzer is introduced to perform experimental analysis of the array's mutual coupling characteristics, forming an accurate mutual coupling matrix. This significantly improves the accuracy of subsequent excitation compensation, providing a physical foundation for beamforming quality. In the excitation matrix construction process, the element phase center method is used to generate ideal excitation vectors, and directional sensitivity weighting is performed in conjunction with the radiation pattern gain. Furthermore, the inverse operation of the mutual coupling matrix is introduced for excitation compensation. The resulting initial excitation matrix exhibits high directional consistency and strong mutual coupling suppression, which helps improve the radiation performance consistency of the entire array in different directions.
[0022] 2. This invention, through a beam scanning controller and its task scheduling mechanism, can generate a priority-based scanning grid within the target area according to dynamic instructions from the host system, and automatically complete the timing scheduling of scanning tasks. This achieves flexible and precise control of the millimeter-wave beam, meeting the needs of multi-target, rapid-response security inspection tasks. In the beam reconstruction stage, this invention constructs a target pattern function that integrates main lobe pointing, resolution constraints, and sidelobe suppression requirements. Based on error modeling, a cost function is established, and an optimization algorithm is used to output the optimal excitation weight vector, ensuring a high degree of consistency between the actual beam pattern and the preset performance indicators, further improving imaging accuracy and edge detail restoration capabilities. Attached Figure Description
[0023] Figure 1 This is a schematic flowchart of a dielectric antenna design method for a millimeter-wave imaging security inspection device according to the present invention.
[0024] Figure 2 This is a schematic diagram of a dielectric antenna design system for a millimeter-wave imaging security inspection device according to the present invention. Detailed Implementation
[0025] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0026] Example 1, Figure 1 This invention provides a method for designing a dielectric antenna for a millimeter-wave imaging security inspection device, comprising the following steps:
[0027] S1, obtain the radiation pattern and mutual coupling characteristics of each dielectric antenna element, and establish the initial excitation matrix.
[0028] In this embodiment, the radiation pattern and mutual coupling characteristics of each dielectric antenna element are obtained, as follows:
[0029] Obtain each dielectric antenna element in the array under test, and let its number be i∈{1,2,...,N}, where N is the total number of antennas in the array;
[0030] For each antenna element, its free space radiation pattern was obtained by performing field measurements using a vector network analyzer (VNA) in an uncoupled environment.
[0031] Simultaneously, based on electromagnetic simulation software such as HFSS or CST, an antenna element simulation model is established in a multilayer dielectric model to obtain its simulation radiation pattern;
[0032] Based on the free-space radiation pattern and the simulated radiation pattern, a radiation pattern is generated using a weighted average fusion method.
[0033] Under full array excitation, the mutual coupling signal between any two antenna elements in the array is measured using a vector network analyzer (VNA) or a millimeter-wave mutual coupling test platform to obtain mutual coupling characteristics, which include the coupling amplitude and corresponding phase changes between the two antennas at different frequencies.
[0034] For example, if the antenna array is 8×8, it is necessary to measure the mutual coupling between all 64 antenna elements and construct a 64×64 coupling response matrix. The measurement frequency band can be from 23.5 GHz to 24.5 GHz, with a step size of 100 MHz.
[0035] During this process, the mutual coupling response of each pair of antennas (such as the i-th and j-th antennas) is recorded, and the data is shown in the table below:
[0036]
[0037] In this embodiment, an initial excitation matrix is established as follows:
[0038] The measured amplitude and phase are converted into complex numbers (i.e., polar coordinates are converted into rectangular coordinates) to form a mutual coupling matrix. Each term of this matrix represents the electromagnetic interference intensity between a pair of antennas at a certain frequency. In addition, to maintain the numerical stability of the matrix, the diagonal elements are uniformly set to 1, indicating that the excitation of each antenna is normalized, and all off-diagonal terms retain the actual measured values.
[0039] Based on the array antenna arrangement and the preset target detection direction (such as forward scanning, lateral scanning, or conical scanning), multiple standard beam directions are set, including but not limited to a set of angle pairs. , where k represents the k-th direction, and each direction represents the spatial region pointed to by the main lobe of the desired beam;
[0040] For each standard beam direction and preset operating frequency, the ideal excitation vector corresponding to each direction is calculated using array factor theory or array element phase center method. Without considering the mutual coupling effect, the excitation vector represents the amplitude and phase weight that each antenna element should bear. All excitation vectors are used to form an initial ideal excitation matrix.
