This article presents a single radio frequency (RF) channel architecture with frequency diversity to implement digital beamforming (DBF). By converting the time-domain switching characteristics into frequency-domain diversity, the signals received by all array elements can be transmitted by sharing a single RF channel. A single-sideband time-modulated array (STMA) with multistep in-phase/quadrature (I/Q) modulation is introduced, which concentrates the signal energy mainly in the first positive harmonic component, significantly suppressing unwanted sidebands and mitigating interference. The different modulation frequencies between the elements can be flexibly configured using a nonuniform period modulation (NUPM) strategy to achieve frequency diversity without adding hardware complexity. Compared with other DBF implementation architectures, this design significantly reduces hardware complexity while maintaining reliable signal recovery performance. Measurement results show that the baseband equivalent signals of the signals received by the array elements, including amplitude and phase distributions, can be recovered correctly and in real time. The resulting DBF-formed radiation patterns in the ±40° angular range are in good agreement with the theoretical results.
{"title":"Single-Channel Digital Beamforming With Frequency Diversity Single-Sideband Time-Modulated Arrays","authors":"Deng-Yue Luo;Jin-Dong Zhang;Qiao-Yu Chen;Wen Wu;Da-Gang Fang","doi":"10.1109/TMTT.2025.3582802","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3582802","url":null,"abstract":"This article presents a single radio frequency (RF) channel architecture with frequency diversity to implement digital beamforming (DBF). By converting the time-domain switching characteristics into frequency-domain diversity, the signals received by all array elements can be transmitted by sharing a single RF channel. A single-sideband time-modulated array (STMA) with multistep in-phase/quadrature (I/Q) modulation is introduced, which concentrates the signal energy mainly in the first positive harmonic component, significantly suppressing unwanted sidebands and mitigating interference. The different modulation frequencies between the elements can be flexibly configured using a nonuniform period modulation (NUPM) strategy to achieve frequency diversity without adding hardware complexity. Compared with other DBF implementation architectures, this design significantly reduces hardware complexity while maintaining reliable signal recovery performance. Measurement results show that the baseband equivalent signals of the signals received by the array elements, including amplitude and phase distributions, can be recovered correctly and in real time. The resulting DBF-formed radiation patterns in the ±40° angular range are in good agreement with the theoretical results.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"73 11","pages":"9509-9521"},"PeriodicalIF":4.5,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145595098","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 : 2025-07-08DOI: 10.1109/TMTT.2025.3576061
Mario Kupresak;Bruno Eckmann;Johannes Hoffmann;Michael Baumann;Philippe Peter;Jasmin Smajic;Juerg Leuthold
In this work, we develop a numerical solver, efficiently and robustly treating highly nonlinear semiconductor device problems. Beyond the capabilities of commercial tools, the solver can compute the time-domain capacitance and the spectrum of the device current. The solver is based on the finite element method (FEM) and employs the successive under-relaxation scheme. Its capability has been assessed and validated in a study of an axisymmetric metal-oxide–semiconductor (MOS) structure, presenting an archetypal scanning microwave microscopy (SMM) calibration sample, with both n- and p-doped semiconductors, including different excitation sources. Excellent agreement was obtained, when testing the tool against features of a commercial tool. By computing the capacitance for the applied low-frequency (LF) bias, combined with a high-frequency (HF) probe signal, the spectrum of the current flowing in the structure was evaluated, revealing mix-product components. This allowed us to verify the solver against measurements, resulting in a very good agreement.
