Pub Date : 2025-11-25DOI: 10.1109/TMTT.2025.3633498
Nils C. Albrecht;Philip Riege;Bartosz Tegowski;Dominik Langer;Alexander Koelpin
This work presents a novel heterodyne radar transceiver architecture based on two separate, incoherent radio frequency (RF) sources. Unlike conventional continuous-wave (CW) radar systems, the proposed approach measures the square of the channel transfer function, resulting in doubled phase sensitivity. This enhancement arises from a differential evaluation of the downconverted intermediate-frequency (IF) signals, which enables precise tracking of phase changes without requiring phase-locked local oscillators. The associated signal-processing and calibration methods are derived, allowing for accurate reconstruction of the dynamic target response, even in the presence of static reflections and without needing knowledge of the calibration target’s absolute position. Additionally, the effect of oscillator phase noise is evaluated. Experimental validation using high-precision linear motion confirms that the system accurately tracks target displacement and delivers results comparable to those obtained with a commercial vector network analyzer (VNA). By eliminating the need for RF phase synchronization between transceivers, the architecture significantly reduces hardware complexity and is well-suited for integration and miniaturization. Although demonstrated with a single transceiver pair, the method scales naturally to multichannel configurations, enabling low-complexity multiple-input–multiple-output (MIMO) radar systems with enhanced sensitivity.
{"title":"A Novel Differential Incoherent Heterodyne Continuous-Wave Radar Receiver Architecture With Increased Phase Sensitivity","authors":"Nils C. Albrecht;Philip Riege;Bartosz Tegowski;Dominik Langer;Alexander Koelpin","doi":"10.1109/TMTT.2025.3633498","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3633498","url":null,"abstract":"This work presents a novel heterodyne radar transceiver architecture based on two separate, incoherent radio frequency (RF) sources. Unlike conventional continuous-wave (CW) radar systems, the proposed approach measures the square of the channel transfer function, resulting in doubled phase sensitivity. This enhancement arises from a differential evaluation of the downconverted intermediate-frequency (IF) signals, which enables precise tracking of phase changes without requiring phase-locked local oscillators. The associated signal-processing and calibration methods are derived, allowing for accurate reconstruction of the dynamic target response, even in the presence of static reflections and without needing knowledge of the calibration target’s absolute position. Additionally, the effect of oscillator phase noise is evaluated. Experimental validation using high-precision linear motion confirms that the system accurately tracks target displacement and delivers results comparable to those obtained with a commercial vector network analyzer (VNA). By eliminating the need for RF phase synchronization between transceivers, the architecture significantly reduces hardware complexity and is well-suited for integration and miniaturization. Although demonstrated with a single transceiver pair, the method scales naturally to multichannel configurations, enabling low-complexity multiple-input–multiple-output (MIMO) radar systems with enhanced sensitivity.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 2","pages":"1903-1916"},"PeriodicalIF":4.5,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11268534","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146154401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article presents a photonic-assisted ultrawideband receiver architecture based on dual-parallel optical subsampling using two mode-locked lasers (MLLs) with distinct repetition rates. The proposed architecture resolves frequency ambiguity and suppresses aliasing without requiring a third optical link, thereby significantly reducing system complexity, size, weight, and power (SWaP). Carrier-suppressed single-sideband (CS-SSB) modulation is implemented using a dual-parallel Mach-Zehnder modulator (DP-MZM), while balanced coherent detection enhances noise suppression. Compared to conventional double-sideband (DSB) schemes, the system achieves a twofold increase in instantaneous processing bandwidth. Simulation and experiments demonstrate frequency measurement errors below 3 MHz across the 2–18-GHz band, with a measured spurious-free dynamic range (SFDR) of 107 dB$cdot $ Hz${}^{{2}/{3}}$ . Fabricated in a 130-nm silicon photonics process, the receiver provides a compact, low-SWaP, and stable solution for wideband electronic reconnaissance.
