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[IEEE 2017 IEEE HISTory of ELectrotechnolgy CONference (HISTELCON) - Kobe, Japan (2017.8.7-2017.8.8)] 2017 IEEE HISTory of ELectrotechnolgy CONference (HISTELCON) - Principle of Self-Complementarity and Application to Broadband Antennas
摘要： Theory of self-complementarity which was derived through an investigation of the input impedance of slot antennas with arbitrary shape is described. Examples of self-complementary antennas, modified self-complementary antennas, and their application are presented. It is pointed out that the self-complementarity is very important to obtain the wide frequency band.
关键词： broadband antenna,self-complementary antenna,constant impedance antenna,wireless broadband
更新于2025-09-10 09:29:36
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Non-linearity Enhances Versatility of Non-Foster Metamaterials and Metasurfaces
摘要： Classical applications of non-Foster elements such as broadband active metamaterials/metasurfaces and broadband matching of small antennas presume their linearity. Here, we show that two well-known types of negative impedance converters - the voltage-conversion type and the current-conversion type, show fundamentally different behavior in non-liner regime. It is followed by different power-dependent properties of generated positive/negative susceptance/reactance. This effect may be used in future self-oscillating and self-mixing metasurfaces as well as in power-tunable metamaterials/metasurfaces.
关键词： negative impedance converters,non-linearity,metamaterials,non-Foster elements,metasurfaces
更新于2025-09-10 09:29:36
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Reduction of the beam-coupling impedance in accelerating structures using metamaterial-based absorbers
摘要： Resistive-wall impedance constitutes a significant percentage of the total beam-coupling impedance budget of an accelerator. Under extreme conditions, like large power handling and ultra-high vacuum, metamaterial-based absorbers can represent a valid alternative to other approaches for impedance mitigation in specific accelerator components, like resonant (parasitic) cavities or collimators operating along the beam line. We design sub-wavelength 2D metallic resonant structures based on split rings or on 3D hyperbolic tapered waveguide arrays that can be employed as mode dampers in accelerating structures. A number of prototypes are fabricated and then measured in a “test model” pillbox cavity.
关键词： accelerators,hyperbolic metamaterials,metamaterials,beam-coupling impedance,split-ring resonators
更新于2025-09-10 09:29:36
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OPTIMIZATION OF MICROMACHINED MILLIMETER-WAVE PLANAR SILICON LENS ANTENNAS WITH CONCENTRIC AND SHIFTED MATCHING REGIONS
摘要： This paper presents a study of planar silicon lens antennas with up to three stepped-impedance matching regions. The e?ective permittivity of the matching regions is tailor-made by etching periodic holes in the silicon substrate. The optimal thickness and permittivity of the matching regions were determined by numerical optimization to obtain the maximum wideband aperture e?ciency and smallest side-lobes. We introduce a new geometry for the matching regions, referred to as shifted matching regions. The simulation results indicate that using three shifted matching regions results in twice as large aperture e?ciency as compared to using three conventional concentric matching regions. By increasing the number of matching regions from one to three, the band-averaged gain is increased by 0.3 dB when using concentric matching regions, and by 3.7 dB when using shifted matching regions, which illustrates the advantage of the proposed shifted matching region design.
关键词： side-lobes,planar silicon lens antennas,shifted matching regions,aperture efficiency,stepped-impedance matching regions
更新于2025-09-10 09:29:36
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AIP Conference Proceedings [AIP Publishing LLC 41ST ANNUAL REVIEW OF PROGRESS IN QUANTITATIVE NONDESTRUCTIVE EVALUATION: Volume 34 - Boise, Idaho (20–25 July 2014)] - Feasibility of PZT ceramics for impact damage detection in composite structures
摘要： Fiber reinforced plastic composites are becoming widely used in vehicles and airframe structures due to their high strength to weight ratio. However unlike metals, the multilayered composite structures are more susceptible to damage mechanisms such as disbonds and delaminations due to impacts. It is often dif?cult to visually detect the damage. Lead-Zirconate-Titanate (PZT) thin ?lms are becoming popular for in-situ structural health monitoring due to their small size, high piezoelectric coupling coef?cient, and ease of surface-mounting and/or embedding in composite structures. A network of such transducers could be utilized for damage detection using guided wave techniques, impedance techniques, or passive impact detection techniques. However, the PZT ?lms are subject to the same impact probabilities that the structure encounters. If the transducers fail due to the subjected impacts, they can result in false readings and ultimately failing to correctly detect damage in the structure. This paper presents a feasibility study using the guided wave S0 mode for detecting impact damage. The health of the structure is quanti?ed using guided wave measurements, and the PZT health is monitored using impedance methods.