{"title":"Robust Numerical Solver for Nonlinear Semiconductor Problems","authors":"Mario Kupresak;Bruno Eckmann;Johannes Hoffmann;Michael Baumann;Philippe Peter;Jasmin Smajic;Juerg Leuthold","doi":"10.1109/TMTT.2025.3576061","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3576061","url":null,"abstract":"In this work, we develop a numerical solver, efficiently and robustly treating highly nonlinear semiconductor device problems. Beyond the capabilities of commercial tools, the solver can compute the time-domain capacitance and the spectrum of the device current. The solver is based on the finite element method (FEM) and employs the successive under-relaxation scheme. Its capability has been assessed and validated in a study of an axisymmetric metal-oxide–semiconductor (MOS) structure, presenting an archetypal scanning microwave microscopy (SMM) calibration sample, with both <italic>n</i>- and <italic>p</i>-doped semiconductors, including different excitation sources. Excellent agreement was obtained, when testing the tool against features of a commercial tool. By computing the capacitance for the applied low-frequency (LF) bias, combined with a high-frequency (HF) probe signal, the spectrum of the current flowing in the structure was evaluated, revealing mix-product components. This allowed us to verify the solver against measurements, resulting in a very good agreement.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"73 9","pages":"6051-6058"},"PeriodicalIF":4.5,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073266","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 : 2025-07-08DOI: 10.1109/TMTT.2025.3580167
Joan Gemio Valero;Giselle González-López;Albert Alcàsser Expósito;Laia Vilalta Estrada;Francisco Jesus Lobo
In-cabin monitoring systems (iCM) are transforming the automotive industry’s approach to safety and occupant well-being. Among the various sensing technologies, radar has emerged as a highly effective solution due to its robustness in challenging conditions such as poor lighting or obstructed view. This article reviews the state-of-the-art radar technologies used for critical automotive safety applications, including child presence detection (CPD), seat belt reminder (SBR), intrusion detection systems (IDS), occupant out-of-position (OOP) analysis, and vital sign monitoring. With emerging regulatory requirements, such as the European New Car Assessment Program (Euro NCAP) standards mandating CPD and SBR, radar technology provides a scalable, cost-effective solution for automakers. This article examines the underlying radar principles, system architectures, capabilities, and limitations of the three main used radar technologies [Doppler, frequency modulated continuous wave (FMCW), and ultrawideband (UWB)] for iCM, addressing both technical challenges and opportunities for enhancing vehicle safety.
{"title":"Automotive In-Cabin Radar Uncovered: The Essential Guide to Choose the Perfect Sensing Technology for Your Vehicle","authors":"Joan Gemio Valero;Giselle González-López;Albert Alcàsser Expósito;Laia Vilalta Estrada;Francisco Jesus Lobo","doi":"10.1109/TMTT.2025.3580167","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3580167","url":null,"abstract":"In-cabin monitoring systems (iCM) are transforming the automotive industry’s approach to safety and occupant well-being. Among the various sensing technologies, radar has emerged as a highly effective solution due to its robustness in challenging conditions such as poor lighting or obstructed view. This article reviews the state-of-the-art radar technologies used for critical automotive safety applications, including child presence detection (CPD), seat belt reminder (SBR), intrusion detection systems (IDS), occupant out-of-position (OOP) analysis, and vital sign monitoring. With emerging regulatory requirements, such as the European New Car Assessment Program (Euro NCAP) standards mandating CPD and SBR, radar technology provides a scalable, cost-effective solution for automakers. This article examines the underlying radar principles, system architectures, capabilities, and limitations of the three main used radar technologies [Doppler, frequency modulated continuous wave (FMCW), and ultrawideband (UWB)] for iCM, addressing both technical challenges and opportunities for enhancing vehicle safety.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"73 8","pages":"4386-4401"},"PeriodicalIF":4.5,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144853431","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 : 2025-07-03DOI: 10.1109/TMTT.2025.3583913
Qunqiang Hu;Huiping Yang;Yufan Rao;Xiu Yin Zhang
Reconfigurable intelligent surface (RIS) has been recognized as a critical part of B5G/6G wireless communications. However, the bandwidth expansion of RIS in millimeter-wave applications remains a significant challenge. In this article, an ultrawideband RIS employing multimode resonances to cover the entire mm-wave n257-n261 frequency bands is presented. First, a systematic analysis of the RIS circuit configuration is performed, which reveals that the circuit bandwidth is expanded as the resonant modes increase. Second, guided by this principle, the bar-shaped slot and split square slots are sequentially added to a typical RIS element to excite multiple resonant modes. Full-wave simulations validate the bandwidth enhancement mechanism, showing that a phase shift range of $180^{circ }~pm ~20^{circ }$ is achieved over the bandwidth from 23.8 to 45.6 GHz. Finally, a prototype array is fabricated and measured for further confirmation. The measured results agree with the simulated ones, demonstrating the favorable broadband operating response. The measured 3-dB gain bandwidth is from 26.9 to 43.5 GHz, featuring a fractional bandwidth of 47.2%. This is the widest mm-wave RIS reported in the literature to date. In addition, the main beam can be scanned from 0° to 60°. The characteristics of ultrawideband operation and wide beam-scanning will facilitate the capacity enhancement and coverage extension of the future mm-wave communications.