本文提出了一种基于双平行光学子采样的光子辅助超宽带接收器结构，该结构使用两个不同重复率的锁模激光器。所提出的架构解决了频率模糊和抑制混叠，而不需要第三条光链路，从而显着降低了系统的复杂性，尺寸，重量和功耗（SWaP）。载波抑制单边带（CS-SSB）调制使用双并行马赫-曾德尔调制器（DP-MZM）实现，而平衡相干检测增强了噪声抑制。与传统的双边带（DSB）方案相比，该系统实现了瞬时处理带宽的两倍增长。仿真和实验表明，在2 - 18 ghz频段内，频率测量误差小于3 MHz，测量的无杂散动态范围（SFDR）为107 dB $cdot $ Hz ${}^{{2}/{3}}$。该接收器采用130纳米硅光子学工艺制造，为宽带电子侦察提供了紧凑、低swap和稳定的解决方案。
{"title":"Design and Test of a Photonic-Assisted Ultrawideband Receiver Based on Optical Subsampling","authors":"Lei Huang;Qihui Zhou;Liyuan Zhao;Xin Zhang;Weicheng Kong;Hongmeng Zhao;Zhuohang Zhang;Jianfeng Zhang;Wuxin Xiao;Xin Zheng;Jianghua Zhang;Tian Jiang","doi":"10.1109/TMTT.2025.3634745","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3634745","url":null,"abstract":"This article presents a photonic-assisted ultrawideband receiver architecture based on dual-parallel optical subsampling using two mode-locked lasers (MLLs) with distinct repetition rates. The proposed architecture resolves frequency ambiguity and suppresses aliasing without requiring a third optical link, thereby significantly reducing system complexity, size, weight, and power (SWaP). Carrier-suppressed single-sideband (CS-SSB) modulation is implemented using a dual-parallel Mach-Zehnder modulator (DP-MZM), while balanced coherent detection enhances noise suppression. Compared to conventional double-sideband (DSB) schemes, the system achieves a twofold increase in instantaneous processing bandwidth. Simulation and experiments demonstrate frequency measurement errors below 3 MHz across the 2–18-GHz band, with a measured spurious-free dynamic range (SFDR) of 107 dB<inline-formula> <tex-math>$cdot $ </tex-math></inline-formula>Hz<inline-formula> <tex-math>${}^{{2}/{3}}$ </tex-math></inline-formula>. Fabricated in a 130-nm silicon photonics process, the receiver provides a compact, low-SWaP, and stable solution for wideband electronic reconnaissance.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 2","pages":"1841-1851"},"PeriodicalIF":4.5,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146154437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The increasing demand for high-speed wireless communication necessitates front ends that combine high spectral efficiency with multiband operation. Integrating in-band full-duplex (IBFD) and carrier aggregation (CA) technologies becomes crucial but is hindered by the complexity and cost of duplicating transmit and receive chains across bands. In this work, we present a single-chain six-port transceiver architecture enabling dual-in-band full-duplex (DIBFD) operation to eliminate replicated chains. By leveraging the common-mode (CM) and differential-mode (DM) orthogonality between transmitted and received signals in intermediate-frequency (IF) spectra, the design dramatically simplifies hardware and reduces local oscillator requirements. Calibration algorithms, combined with digital self-interference (SI) cancellation, are deployed to optimize performance. Compared to traditional solutions, this architecture achieves wide bandwidth, strong SI suppression, and dual-band operation with lower complexity and cost. This approach paves the way for more efficient multiband, full-duplex wireless systems critical for meeting future data-intensive communication demands.
