bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optical fiber sensor for localizing heating positions in multiple points using multichannel gratings with phase sampling and wavelength division multiplexing techniques
Authors: Xia Li , Shum P. 
Published: August 2008

AbstractAn optical fiber sensor system with multichannel fiber Bragg gratings (FBGs) is proposed. The gratings are designed and fabricated by phase sampling technique within strongly chirped phase masks. The sensing application can be realized at multiple points through wavelength division multiplexing (WDM) technique. It means that the different point can be monitored by different gratings, which occupies different wavelength region, according to the central pitch and chirp coefficient of phase masks. The heating position with high resolution can be analyzed through three corresponding channel shifts in the multichannel profile. In our experiment, the two multichannel gratings with channel spacing of 0.8 and 1.6 nm, respectively, are fabricated and used for sensing in two points. At last, the 400 μm accuracy of localizing the heating position is achieved. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2951–2954, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23832
Integration of internal 700 MHz and WLAN/WiMAX antennas for palm‐sized mobile devices
Authors: Chou Jui‐Hung , Su Saou‐Wen 
Published: August 2008

AbstractTwo promising, internal, shorted monopole antennas for 700 MHz and WLAN/WiMAX operation are combined in an arrangement with minimized mutual coupling for palm‐sized mobile applications. The two stamped, metal‐plate antennas with a 2‐mm gap therein between can be integrated into a compact configuration and are then mounted near one side of the system circuit board. With the suitable shorting locations and arrangement of the two antennas, good isolation (S21 < −20 dB) between the two ports can easily be obtained. Analysis of placing a CCD shielding cylinder between the two antennas and the two shorting strips joined to form a shorting wall are also conducted. Detailed designs of the two antennas are described, and the results thereof are discussed. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2948–2951, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23833
Studies on ultrawideband filters using stub‐loaded circular and triangular resonators
Authors: Gupta Ravi Dutt , Abegaonkar Mahesh P. , Basu Ananjan , Koul Shiban K. 
Published: August 2008

AbstractCompact UWB bandpass filters using stub‐loaded ring and triangular resonators fed with capacitive‐ended interdigital coupled lines are proposed. The proposed structures are fed with capacitive‐ended interdigital coupled lines. The measured insertion loss for ring resonator filter is 1.0 dB and that for triangular resonator is 2.0 dB with corresponding group delays of 0.6 and 0.3 ns, respectively. These filters show sharp transitions at the edges of the UWB passband and improved out‐of‐band performance. The simulated and measured results are in good agreement and satisfy the FCC mask for indoor applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2917–2922, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23834
High‐gain multilayer 2×2 antenna array for wireless applications
Authors: Gupta R. K. , Kumar G. 
Published: August 2008

AbstractThis article proposes an efficient high‐gain multilayer 2×2 antenna array for wireless applications. The prototype antenna consists of a microstrip antenna which feeds 2×2 array of square parasitic patches fabricated on a low‐cost easily available FR4 superstrate. The patches on superstrate are suspended in air at λ0/2. The structure is designed, fabricated, and tested. The measured VSWR is < 2 over 5.725–5.875 GHz frequency band. The proposed antenna with 2×2 array of square parasitic patches provides 80% efficiency and SLL of −24 dB with an associated gain of 14.9 dB. The proposed structure can be packaged inside an application platform. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2911–2917, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23835
A novel ultra‐wideband monopole antenna with two symmetrical strips
Authors: Song Hyo W. , Park Jong K. , Yoo Jin H. 
Published: August 2008

AbstractIn this article, we have described a novel ultra‐wideband (UWB) monopole antenna with two symmetrical strips for wireless UWB communications. The proposed antenna consists of a center monopole, two symmetrical strips having one step on the strip, and CPW feeding. Three techniques (one monopole and two strips, symmetrical structure, and step on the strip) are used to produce the multiple resonance and low dispersion. The proposed UWB antenna has an omnidirectional radiation pattern, UWB, compact size, almost flat gain and linear phase, and low cost. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2845–2848, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23838
A compact filter‐combined ultra‐wide band antenna for UWB applications
Authors: Lee Jung N. , Park Jong K. , Choi Il H. 
Published: August 2008

AbstractWe have proposed a compact filter‐combined ultra‐wide band antenna for the use of DS‐UWB low band or MB‐OFDM lower three bands (3.1–5.2 GHz). The designed antenna has a microstrip‐fed trapezoidal radiating patch, UWB band pass filter using the dumbbell‐shaped DGS (defected ground structure), and IDC (interdigital capacitor): two steps for impedance matching, and microstrip feeding. Three kinds of prototypes (trapezoidal UWB antenna, UWB band pass filter, and the compact filter‐combined ultra wideband antenna) are fabricated and measured. The designed antenna has the figure‐of‐eight radiation pattern, wide bandwidth, and negligible dispersion over the operating frequency band. Details of the proposed antenna design and the simulated and measured results are presented and discussed. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2839–2845, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23839
Uniplanar harmonic suppressed compact rat‐race couplers
Authors: Krishna Velidi Vamsi , Kanti Mandal Mrinal , Bhattacharya Amitabha 
Published: August 2008