关键词： impact damage detection,impedance techniques,PZT ceramics,composite structures,guided wave techniques
更新于2025-09-10 09:29:36
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Study of complex impedance spectroscopic properties of La <sub/> 0.7? <i>x</i> </sub> Dy <i> <sub/>x</sub></i> Sr <sub/>0.3</sub> MnO <sub/>3</sub> perovskite oxides
摘要： The dysprosium perovskite La0.72xDyxSr0.3MnO3 [LSMO] and 0.03 [LDSMO]) compounds were prepared by the sol–gel reaction and characterized by the X-ray diffraction technique. The electrical conductivity and modulus characteristics of the system have been investigated in the temperature and the frequency range 311–356 K and 209–5 (cid:2) 107 Hz, respectively, by means of impedance spectroscopy. The ac and dc conductivities were studied to explore the mechanisms of conduction of LSMO and LDSMO. The insertion of a small amount of Dy3t in the La-site of LSMO perovskite oxide increases the value of the activation energy from 0.2106 to 0.5357 eV and enhances electrical resistivity values for almost two orders of magnitude.
关键词： the non-overlapping small polaron tunneling,impedance spectroscopy,correlated barrier hopping,modulus,ac conductivity
更新于2025-09-10 09:29:36
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Beyond the Bode-Fano Bound: Wideband Impedance Matching for Short Pulses Using Temporal Switching of Transmission-Line Parameters
摘要： Impedance matching is one of the most important practices in wave engineering as it enables one to maximize the power transfer from the signal source to the load in the wave system. Unfortunately, it is bounded by the Bode-Fano criterion which states that, for any passive, linear, and time-invariant matching network, there is a stringent trade-off between the matching bandwidth and efficiency, implying severe constraints on various electromagnetic and acoustic wave systems. Here, we propose a matching paradigm that overcomes this issue by using a temporal switching of the parameters of a metamaterial-based transmission line, thus revoking the time-invariance assumption underlying the Bode-Fano criterion. Using this scheme we show theoretically that an efficient wideband matching, beyond the Bode-Fano bound, can be achieved for short-time pulses in challenging cases of very high contrast between the load and the generator impedances, and with significant load dispersion, situations common in, e.g., small antenna matching, cloaking, and with applications for ultrawideband communication, high resolution imaging, and more.
关键词： Bode-Fano criterion,wideband matching,metamaterial,transmission line,Impedance matching
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Development of AC Quantum Hall Measurements at CMI
摘要： This paper describes results and equipment involved in experiments with realization of quantum impedance standard, based on ac quantum Hall resistance standard. CMI developed cryogenic probe with TO-8 holder and coaxial wiring, device holder and digitally assisted (DA) bridge suitable for ac measurements of quantum Hall effect. Experiments were performed at liquid helium temperatures with GaAs devices placed in double shielded holders.
关键词： traceability,quantum Hall effect,standards,electrical impedance
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Progress on a New Measurement of von Klitzing Constant at NIM
摘要： This paper describes the progress on a new measurement of von Klitzing constant (Rk) through an experiment linking the new calculable capacitor and the quantized Hall resistance by means of a quadrature transfer at NIM. The recent improvements of the new calculable capacitor, the optical interferometry, the impedance measurement chain are presented.
关键词： von Klitzing constant,optical interferometry,bridge circuits,Calculable capacitor,impedance measurement,measurement standards
更新于2025-09-10 09:29:36
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Current Comparator Based Current Divider
摘要： The paper describes a current divider (or splitter), i.e., a device that allows the splitting of an alternating current (ac) in two parts in a precise and accurate current ratio. It is based on current comparator techniques so that precise current ratios can be attained with ratio errors bearing parts in 106 to 109. A binary current divider can be made virtually exact (i.e., with unitary current ratio errors of the order of some 10-9 only), if aided by electronic flux error compensation. Further, coupled transmission lines modeling can assess its current ratio errors over frequency. A current divider finds application in many areas of ac metrology as in highly accurate impedance bridges and current measurements.
关键词： Circuit and systems,current measurement,measurement uncertainty,measurement techniques,impedance measurement,current mode circuits
更新于2025-09-10 09:29:36