{"title":"Single-Chain Six-Port Transceiver Front End With Dual-in-Band Full-Duplex Capability","authors":"Ronghao Chen;Mengting Tu;Guangyou Xu;Wai-Wa Choi;Ke Wu;Pedro Cheong","doi":"10.1109/TMTT.2025.3633423","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3633423","url":null,"abstract":"The increasing demand for high-speed wireless communication necessitates front ends that combine high spectral efficiency with multiband operation. Integrating in-band full-duplex (IBFD) and carrier aggregation (CA) technologies becomes crucial but is hindered by the complexity and cost of duplicating transmit and receive chains across bands. In this work, we present a single-chain six-port transceiver architecture enabling dual-in-band full-duplex (DIBFD) operation to eliminate replicated chains. By leveraging the common-mode (CM) and differential-mode (DM) orthogonality between transmitted and received signals in intermediate-frequency (IF) spectra, the design dramatically simplifies hardware and reduces local oscillator requirements. Calibration algorithms, combined with digital self-interference (SI) cancellation, are deployed to optimize performance. Compared to traditional solutions, this architecture achieves wide bandwidth, strong SI suppression, and dual-band operation with lower complexity and cost. This approach paves the way for more efficient multiband, full-duplex wireless systems critical for meeting future data-intensive communication demands.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 2","pages":"2065-2075"},"PeriodicalIF":4.5,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146154471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-24DOI: 10.1109/TMTT.2025.3629611
Li Wen;Jie Cao;Yijing Guo;Zi Zeng;Qing Cao;Kang Chen;Changzhan Gu
In long-term clinical monitoring, random body movements or clutter from nearby objects introduce time-varying dc offsets in the microwave biomedical radar system. The conventional dc offset calibration methods based on least-square (LS) circle fitting are ineffective for weak cardiopulmonary motions with low signal-to-noise ratio (SNR). To address the challenge, this article proposes a novel dc offset calibration technique that enables joint circle fitting of multiple segmented radar signal traces under approximately uniform maximum amplitude modulation. The proposed technique preserves amplitude and phase relationships through geometric space transformation, adaptively processes noise via a dual-mode fitting mechanism for dc offset calibration, and enhances robustness by integrating Huber loss residual computation with threshold-based optimization and averaged positioning. Validated across simulations and experiments in both lab and clinical environments, the proposed technique reduces demodulation errors by 10–$1000times $ (for a $0.004lambda $ displacement) compared to conventional LS single-segment circle fitting under comparable SNR conditions. It helps to tackle the imperfections of dc offsets in the microwave biomedical radar system, thus allowing microwave cardiogram-electrocardiogram feature alignment in arrhythmia patients and advancing radar-based long-term arrhythmia monitoring. The demonstrated mechanical-electrical correlation supports early risk prediction.
{"title":"Robust and Adaptive DC Offset Calibration in Microwave Sensing Systems for Long-Term Microwave Cardiogram Detection","authors":"Li Wen;Jie Cao;Yijing Guo;Zi Zeng;Qing Cao;Kang Chen;Changzhan Gu","doi":"10.1109/TMTT.2025.3629611","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3629611","url":null,"abstract":"In long-term clinical monitoring, random body movements or clutter from nearby objects introduce time-varying dc offsets in the microwave biomedical radar system. The conventional dc offset calibration methods based on least-square (LS) circle fitting are ineffective for weak cardiopulmonary motions with low signal-to-noise ratio (SNR). To address the challenge, this article proposes a novel dc offset calibration technique that enables joint circle fitting of multiple segmented radar signal traces under approximately uniform maximum amplitude modulation. The proposed technique preserves amplitude and phase relationships through geometric space transformation, adaptively processes noise via a dual-mode fitting mechanism for dc offset calibration, and enhances robustness by integrating Huber loss residual computation with threshold-based optimization and averaged positioning. Validated across simulations and experiments in both lab and clinical environments, the proposed technique reduces demodulation errors by 10–<inline-formula> <tex-math>$1000times $ </tex-math></inline-formula> (for a <inline-formula> <tex-math>$0.004lambda $ </tex-math></inline-formula> displacement) compared to conventional LS single-segment circle fitting under comparable SNR conditions. It helps to tackle the imperfections of dc offsets in the microwave biomedical radar system, thus allowing microwave cardiogram-electrocardiogram feature alignment in arrhythmia patients and advancing radar-based long-term arrhythmia monitoring. The demonstrated mechanical-electrical correlation supports early risk prediction.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 2","pages":"1756-1769"},"PeriodicalIF":4.5,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146154475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article presents a V-band highly integrated frequency-modulated continuous-wave (FMCW) radar transceiver fabricated in 65-nm CMOS for indoor sensing applications. The chip features a four-channel receiver (RX) and a three-channel transmitter (TX), enabling multi-input multi-output (MIMO) capabilities. A 15-GHz frequency synthesizer with injection-locking frequency multipliers is employed to generate sawtooth FMCW signals. To achieve a wide chirp bandwidth (BW) with high phase linearity, reconfigurable capacitor banks are employed in the frequency multipliers and drivers to overcome the limitation of the locking range and nonlinear phase response. Furthermore, a fast-settling circuit is designed to reduce the settling time at the end of a sawtooth sweep. The TX delivers a maximum output power of 14.3 dBm, and the RX achieves a minimum noise figure (NF) of 7.8 dB at 5-MHz intermediate frequency (IF) and an adjustable gain of 18–82 dB including 8/56-dB RF/IF gain range. The FMCW signal generator achieves an 8-GHz chirp BW with 80-MHz/$mu $ s chirp rate, with the measured phase noise −95.3 dBc/Hz at 1-MHz offset from a 60-GHz carrier. The radar transceiver occupies $4.8times 2.8$ mm2 area and consumes 674 mW. Using a substrate-integrated waveguide (SIW) slot antenna array with a 14-dBi gain, the radar system achieves a measured range resolution of 3.5 cm and an angular resolution of 17°, and demonstrates indoor sensing capabilities along with a digital signal processing (DSP) platform.