{"title":"Ultrawideband Millimeter-Wave RIS Based on Multimode Resonances","authors":"Qunqiang Hu;Huiping Yang;Yufan Rao;Xiu Yin Zhang","doi":"10.1109/TMTT.2025.3583913","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3583913","url":null,"abstract":"Reconfigurable intelligent surface (RIS) has been recognized as a critical part of B5G/6G wireless communications. However, the bandwidth expansion of RIS in millimeter-wave applications remains a significant challenge. In this article, an ultrawideband RIS employing multimode resonances to cover the entire mm-wave n257-n261 frequency bands is presented. First, a systematic analysis of the RIS circuit configuration is performed, which reveals that the circuit bandwidth is expanded as the resonant modes increase. Second, guided by this principle, the bar-shaped slot and split square slots are sequentially added to a typical RIS element to excite multiple resonant modes. Full-wave simulations validate the bandwidth enhancement mechanism, showing that a phase shift range of <inline-formula> <tex-math>$180^{circ }~pm ~20^{circ }$ </tex-math></inline-formula> is achieved over the bandwidth from 23.8 to 45.6 GHz. Finally, a prototype array is fabricated and measured for further confirmation. The measured results agree with the simulated ones, demonstrating the favorable broadband operating response. The measured 3-dB gain bandwidth is from 26.9 to 43.5 GHz, featuring a fractional bandwidth of 47.2%. This is the widest mm-wave RIS reported in the literature to date. In addition, the main beam can be scanned from 0° to 60°. The characteristics of ultrawideband operation and wide beam-scanning will facilitate the capacity enhancement and coverage extension of the future mm-wave communications.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"73 11","pages":"9596-9604"},"PeriodicalIF":4.5,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145595111","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 : 2025-06-27DOI: 10.1109/TMTT.2025.3580804
Xiangyan Liu;Ning Liu;Xianjun Sheng;Haoyong Ding;Xiao Li
This article presents a simple, low-cost, dual-band RF energy harvester, which includes a metasurface array and a low-cost rectifier. The metasurface unit consists of a solid patch with two through vias, in which squared complementary split ring resonators (CSRRs) are etched. By combining CSRR with different sizes, two current distributions are created, thereby achieving dual-band characteristic. Then, microstrip lines are introduced into the unit to release the energy constrained within the resonators, further enhancing current aggregation at through vias and improving energy harvesting efficiency. The low-cost rectifier adopts a single-series topology, ensuring RF-dc conversion at a low input power level of −10 dBm. To validate the design, a $5times 5$ metasurface prototype together with a single-series rectifier has been fabricated and measured. The measured results show that the maximum harvesting efficiency of the proposed metasurface is 90.4% at 2.05 GHz and 86.5% at 3.05 GHz. At a large incidence angle of 60°, the maximum efficiency in the operating bands (2–2.1 and 3–3.1 GHz) reaches 68.3% and 76.6% under TE polarization and 78.4% and 65.2% under TM polarization, with the lower operating frequency unchanged. For the proposed energy harvester, the optimal RF-dc efficiency reaches 20.9% at an incident power density of $17.7~mu $ W/cm2 and normal incidence. The proposed harvester exhibits dual band, high harvesting efficiency, and simple structure, making it suitable for providing sufficient energy to low-power electronic devices and wireless sensor networks in complex environments.
