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Search Results (239)

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15 pages, 3152 KiB  
Article
Advanced Modeling of GaN-on-Silicon Spiral Inductors
by Simone Spataro, Giuseppina Sapone, Marcello Giuffrida and Egidio Ragonese
Electronics 2025, 14(15), 3079; https://doi.org/10.3390/electronics14153079 - 31 Jul 2025
Viewed by 88
Abstract
In this paper, the accuracy of basic and advanced spiral inductor models for gallium nitride (GaN) integrated inductors is evaluated. Specifically, the experimental measurements of geometrically scaled circular spiral inductors, fabricated in a radio frequency (RF) GaN-on silicon technology, are exploited to estimate [...] Read more.
In this paper, the accuracy of basic and advanced spiral inductor models for gallium nitride (GaN) integrated inductors is evaluated. Specifically, the experimental measurements of geometrically scaled circular spiral inductors, fabricated in a radio frequency (RF) GaN-on silicon technology, are exploited to estimate the errors of two lumped geometrically scalable models, i.e., a simple π-model with seven components and an advanced model with thirteen components. The comparison is performed by using either the standard performance parameters, such as inductance (L), quality factor (Q-factor), and self-resonance frequency (SRF), or the two-port scattering parameters (S-parameters). The comparison reveals that despite a higher complexity, the developed advanced model achieves a significant reduction in SRF percentage errors in a wide range of geometrical parameters, while enabling an accurate estimation of two-port S-parameters. Indeed, the correct evaluation of both SRF and two-port S-parameters is crucial to exploit the model in an actual circuit design environment by properly setting the inductor geometrical parameters to optimize RF performance. Full article
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10 pages, 3595 KiB  
Article
EM Characterization of a Compact RFQ Cold Model Prototype Employing a New Power Injection Scheme
by Marco A. López, Joaquín Portilla, Victor Etxebarria, Iñigo Arredondo and Jorge Feuchtwanger
Particles 2025, 8(3), 67; https://doi.org/10.3390/particles8030067 - 1 Jul 2025
Viewed by 365
Abstract
The experimental and computational characterization of a cold model prototype designed to test the electromagnetic properties of a new RFQ (Radio-Frequency Quadrupole) cavity is reported. This cavity is intended to be an essential part of a compact, high-gradient proton accelerator for medical purposes. [...] Read more.
The experimental and computational characterization of a cold model prototype designed to test the electromagnetic properties of a new RFQ (Radio-Frequency Quadrupole) cavity is reported. This cavity is intended to be an essential part of a compact, high-gradient proton accelerator for medical purposes. The RFQ’s design employs a novel RF power-coupler injection solution. One common way to couple the RF power in proton RFQs has been the use of loop-couplers inserted into the mid-section of the RFQ’s lobe sections. This technique has been demonstrated to be reliable and effective but introduces a significant perturbation into the lobe that can be more noticeable when dealing with compact structures. We propose a RF injection scheme that uses direct transition from a coaxial cable to the RFQ by connecting the inner coaxial conductor to the RFQ vane body. As a consequence, the lobe geometry is not perturbed, and the transversal electrical fields are directly excited through the vanes. Moreover, by using a pair of such couplers connected to opposite vanes at a given transversal plane of the RFQ, it is also possible to excite the desired quadrupolar TE210 modes while avoiding the excitation of dipolar TE110 modes. The resonances corresponding to different RFQ modes have been characterized, and the dependence of the amplitude of the modes on the relative phase of the field injected through the RF power ports has been demonstrated both by measurements and simulations. Full article
(This article belongs to the Section Experimental Physics and Instrumentation)
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15 pages, 1496 KiB  
Article
Capacitive-Loaded High-Power Low-Loss 3.0 T Magnetic Resonance Imaging Radio Frequency Combiner Design and Integrated Application
by Yingliang Li and Shouhua Luo
Appl. Sci. 2025, 15(11), 5940; https://doi.org/10.3390/app15115940 - 25 May 2025
Viewed by 438
Abstract
For high-power magnetic resonance imaging (MRI) radio frequency (RF) combiners operating in the frequency range from 60 MHz to 300 MHz, the primary challenges lie in achieving high-power transmission capability while minimizing the insertion loss (IL), reducing the physical dimensions, and meeting application [...] Read more.
