This article proposes the study and development of interferometric synthetic aperture radar (InSAR) from compact, high-frequency radar sensors onboard commercial uncrewed aerial vehicles (UAVs), (often referred to as “drones”) to create precision digital elevation models (DEMs). The potential of such InSAR systems, due to the higher operating frequency and target proximity, is quantified, but it is also shown how the same features, combined with the instability of UAV platforms, lead to motion errors that either deteriorate or altogether deny capability. This article thus quantifies acceptable motion error limits and shows how complex autofocus can restore height estimation performance, through analytical modeling that is verified by simulation and validated through outdoor experiments with a 24 GHz UAV-based demonstrator. To our knowledge, this is the first demonstration of a UAV-based InSAR system in this high-frequency band.
{"title":"Uncrewed Aerial Vehicle (UAV)-Based, K-Band Interferometric Synthetic Aperture Radar (SAR)","authors":"Yaxuan Li;Ali Bekar;Marco Martorella;Michail Antoniou","doi":"10.1109/TRS.2026.3661483","DOIUrl":"https://doi.org/10.1109/TRS.2026.3661483","url":null,"abstract":"This article proposes the study and development of interferometric synthetic aperture radar (InSAR) from compact, high-frequency radar sensors onboard commercial uncrewed aerial vehicles (UAVs), (often referred to as “drones”) to create precision digital elevation models (DEMs). The potential of such InSAR systems, due to the higher operating frequency and target proximity, is quantified, but it is also shown how the same features, combined with the instability of UAV platforms, lead to motion errors that either deteriorate or altogether deny capability. This article thus quantifies acceptable motion error limits and shows how complex autofocus can restore height estimation performance, through analytical modeling that is verified by simulation and validated through outdoor experiments with a 24 GHz UAV-based demonstrator. To our knowledge, this is the first demonstration of a UAV-based InSAR system in this high-frequency band.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"4 ","pages":"535-548"},"PeriodicalIF":0.0,"publicationDate":"2026-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11414200","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147362378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-18DOI: 10.1109/TRS.2026.3666094
Christian Oswald;Franz Pernkopf
In this article, we propose a novel method for frequency modulated continuous wave (FMCW) radar mutual interference mitigation (IM) based on the discrete fractional Fourier transform (DFrFT). Interference chirps are detected and mitigated by compression and zeroing in the fractional domain. We provide an efficient implementation that can deal with multiple interferers, where we perform consecutive DFrFTs utilizing its angle-additivity property. For that purpose, we generalize and reduce the computational complexity of the multiangle centered DFrFT. Our algorithm is designed to be simple and fast such that it can be implemented in hardware. We evaluate our algorithm on a synthetic I/Q-modulated dataset and outperform reference methods in terms of the mean squared error (MSE), signal-to-interference-plus-noise ratio (SINR), error vector magnitude (EVM), true positive rate (TPR), false alarm rate (FAR), and $F1$ -score.