AbstractA design of a miniaturized rat‐race coupler with higher‐order harmonic suppression is presented in this article. The slow wave effect and stopband produced by a shunt open‐stub is utilized to miniaturize the occupying area and suppress higher order harmonics, respectively. Design guidelines are obtained using a transmission line model. A prototype coupler has been fabricated in microstrip line to validate the theoretical predictions. The fabricated coupler occupies 18.4% area of that of a conventional coupler. At the same time, the second to tenth harmonics are suppressed by at least 15 dB. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2812–2814, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23840
Broadband internal antenna by combination of a loop type antenna and a shorted monopole
Authors: Bin Park Su , Min Kim Sung , Geun Yang Woon 
Published: August 2008

AbstractBroadband internal antenna by combination of a loop type antenna and a shorted monopole is proposed for GSM/GPS/DCS/PCS/UMTS/WiBro/WLAN applications. The proposed antenna shows wide impedance bandwidths as well as good radiation patterns and high antenna gains, despite very small volume. And wide impedance bandwidth can be achieved without increasing the implementation complexity compared with that of existing antennas. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2810–2812, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23841
Analysis of propagation loss of metallic photonic crystal waveguides
Authors: Kokubo Yoshihiro 
Published: August 2008

AbstractMetallic waveguides can be constructed with sidewalls consisting of metallic rods instead of sheets. The attenuation constants and bandwidths of such waveguides are calculated for a fixed cutoff frequency while the radii of the metallic rods are varied. The propagation losses are found to decrease when the radii of the rods is increased. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2942–2945, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23844
Study on the induced current measurement in bridgewire EED
Authors: Mei Shu‐Gang , Wang Tao , Yin Fei , He Jun‐Fang , Ruan Chi , Wu Lei‐Xue , Zhao Tuan 
Published: August 2008

AbstractIn this study, an infrared optical fiber light splitting system is proposed for the measurement of induced current in bridgewire electroexplosive device (EED). The system includes infrared optical fiber that eliminates interference from external electromagnetic radiation, a lens assembly that optimally focuses the infrared energy from the bridgewire to the infrared fiber and no‐touch the bridgewire, two infrared detectors that measure the middle and near infrared radiation from bridgewire, respectively, and a photomodulator and phase‐locked amplifiers that depress the noises. The experimental results suggest that the induced current in bridgewire can be an accurate determination by using this system, and the measurement error is less than 0.0154 mA in high‐temperature region. A new method is provided to confirm the safety and reliability of the electric ignition system in electromagnetic environment. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2833–2835, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23845
Compact dual‐band filter design using crossly coupled λ/4 SIRs embedded with spur‐line for WLAN applications
Authors: Chen Pow‐Wen , Ho Min‐Hua , Hong Wanchu 
Published: August 2008

AbstractThis article presents a compact dual‐band bandpass filter (BPF) design using λ/4 stepped impedance resonators (SIRs) embedded with spur‐line for the WLAN applications. The filter covers both the operating frequencies of 2.45 GHz and 5.2–5.8 GHz. The crossly coupled mechanism is used in the filter design to provide attenuation poles by the passband edges for enhancing the signal selectivity and increasing stopband rejection levels. The tapped‐line is incorporated in feed structure to save the circuit space. The spur‐line is embedded in each I/O SIRs to push the upper stopband limit to a higher frequency. Experiments are conducted to verify the circuit performance. A good agreement is observed between the simulation and the measurement. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2807–2810, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23846
A magnetic field controlled negative‐index microwave lens
Authors: Petrov R. V. , Pandey R. , Srinivasan G. , Bichurin M. I. 
Published: August 2008

AbstractA three‐dimensional lens with magnetic field control of the index of refraction and focal length has been designed and characterized over 2‐18 GHz. The lens is made of a lattice of cross‐wire resonators and ferrite cubes. For the lattice without the ferrite cubes, a refractive index n ≈ −1 is measured at 11.25 GHz. With the introduction of ferrite cubes in the lattice, n could be tuned over the range −1.2 to +1.8 for nominal bias magnetic fields H. The focal point for the lens with n ≈ −1, for example, could be displaced by 2 cm by tuning H from 4100 to 4125 Oe. Theoretical estimates of the lens characteristics are in agreement with the data. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2804–2807, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23847
396 fs pulse from an asynchronous mode‐locked erbium fiber laser with 2.5 12 GHz repetition rate
Authors: Boncristiano E. S. , Saito L. A. M. , De Souza E. A. 
Published: August 2008

AbstractWe have demonstrated an Erbium fiber laser hybridly mode‐locked by a phase modulator in conjunction with intracavity soliton effect producing pulses as short as 396 fs at 10 GHz. The laser repetition rate is variable from 2 to 12 GHz keeping pulses with duration shorter than 500 fs in this range. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2994–2996, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23849
AlGaN/GaN‐based SAW delay‐line oscillators
Authors: Jesús Grajal  , Calle Fernando , Pedrós Jorge , Martínez‐Chacón José Luis , Jiménez Ana 
Published: August 2008

