bluuebunny/crossref_metadata_2025_split huggingface dataset:
Propagation of electromagnetic waves generated by modulated moving source in dispersive lossy media
Authors: Burlak G. , Rabinovich V. 
Published: June 2014

AbstractWe apply the complex two‐dimensional stationary‐phase method for problems of electromagnetic waves radiation from the moving modulated sources in dispersive and lossy medium. The explicit formulas for fields generated by a moving source, the Doppler effect, and the retarded time are obtained. We apply the developed approach to numerical study of the Cherenkov radiation in a dispersive medium (Drude model). Our simulations have shown that in double negative dispersive metamaterials, the Cherenkov cone splits in two branches. Copyright © 2014 John Wiley & Sons, Ltd.
Measurement of thin film composites using microstrip line fixtures
Authors: Nguyen Phuong Minh , Chung Jae‐Young 
Published: June 2014

ABSTRACTWe present a technique to measure the material parameters of a thin film composite over a broad frequency range (50 MHz to 2.5 GHz). Two different microstrip line fixtures are prepared for the in‐plane permittivity and permeability measurements, respectively, and their geometries are optimized to uniformly excite the E‐field and H‐field on the film surface. With this, broadband S‐parameter responses of the film can be captured and used in the material parameter retrieval process. The latter is based on the well‐known Nicolson–Ross–Weir equations in conjunction with curve fitting a set of full‐wave simulation data. A patterned magnetic film composite with thin (150 µm) and small (1 × 1 cm2) form factor is characterized using the proposed method. The measurement results demonstrate a constant in‐plane permittivity but a dispersive in‐plane permeability over the target frequency range. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2071–2074, 2014
An eye‐opening measurement circuit for a feed‐forward equalizer
Authors: Arigong Bayaner , Zhang Hualiang , Yoon Sangwoog , Jung Sungyong , Kim Hyoungsoo 
Published: June 2014

ABSTRACTAn eye‐opening measurement circuit provides information about the signal quality of the high‐speed data through the band‐limited channel. Thus this information can be used to evaluate the channel performance, especially when the communication environments are changing constantly. By implementing this as a system‐on‐a chip, it is possible to realize the reconfigurable system such as an adaptable feed‐forward equalizer, which will adapt itself through the changes of the communication channel. Moreover, the highly integrated single‐chip eye‐opening monitoring block can achieve more efficient and cost‐effective communication chip test. In this article, we propose a new eye‐opening measurement circuit, which can work up to 10 GHz. Using the fall time and rise time of the signal, which are affected by intersymbol interference, the corresponding characteristic is converted to DC values to assess the channel performance. The proposed eye‐opening measurement circuit and tunable delay line are fabricated in 0.18‐µm CMOS technology. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2136–2141, 2014
Fabrication and measurement of a monopole antenna with three arc‐shaped strips for WLAN/WiMAX applications
Authors: Yoon Joong Han 
Published: June 2014

ABSTRACTIn this article, a novel, compact, printed antenna is applied to simultaneous wireless local area network (WLAN)/Worldwide Interoperability of Microwave Access (WiMAX) applications. The proposed antenna is composed of three arc‐shaped monopole strips and a rectangular ground plane. The three arc‐shaped strips of the antenna generate three desired resonate frequencies and exhibit relative independence while being tuned separately. Based on the concept, a prototype of the proposed triple‐band antenna is designed, fabricated, and tested. The numerical and experiment results demonstrated that the proposed antenna satisfied the −10 dB impedance bandwidth requirement (467.5 MHz for the 2.4/2.5 GHz bands, from 2.23 to 2.6975 GHz; 857.5 MHz for the 3.5 GHz bands, from 3.3975 to 4.255 GHz; 2,012.5 MHz for the 5 GHz bands, from 5.06 to 7.0725 GHz), while simultaneously covering the WLAN and WiMAX bands. The proposed triple band antenna achieves omnidirectional radiation patterns at all three frequency bands with an antenna peak gain of 4.68 dBi for the lowest band, 2.74 dBi for the middle band, and 3.11 dBi for the highest band. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2061–2066, 2014
Microstrip lowpass–highpass diplexer for a quadplexer application
Authors: Jung Minjae , Min Byung‐Wook 
Published: June 2014