{"title":"Design of Simple Dual-Band RF Energy Harvester Using CSRR Metasurface for Low-Power Devices","authors":"Xiangyan Liu;Ning Liu;Xianjun Sheng;Haoyong Ding;Xiao Li","doi":"10.1109/TMTT.2025.3580804","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3580804","url":null,"abstract":"This article presents a simple, low-cost, dual-band RF energy harvester, which includes a metasurface array and a low-cost rectifier. The metasurface unit consists of a solid patch with two through vias, in which squared complementary split ring resonators (CSRRs) are etched. By combining CSRR with different sizes, two current distributions are created, thereby achieving dual-band characteristic. Then, microstrip lines are introduced into the unit to release the energy constrained within the resonators, further enhancing current aggregation at through vias and improving energy harvesting efficiency. The low-cost rectifier adopts a single-series topology, ensuring RF-dc conversion at a low input power level of −10 dBm. To validate the design, a <inline-formula> <tex-math>$5times 5$ </tex-math></inline-formula> metasurface prototype together with a single-series rectifier has been fabricated and measured. The measured results show that the maximum harvesting efficiency of the proposed metasurface is 90.4% at 2.05 GHz and 86.5% at 3.05 GHz. At a large incidence angle of 60°, the maximum efficiency in the operating bands (2–2.1 and 3–3.1 GHz) reaches 68.3% and 76.6% under TE polarization and 78.4% and 65.2% under TM polarization, with the lower operating frequency unchanged. For the proposed energy harvester, the optimal RF-dc efficiency reaches 20.9% at an incident power density of <inline-formula> <tex-math>$17.7~mu $ </tex-math></inline-formula>W/cm<sup>2</sup> and normal incidence. The proposed harvester exhibits dual band, high harvesting efficiency, and simple structure, making it suitable for providing sufficient energy to low-power electronic devices and wireless sensor networks in complex environments.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"73 11","pages":"9645-9657"},"PeriodicalIF":4.5,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145674665","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 presence of multipath effects in terahertz wireless links degrades signal quality, making absorbers a critical component of 5G/6G wireless systems. Here, we leverage the innately high loss of liquid water, combined with the microscale precision of UV-cured resin-based micro 3-D printing, to realize a viable pyramidal absorber for terahertz waves. Both simulation and experimental results confirm near-unity absorption, achieving over 99% in the 75–190 GHz range and 99.99% over 190–500 GHz. Furthermore, simulations show that the absorber maintains high performance up to 1000 GHz, with absorption exceeding 99.999%. These results demonstrate potential for future micro 3-D-printed resin-based absorbers that can be readily tailored to serve in communication, sensing, and radar applications, thanks to their microscale size, cost-effectiveness, and adaptability to broadband terahertz wireless systems.
{"title":"Microstructured Water-Based Broadband Terahertz Pyramidal Absorber","authors":"Kalliopi Spanidou;Daniel Headland;Sharath Sriram;Itziar Maestrojuán Biurrun;Guillermo Carpintero","doi":"10.1109/TMTT.2025.3580219","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3580219","url":null,"abstract":"The presence of multipath effects in terahertz wireless links degrades signal quality, making absorbers a critical component of 5G/6G wireless systems. Here, we leverage the innately high loss of liquid water, combined with the microscale precision of UV-cured resin-based micro 3-D printing, to realize a viable pyramidal absorber for terahertz waves. Both simulation and experimental results confirm near-unity absorption, achieving over 99% in the 75–190 GHz range and 99.99% over 190–500 GHz. Furthermore, simulations show that the absorber maintains high performance up to 1000 GHz, with absorption exceeding 99.999%. These results demonstrate potential for future micro 3-D-printed resin-based absorbers that can be readily tailored to serve in communication, sensing, and radar applications, thanks to their microscale size, cost-effectiveness, and adaptability to broadband terahertz wireless systems.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"73 9","pages":"5992-6000"},"PeriodicalIF":4.5,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11053690","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073205","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}
Pub Date : 2025-06-19DOI: 10.1109/TMTT.2025.3579467
Hao Jiang;Mei Qian;Cao Wan;Zhi Ning Chen;Quan Xue
The large-scale deployment of low-Earth orbit (LEO) satellites opens significant commercial opportunities for developing low-cost satellite communication (SATCOM) user terminals. To meet the growing demand for dynamic tracking of fast-moving LEO targets, we present a dual-beam, independently controlled K band (17.7–21.2 GHz) SATCOM phased-array receiver. This system integrates a dual-beam architecture, a new dual-circular-polarization (CP) antenna, a passive power combiner network, and a dual-beam digital control system. The designed antenna element, formed by a dual-layer asymmetric metasurface patch embedded in metal vias, achieves excellent impedance matching for large-angle incoming waves, enabling the configured array to achieve wide-angle scanning of ±70° following $cos theta $ roll-offs and superior axial-ratio (AR) bandwidth under extreme scanning conditions. Experimental measurements confirm its outstanding performance, including low-sidelobe levels (SLLs), high-cross-polarization discrimination (XPD), a wide 3-dB AR bandwidth, and a wide-angle (>60°) AR scanning across the spectrum. The receiver supports independent dual-beam operation at arbitrary frequencies, polarizations, and scan angles and enables an excellent gain-to-noise temperature (G/T) of 9.45 dB/K, a high signal-to-noise ratio (SNR), and a proven communication link with a high data rate (the actual throughput reaches 60 Mb/s), marking a leap forward for commercial SATCOM systems.