[0041] Based on the pattern gain of each antenna element, the initial ideal excitation vector is weighted by directional sensitivity to obtain the pattern-corrected excitation vector.
[0042] For each target direction operating frequency and its corresponding mutual coupling matrix, the ideal excitation vector is multiplied by the inverse of the mutual coupling matrix to compensate for each pattern correction excitation vector, thus obtaining the compensated excitation vector.
[0043] All compensation incentive vectors are merged column-wise to form a compensation incentive matrix, i.e., the initial incentive matrix.
[0044] Furthermore, by converting the measured amplitude and phase information into complex numbers, constructing a mutual coupling matrix, and normalizing the diagonal elements, the stability and invertibility of the matrix in subsequent numerical calculations are effectively improved, avoiding excitation anomalies caused by diagonal element amplitude shifts, thereby ensuring the uniformity of the excitation reference of the antenna element itself.
[0045] Secondly, based on the array arrangement structure and the characteristics of the detection mission, multiple representative standard beam directions are set, which can cover target areas in various scenarios, including forward, lateral, and conical shapes, making the designed excitation scheme more adaptable to the mission. This spatial angle distribution design facilitates subsequent comprehensive optimization of the radiation pattern performance and meets the high-precision pointing requirements in millimeter-wave security imaging.
[0046] Furthermore, based on the actual gain characteristics of the radiation patterns of each antenna element, directional sensitivity weighting is introduced to effectively correct the radiation inhomogeneity of different elements in different directions, making the excitation vector more consistent in directional response, which is beneficial for main lobe energy focusing and sidelobe suppression, thereby enhancing the beam control capability of the entire array.
[0047] In this embodiment, the initial ideal excitation vector is weighted by direction sensitivity to obtain the pattern-corrected excitation vector, as follows:
[0048] Based on the radiation pattern, extract the radiation pattern gain of each antenna element in each target direction to obtain the radiation pattern gain column vector;
[0049] Based on the pattern gain vector, an element-wise multiplication operation is performed on the initial ideal excitation vector to obtain the pattern-corrected excitation vector.
[0050] S2, obtain the dynamic scanning command from the beam scanning controller and generate a beam scanning task scheduling table. The scanning command includes the target area range, target resolution, and beam direction sequence.
[0051] In this embodiment, the dynamic scanning command of the beam scanning controller is obtained, and a beam scanning task scheduling table is generated, as follows:
[0052] The beam scanning controller receives dynamic scanning instructions from the host control system. These instructions include the target area range (defining the angular range to be covered by millimeter-wave imaging), the target resolution (setting the spatial resolution accuracy of beam scanning to control the step size of angle discretization), and the beam direction sequence (a set of beam main lobe directions arranged in priority or time sequence).
[0053] Within the target area, a two-dimensional scanning grid is generated using a specified step discretization. Each grid point is defined as a potential beam pointing angle for subsequent beam synthesis excitation matching.
[0054] If a preset beam direction sequence exists, the beam direction sequence is preferentially matched and mapped to the scanning grid, and its corresponding position and scanning priority are marked in the grid.
[0055] Based on the scanning grid points and directional priority, an initial beam scanning task scheduling table is generated, which includes the following fields: target number and corresponding grid coordinates, scanning priority weight, target main lobe direction and neighborhood step range, and required beam dwell time.
[0056] It should be noted that the beam scanning task scheduling table is used for unified planning and management of the beam scanning strategy of the millimeter-wave array antenna system. By structurally organizing parameters such as target direction, priority, step range, and dwell time, dynamic optimization of beam resources can be achieved, thereby improving scanning efficiency and imaging accuracy.
[0057] S3, based on the initial excitation matrix and scanning command, outputs the optimal excitation weight vector corresponding to the current frame based on the beam reconstruction algorithm.
[0058] In this embodiment, based on the initial excitation matrix and the beam scanning task scheduling table, the optimal excitation weight vector corresponding to the current frame is output according to the beam reconstruction algorithm, as follows:
[0059] Based on the system clock or triggering mechanism, the task data corresponding to the current frame is extracted from the beam scanning task scheduling table. The task data includes: the target main lobe direction or corresponding direction vector of the current frame, the sidelobe suppression level, and the corresponding initial excitation vector (extracted by column index from the initial excitation matrix).
[0060] Based on the main lobe pointing of the current frame and the task data, a target radiation pattern function is constructed, and an error model is performed on the actual radiation pattern corresponding to the current excitation using a beam reconstruction algorithm. A cost function is then constructed to characterize the expected beam radiation intensity distribution of the current frame scan.