{"title":"FMCW Radar Interference Mitigation Based on the Fractional Fourier Transform","authors":"Christian Oswald;Franz Pernkopf","doi":"10.1109/TRS.2026.3666094","DOIUrl":"https://doi.org/10.1109/TRS.2026.3666094","url":null,"abstract":"In this article, we propose a novel method for frequency modulated continuous wave (FMCW) radar mutual interference mitigation (IM) based on the discrete fractional Fourier transform (DFrFT). Interference chirps are detected and mitigated by compression and zeroing in the fractional domain. We provide an efficient implementation that can deal with multiple interferers, where we perform consecutive DFrFTs utilizing its angle-additivity property. For that purpose, we generalize and reduce the computational complexity of the multiangle centered DFrFT. Our algorithm is designed to be simple and fast such that it can be implemented in hardware. We evaluate our algorithm on a synthetic I/Q-modulated dataset and outperform reference methods in terms of the mean squared error (MSE), signal-to-interference-plus-noise ratio (SINR), error vector magnitude (EVM), true positive rate (TPR), false alarm rate (FAR), and <inline-formula> <tex-math>$F1$ </tex-math></inline-formula>-score.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"4 ","pages":"549-563"},"PeriodicalIF":0.0,"publicationDate":"2026-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147362495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-13DOI: 10.1109/TRS.2026.3664505
Tao Jian;Jia He;Haipeng Wang;Guangfen Wei;Xiaoming Tang
This article investigates the adaptive detection problem of range-spread targets in Gaussian clutter, where the target complex amplitudes, the steering vectors, and the clutter covariance matrix (CCM) are all unknown. Specifically, the steering vectors exhibit a complex exponential structure with uncertain phase components. Following the two-step generalized likelihood ratio test (GLRT) approach, two adaptive detectors are devised: one is designed to handle the scenarios where the phase is completely unknown, while the other is tailored to accommodate the situations where partial information about the phase is available. By exploiting the fundamental properties of trigonometric polynomials, we reformulate the original nonconvex optimization problem about phase into a computationally tractable semidefinite programming (SDP) framework, facilitating efficient convex optimization. Numerical results demonstrate that the two designed detectors maintain constant false alarm rate (CFAR) properties with respect to the unknown CCM. Compared to the existing one-step SDP-based GLRT detector, the proposed detectors demonstrate superior performance at high signal-to-clutter ratios (SCRs), albeit with some performance degradation in low SCR scenarios. However, as the number of training data increases, the performance advantages of both proposed detectors become increasingly pronounced relative to the existing detectors.
{"title":"Adaptive Detection of Range-Spread Targets With Phase Uncertainty via Semidefinite Programming","authors":"Tao Jian;Jia He;Haipeng Wang;Guangfen Wei;Xiaoming Tang","doi":"10.1109/TRS.2026.3664505","DOIUrl":"https://doi.org/10.1109/TRS.2026.3664505","url":null,"abstract":"This article investigates the adaptive detection problem of range-spread targets in Gaussian clutter, where the target complex amplitudes, the steering vectors, and the clutter covariance matrix (CCM) are all unknown. Specifically, the steering vectors exhibit a complex exponential structure with uncertain phase components. Following the two-step generalized likelihood ratio test (GLRT) approach, two adaptive detectors are devised: one is designed to handle the scenarios where the phase is completely unknown, while the other is tailored to accommodate the situations where partial information about the phase is available. By exploiting the fundamental properties of trigonometric polynomials, we reformulate the original nonconvex optimization problem about phase into a computationally tractable semidefinite programming (SDP) framework, facilitating efficient convex optimization. Numerical results demonstrate that the two designed detectors maintain constant false alarm rate (CFAR) properties with respect to the unknown CCM. Compared to the existing one-step SDP-based GLRT detector, the proposed detectors demonstrate superior performance at high signal-to-clutter ratios (SCRs), albeit with some performance degradation in low SCR scenarios. However, as the number of training data increases, the performance advantages of both proposed detectors become increasingly pronounced relative to the existing detectors.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"4 ","pages":"515-524"},"PeriodicalIF":0.0,"publicationDate":"2026-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147299503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-12DOI: 10.1109/TRS.2026.3664255
Lumumba A. Harnett;Brandon Ravenscroft;David G. Felton;Patrick M. McCormick;Jonathan W. Owen;Shannon D. Blunt
The combination of clutter cancellation and adaptive Doppler estimation is examined in the context of random pulse repetition interval (PRI) staggering, which permits a greatly expanded unambiguous Doppler span, albeit at the cost of higher sidelobes. It is shown that estimation of movers otherwise masked by clutter or the sidelobes of other larger movers can be uncovered by this combination, with adaptive estimation being particularly useful at suppressing the attendant increase in sidelobes. Using the reiterative super-resolution (RISR) method as a representative method for adaptive estimation (a variety exists), the efficacy of this combination is demonstrated using both simulated data and open-air measurements. A clairvoyant form of signal-to-interference-plus-noise ratio (SINR) is also used to assess analytically the behavior observed in simulation, particularly the loss tradespace between straddling and super-resolution.