For high-power magnetic resonance imaging (MRI) radio frequency (RF) combiners operating in the frequency range from 60 MHz to 300 MHz, the primary challenges lie in achieving high-power transmission capability while minimizing the insertion loss (IL), reducing the physical dimensions, and meeting application bandwidth requirements. This paper presents a high-performance RF power combiner based on capacitor-loaded microstrip technology for 3.0T MRI radio frequency power amplifier (RFPA) systems. The proposed combiner features low loss, high integration, and miniaturization, and it comprises multiple branches, each employing microstrip lines and capacitors in a series–parallel arrangement to achieve an impedance transformation of 50 Ω to 100 Ω. Each branch was designed through theoretical analysis and electromagnetic simulations to achieve a line length 30% shorter than λ/4, a 6.2 mm line width, and 0.08 dB IL at the 3.0T MRI operation frequency band. A two-way to one-way combiner was further designed using this branch structure to achieve 0.2 dB IL through simulation optimization. A four-way to one-way combiner was then constructed by cascading two-way combiners and optimized via ADS-HFSS software(ADS2014 HFSS19) co-simulation. The fabricated combiner module uses an FR4 substrate and achieves a 0.4 dB insertion loss, −25 dB return loss, and 25 dB port isolation at 128 MHz ± 1 MHz, with compact dimensions (320 × 200 × 10 mm). To ensure high power capability, thermal analysis was performed to confirm that the module’s power-handling capacity exceeded 8 kW, and experimental validation with the 8 kW 3.0T RFPA demonstrated a stable temperature rise of approximately 2 °C. In this study, the innovative single-branch topology and the RF high-power four-to-one combiner for 3.0T MRI systems were used, resolving the trade-offs between power-handling capability, insertion loss, structural compactness, and operating bandwidth in MRI power combiners. The combiner was successfully integrated into the 3.0T MRI RFPA system, reducing the overall dimensions of the RFPA system and simplifying its installation, thereby enabling high-quality imaging validation. This solution demonstrates the scalable potential of the design for other high-field MRI systems operating in the MHz range (from tens to hundreds of MHz), including in 1.5T and 7.0T MRI systems. Full article
(This article belongs to the Special Issue Advanced RF/MM-Wave Circuits Design and Applications)
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20 pages, 8249 KiB  
Article
A Wideband and High-Power RF Switching Design
by Xindong Huang, Chengying Chen and Shaokang Zhou
Sensors 2025, 25(10), 3209; https://doi.org/10.3390/s25103209 - 20 May 2025
Viewed by 547
Abstract
This paper presents an RF switch chip with a wide operating bandwidth from 6 to 18 GHz, designed for RF front-end applications in mobile communications. A series-parallel topology combined with a stacked transistor structure was employed to improve power handling while maintaining low [...] Read more.
This paper presents an RF switch chip with a wide operating bandwidth from 6 to 18 GHz, designed for RF front-end applications in mobile communications. A series-parallel topology combined with a stacked transistor structure was employed to improve power handling while maintaining low insertion loss and high isolation. To further optimize isolation and return loss, LC resonant circuits were introduced by utilizing off-state transistors as capacitive elements. Compared to existing designs, the proposed switch achieved an improved trade-off between bandwidth, power capacity, and port performance. Measurement results showed insertion loss below 1.917 dB, isolation above 38.839 dB, return loss better than 13.075 dB, and 1 dB input compression point above 32 dBm at 12 GHz, confirming the effectiveness and novelty of the broadband design. Full article
(This article belongs to the Section Electronic Sensors)
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25 pages, 4440 KiB  
Article
PWM–PFM Hybrid Control of Three-Port LLC Resonant Converter for DC Microgrids
by Yi Zhang, Xiangjie Liu, Jiamian Wang, Baojiang Wu, Feilong Liu and Junfeng Xie
Energies 2025, 18(10), 2615; https://doi.org/10.3390/en18102615 - 19 May 2025
Viewed by 542
Abstract
This article proposes a high-efficiency isolated three-port resonant converter for DC microgrids, combining a dual active bridge (DAB)–LLC topology with hybrid Pulse Width Modulat-Pulse Frequency Modulation (PWM-PFM) phase shift control. Specifically, the integration of a dual active bridge and LLC resonant structure with [...] Read more.