{"title":"Wide Axial-Ratio Bandwidth and Scanning in Dual-Beam Phased Array for SATCOM Receiver","authors":"Hao Jiang;Mei Qian;Cao Wan;Zhi Ning Chen;Quan Xue","doi":"10.1109/TMTT.2025.3579467","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3579467","url":null,"abstract":"The large-scale deployment of low-Earth orbit (LEO) satellites opens significant commercial opportunities for developing low-cost satellite communication (SATCOM) user terminals. To meet the growing demand for dynamic tracking of fast-moving LEO targets, we present a dual-beam, independently controlled <italic>K</i> band (17.7–21.2 GHz) SATCOM phased-array receiver. This system integrates a dual-beam architecture, a new dual-circular-polarization (CP) antenna, a passive power combiner network, and a dual-beam digital control system. The designed antenna element, formed by a dual-layer asymmetric metasurface patch embedded in metal vias, achieves excellent impedance matching for large-angle incoming waves, enabling the configured array to achieve wide-angle scanning of ±70° following <inline-formula> <tex-math>$cos theta $ </tex-math></inline-formula> roll-offs and superior axial-ratio (AR) bandwidth under extreme scanning conditions. Experimental measurements confirm its outstanding performance, including low-sidelobe levels (SLLs), high-cross-polarization discrimination (XPD), a wide 3-dB AR bandwidth, and a wide-angle (>60°) AR scanning across the spectrum. The receiver supports independent dual-beam operation at arbitrary frequencies, polarizations, and scan angles and enables an excellent gain-to-noise temperature (G/T) of 9.45 dB/K, a high signal-to-noise ratio (SNR), and a proven communication link with a high data rate (the actual throughput reaches 60 Mb/s), marking a leap forward for commercial SATCOM systems.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"73 11","pages":"9565-9582"},"PeriodicalIF":4.5,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145595101","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 : 2025-06-19DOI: 10.1109/TMTT.2025.3577733
Lu Qian;Talal Skaik;Yi-Wen Wu;Yi Wang
This article presents an end-to-end manufacturing and post-processing solution for 3-D-printed millimeter-wave (mm-Wave) monolithic waveguide (WG) components. A high-precision micro laser sintering (MLS) process, two internal surface polishing methods—abrasive flow machining (AFM) and Hirtisation—and an electroless gold plating process are combined to address the surface quality challenges commonly associated with current 3-D-printed mm-Wave components. This is the first demonstration of the two polishing techniques on mm-Wave devices. An experimental study was conducted on two mm-Wave WG twists for WR-15 and WR-5 bands, respectively. The impact of the surface treatment processes on both mechanical and electrical properties was investigated. The surface roughness of both WG twists was reduced to below $1~mu $ m. For the WR-15 WG twist, the dissipative attenuation factor ranged from 5.4 to 2.7 dB/m, with a worst case return loss of 30 dB. For the WR-05 WG twist, the dissipative attenuation factor ranged from 17 to 10 dB/m, with a worst case return loss of 14 dB. The significant improvement in insertion losses (ILs) demonstrates the effectiveness of the two surface treatment methods, enabling complex monolithic mm-Wave WG components with enhanced surface quality.