{"title":"Adaptive Doppler Estimation for Random PRI Staggering With Clutter Cancellation","authors":"Lumumba A. Harnett;Brandon Ravenscroft;David G. Felton;Patrick M. McCormick;Jonathan W. Owen;Shannon D. Blunt","doi":"10.1109/TRS.2026.3664255","DOIUrl":"https://doi.org/10.1109/TRS.2026.3664255","url":null,"abstract":"The combination of clutter cancellation and adaptive Doppler estimation is examined in the context of random pulse repetition interval (PRI) staggering, which permits a greatly expanded unambiguous Doppler span, albeit at the cost of higher sidelobes. It is shown that estimation of movers otherwise masked by clutter or the sidelobes of other larger movers can be uncovered by this combination, with adaptive estimation being particularly useful at suppressing the attendant increase in sidelobes. Using the reiterative super-resolution (RISR) method as a representative method for adaptive estimation (a variety exists), the efficacy of this combination is demonstrated using both simulated data and open-air measurements. A clairvoyant form of signal-to-interference-plus-noise ratio (SINR) is also used to assess analytically the behavior observed in simulation, particularly the loss tradespace between straddling and super-resolution.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"4 ","pages":"564-585"},"PeriodicalIF":0.0,"publicationDate":"2026-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147440647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
3-D spatial information, such as position and orientation estimation, is essential for autonomous systems operating in dynamic and unstructured environments. In this context, radar sensors, known for their robustness to environmental conditions such as dust, fog, and varying lighting, offer promising capabilities for spatial awareness. Therefore, this article presents a radar-based approach for 3-D positioning and orientation estimation using fast-chirp frequency-modulated continuous-wave (FC-FMCW) radar in conjunction with uniquely identifiable Doppler tags. They enable simultaneous identification and high-accuracy range estimation of multiple tagged reference points. The range information is extracted in signal processing while suppressing interference from static objects and other tags. Positioning with four tags is demonstrated as a well-investigated application, while orientation estimation—typically less explored in radar systems—is addressed using a two-tag geometry. Experimental results validate the feasibility and accuracy of the approaches, showing potential for scalable deployment in an industrial context. The findings highlight the capability of radar-tag systems to provide accurate and reliable spatial information and extend their applicability.
{"title":"Radar-Based 3-D Spatial Estimation Using Uniquely Identifiable Doppler Tags","authors":"Theresa Antes;Alexander Backes;Thomas Zwick;Benjamin Nuss","doi":"10.1109/TRS.2026.3662782","DOIUrl":"https://doi.org/10.1109/TRS.2026.3662782","url":null,"abstract":"3-D spatial information, such as position and orientation estimation, is essential for autonomous systems operating in dynamic and unstructured environments. In this context, radar sensors, known for their robustness to environmental conditions such as dust, fog, and varying lighting, offer promising capabilities for spatial awareness. Therefore, this article presents a radar-based approach for 3-D positioning and orientation estimation using fast-chirp frequency-modulated continuous-wave (FC-FMCW) radar in conjunction with uniquely identifiable Doppler tags. They enable simultaneous identification and high-accuracy range estimation of multiple tagged reference points. The range information is extracted in signal processing while suppressing interference from static objects and other tags. Positioning with four tags is demonstrated as a well-investigated application, while orientation estimation—typically less explored in radar systems—is addressed using a two-tag geometry. Experimental results validate the feasibility and accuracy of the approaches, showing potential for scalable deployment in an industrial context. The findings highlight the capability of radar-tag systems to provide accurate and reliable spatial information and extend their applicability.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"4 ","pages":"525-534"},"PeriodicalIF":0.0,"publicationDate":"2026-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147299529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-06DOI: 10.1109/TRS.2026.3662063
Yuepeng Wu;Mengyang Shi;Yesheng Gao;Bin Yuan;Xingzhao Liu