This article proposes a high-efficiency isolated three-port resonant converter for DC microgrids, combining a dual active bridge (DAB)–LLC topology with hybrid Pulse Width Modulat-Pulse Frequency Modulation (PWM-PFM) phase shift control. Specifically, the integration of a dual active bridge and LLC resonant structure with interleaved buck/boost stages eliminates cascaded conversion losses. Energy flows bidirectionally between ports via zero-voltage switching, achieving a 97.2% efficiency across 150–300 V input ranges, which is a 15% improvement over conventional cascaded designs. Also, an improved PWM-PFM shift control scheme dynamically allocates power between ports without altering switching frequency. By decoupling power regulation and leveraging resonant tank optimization, this strategy reduces control complexity while maintaining a ±2.5% voltage ripple under 20% load transients. Additionally, a switch-controlled capacitor network and frequency tuning enable resonant parameter adjustment, achieving a 1:2 voltage gain range without auxiliary circuits. It reduces cost penalties compared to dual-transformer solutions, making the topology viable for heterogeneous DC microgrids. Based on a detailed theoretical analysis, simulation and experimental results verify the effectiveness of the proposed concept. Full article
(This article belongs to the Section F3: Power Electronics)
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18 pages, 6756 KiB  
Article
An Isolated Resonant Voltage Balancing Charger of Series-Connected Lithium-Ion Batteries Based on Multi-Port Transformer
by Xifeng Xie, Chunjian Cai, Jianglin Nie, Shijie Jiao and Zeliang Shu
Electronics 2025, 14(9), 1861; https://doi.org/10.3390/electronics14091861 - 2 May 2025
Viewed by 398
Abstract
The inconsistency of individual lithium-ion batteries causes the voltage imbalance of the batteries. An effective voltage-balancing circuit is essential to improve the inconsistency of series-connected batteries. This paper presents an isolated resonant voltage-balancing circuit for series-connected lithium-ion batteries based on a multi-port transformer. [...] Read more.
The inconsistency of individual lithium-ion batteries causes the voltage imbalance of the batteries. An effective voltage-balancing circuit is essential to improve the inconsistency of series-connected batteries. This paper presents an isolated resonant voltage-balancing circuit for series-connected lithium-ion batteries based on a multi-port transformer. This circuit utilizes the multi-port transformer to enable free energy flow among the batteries. Without any direct transmission path between the capacitor and the battery string, it achieves full isolation between them. The resonant circuit is adopted to realize the soft-switching operation. Compared with other active balancing circuits, the proposed circuit requires only half a winding and one transistor per individual battery. Consequently, the proposed circuit enhances power density and further improves efficiency and reliability. Additionally, a fixed-group-number control strategy is introduced to enhance the circuit’s equalization voltage capabilities. Finally, a prototype of the voltage-balancing circuit for 24 series-connected lithium-ion batteries is established to verify the effectiveness and feasibility of the proposed circuit. Full article
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13 pages, 4750 KiB  
Article
Three-Dimensional Gel Dosimetry in a Simulated Postmastectomy with Expandable Prosthesis Radiotherapy
by Juliana Fernandes Pavoni, Jessica Caroline Lizar, Leandro Frederiche Borges, Patricia Nicolucci, Yanai Krutman and Oswaldo Baffa
Gels 2025, 11(5), 335; https://doi.org/10.3390/gels11050335 - 30 Apr 2025
Viewed by 692
Abstract
Postmastectomy radiation therapy (PMRT) is an adjuvant treatment for breast cancer. Some mastectomized women undergoing PMRT can have breast reconstruction with expander implant reconstruction. However, the expander implant contains a magnetic metal port for its inflation, and in patients with a high risk [...] Read more.