{"title":"A 56–66-GHz FMCW Radar Transceiver With Wide Chirp Bandwidth for Indoor Sensing Applications","authors":"Jiangbo Chen;Shengjie Wang;Quanyong Li;Hui Nie;Wenyan Zhao;Jingwen Xu;Nayu Li;Gaopeng Chen;Xiaokang Qi;Na Yan;Chunyi Song;Qun Jane Gu;Zhiwei Xu","doi":"10.1109/TMTT.2025.3633165","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3633165","url":null,"abstract":"This article presents a V-band highly integrated frequency-modulated continuous-wave (FMCW) radar transceiver fabricated in 65-nm CMOS for indoor sensing applications. The chip features a four-channel receiver (RX) and a three-channel transmitter (TX), enabling multi-input multi-output (MIMO) capabilities. A 15-GHz frequency synthesizer with injection-locking frequency multipliers is employed to generate sawtooth FMCW signals. To achieve a wide chirp bandwidth (BW) with high phase linearity, reconfigurable capacitor banks are employed in the frequency multipliers and drivers to overcome the limitation of the locking range and nonlinear phase response. Furthermore, a fast-settling circuit is designed to reduce the settling time at the end of a sawtooth sweep. The TX delivers a maximum output power of 14.3 dBm, and the RX achieves a minimum noise figure (NF) of 7.8 dB at 5-MHz intermediate frequency (IF) and an adjustable gain of 18–82 dB including 8/56-dB RF/IF gain range. The FMCW signal generator achieves an 8-GHz chirp BW with 80-MHz/<inline-formula> <tex-math>$mu $ </tex-math></inline-formula>s chirp rate, with the measured phase noise −95.3 dBc/Hz at 1-MHz offset from a 60-GHz carrier. The radar transceiver occupies <inline-formula> <tex-math>$4.8times 2.8$ </tex-math></inline-formula> mm<sup>2</sup> area and consumes 674 mW. Using a substrate-integrated waveguide (SIW) slot antenna array with a 14-dBi gain, the radar system achieves a measured range resolution of 3.5 cm and an angular resolution of 17°, and demonstrates indoor sensing capabilities along with a digital signal processing (DSP) platform.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 2","pages":"1930-1947"},"PeriodicalIF":4.5,"publicationDate":"2025-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146154455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-19DOI: 10.1109/TMTT.2025.3632624
Yasser Bigdeli;Pascal Burasa;Ke Wu
This article introduces a transmitter (TX) array topology that employs QPSK direct-RF TX units for realizing scalable large-array wireless communication and multifunction systems. By leveraging spatial power combination, the TX units are set to synthesize an extended M-QAM constellation, enabling flexible and high-order modulation. The QPSK modulation, when transmitted in an array, bolsters physical layer security by confining the constellation retrieval to the intended radiation angle, exhibiting high selectivity. Additionally, its low-dynamic-range (DR) waveform supports high-power output and improves the efficiency of power amplifiers (PAs) compared to higher-order constellations, thus significantly enhancing the array’s overall power–performance ratio. A comprehensive analysis is conducted on key performance factors, including location-dependent antenna gain variations, beamforming effectiveness, and phase front flatness. To validate the proposed technique, a $2times 4$ array proof-of-concept (PoC) implementation is presented. Measurement results demonstrate robust performance across modulation orders ranging from 16-QAM to 256-QAM, aligning with theoretical predictions. This topology effectively integrates spatial constellation formation with the requirements of large-array systems, offering superior power efficiency. Its scalable building blocks, reconfigurability, and inherent secure communication capabilities make it a strong candidate for next-generation high-data-rate large-array TX systems.