Overcoming the angular resolution limitations imposed by antenna apertures remains a critical challenge in radar systems. The nonlinear wavefront modulation technique enables angular resolution beyond the limitations of antenna beamwidths while maintaining the physical aperture size. This article proposes a novel method to enhance angular resolution within a single beamwidth by employing nonlinear wavefront modulation and investigates both the theoretical and experimental aspects of this technology. First, a wavefront modulation signal model is established, and the resolution enhancement factor (REF) is defined to quantify the performance of angular resolution enhancement. Two analytical criteria—the subspace distance criterion and Cramér–Rao bound (CRB) criterion—are proposed to evaluate resolution performance. An $L$ -band verification system is constructed, and experiments are conducted in a microwave anechoic chamber. Results validate the angular resolution enhancement principle and confirm the system’s ability to resolve multiple targets within the single beamwidth in both azimuth and elevation. In the experiment, our method successfully discriminates multiple targets with a minimum azimuth separation of 1.08° and a minimum elevation separation of 5.14°, despite the broad beamwidths of the receiving antenna (67° in azimuth and 98° in elevation). Finally, a comprehensive analysis assesses the system under varying signal-to-noise ratios (SNRs), numbers of wavefront modulation states, and calibration errors. This study provides a rigorous foundation for the principles and engineering implementation of nonlinear wavefront modulation, offering significant utility for future radar system design.
{"title":"Enhancing Radar Angular Resolution Within Single Beamwidth via Nonlinear Wavefront Modulation: A Theoretical and Experimental Investigation","authors":"Yuepeng Wu;Mengyang Shi;Yesheng Gao;Bin Yuan;Xingzhao Liu","doi":"10.1109/TRS.2026.3662063","DOIUrl":"https://doi.org/10.1109/TRS.2026.3662063","url":null,"abstract":"Overcoming the angular resolution limitations imposed by antenna apertures remains a critical challenge in radar systems. The nonlinear wavefront modulation technique enables angular resolution beyond the limitations of antenna beamwidths while maintaining the physical aperture size. This article proposes a novel method to enhance angular resolution within a single beamwidth by employing nonlinear wavefront modulation and investigates both the theoretical and experimental aspects of this technology. First, a wavefront modulation signal model is established, and the resolution enhancement factor (REF) is defined to quantify the performance of angular resolution enhancement. Two analytical criteria—the subspace distance criterion and Cramér–Rao bound (CRB) criterion—are proposed to evaluate resolution performance. An <inline-formula> <tex-math>$L$ </tex-math></inline-formula>-band verification system is constructed, and experiments are conducted in a microwave anechoic chamber. Results validate the angular resolution enhancement principle and confirm the system’s ability to resolve multiple targets within the single beamwidth in both azimuth and elevation. In the experiment, our method successfully discriminates multiple targets with a minimum azimuth separation of 1.08° and a minimum elevation separation of 5.14°, despite the broad beamwidths of the receiving antenna (67° in azimuth and 98° in elevation). Finally, a comprehensive analysis assesses the system under varying signal-to-noise ratios (SNRs), numbers of wavefront modulation states, and calibration errors. This study provides a rigorous foundation for the principles and engineering implementation of nonlinear wavefront modulation, offering significant utility for future radar system design.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"4 ","pages":"495-514"},"PeriodicalIF":0.0,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-06DOI: 10.1109/TRS.2026.3662295
Neha Singh;Amitabha Bhattacharya
The impedance discontinuity at the air–ground interface leads to strong reflections, which reduce the energy coupled to the subsurface and, hence, limit the penetration depth of the radar signal. Metasurfaces have shown significant potential in enhancing the transmission of ground-penetrating radar (GPR) signals into the subsurface by enabling a gradual impedance transition from air to the ground. This article presents an electrically thin bilayer metasurface with a passive substrate, designed and optimized for effective impedance matching with enhanced transmission and reduced reflection. The proposed structure achieves a transmission bandwidth of 70.83% over the frequency range of 0.62–1.3 GHz, while satisfying the antireflection criterion $Rleq 0.1$ for varying ground characteristics. It is designed to operate at relatively lower frequencies, which allows deeper subsurface detection compared to existing solutions. Moreover, its broadband feature ensures stable performance across a wide frequency range, enabling reliable detection under varying soil conditions. Experimental investigations were conducted to validate the simulation outcomes, focusing on pipe detection in subsurface environments. The results confirm the practical effectiveness and robustness of the proposed metasurface in realistic scenarios.