Postmastectomy radiation therapy (PMRT) is an adjuvant treatment for breast cancer. Some mastectomized women undergoing PMRT can have breast reconstruction with expander implant reconstruction. However, the expander implant contains a magnetic metal port for its inflation, and in patients with a high risk of recurrence, the PMRT is performed before the expander replacement. The difficulties in radiation treatment near high-Z metals are mainly due to dose alterations around them. Therefore, this study proposes using a realistic breast phantom and gel dosimetry to investigate the effects of the metallic parts of the expandable prosthesis on the 3D delivery of the treatment. A conformal radiation treatment was planned and delivered to the gel phantom with the metal port. MAGIC-f gel was used with magnetic resonance imaging for dose assessment. The treatment plan dose distribution was compared to the measured dose distribution by gamma analysis (3%/3 mm/15% threshold). A significant gamma fail region was found near the metal port, corresponding to a dose reduction of approximately 5%. This underdose is within the tolerance threshold for dose heterogeneity established by the International Commission on Radiation Units (ICRU), but should be considered when treating these patients. Full article
(This article belongs to the Special Issue Gel Dosimetry (2nd Edition))
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10 pages, 3458 KiB  
Communication
Sub-6 GHz GaAs SPDT Switch Co-Designed with Shunt Inductor for ESD Protection
by Jaehyun Kwon, Jaeyong Lee, Jinho Yoo, Taehun Kim and Changkun Park
Electronics 2025, 14(9), 1707; https://doi.org/10.3390/electronics14091707 - 23 Apr 2025
Viewed by 562
Abstract
In this study, a single-pole double-throw (SPDT) switch for Sub-6 GHz application is designed. In particular, a shunt inductor is connected to the antenna port of the switch for ESD (electrostatic discharge) protection in RF (radio frequency) front end module. The shunt inductor [...] Read more.
In this study, a single-pole double-throw (SPDT) switch for Sub-6 GHz application is designed. In particular, a shunt inductor is connected to the antenna port of the switch for ESD (electrostatic discharge) protection in RF (radio frequency) front end module. The shunt inductor not only serves as an ESD protection device, but also serves as a component of a parallel resonance circuit to suppress insertion loss of the switch. In addition, in order to secure the power handling capability, transistors turned off in the transmit (Tx) mode are implemented as quadruple-gate transistors. An SPDT switch is fabricated using GaAs pHEMT provided in the 500 nm GaAs BiFET process to verify the feasibility of the proposed switch structure. The operating frequency is set from 3 GHz to 5 GHz. The insertion loss and isolation measured in the Tx mode are lower than 0.35 dB and higher than 31.6 dB, respectively. The insertion loss and isolation measured in the Rx mode are lower than 0.32 dB and higher than 33.9 dB, respectively. The chip size including test pads is 0.890 × 0.875 mm2. Full article
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9 pages, 2086 KiB  
Article
Effective Enhancement for Printed Circuit Board Imaging in Near-Field Scanning Microwave Microscopy
by Tao Zhou, Quanxin Zhou, Hao Liu, Haoyun Liu, Zhe Wu, Jianlong Liu, Yubin Gong and Baoqing Zeng
Symmetry 2025, 17(4), 561; https://doi.org/10.3390/sym17040561 - 8 Apr 2025
Viewed by 505
Abstract
Near-field microwave microscopy (NSMM) is a promising technique for the non-destructive, high-resolution imaging of electrical and dielectric properties at the microscale. However, its performance is highly sensitive to the probe-to-sample distance, often requiring extremely close proximity, which limits its practical application in device [...] Read more.