ABSTRACTA microstrip low‐loss diplexer is designed based on a lowpass and highpass Chebyshev filter configuration and combined with two duplexers for a quadplexer application. A 50‐Ω transmission line is added to the lowpass filter to have a high impedance at the highpass frequency band, resulting in low loss and high isolation. To minimize size of the diplexer, high impedance meander lines, interdigitated capacitors, and stepped impedance transmission lines are used. The proposed diplexer has the isolation higher than 41 dB with the insertion loss less than 1.6 dB at the designed frequencies. The designed quadplexer has a good transmission performances at all four frequency bands, and can be used for a dual‐band frequency division multiplexing system with a dual‐band/broadband antenna. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2026–2028, 2014
Direct conversion Doppler radar vital sign detection system using power management technique
Authors: Lee Chie‐In , Lin Yan‐Ting , Chen Jhih‐Jie , Lin Wei‐Cheng 
Published: June 2014

ABSTRACTThis article is the first to present a low power consumption direct conversion Doppler radar vital sign detection system using a power management technique to detect biomedical signals. The optimal pulse bias with simultaneous switching noise considered was designed to decrease power consumption of the sensor. A noncontact vital sign detection measurement using the optimal pulse bias was performed on a human subject. Based on experimental results, the presented simple and low power system can accurately detect human cardiopulmonary activity, including respiration and heartbeat. Calculated physiological signal amplitudes based on a spectral analysis validates the detection result from presented work. When compared with the sensor using a power amplifier, the proposed sensor can achieve low power dissipation for biomedical monitoring and green energy applications. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2167–2174, 2014
Implementation of cross couplings in microwave bandpass filters
Authors: Belyaev B. A. , Serzhantov A. M. , Bal'va Y. F. , Tyurnev V. V. , Leksikov A. A. , Galeev R. G. 
Published: June 2014

ABSTRACTNew quasi‐lumped resonator bandpass filters with cross couplings are presented. Coaxial and suspended stripline structures are considered. These filters are notable for their extremely wide and deep upper stopbands at small dimensions. They also have transmission zeros near the passband that significantly improve frequency selectivity. Photographs and measured frequency responses for the four fabricated filters are presented. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2021–2025, 2014
Compact ultra‐wideband bandpass filter using quad‐T‐stub‐loaded ring structure
Authors: Xu Kai‐Da , Zhang Yong‐Hong , Li Joshua Le‐Wei , Joines William T. , Liu Qing Huo 
Published: June 2014

ABSTRACTA compact ultrawideband (UWB) planar bandpass filter (BPF) using quad‐T‐stub‐loaded ring resonator is presented. At this filter, two sets of the four high impedance lines at the two sides of the ring as the coupling fed structure are used to gain much stronger coupling effect. Compared with the conventional ring resonator filter, the bandwidth of the UWB BPF can be improved after we load four T‐shaped stubs on the ring resonator. That is because these stubs can increase the effective electrical lengths, and also lower the second and third resonant frequencies of the ring resonator at no expense of the size increase. Finally, a prototype of the proposed UWB BPF with 3 dB fractional bandwidth of 101% has been designed and fabricated. The measured results are in good agreement with the full‐wave simulations. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1988–1991, 2014
Analysis and design of a compact ultrawideband LNA with 2.3 ± 0.1 dB NF and ±14.6 ps group‐delay‐variation in 0.18‐µm CMOS
Authors: Lin Yo‐Sheng , Wang Chien‐Chin , Lee Guan‐Lin , Wang Chiu‐Hsuan 
Published: June 2014