[0061] Based on the cost function, the optimal excitation weight vector corresponding to the current scan frame is solved.
[0062] The cost function is as follows:
[0063]
[0064] In the formula: This is the cost function value, used to measure the deviation between the current stimulus pattern and the target stimulus pattern. It is the objective function for subsequent stimulus optimization calculations. The set of angles covering the main lobe and side lobes. This is the current array excitation weight vector, representing the amplitude and phase excitation control quantities of each element in the antenna array. This represents the pattern function that the current frame scanning task expects to achieve. Excitation vector The actual radiation pattern generated below, It is at each direction point The difference in power between the actual beam and the target beam is shown above.
[0065] Furthermore, by dynamically extracting the target main lobe direction, sidelobe suppression requirements, and initial excitation vector needed for the current frame through a task scheduling table, a beam optimization mechanism that is linked with the scanning task in real time is realized. Compared with traditional fixed beamforming methods, this method has stronger adaptability and real-time performance, and can quickly adjust beam characteristics according to different security inspection task requirements, thereby improving the system's ability to focus on key local areas.
[0066] Secondly, by constructing a target pattern function and comparing it with the actual pattern under the current excitation, the desired characteristics of the main and side lobes can be accurately characterized, thus forming a physically interpretable cost function. This method not only considers the main lobe alignment capability but also introduces performance indicators such as side lobe suppression, enabling a more comprehensive evaluation of the effectiveness of the excitation weights and avoiding the situation where only the main lobe is optimized while neglecting the overall beam quality.
[0067] In this embodiment, a target pattern function is constructed based on the main lobe pointing of the current frame and the task data, as follows:
[0068] Parse the main lobe direction vector of the current frame in the scan schedule table and convert it into polar coordinates, i.e., the azimuth angle of the main lobe center. and pitch angle , used to determine the center position of the main lobe of the pattern function;
[0069] Based on the angular resolution specified in the current frame task, determine the angular width range of the main lobe coverage area. For example, if the resolution requirement is 1∘, then define the main lobe coverage area as follows: , ;
[0070] Based on the task scheduling table, extract the sidelobe level limiting constraints (e.g., -13dB, -20dB), and set the sidelobe suppression level in the region outside the main lobe. For example, the sidelobe power must not exceed 10% of the main lobe power, meaning the target pattern function should not exceed 0.1 (normalized power unit) outside the main lobe region. Limit the power response in the non-main lobe region of the pattern according to the sidelobe level limiting constraints, specifically: ,in This represents the maximum allowable gain threshold in the sidelobe region, used to limit stray energy in non-imaging directions, and is set to 0.05~0.1 times the main lobe peak value. The target directional region covered by the main lobe, i.e. the directional range in which high-gain output is allowed;
[0071] Based on the azimuth and elevation angles of the main lobe center, the angular width range of the main lobe coverage area, and the sidelobe suppression level, a target pattern function is constructed using an adjustable cosine window function.
[0072] Construct an angular grid within the scanned area (e.g., with...) (For stepping), and discretize the target direction pattern function into a two-dimensional function matrix, which serves as the target template input for the current frame excitation weight optimization.
[0073] Furthermore, this step accurately expresses the desired beam shape and performance requirements of the current scanning task. By converting the main lobe direction vector into polar coordinates, the azimuth and elevation angles of the main lobe are clearly defined, thus providing accurate calibration for the center position of the subsequent radiation pattern function. This refined processing of angle parameters makes the main lobe alignment more precise, effectively improving target recognition and image clarity.
[0074] Secondly, regarding angular resolution control, by analyzing the resolution requirements set in the task (e.g., 1°), it is converted into a specific angular width range (±0.5°) of the main lobe coverage area, thus achieving flexible definition and high-resolution adjustment of the main lobe region. This method of defining the main lobe width on demand is more adaptive than the traditional design with a fixed beamwidth, and can accommodate the differentiated resolution requirements in different scenarios.
[0075] Finally, by discretizing the entire scanning area using an angular grid and generating a two-dimensional target radiation pattern function matrix, which serves as the input template for the weight optimization algorithm, the structure and numerical operability of radiation pattern modeling are greatly enhanced. This two-dimensional function discretization method not only supports rapid computer processing and algorithm iteration but also enables more granular and precise radiation pattern control, better adapting to the needs of millimeter-wave image reconstruction and target detection in complex scenarios.
[0076] S4, dynamically adjusts the millimeter-wave beam according to the optimal excitation weight vector.