Near-field microwave microscopy (NSMM) is a promising technique for the non-destructive, high-resolution imaging of electrical and dielectric properties at the microscale. However, its performance is highly sensitive to the probe-to-sample distance, often requiring extremely close proximity, which limits its practical application in device manufacturing, especially in scenarios involving coatings and packaging. In this study, we propose a distance inversion method based on a dual-port symmetrical microwave probe to improve imaging performance at larger, safer scanning distances. This method utilizes the correlation between probe height and resonant frequency to compensate for distance-induced signal distortions. The experimental results demonstrate that even at a probe–sample distance of 80 µm, clear and distinguishable NSMM images of printed circuit boards (PCBs) can be obtained. The imaging resolution reached 13 µm. The defect structure with dimensions of 130 × 130 µm2 on the PCB was successfully identified. The signal-to-noise ratio was significantly enhanced after applying the correction method. This approach not only improves the robustness and flexibility of NSMM in industrial scenarios but also extends its applicability to packaged or coated electronic devices, offering a valuable tool for advanced non-destructive testing. Full article
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14 pages, 4110 KiB  
Review
Sturge–Weber Syndrome: A Narrative Review of Clinical Presentation and Updates on Management
by Aarnav D. Shah, Peter Alexieff and Priyamvada Tatachar
J. Clin. Med. 2025, 14(7), 2182; https://doi.org/10.3390/jcm14072182 - 22 Mar 2025
Cited by 1 | Viewed by 2239
Abstract
Sturge–Weber Syndrome (SWS) is a rare neurocutaneous disorder caused by a somatic nonsynonymous mosaic mutation most commonly in the GNAQ gene (G protein guanine Nucleotide-binding protein Alpha subunit q). SWS is characterized by capillary-venous malformations in the brain and eyes and a characteristic [...] Read more.
Sturge–Weber Syndrome (SWS) is a rare neurocutaneous disorder caused by a somatic nonsynonymous mosaic mutation most commonly in the GNAQ gene (G protein guanine Nucleotide-binding protein Alpha subunit q). SWS is characterized by capillary-venous malformations in the brain and eyes and a characteristic facial port wine (PW) birthmark (previously called port wine stain/PWS) in the head/neck region. Clinical manifestations vary and include epilepsy, stroke-like episodes, migraine headaches, cognitive delays, glaucoma, ocular vascular anomalies, heterochromia of the iris, visual field defects, and endocrine disorders like growth hormone deficiency or central hypothyroidism. The pathognomonic findings seen in neuroimaging with magnetic resonance imaging (MRI) include the presence of unilateral intracranial leptomeningeal angiomatosis, typically ipsilateral to the facial birthmark. SWS does not currently have a definitive cure, and management strategies focus on symptomatic management such as anti-seizure medications, limited surgical resection of the epileptogenic tissue or hemispherectomy for cases of drug-resistant epilepsy (DRE), selective photo-thermolysis of the PWS using a pulsed dye laser, and the medical and/or surgical management of glaucoma. In addition to these symptomatic treatments, the use of preventive, modifying, or stabilizing treatments like low-dose aspirin in reducing the frequency and severity of seizures and stroke-like events and the use of newer therapies like cannabidiols and mTOR inhibitors are being reviewed and have shown promising early results. This comprehensive narrative review summarizes the current literature on clinical management strategies, ongoing research studies, and future directions in the diagnosis and management of SWS. Full article
(This article belongs to the Section Clinical Neurology)
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11 pages, 2654 KiB  
Article
Design of a High Coupling SAW Resonator Based on an Al/41° Y-X LiNbO3/SiO2/poly-Si/Si Structure for Wideband Filter
by Xiaoyu Wang, Yang Chang, Qiaozhen Zhang, Luyao Liu, Xinyi Wang and Haodong Wu
Micromachines 2025, 16(3), 323; https://doi.org/10.3390/mi16030323 - 11 Mar 2025
Cited by 1 | Viewed by 708
Abstract
With the rapid development of fifth-generation (5G) mobile communication technology, the performance requirements for radio frequency front-end surface acoustic wave (SAW) devices have become increasingly stringent. Surface acoustic wave devices on piezoelectric thin film-based layered structures with high electromechanical coupling coefficients and low-frequency [...] Read more.