地空界面处的阻抗不连续导致强反射，从而减少了与地下耦合的能量，从而限制了雷达信号的穿透深度。超表面通过实现从空气到地面的逐渐阻抗转换，在增强探地雷达（GPR）信号到地下的传输方面显示出巨大的潜力。本文提出了一种具有无源衬底的电薄双层超表面，设计和优化了有效的阻抗匹配，增强了传输和减少了反射。该结构的传输带宽为70.83% over the frequency range of 0.62–1.3 GHz, while satisfying the antireflection criterion $Rleq 0.1$ for varying ground characteristics. It is designed to operate at relatively lower frequencies, which allows deeper subsurface detection compared to existing solutions. Moreover, its broadband feature ensures stable performance across a wide frequency range, enabling reliable detection under varying soil conditions. Experimental investigations were conducted to validate the simulation outcomes, focusing on pipe detection in subsurface environments. The results confirm the practical effectiveness and robustness of the proposed metasurface in realistic scenarios.
{"title":"Design and Investigation of a Metasurface-Enabled Broadband Impedance Matching for Efficient GPR Signal Transmission","authors":"Neha Singh;Amitabha Bhattacharya","doi":"10.1109/TRS.2026.3662295","DOIUrl":"https://doi.org/10.1109/TRS.2026.3662295","url":null,"abstract":"The impedance discontinuity at the air–ground interface leads to strong reflections, which reduce the energy coupled to the subsurface and, hence, limit the penetration depth of the radar signal. Metasurfaces have shown significant potential in enhancing the transmission of ground-penetrating radar (GPR) signals into the subsurface by enabling a gradual impedance transition from air to the ground. This article presents an electrically thin bilayer metasurface with a passive substrate, designed and optimized for effective impedance matching with enhanced transmission and reduced reflection. The proposed structure achieves a transmission bandwidth of 70.83% over the frequency range of 0.62–1.3 GHz, while satisfying the antireflection criterion <inline-formula> <tex-math>$Rleq 0.1$ </tex-math></inline-formula> for varying ground characteristics. It is designed to operate at relatively lower frequencies, which allows deeper subsurface detection compared to existing solutions. Moreover, its broadband feature ensures stable performance across a wide frequency range, enabling reliable detection under varying soil conditions. Experimental investigations were conducted to validate the simulation outcomes, focusing on pipe detection in subsurface environments. The results confirm the practical effectiveness and robustness of the proposed metasurface in realistic scenarios.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"4 ","pages":"486-494"},"PeriodicalIF":0.0,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11373599","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146223622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-26DOI: 10.1109/TRS.2026.3657792
Jiahao Cui;Wang Guo;Qi Wang;Keyi Zhang;Lingquan Meng;Haifeng Li
The presence of adversarial examples can cause synthetic aperture radar (SAR) image classification systems to produce incorrect predictions, severely compromising their accuracy and robustness. However, existing adversarial example generation methods for SAR images often suffer from limited physical interpretability, low perturbation energy utilization, and insufficient perturbation stealthiness. To address the above issues, this article proposes SAR-PMAE, a phase-modulation-guided adversarial example generation method for SAR images. In particular, to tackle the lack of physical interpretability, a phase-modulation strategy based on the point-target scattering model is employed, coupling adversarial perturbations with the EM scattering mechanism to enhance their physical interpretability; to improve perturbation energy utilization, a local focusing strategy is adopted, in which foreground targets are precisely segmented and centered via a watershed algorithm combined with morphological operations, concentrating perturbations in strong response regions and avoiding redundant energy dispersion into background clutter; and to enhance perturbation stealthiness, constraints are applied separately to the phase in the complex coherent domain, thereby maximally preserving SAR speckle statistics and improving perturbation concealment. Experimental results show that the proposed method achieves an average untargeted attack success rate (ASR) of 55.53% and a targeted ASR of 20.92% across ten classifiers based on convolutional neural network (CNN) and Transformer architectures, while exhibiting strong attack transferability. The complete implementation is publicly available at https://github.com/muzhengcui/SAR-PMAE