{"title":"A Scalable Large-Array M-QAM Direct-RF Transmitter Topology With Integrated Physical Layer Security—A Proof of Concept","authors":"Yasser Bigdeli;Pascal Burasa;Ke Wu","doi":"10.1109/TMTT.2025.3632624","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3632624","url":null,"abstract":"This article introduces a transmitter (TX) array topology that employs QPSK direct-RF TX units for realizing scalable large-array wireless communication and multifunction systems. By leveraging spatial power combination, the TX units are set to synthesize an extended M-QAM constellation, enabling flexible and high-order modulation. The QPSK modulation, when transmitted in an array, bolsters physical layer security by confining the constellation retrieval to the intended radiation angle, exhibiting high selectivity. Additionally, its low-dynamic-range (DR) waveform supports high-power output and improves the efficiency of power amplifiers (PAs) compared to higher-order constellations, thus significantly enhancing the array’s overall power–performance ratio. A comprehensive analysis is conducted on key performance factors, including location-dependent antenna gain variations, beamforming effectiveness, and phase front flatness. To validate the proposed technique, a <inline-formula> <tex-math>$2times 4$ </tex-math></inline-formula> array proof-of-concept (PoC) implementation is presented. Measurement results demonstrate robust performance across modulation orders ranging from 16-QAM to 256-QAM, aligning with theoretical predictions. This topology effectively integrates spatial constellation formation with the requirements of large-array systems, offering superior power efficiency. Its scalable building blocks, reconfigurability, and inherent secure communication capabilities make it a strong candidate for next-generation high-data-rate large-array TX systems.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 2","pages":"2035-2048"},"PeriodicalIF":4.5,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146154411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-17DOI: 10.1109/TMTT.2025.3628263
Wenrui Zheng;Yunlai Yang;Tian-Xi Feng;Ning Liu;Hui Li
Designing a compact and wideband orbital angular momentum (OAM) generator with high purity is challenging. To address this challenge, a systematic atom-to-array methodology is developed. First, the miniaturization potential of a dual-layered pixel-based meta-atom with a central metallic via is evaluated using an efficient multiport network model. Based on the identified miniaturization limit, a set of meta-atoms with 4-bit full-angle reflection phase control at a center frequency of 10.5 GHz is synthesized. As a result, a compact periodicity of $mathbf {0.14}boldsymbol {lambda }_{mathbf {0}}$ is achieved while enforcing near-uniform dispersion across the 16 states over a wide band and enabling finer azimuthal phase sampling. At the array level, the effect of the focal-to-diameter ratio ($boldsymbol {F}/boldsymbol {D}$ ) on the achievable bandwidth is investigated through numerical analysis. Subsequently, the pixel-based meta-atoms are applied to simulate OAM generation for modes $boldsymbol {l}=mathbf {+1},mathbf {+2},mathbf {+3}$ under $boldsymbol {F}/boldsymbol {D}=mathbf {0.85}$ . With this miniaturization, a $mathbf {40}times mathbf {40}$ array reaches only $mathbf {5.6}boldsymbol {lambda }_{mathbf {0}}$ in aperture while still providing clear helical wavefronts, which significantly improves mode purity, particularly for higher-order modes. Stable wideband OAM generation with mode purity greater than 0.8 is achieved across a fractional bandwidth exceeding 45% for $boldsymbol {l}=mathbf {+1}$ to $mathbf {+3}$ , highlighting the effectiveness of the proposed concept and methodology. A prototype of the miniaturized $boldsymbol {l}=mathbf {+2}$ OAM generator was fabricated and measured, and the measured results showed good agreement with simulations.