With the rapid development of fifth-generation (5G) mobile communication technology, the performance requirements for radio frequency front-end surface acoustic wave (SAW) devices have become increasingly stringent. Surface acoustic wave devices on piezoelectric thin film-based layered structures with high electromechanical coupling coefficients and low-frequency temperature compensation characteristics have emerged as a key solution. In this work, a SAW resonator based on an Al/41° Y-X LiNbO3/SiO2/poly-Si/Si multi-layered structure is proposed. FEM modeling of the proposed resonator and the influences of the thicknesses of the LiNbO3, SiO2, and Al electrodes on performances such as the parasitic noise, bandwidth, and electromechanical coupling coefficient are analyzed. Optimal parameters for the multi-layer piezoelectric structure are identified for offering large coupling up to 24%. Based on these findings, a single-port SAW resonator with an Al/41° Y-X LiNbO3/SiO2/poly-Si/Si substrate structure is fabricated. The experimental results align well with the simulation results; meanwhile, the SAW filter based on the proposed resonator demonstrates that a center frequency of 2.3 GHz, a 3-dB fractional bandwidth of 23.48%, and a minimum in-band insertion loss of only 0.343 dB are simultaneously achieved. This study provides guidance for the development of multi-layer film SAW resonator-based filters with high-performance. Full article
(This article belongs to the Section A:Physics)
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13 pages, 3936 KiB  
Communication
Study on Vibration Characteristics of Functionally Graded Material Composite Spherical Piezoelectric Transducer
by Sha Wang and Junjie Shan
Sensors 2025, 25(5), 1514; https://doi.org/10.3390/s25051514 - 28 Feb 2025
Viewed by 714
Abstract
Non-uniform composite structures for transducers exhibit considerable potential in enhancing impedance matching and efficiency. Here, a functionally graded material composite spherical piezoelectric transducer (FGM-cSPT) is proposed, and a three-port electromechanical equivalent circuit model is established. The correctness of the theoretical model is verified [...] Read more.
Non-uniform composite structures for transducers exhibit considerable potential in enhancing impedance matching and efficiency. Here, a functionally graded material composite spherical piezoelectric transducer (FGM-cSPT) is proposed, and a three-port electromechanical equivalent circuit model is established. The correctness of the theoretical model is verified using the finite element method and experiment. Based on the theoretical model, the effects of the non-uniform coefficient and the geometric dimension of FGM-cSPT on the electromechanical vibration characteristics (resonance frequency, anti-resonance frequency, and effective electromechanical coupling coefficient) of the transducer are analyzed. The results show that the non-uniform coefficient and geometric dimension can effectively regulate the vibration characteristics of the FGM-cSPT, which can be used to guide engineering design. Our methodology will offer possibilities for designing FGM-cSPTs and may promote applications in various fields, such as marine exploitation, structural health detection, and energy collection. Full article
(This article belongs to the Section Electronic Sensors)
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18 pages, 5276 KiB  
Article
The Pore Structure Characteristics of Mortar and Its Application in the Study of Chloride Ion Transport Performance
by Zhidan Rong, Hanliang Ouyang, Yun Gao and Hao Chen
Buildings 2025, 15(3), 383; https://doi.org/10.3390/buildings15030383 - 26 Jan 2025
Cited by 2 | Viewed by 879
Abstract
The cement-based materials widely used in infrastructure construction, such as bridges and ports, are subjected to seawater erosion and medium erosion during their service life, and their durability has always been a concern. The diffusion coefficient of chloride ions is an important indicator [...] Read more.