{"title":"SAR-PMAE: Phase-Modulation-Guided Adversarial Example Generation for SAR Images","authors":"Jiahao Cui;Wang Guo;Qi Wang;Keyi Zhang;Lingquan Meng;Haifeng Li","doi":"10.1109/TRS.2026.3657792","DOIUrl":"https://doi.org/10.1109/TRS.2026.3657792","url":null,"abstract":"The presence of adversarial examples can cause synthetic aperture radar (SAR) image classification systems to produce incorrect predictions, severely compromising their accuracy and robustness. However, existing adversarial example generation methods for SAR images often suffer from limited physical interpretability, low perturbation energy utilization, and insufficient perturbation stealthiness. To address the above issues, this article proposes SAR-PMAE, a phase-modulation-guided adversarial example generation method for SAR images. In particular, to tackle the lack of physical interpretability, a phase-modulation strategy based on the point-target scattering model is employed, coupling adversarial perturbations with the EM scattering mechanism to enhance their physical interpretability; to improve perturbation energy utilization, a local focusing strategy is adopted, in which foreground targets are precisely segmented and centered via a watershed algorithm combined with morphological operations, concentrating perturbations in strong response regions and avoiding redundant energy dispersion into background clutter; and to enhance perturbation stealthiness, constraints are applied separately to the phase in the complex coherent domain, thereby maximally preserving SAR speckle statistics and improving perturbation concealment. Experimental results show that the proposed method achieves an average untargeted attack success rate (ASR) of 55.53% and a targeted ASR of 20.92% across ten classifiers based on convolutional neural network (CNN) and Transformer architectures, while exhibiting strong attack transferability. The complete implementation is publicly available at <uri>https://github.com/muzhengcui/SAR-PMAE</uri>","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"4 ","pages":"407-429"},"PeriodicalIF":0.0,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-26DOI: 10.1109/TRS.2026.3657920
Bangjie Zhang;Marina S. Gashinova;Marco Martorella
Sub-terahertz (sub-THz) radar enables high-resolution and highly detailed imaging of space objects, offering substantial advantages for space domain awareness (SDA). Accurate estimation of spin motion and 3-D geometry of noncooperative space targets is essential for SDA tasks such as target characterization, autonomous rendezvous, and proximity operation (RPO), and debris removal. Interferometric ISAR (InISAR), which generates 3-D images in the form of point clouds, can also resolve the effective rotation vector—defined as the component of the total rotation vector perpendicular to the line of sight (LOS). This component is critical for 2-D image scaling and for enhancing understanding of the imaging projection plane (IPP). However, the component along the LOS remains unknown, which limits the ability to fully exploit multiperspective ISAR imaging to characterize targets. In this article, a novel spin estimation framework is proposed based on multiperspective InISAR, which leverages viewing angle diversity during on-orbit observation to resolve the total rotation vector of space targets. The proposed method performs InISAR imaging and the estimation of the effective rotation vector for each perspective, followed by the combination of effective rotation vectors to determine the total rotation vector as a unified least-squares solution. The framework requires no prior 3-D model and achieves robust spin estimation. Both simulation experiments using sub-THz radar parameters and laboratory validation using W-band radar are carried out to verify the effectiveness of the proposed method, demonstrating its potential for future SDA and on-orbit servicing applications.