ABSTRACTA low‐noise figure (NF) and high power gain (S21) 3–10 GHz ultrawideband low‐noise amplifier (UWB LNA) with excellent phase linearity using standard 0.18‐µm CMOS technology is reported. An enhanced π‐match input network is used to achieve wideband input impedance matching. Both high and flat S21 and low and flat NF frequency responses are achieved by tuning the pole frequencies and pole quality factors of the second‐order gain and NF frequency responses to approximate the maximally flat condition simultaneously. The LNA consumes 18 mW, achieving S11 better than −10 dB for frequency lower than 12.2 GHz and group‐delay‐variation smaller than ±14.6 ps for frequencies 3–10 GHz. Additionally, high and flat S21 of 13.7 ± 1.5 dB is achieved for frequencies 1–12.5 GHz, which means the corresponding 3‐dB bandwidth is 11.5 GHz. Furthermore, the LNA achieves minimum NF of 2.2 dB at 4 GHz and NF of 2.3 ± 0.1 dB for frequencies 3–10 GHz, one of the best NF results ever reported for a 3–10 GHz CMOS UWB LNA. The measured input third‐order intermodulation point (IIP3) is −0.2 dBm at 6 GHz. The chip area is only 0.601 × 0.662 mm2 (i.e., 0.4 mm2) excluding the test pads. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2047–2053, 2014
Ultrabroadband balun with 1:4 impedance transformation ratio using transmission‐line transformers
Authors: Lee H. , Gu J. , Kwon J. , Seo M. , Ham J. , Kim H. , Yang Y. 
Published: June 2014

ABSTRACTThis article presents an ultrabroadband balun with 1:4 impedance transformation ratio using transmission‐line transformers. The proposed ultrabroadband balun consists of one 1:1 transmission‐line transformer as a balun and two 1:4 transmission‐line transformers for impedance transformation. Each transmission‐line transformer is based on a coaxial line, which is wound around a ferrite core to extend the bandwidth to the lower frequency region. Experimentally optimized offset transmission lines are used to compensate for the phase imbalance characteristics at the high frequency band. The implemented ultrabroadband balun operates from 300 kHz to 400 MHz with a return loss of below 12 dB and an insertion loss of less than 1 dB. The magnitude and phase imbalance for the balanced signal output are both less than 0.5 dB and 2.0°, respectively. An outstanding relative bandwidth (the ratio of the highest frequency to the lowest frequency in the operational band) of 1330 was achieved. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1974–1978, 2014
Design of 64‐mA laser diode drive amplifier for 2.4‐GHz radio‐over‐fiber transmission systems
Authors: Hu Zhengfei , Chen Yingmei , Huang Mindi 
Published: June 2014

ABSTRACTThis article presented the design of a large drive current laser diode amplifier for 2.4‐GHz radio‐over‐fiber transmission systems in TSMC 0.18‐µm CMOS technology. The proposed drive amplifier adopted a single‐ended two‐stage amplifier structure with the operating voltages of 1.8 and 3.6 V. The technique of dynamic bias is used to enhance linearity. The measurement results show that the linear amplifier achieves the power gain of 16.9 dB, the output 1‐dB compression point of 20.1 dBm at 2.4 GHz. The maximum output modulation current is up to 64 mA. The components are all on chip including the input and output matching network, and the total chip area is 1.0 × 0.73 mm2. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1971–1974, 2014
UWB antenna size reduction methods using fractal, matrix, and serrated structures
Authors: Bounif Anis , Desmarais Alexandre , Nabki Frederic , Deslandes Dominic 
Published: June 2014

ABSTRACTFour ultrawideband monopole antennas exploiting periodicity to reduce their size are presented. Experimental results are also discussed for these antennas. The first antenna uses a fractal topology based on a hexagonal pattern. It achieves a bandwidth of 8.85 GHz from 3.65 to 12.5 GHz with a 14 × 16.52 mm2 footprint. The second antenna uses an electric‐magnetic‐electric matrix and provides a 7 GHz bandwidth from 3.5 to 10.5 GHz with a 14 × 15.9 mm2 footprint. Two antennas based on a serrated structure which reduces the surface up to 15% are also presented with dimensions of 15 × 16.3 mm2: the first one covers a bandwidth of 3.5 to 11.73 GHz, whereas the second adds a notch between 5.15 to 5.825 GHz to reject the wireless LAN band. All these antennas can be incorporated into very small communication modules while maintaining excellent performances with a return loss below −10 dB and with a good multidirectional radiation pattern. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2038–2044, 2014
Analysis of lumped element periodically loaded vertical wire grid frequency selective surfaces
Authors: Mias Christos , Freni Angelo 
Published: June 2014