The cement-based materials widely used in infrastructure construction, such as bridges and ports, are subjected to seawater erosion and medium erosion during their service life, and their durability has always been a concern. The diffusion coefficient of chloride ions is an important indicator in the research of cement-based materials’ durability, and the pore structure is one of the most fundamental reasons affecting the diffusion behavior of chloride ions. In this paper, Mercury intrusion porosimetry (MIP), Nuclear magnetic resonance (NMR), and Nitrogen adsorption method (NAD) were used to analyze the pore structures of mortars with different volume fractions of sands. The relationship between mortar pore structure and chloride ion diffusion coefficient was established to predict its chloride ion diffusion coefficient. It may provide a new idea for studying the durability of cement-based materials. Results indicated that similar to cement paste, the pore structure of mortar satisfied the fractal characteristics of solid phase within a certain range of pores. The most probable gel pore diameter of mortars with different sand volume fractions was about 4 nm, while the most probable capillary pore diameter was approximately 46 nm, and the critical pore diameter was ranging from 50 to 60 nm. MIP results indicated that with the increase in sand volume fraction (ϕagg), the total porosity (fmip) of the mortar decreased, satisfying the relationship of fmip = 0.1859 − 0.0789ϕagg. However, the porosity of the matrix (fbase) increased with the increase in sand volume fraction, which was due to the introduction of more interfaces by the addition of aggregates. The effective chloride ion diffusion coefficient (Dcp,base) of the matrix can be obtained by fitting. Based on this, the interface transition zone (ITZ) and the cement matrix were comprehensively considered as a whole fractal phase. The predicted value of the chloride ion diffusion coefficient obtained by the Mori–Tanaka homogenization method was in good agreement with the results obtained from rapid chloride migration (RCM) experiments, and the maximum error between the simulated and experimental values did not exceed 11%. This finding can provide new ideas for accurately predicting the chloride ion diffusion coefficient of mortar and even concrete. Full article
(This article belongs to the Special Issue Research on the Mechanical and Durability Properties of Concrete)
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12 pages, 4233 KiB  
Article
Theoretical Investigation of Terahertz Spoof Surface-Plasmon-Polariton Devices Based on Ring Resonators
by Can Liu, Shenghao Gu, Mingming Sun, Ya Liu, Ying Zhang and Jiaguang Han
Photonics 2025, 12(1), 70; https://doi.org/10.3390/photonics12010070 - 15 Jan 2025
Viewed by 1111
Abstract
Terahertz is one of the most promising technologies for high-speed communication and large-scale data transmission. As a classical optical component, ring resonators are extensively utilized in the design of band-pass and frequency-selective devices across various wavebands, owing to their unique characteristics, including optical [...] Read more.
Terahertz is one of the most promising technologies for high-speed communication and large-scale data transmission. As a classical optical component, ring resonators are extensively utilized in the design of band-pass and frequency-selective devices across various wavebands, owing to their unique characteristics, including optical comb generation, compactness, and low manufacturing cost. While substantial progress has been made in the study of ring resonators, their application in terahertz surface wave systems remains less than fully optimized. This paper presents several spoof surface plasmon polariton-based devices, which were realized using ring resonators at terahertz frequencies. The influence of both the radius of the ring resonator and the width of the waveguide coupling gap on the coupling coefficient are investigated. The band-stop filters based on the cascaded ring resonator exhibit a 0.005 THz broader frequency bandwidth compared to the single-ring resonator filter and achieve a minimum stopband attenuation of 28 dB. The add–drop multiplexers based on the asymmetric ring resonator enable selective surface wave outputs at different ports by rotating the ring resonator. The devices designed in this study offer valuable insights for the development of on-chip terahertz components. Full article
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9 pages, 4231 KiB  
Communication
A Low-Profile Balanced Dielectric Resonator Filtering Power Divider with Isolation
by Rong Cai, Chuan Shao and Kai Xu
Micromachines 2025, 16(1), 88; https://doi.org/10.3390/mi16010088 - 14 Jan 2025
Cited by 1 | Viewed by 834
Abstract
A balanced dielectric resonator filtering power divider with isolation performance is proposed. By using the coupling of the TE111y modes between three rectangle dielectric resonators, combined with balanced feed structures, the differential-mode filtering and power dividing functions, as well as [...] Read more.
A balanced dielectric resonator filtering power divider with isolation performance is proposed. By using the coupling of the TE111y modes between three rectangle dielectric resonators, combined with balanced feed structures, the differential-mode filtering and power dividing functions, as well as the common-mode suppression were achieved effectively. Additionally, by technically utilizing the hollow structure of the stacked substrates, isolation resistor structures are introduced at the two output ports to improve the isolation level of the power divider. It can solve the problem of traditional metal-cavity dielectric resonator filter power dividers being unable to add isolation structures due to structural reasons. Compared with the reported dielectric resonator filtering power dividers, the proposed one has the characters of a lower profile and high isolation. For demonstration, one dielectric resonator filtering power divider was fabricated and measured at 11.65 GHz with the profile of 0.66 λg and an isolation higher than 15 dB. The simulation results are in good agreement with the measured results. Full article
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