[0077] In this embodiment, the millimeter-wave beam is dynamically controlled according to the optimal excitation weight vector, as follows:
[0078] The complex excitation weights in the optimal excitation weight vector are converted into amplitude-phase form and amplitude normalized to ensure output power balance.
[0079] Based on the normalized excitation weight vector, corresponding amplitude control values and phase control values are generated for each antenna element in the array and stored in the form of digital control words for use by the numerical control radio frequency link.
[0080] The digital control word is sent to the array beamforming module to drive the amplitude controller and phase shifter (such as phase shifting network, programmable phase shifter or phase shifting switch array) of each antenna element in real time to complete the directional control of the beam in the current frame.
[0081] After the antenna actually outputs a beam, the beamforming effect is fed back and detected by built-in and external beam sensing modules (such as near-field detectors, calibration sensors, etc.), and the error is compared with the preset radiation pattern.
[0082] If the error exceeds the threshold, an adaptive fine-tuning mechanism is triggered to quickly correct and iterate the incentive weights.
[0083] Furthermore, this step effectively ensures the balance and stability of the output power by converting the complex excitation weights into amplitude-phase form and performing amplitude normalization. Amplitude normalization not only prevents some antenna elements from being too strong or too weak, avoiding beam distortion and signal distortion caused by uneven power distribution, but also improves the overall energy efficiency of the system, extends device lifespan, and enhances the reliability and consistency of the system.
[0084] Secondly, by using digital control words to store amplitude and phase control values, fine-grained adjustment of each antenna element is achieved. This digital control method has extremely high flexibility and repeatability, enabling the RF link to respond to control commands quickly and accurately, supporting high-frequency beam switching and real-time dynamic adjustment, meeting the scanning needs of multiple tasks and multiple targets in complex environments, and improving imaging speed and accuracy.
[0085] Furthermore, the integrated built-in and external beam sensing modules provide a closed-loop feedback mechanism, enabling real-time monitoring of the actual beamforming effect and error comparison with the preset radiation pattern. This feedback mechanism greatly enhances the system's self-correction capability, promptly detecting issues such as beam deviation and phase mismatch, ensuring the accuracy and stability of beamforming.
[0086] Example 2, Figure 2 The present invention provides a dielectric antenna design system for a millimeter-wave imaging security inspection device, comprising an initial excitation matrix module, a form module, a reconstruction module, and a control module, with connections between the modules;
[0087] The initial excitation matrix module is used to obtain the radiation pattern and mutual coupling characteristics of each dielectric antenna element and to establish the initial excitation matrix.
[0088] The form module is used to obtain dynamic scanning instructions from the beam scanning controller and generate a beam scanning task scheduling table.
[0089] The reconstruction module is used to output the optimal excitation weight vector corresponding to the current frame based on the beam reconstruction algorithm, according to the initial excitation matrix and the beam scanning task schedule table.
[0090] The control module is used to dynamically control the millimeter-wave beam according to the optimal excitation weight vector.
[0091] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.
[0092] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.
[0093] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.
[0094] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
[0095] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for designing a dielectric antenna for a millimeter-wave imaging security inspection device, characterized in that, include: Obtain the radiation pattern and mutual coupling characteristics of each dielectric antenna element, and establish the initial excitation matrix; Obtain the dynamic scanning instructions from the beam scanning controller and generate a beam scanning task scheduling table; Based on the initial excitation matrix and the beam scanning task schedule, the optimal excitation weight vector corresponding to the current frame is output based on the beam reconstruction algorithm. The millimeter-wave beam is dynamically controlled based on the optimal excitation weight vector; The establishment of the initial excitation matrix is as follows: The mutual coupling features are converted into complex numbers to form a mutual coupling matrix; Based on the arrangement of the array antennas and the preset target detection direction, multiple standard beam directions are set respectively; For each standard beam direction and preset operating frequency, the ideal excitation vector corresponding to each direction is output by the array element phase center method, and all excitation vectors are used to form an initial ideal excitation matrix. Based on the pattern gain of each antenna element, the initial ideal excitation vector is weighted by directional sensitivity to obtain the pattern-corrected excitation vector. For each target direction operating frequency and its corresponding mutual coupling matrix, the ideal excitation vector is multiplied by the inverse of the mutual coupling matrix to obtain the compensation excitation vector. All compensation incentive vectors are merged column-wise to form a compensation incentive matrix, i.e., the initial incentive matrix; The direction-sensitivity weighting of the initial ideal excitation vector yields the pattern-corrected excitation