ABSTRACTWe report how the Wait's formulation for periodically loaded wire grids can be used to analyze bandstop lumped element periodically loaded vertical wire grid frequency selective surfaces. In particular, a novel exact analytical expression for the harmonic currents is derived in the case of a lumped element of infinitesimal length. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2075–2078, 2014
How nonreciprocal is an effective permittivity matrix?
Authors: Valagiannopoulos Constantinos A. 
Published: June 2014

ABSTRACTThe property of nonreciprocity in electromagnetic structures is a pivotal feature when designing useful devices such as directional phase shifters, circulators, isolators, and gyrators. The performance of these components is judged by the “nonreciprocity index,” indicating the degree of nonreciprocity. In this work, we consider a slab filled with a homogeneous anisotropic medium with an arbitrary and full permittivity matrix. The scattering parameters of the formulated four‐port network are analytically evaluated and a “nonreciprocity index” is defined. The variations of this function with respect to the complex elements of the effective permittivity matrix are shown and general conclusions are drawn. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2018–2021, 2014
A high gain broadband circular patch antenna with spiral‐shaped slot‐loaded modified ground plane
Authors: Mondal Kalyan , Sarkar Partha P. 
Published: June 2014

ABSTRACTA high gain broadband circular microstrip patch antenna with spiral shape slot‐loaded square ground plane is presented. The effects of introduction of spiral shaped slots of the square ground plane on different parameters of the antenna are studied. Maximum impedance bandwidth of 123% is obtained with modified square ground plane of size 60 × 60 mm. Highest gain achieved is 6 dBi. Simultaneously, the antenna also exhibits a compactness of 93%. The simulated results are confirmed experimentally. The proposed antenna is simple in structure and may be widely used in wireless communications. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2044–2046, 2014
A compact antenna for 4G mobile handset
Authors: Jiu‐Sheng Li , Di Wu 
Published: June 2014

ABSTRACTIn this article, we propose a compact antenna using S‐shaped shorted strip and inverted L‐shaped shorted strip for 4G mobile handset. The measured impedance bandwidth defined by VSWR < 3 of 750 MHz (0.66–0.81 GHz), 2.6 GHz (2.25–2.85 GHz) and 3.5 GHz (3.28–3.97 GHz) are obtained, with the peak gains of 3.0/4.7/3.6 dBi. The presented antenna has a small size of only 21 × 15 mm2 and demonstrates omnidirectional radiation patterns, which show good performance for 4G application. The measured results are in agreement with the simulation. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2199–2203, 2014
Gain enhancement and broadband using helical resonating metamaterial superstrate in stacked microstrip patch antenna
Authors: Mendhe Shridhar E. , Kosta Y. P. 
Published: June 2014

ABSTRACTMetamaterial superstrate performs unique electromagnetic properties which are used in antenna design. In this article, a novel design of stacked with parasitic element multilayer rectangular microstrip patch antenna using single layer single turn helical resonator based on metamaterial superstrate is presented. The return loss, smith chart, impedance, radiation pattern, gain, VSWR, and directivity of such an antenna are studied. The possibility of increasing bandwidth, gain and directivity of the printed patch antenna using metamaterial superstrate is examined and verified with the realized antenna. The analysis of reduction in the size of helical resonator is given and it is found that maximum reduction in size is obtained at a metallic fill ratio of 0.2. The stacked antenna is realized and successfully tested and verified measured results with the simulated results. Investigation is performed related to gain enhance using metamaterial. Percentage bandwidth of antenna is approximately 64.84% with constant gain in specified bandwidth with good cross‐polarization. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1978–1982, 2014
Polarization properties of a 2‐D split ring resonator and rod type metamaterial lens
Authors: McGillivray Duncan A. , Cravey Robin L. , Dudley Kenneth L. , Vedeler Erik , Gupta Mool C. 
Published: June 2014

ABSTRACTThe polarization state of microwave (MW) radiation transmitted through a 2‐D split ring resonator and rod metamaterial (MTM) lens is investigated. At a resonance frequency of 3.63 GHz, the 2‐D lens modifies the polarization state of the incident radiation. For Ey incident polarization, the transmitted wave exhibits elliptical polarization as well as a tilt in the principal axis. The ellipticity is dependent on the incident polarization angle. A Ex polarized incident MW is unaffected. Transformation of polarization properties plays an important role for manipulation and control of MW radiation, impacting existing applications and providing opportunities for novel MTMs‐based sensors and other applications. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2146–2150, 2014
Comparison of two triple‐fiber sensor designs for small distance measurements
Authors: Golnabi H. 
Published: June 2014