{"title":"Wideband High-Purity OAM Generation Using a Compact Reflective Metasurface With Miniaturized Pixel Meta-Atoms","authors":"Wenrui Zheng;Yunlai Yang;Tian-Xi Feng;Ning Liu;Hui Li","doi":"10.1109/TMTT.2025.3628263","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3628263","url":null,"abstract":"Designing a compact and wideband orbital angular momentum (OAM) generator with high purity is challenging. To address this challenge, a systematic atom-to-array methodology is developed. First, the miniaturization potential of a dual-layered pixel-based meta-atom with a central metallic via is evaluated using an efficient multiport network model. Based on the identified miniaturization limit, a set of meta-atoms with 4-bit full-angle reflection phase control at a center frequency of <bold>10.5</b> GHz is synthesized. As a result, a compact periodicity of <inline-formula> <tex-math>$mathbf {0.14}boldsymbol {lambda }_{mathbf {0}}$ </tex-math></inline-formula> is achieved while enforcing near-uniform dispersion across the 16 states over a wide band and enabling finer azimuthal phase sampling. At the array level, the effect of the focal-to-diameter ratio (<inline-formula> <tex-math>$boldsymbol {F}/boldsymbol {D}$ </tex-math></inline-formula>) on the achievable bandwidth is investigated through numerical analysis. Subsequently, the pixel-based meta-atoms are applied to simulate OAM generation for modes <inline-formula> <tex-math>$boldsymbol {l}=mathbf {+1},mathbf {+2},mathbf {+3}$ </tex-math></inline-formula> under <inline-formula> <tex-math>$boldsymbol {F}/boldsymbol {D}=mathbf {0.85}$ </tex-math></inline-formula>. With this miniaturization, a <inline-formula> <tex-math>$mathbf {40}times mathbf {40}$ </tex-math></inline-formula> array reaches only <inline-formula> <tex-math>$mathbf {5.6}boldsymbol {lambda }_{mathbf {0}}$ </tex-math></inline-formula> in aperture while still providing clear helical wavefronts, which significantly improves mode purity, particularly for higher-order modes. Stable wideband OAM generation with mode purity greater than <bold>0.8</b> is achieved across a fractional bandwidth exceeding <bold>45%</b> for <inline-formula> <tex-math>$boldsymbol {l}=mathbf {+1}$ </tex-math></inline-formula> to <inline-formula> <tex-math>$mathbf {+3}$ </tex-math></inline-formula>, highlighting the effectiveness of the proposed concept and methodology. A prototype of the miniaturized <inline-formula> <tex-math>$boldsymbol {l}=mathbf {+2}$ </tex-math></inline-formula> OAM generator was fabricated and measured, and the measured results showed good agreement with simulations.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 2","pages":"2007-2022"},"PeriodicalIF":4.5,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146154433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-17DOI: 10.1109/TMTT.2025.3629103
Xinhai Zou;Xin Wang;Lingjie Zhang;Chao Jing;Yali Zhang;Zhiyao Zhang;Shang Jian Zhang;Yong Liu
A high-resolution and multiple-tone microwave frequency measurement (MFM) method is proposed based on predefinable optical frequency combs (OFCs) using a dual-polarization dual-drive Mach–Zehnder modulator (Dpol-DDMZM). Two OFCs with predefinable spectrum shape are generated by electro-optic modulation (EOM) and mixed with the microwave signal under test (SUT) through photonic mixing with a single Dpol-DDMZM simultaneously, in which two minimum frequency components are generated mapping from SUT and used for SUT frequency recovery, respectively. The relative position between SUT and comb teeth can be determined with the power difference of the above two minimum frequency tones. In the proposed method, wideband and high-resolution are simultaneously guaranteed due to the combination of wideband photonic-assisted microwave photonic mixing and hyperfine electrical analysis. Moreover, it also enables multiple-tone measurement relying on the unique frequency-to-frequency mapping (FTFM) relationship between the SUT and the mixing frequency components. In the proof of concept, MFM is experimentally demonstrated up to a 40-GHz frequency range with a 10-kHz measurement error, and a two-tone MFM is also successfully implemented. More importantly, the proposed method features a reconfigurable measurement range just using a single Dpol-DDMZM and automatic frequency recovery with a frequency discrimination algorithm, which makes the measurement simple and compact.