{"title":"Spin Estimation and 3-D Geometry Reconstruction Using Multiperspective Space-Borne Sub-THz Interferometric Inverse Synthetic Aperture Radar","authors":"Bangjie Zhang;Marina S. Gashinova;Marco Martorella","doi":"10.1109/TRS.2026.3657920","DOIUrl":"https://doi.org/10.1109/TRS.2026.3657920","url":null,"abstract":"Sub-terahertz (sub-THz) radar enables high-resolution and highly detailed imaging of space objects, offering substantial advantages for space domain awareness (SDA). Accurate estimation of spin motion and 3-D geometry of noncooperative space targets is essential for SDA tasks such as target characterization, autonomous rendezvous, and proximity operation (RPO), and debris removal. Interferometric ISAR (InISAR), which generates 3-D images in the form of point clouds, can also resolve the effective rotation vector—defined as the component of the total rotation vector perpendicular to the line of sight (LOS). This component is critical for 2-D image scaling and for enhancing understanding of the imaging projection plane (IPP). However, the component along the LOS remains unknown, which limits the ability to fully exploit multiperspective ISAR imaging to characterize targets. In this article, a novel spin estimation framework is proposed based on multiperspective InISAR, which leverages viewing angle diversity during on-orbit observation to resolve the total rotation vector of space targets. The proposed method performs InISAR imaging and the estimation of the effective rotation vector for each perspective, followed by the combination of effective rotation vectors to determine the total rotation vector as a unified least-squares solution. The framework requires no prior 3-D model and achieves robust spin estimation. Both simulation experiments using sub-THz radar parameters and laboratory validation using W-band radar are carried out to verify the effectiveness of the proposed method, demonstrating its potential for future SDA and on-orbit servicing applications.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"4 ","pages":"473-485"},"PeriodicalIF":0.0,"publicationDate":"2026-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1109/TRS.2026.3657154
Marcin Wachowiak;André Bourdoux;Sofie Pollin
This article investigates the range ambiguity function of near-field (NF) systems where bandwidth and NF beamfocusing jointly determine the resolution. First, the general matched filter ambiguity function is derived and the NF array factors of different antenna array geometries are introduced. Next, the NF ambiguity function is approximated as a product of the range-dependent NF array factor and the ambiguity function due to the utilized waveform and bandwidth. An approximation criterion based on the aperture–bandwidth product is formulated, and its accuracy is examined. Finally, the improvements to the ambiguity function offered by the NF beamfocusing, as compared to the far-field case, are presented. The performance gains are evaluated in terms of resolution improvement offered by beamfocusing, peak-to-sidelobe, and integrated-sidelobe-level improvement for a few popular array geometries. The gains offered by the NF regime are shown to be range-dependent and substantial only in close proximity to the array.
{"title":"Approximation of the Range Ambiguity Function in Near-Field Sensing Systems","authors":"Marcin Wachowiak;André Bourdoux;Sofie Pollin","doi":"10.1109/TRS.2026.3657154","DOIUrl":"https://doi.org/10.1109/TRS.2026.3657154","url":null,"abstract":"This article investigates the range ambiguity function of near-field (NF) systems where bandwidth and NF beamfocusing jointly determine the resolution. First, the general matched filter ambiguity function is derived and the NF array factors of different antenna array geometries are introduced. Next, the NF ambiguity function is approximated as a product of the range-dependent NF array factor and the ambiguity function due to the utilized waveform and bandwidth. An approximation criterion based on the aperture–bandwidth product is formulated, and its accuracy is examined. Finally, the improvements to the ambiguity function offered by the NF beamfocusing, as compared to the far-field case, are presented. The performance gains are evaluated in terms of resolution improvement offered by beamfocusing, peak-to-sidelobe, and integrated-sidelobe-level improvement for a few popular array geometries. The gains offered by the NF regime are shown to be range-dependent and substantial only in close proximity to the array.","PeriodicalId":100645,"journal":{"name":"IEEE Transactions on Radar Systems","volume":"4 ","pages":"430-442"},"PeriodicalIF":0.0,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：