ABSTRACTOperation of two different optical fiber sensor designs for distance measurements with a good sensitivity, resolution, and wide dynamic range is reported. Design is based on the intensity modulation due to reflectance measurement from a target surface. Two reported designs are fabricated with a triple‐fiber assembly, in which one uses a double‐transmitter, while another one uses a double‐receiver fiber design. Reflection signals from different targets are tested with these sensors and results for the mirror and A4 paper surfaces are described. The response curve for both experiments starts from a near zero level, shows a maximum at a certain distance and gradually drops to the background voltage level. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1997–2001, 2014
Design of a broadband planar monopole MIMO antenna
Authors: Kazim Jalil ur Rehman , Ahmad Salman , Ali Usman , Owais Owais 
Published: June 2014

ABSTRACTA broadband multiple‐input multiple‐output antenna with a size of 60 × 120 × 1.6 mm is presented for the smart phones. Enhanced performance of the antenna is achieved by utilizing dual radiator chopping and ground plane slitting. Supplemental L‐shaped meandered ground structure over the top of radiator was added to enhance the performance in the lower frequency band. The proposed antenna covers two frequency bands for return loss <−6 dB, that is, 0.8–0.96 and 1.7–2.7 GHz, respectively, specified for mobile phone operation. The antenna is fabricated and measured results are obtained for return loss, isolation, envelope correlation, and radiation pattern. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1994–1997, 2014
A study of the impedance and pattern bandwidths of aperture‐coupled cylindrical dielectric resonator antennas
Authors: Huynh Adam P. , Jackson David R. , Long Stuart A. , Wilton Donald R. 
Published: June 2014

ABSTRACTAperture‐coupled cylindrical dielectric resonator antennas (DRAs) fed by a microstrip line are investigated by varying their aspect ratio and permittivity to maximize their impedance bandwidth, while maintaining an acceptable radiation pattern. Although the maximum impedance bandwidth attainable by an aperture‐coupled DRA is comparable to that of a probe‐fed one (40% vs. 45%), the maximum combined bandwidth (which also accounts for the pattern shape) is smaller—about 30% versus 45%. The study reveals a very important conclusion: while a probe feed is good for obtaining broadband DRAs that are tall or pencil‐like, an aperture‐coupled feed is more suitable for applications that require low‐profile or pancake‐like broadband DRAs. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2129–2132, 2014
Magnetization transfer from inhomogeneously broadened lines (ihMT): Experimental optimization of saturation parameters for human brain imaging at 1.5 Tesla
Authors: Girard Olivier M. , Prevost Valentin H. , Varma Gopal , Cozzone Patrick J. , Alsop David C. , Duhamel Guillaume 
Published: June 2014

PurposeRecently a new MR endogenous contrast mechanism was reported. It allows specifically imaging the magnetization transfer (MT) effect arising from inhomogeneously broadened components of the NMR spectrum, and was hence dubbed ihMT. Such unique NMR lineshape properties are presumably occurring in myelin because of its specifically ordered, multilayered sheath structure. Here, optimization of a pulsed ihMT preparation module is presented to provide guidance for future studies and improve the understanding of underlying contrast mechanisms.MethodsThis study was performed at 1.5 Tesla on healthy volunteers. A pulsed ihMT preparation was implemented in combination with a HASTE readout module. The pulse width, interpulse repetition time, total saturation duration and RF saturation power were considered for optimization of the ihMT sensitivity and contrast.ResultsAn optimal configuration of the preparation module was derived, leading to 10% ihMT signal in internal capsule (relative to unsaturated data) and around 200% signal increase relative to gray matter, i.e., approximately 10‐fold superior contrast compared with conventional MT ratios, measured under similar experimental conditions.ConclusionOverall the ihMT sequence was robust, sensitive and very specific for white matter. These findings suggest great potential for assessing brain myelination and for better characterization of myelin related disorders. Magn Reson Med 73:2111–2121, 2015. © 2014 Wiley Periodicals, Inc.