{"title":"High-Resolution and Multiple-Tone Microwave Frequency Measurement Based on Predefinable Optical Frequency Combs Utilizing a Dual-Polarization Dual-Drive Mach–Zehnder Modulator","authors":"Xinhai Zou;Xin Wang;Lingjie Zhang;Chao Jing;Yali Zhang;Zhiyao Zhang;Shang Jian Zhang;Yong Liu","doi":"10.1109/TMTT.2025.3629103","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3629103","url":null,"abstract":"A high-resolution and multiple-tone microwave frequency measurement (MFM) method is proposed based on predefinable optical frequency combs (OFCs) using a dual-polarization dual-drive Mach–Zehnder modulator (Dpol-DDMZM). Two OFCs with predefinable spectrum shape are generated by electro-optic modulation (EOM) and mixed with the microwave signal under test (SUT) through photonic mixing with a single Dpol-DDMZM simultaneously, in which two minimum frequency components are generated mapping from SUT and used for SUT frequency recovery, respectively. The relative position between SUT and comb teeth can be determined with the power difference of the above two minimum frequency tones. In the proposed method, wideband and high-resolution are simultaneously guaranteed due to the combination of wideband photonic-assisted microwave photonic mixing and hyperfine electrical analysis. Moreover, it also enables multiple-tone measurement relying on the unique frequency-to-frequency mapping (FTFM) relationship between the SUT and the mixing frequency components. In the proof of concept, MFM is experimentally demonstrated up to a 40-GHz frequency range with a 10-kHz measurement error, and a two-tone MFM is also successfully implemented. More importantly, the proposed method features a reconfigurable measurement range just using a single Dpol-DDMZM and automatic frequency recovery with a frequency discrimination algorithm, which makes the measurement simple and compact.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 2","pages":"1790-1799"},"PeriodicalIF":4.5,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146154472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-14DOI: 10.1109/TMTT.2025.3628749
Pouya Mehrjouseresht;Vladimir Volski;Ihsane Gryech;Robbert Beerten;Alexander Ye Svezhentsev;Marco Mercuri;Ping Jack Soh;Dominique M. M.-P. Schreurs
This article introduces an innovative approach integrating machine learning (ML) methods into a far-field wireless power transfer (WPT) system. Within this system, a radar is employed to detect the presence and height of individuals. These data, combined with information on the location of nodes, as well as the propagation channel between transmitters and nodes, are fed into the proposed ML algorithm. The ML model aims to predict the optimal power level for each transmitter, effectively establishing a safe 3-D zone around people while also maximizing power transfer efficiency. The advantages of using ML are the realization of a real-time system, which is crucial in indoor applications, keeping dangerous radiation at a safe level with a very low risk of harmful exposure, and simultaneously enhancing efficiency. Three ML models are evaluated, namely the random forest (RF), support vector machine (SVM), and neural network (NN). Simulation results highlight the superior performance of the NN model, demonstrating its ability to effectively capture the complex nonlinear characteristics of indoor propagation environments, with only approximately 6% of its predictions exceeding the predefined safety threshold. The experimental results show that NN-based WPT can maintain the electric field amplitude (EFA) below a defined threshold for multiple indoor experimental scenarios over the person’s height. In addition, the proposed approach outperformed the maximum ratio transmission (MRT) approach in terms of radio frequency–radio frequency (RF–RF) transmission efficiency in 21.43% of the measurements conducted with multiple people present in the testbed.