vector, as detailed below: Based on the radiation pattern, extract the radiation pattern gain of each antenna element in each target direction to obtain the radiation pattern gain column vector; Based on the pattern gain column vector, an element-wise multiplication operation is performed on the initial ideal excitation vector to obtain the pattern-corrected excitation vector; The optimal excitation weight vector for the current frame is output based on the initial excitation matrix and the beam scanning task scheduling table, using the beam reconstruction algorithm, as follows: Extract the task data corresponding to the current frame from the beam scan task scheduling table; Based on the main lobe pointing of the current frame and the task data, construct the target pattern function, and perform error modeling based on the beam reconstruction algorithm with the actual pattern corresponding to the current excitation to construct the cost function. Based on the cost function, the optimal excitation weight vector corresponding to the current scan frame can be obtained; The target pattern function is constructed based on the main lobe pointing of the current frame and the task data, as follows: Parse the main lobe direction vector of the current frame in the scan schedule table and convert it into polar coordinates, namely the azimuth and elevation angles of the main lobe center; Determine the angular width range of the main lobe coverage area based on the angular resolution specified in the current frame task; Based on the task scheduling table, extract the sidelobe level limit constraints and set the sidelobe suppression level in the region outside the main lobe. Based on the azimuth and elevation angles of the main lobe center, the angular width range of the main lobe coverage area, and the sidelobe suppression level, a target pattern function is constructed using an adjustable cosine window function. An angular grid is constructed within the scanning area, and the target orientation pattern function is discretized into a two-dimensional function matrix.
2. The dielectric antenna design method for millimeter-wave imaging security inspection devices according to claim 1, characterized in that, The acquisition of the radiation pattern and mutual coupling characteristics of each dielectric antenna element is as follows: Obtain the dielectric antenna element in the array under test, and perform actual measurements using a vector network analyzer in an uncoupled environment to obtain the free space radiation pattern of the antenna element; Based on HFSS electromagnetic simulation software, an antenna element simulation model is established in a multilayer dielectric model to obtain its simulation radiation pattern; Based on the free-space radiation pattern and the simulated radiation pattern, a radiation pattern is generated using a weighted average fusion method. Under full array excitation, the mutual coupling signal between any two antenna elements in the array is measured using a vector network analyzer to obtain the mutual coupling characteristics.
3. The dielectric antenna design method for millimeter-wave imaging security inspection devices according to claim 2, characterized in that, The process of obtaining dynamic scanning commands from the beam scanning controller and generating a beam scanning task scheduling table is as follows: The beam scanning controller receives dynamic scanning commands from the upper control system and generates a two-dimensional scanning grid within the target area by specifying step discretization. If a preset beam direction sequence exists, the beam direction sequence is matched and mapped to the scanning grid first, and its corresponding position in the grid and scanning priority are marked. An initial beam scanning task schedule is generated based on the scanning grid points and directional priority.
4. The dielectric antenna design method for millimeter-wave imaging security inspection devices according to claim 3, characterized in that, The dynamic control of the millimeter-wave beam based on the optimal excitation weight vector is as follows: The complex excitation weights in the optimal excitation weight vector are converted into amplitude-phase form and then normalized. Based on the normalized excitation weight vector, the corresponding amplitude control value and phase control value are generated for each antenna element in the array and stored in the form of digital control words. The digital control word is sent to the array beamforming module to drive the amplitude controller and phase shifter of each antenna element in real time, thereby completing the directional control of the beam in the current frame. After the antenna actually outputs a beam, the beamforming effect is detected by the built-in and external beam sensing modules, and the error is compared with the preset pattern. If the error exceeds the threshold, an adaptive fine-tuning mechanism is triggered to quickly correct and iterate the incentive weights.
5. A system using the dielectric antenna design method for millimeter-wave imaging security inspection devices as described in any one of claims 1-4, characterized in that, It includes an initial incentive matrix module, a form module, a reconstruction module, and a control module, and the modules are interconnected. The initial excitation matrix module is used to obtain the radiation pattern and mutual coupling characteristics of each dielectric antenna element and to establish the initial excitation matrix. The form module is used to obtain dynamic scanning instructions from the beam scanning controller and generate a beam scanning task scheduling table. The reconstruction module is used to output the optimal excitation weight vector corresponding to the current frame based on the beam reconstruction algorithm, according to the initial excitation matrix and the beam scanning task schedule table. The control module is used to dynamically control the millimeter-wave beam according to the optimal excitation weight vector.