{"title":"Three-Dimensional Printed mm-Wave Monolithic Waveguide Twists: End-to-End Manufacturing and Surface-Treatment Solutions","authors":"Lu Qian;Talal Skaik;Yi-Wen Wu;Yi Wang","doi":"10.1109/TMTT.2025.3577733","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3577733","url":null,"abstract":"This article presents an end-to-end manufacturing and post-processing solution for 3-D-printed millimeter-wave (mm-Wave) monolithic waveguide (WG) components. A high-precision micro laser sintering (MLS) process, two internal surface polishing methods—abrasive flow machining (AFM) and Hirtisation—and an electroless gold plating process are combined to address the surface quality challenges commonly associated with current 3-D-printed mm-Wave components. This is the first demonstration of the two polishing techniques on mm-Wave devices. An experimental study was conducted on two mm-Wave WG twists for WR-15 and WR-5 bands, respectively. The impact of the surface treatment processes on both mechanical and electrical properties was investigated. The surface roughness of both WG twists was reduced to below <inline-formula> <tex-math>$1~mu $ </tex-math></inline-formula>m. For the WR-15 WG twist, the dissipative attenuation factor ranged from 5.4 to 2.7 dB/m, with a worst case return loss of 30 dB. For the WR-05 WG twist, the dissipative attenuation factor ranged from 17 to 10 dB/m, with a worst case return loss of 14 dB. The significant improvement in insertion losses (ILs) demonstrates the effectiveness of the two surface treatment methods, enabling complex monolithic mm-Wave WG components with enhanced surface quality.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"73 9","pages":"5909-5917"},"PeriodicalIF":4.5,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073417","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 : 2025-06-17DOI: 10.1109/TMTT.2025.3577467
Sebastian Mettes;Christopher T. Howard;Joshua Roper;Taylor M. Shapero;Kenneth W. Allen;Yi Chen Mazumdar
Advances in computational design methods have enabled the development of increasingly sophisticated frequency selective surfaces (FSSs). However, manufacturing these complex designs on doubly-curved shapes remains challenging. In this work, we design, fabricate, and experimentally validate an additively manufactured, doubly-curved, multimaterial, and multilayer FSS subreflector for L passband and Ku and Ka stopband frequencies. By employing this subreflector in a Cassegrain antenna configuration, broadband satellites operating in the Ku-Ka-bands can gain access to L-band frequencies without the need for separate antenna systems. To achieve the desired tri-band frequency response, the FSS elements are first synthesized using periodic level set functions with a target passband from 1 to 6 GHz and stopbands from 17.7 to 20.2 and 27.5 to 30.0 GHz. Then, a planar FSS sample is 3-D-printed using fused filament fabrication (FFF) for the dielectric layers and direct ink write (DIW) with silver nanoparticle ink for the conductive layers. Sample testing in a free space focused beam indicates good agreement with the simulation results. Next, spatially variant lattices (SVLs) are employed to map the synthesized elements onto a hyperbolic surface and advanced, nonplanar 3-D-printing techniques are implemented to manufacture the doubly-curved FSS subreflector. These techniques greatly improve surface quality and enable the printing of multiple layers of continuous conductive patterns on curved surfaces. To demonstrate the performance of the subreflector, it is tested in a Cassegrain antenna system on a compact range with experimental results showing fair agreement with simulation results. Overall, these findings demonstrate the potential for advanced additive manufacturing (AM) to produce high-performance, conformal FSS structures for next-generation radome and spectral filtering applications.