{"title":"Indoor Safety of Wireless Power Transfer: A Machine Learning Approach","authors":"Pouya Mehrjouseresht;Vladimir Volski;Ihsane Gryech;Robbert Beerten;Alexander Ye Svezhentsev;Marco Mercuri;Ping Jack Soh;Dominique M. M.-P. Schreurs","doi":"10.1109/TMTT.2025.3628749","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3628749","url":null,"abstract":"This article introduces an innovative approach integrating machine learning (ML) methods into a far-field wireless power transfer (WPT) system. Within this system, a radar is employed to detect the presence and height of individuals. These data, combined with information on the location of nodes, as well as the propagation channel between transmitters and nodes, are fed into the proposed ML algorithm. The ML model aims to predict the optimal power level for each transmitter, effectively establishing a safe 3-D zone around people while also maximizing power transfer efficiency. The advantages of using ML are the realization of a real-time system, which is crucial in indoor applications, keeping dangerous radiation at a safe level with a very low risk of harmful exposure, and simultaneously enhancing efficiency. Three ML models are evaluated, namely the random forest (RF), support vector machine (SVM), and neural network (NN). Simulation results highlight the superior performance of the NN model, demonstrating its ability to effectively capture the complex nonlinear characteristics of indoor propagation environments, with only approximately 6% of its predictions exceeding the predefined safety threshold. The experimental results show that NN-based WPT can maintain the electric field amplitude (EFA) below a defined threshold for multiple indoor experimental scenarios over the person’s height. In addition, the proposed approach outperformed the maximum ratio transmission (MRT) approach in terms of radio frequency–radio frequency (RF–RF) transmission efficiency in 21.43% of the measurements conducted with multiple people present in the testbed.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 2","pages":"2076-2088"},"PeriodicalIF":4.5,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146154466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-14DOI: 10.1109/TMTT.2025.3630829
Emanuele Cardillo
Existing IQ imbalance correction methods are often impractical or challenging in real cases. Indeed, they usually require hardware modification or expensive precision actuators to create accurate and, above all, small movements. This last characteristic is strategic; indeed, if the range varies significantly during measurement, the signal-to-noise ratio (SNR) is not constant, and thus, the IQ module varies, too. As explained in the text, a constant SNR during calibration is often required to ensure that the IQ imbalance is solely due to hardware imperfections and not to changing environmental conditions. This poses several practical challenges in replicating the procedures described in the current literature. In this article, an automatic IQ imbalance calibration method is proposed; it does not require any specific measurement settings. It finds the IQ trajectory with the maximum SNR, thus ensuring not only a constant SNR but also optimal performance, as the accuracy of ellipse-fitting methods is directly proportional to the SNR. The theoretical basis of the calibration method is carefully provided and validated with simulations and measurements. Its effectiveness is investigated both for displacement and micro-Doppler signature detection. This method can be used for many radar applications, from physiological and healthcare sensing to motion tracking and gesture detection, as shown experimentally; moreover, it can be implemented online, thus enabling the system’s automatic calibration.
{"title":"Setup-Independent Quadrature Imbalance Calibration for Microwave and Millimeter-Wave Doppler Radars","authors":"Emanuele Cardillo","doi":"10.1109/TMTT.2025.3630829","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3630829","url":null,"abstract":"Existing <italic>IQ</i> imbalance correction methods are often impractical or challenging in real cases. Indeed, they usually require hardware modification or expensive precision actuators to create accurate and, above all, small movements. This last characteristic is strategic; indeed, if the range varies significantly during measurement, the signal-to-noise ratio (SNR) is not constant, and thus, the <italic>IQ</i> module varies, too. As explained in the text, a constant SNR during calibration is often required to ensure that the <italic>IQ</i> imbalance is solely due to hardware imperfections and not to changing environmental conditions. This poses several practical challenges in replicating the procedures described in the current literature. In this article, an automatic <italic>IQ</i> imbalance calibration method is proposed; it does not require any specific measurement settings. It finds the <italic>IQ</i> trajectory with the maximum SNR, thus ensuring not only a constant SNR but also optimal performance, as the accuracy of ellipse-fitting methods is directly proportional to the SNR. The theoretical basis of the calibration method is carefully provided and validated with simulations and measurements. Its effectiveness is investigated both for displacement and micro-Doppler signature detection. This method can be used for many radar applications, from physiological and healthcare sensing to motion tracking and gesture detection, as shown experimentally; moreover, it can be implemented online, thus enabling the system’s automatic calibration.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"74 2","pages":"1893-1902"},"PeriodicalIF":4.5,"publicationDate":"2025-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146154435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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