{"title":"3-D-Printed Doubly-Curved Multilayer Tri-Band Frequency Selective Surface","authors":"Sebastian Mettes;Christopher T. Howard;Joshua Roper;Taylor M. Shapero;Kenneth W. Allen;Yi Chen Mazumdar","doi":"10.1109/TMTT.2025.3577467","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3577467","url":null,"abstract":"Advances in computational design methods have enabled the development of increasingly sophisticated frequency selective surfaces (FSSs). However, manufacturing these complex designs on doubly-curved shapes remains challenging. In this work, we design, fabricate, and experimentally validate an additively manufactured, doubly-curved, multimaterial, and multilayer FSS subreflector for L passband and Ku and Ka stopband frequencies. By employing this subreflector in a Cassegrain antenna configuration, broadband satellites operating in the Ku-Ka-bands can gain access to L-band frequencies without the need for separate antenna systems. To achieve the desired tri-band frequency response, the FSS elements are first synthesized using periodic level set functions with a target passband from 1 to 6 GHz and stopbands from 17.7 to 20.2 and 27.5 to 30.0 GHz. Then, a planar FSS sample is 3-D-printed using fused filament fabrication (FFF) for the dielectric layers and direct ink write (DIW) with silver nanoparticle ink for the conductive layers. Sample testing in a free space focused beam indicates good agreement with the simulation results. Next, spatially variant lattices (SVLs) are employed to map the synthesized elements onto a hyperbolic surface and advanced, nonplanar 3-D-printing techniques are implemented to manufacture the doubly-curved FSS subreflector. These techniques greatly improve surface quality and enable the printing of multiple layers of continuous conductive patterns on curved surfaces. To demonstrate the performance of the subreflector, it is tested in a Cassegrain antenna system on a compact range with experimental results showing fair agreement with simulation results. Overall, these findings demonstrate the potential for advanced additive manufacturing (AM) to produce high-performance, conformal FSS structures for next-generation radome and spectral filtering applications.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"73 9","pages":"5864-5875"},"PeriodicalIF":4.5,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073405","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 : 2025-06-12DOI: 10.1109/TMTT.2025.3576125
Hai-Xu Liu;Yong-Hong Zhang
This work presents a broadband isolated Ka-band radial space power combiner based on TE01 mode in a circular waveguide. The combiner consists of two parts: an isolated 24-way radial power combiner and a broadband circular waveguide TE01-mode transducer. A kind of approximate half-height waveguide absorbers are embedded at the circular bottom of the radial power combiner for the first time, which significantly increases the input port’s return loss (RL) and isolation among input ports while also improving the size tolerance of the absorber and lowering installation difficulty. After employing the absorbers, the measured results of minimum isolation of 16 dB among input ports, the average RL improvement of 13 dB at the input ports, the minimum RL of 14 dB at the output port, the maximum insert loss of 0.75 dB, and the lowest passive combining efficiency of 84% are realized within 26–42 GHz with a relative operating bandwidth of 47%. Additionally, the analysis of power-handling capability and the high-power tests under a continuous wave power of 300 W were carried out. To the best of our knowledge, this is the widest operational bandwidth power combiner based on the circular waveguide.
{"title":"A Ka-Band Broadband Radial Power Combiner With High Isolation Among All Input Ports","authors":"Hai-Xu Liu;Yong-Hong Zhang","doi":"10.1109/TMTT.2025.3576125","DOIUrl":"https://doi.org/10.1109/TMTT.2025.3576125","url":null,"abstract":"This work presents a broadband isolated Ka-band radial space power combiner based on TE<sub>01</sub> mode in a circular waveguide. The combiner consists of two parts: an isolated 24-way radial power combiner and a broadband circular waveguide TE<sub>01</sub>-mode transducer. A kind of approximate half-height waveguide absorbers are embedded at the circular bottom of the radial power combiner for the first time, which significantly increases the input port’s return loss (RL) and isolation among input ports while also improving the size tolerance of the absorber and lowering installation difficulty. After employing the absorbers, the measured results of minimum isolation of 16 dB among input ports, the average RL improvement of 13 dB at the input ports, the minimum RL of 14 dB at the output port, the maximum insert loss of 0.75 dB, and the lowest passive combining efficiency of 84% are realized within 26–42 GHz with a relative operating bandwidth of 47%. Additionally, the analysis of power-handling capability and the high-power tests under a continuous wave power of 300 W were carried out. To the best of our knowledge, this is the widest operational bandwidth power combiner based on the circular waveguide.","PeriodicalId":13272,"journal":{"name":"IEEE Transactions on Microwave Theory and Techniques","volume":"73 10","pages":"8288-8298"},"PeriodicalIF":4.5,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145428965","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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