AbstractSurface acoustic wave filters fabricated on AlGaN/GaN heterostructures allow the control of their insertion losses through external voltages applied to the interdigital transducers. A novel SAW delay‐line oscillator based on an AlGaN/GaN‐on‐sapphire SAW device with an oscillation frequency of 475 MHz has been developed. Its waveform compression is controlled by varying the insertion losses of the active SAW filter. A small temperature coefficient of delay of 17.5 ppm/°C has been obtained. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2967–2970, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23852
Characteristics of GaAs transformers for RFIC applications
Authors: Meng Chinchun , Teng Ya‐Hui , Syu Jin‐Siang , Lin Yi‐Chen , Jhong Jhin‐Ci , Yen Ying‐Chieh 
Published: August 2008

AbstractIn this article, stacked transformers, coupling stacked transformers, interleave transformers, and symmetrical transformers on GaAs substrate are systematically studied. Two kinds of stacked transformer are under study. One has the symmetrical electric property while the other one has a better quality factor for the primary port. The stack transformers have achieved the highest coupling coefficient (∼0.9) at the cost of lower self‐resonance frequency. The interleave transformers have the identical electrical properties for the primary and the secondary ports. However, the layout is incompatible with the differential operation. On the other hand, the symmetrical transformer is compatible with the differential operation and can have the center‐tapped biasing option. The data established here provides a useful design library for the GaAs RFIC. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2937–2942, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23853
CMOS bandpass filters for 77 GHz automotive radar systems
Authors: Nan Lan , Mouthaan Koen , Xiong Yong‐Zhong , Shi Jinglin , Chander Rustagi Subhash , Brinkhoff James , Ooi Ban‐Leong 
Published: August 2008

AbstractThis article presents a systematic design and measurement of narrow and wide bandpass filters at 77 GHz in a 0.18‐μm CMOS technology. Various bandwidths from 10 to 50% are realized using a parallel coupled line topology in a thin film microstrip configuration. The relationship between the insertion loss and the 3‐dB bandwidth of the filters is experimentally determined for this technology. The result is also compared with theoretical prediction. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2934–2937, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23854
A directive dual‐band and dual‐polarized antenna with zero index metamaterial
Authors: Weng Zi‐Bin , Song Yue , Jiao Yong‐Chang , Zhang Fu‐Shun 
Published: August 2008

AbstractA novel directive dual‐band and dual‐polarized microstrip antenna with ZIM is presented. An averaging effect over constituent materials of the metamaterial structure yields an effective permittivity that approaches zero at dual band with different polarizations, and then it results in a metamaterial with zero index of refraction and the radiation energy of this antenna is congregated. The experimental results show that this method is effective, and this structure can greatly increase the gain at dual frequencies. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2902–2904, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23855
A compact broadband circularly polarized composite antenna with wide beamwidth
Authors: Houjun  , Sun  , Shi Lei , Li Jingtao 
Published: August 2008

AbstractA compact composite antenna applied to the satellite movable termination is presented in this article. The antenna unit is composed of a monofilar conical helix and a radial omnidirectional waveguide antenna with eight vertical metal rods. From the viewpoint of widening the circularly polarized (CP) beamwidth in vertical plane and frequency bandwidth, these components are unified as a single composite antenna. Both the simulated and measured results show that the broad CP beamwidth can be obtained over the frequency range from 2.3 to 3.3 GHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2973–2975, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23857
Five‐port receiver with improved sensitivity
Authors: de Sousa Fernando Rangel , Huyart Bernard 
Published: August 2008

AbstractThis article reports the architecture of a five‐port receiver without vector base circuit generators in which three antennas provide three phase‐shifted copies of the received signal. A 2.4‐GHz prototype was implemented for concept proofing, and the measurements point to a sensitivity improvement of 6 dB with respect to comparable classic five‐port receivers. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2945–2947, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23858
The 5.8‐GHz fully integrated low‐power low‐phase‐noise CMOS LC VCOs using RC noise‐filtering technique
Authors: Lee Jen‐How , Chen Chi‐Chen , Lin Yo‐Sheng 
Published: August 2008

AbstractIn this work, two 5.8‐GHz fully integrated LC differential voltage‐controlled oscillators (VCOs) using standard 0.18 μm CMOS technology were implemented. One of them adopted a standard differential inductor (STD VCO). The other (PPGS VCO) comprised the same layout except that PPGS (poly‐silicon partial pattern‐ground‐shields) was added beneath its differential inductor for Q‐factor enhancement. Low‐power consumption was achieved by maximizing the equivalent parallel resistance (RP) of the LC tank by layout optimization. In addition, low‐phase noise was achieved mainly by adding two parallel capacitors to the cross‐coupled transistors and a resistor (Rfilter) to the biasing transistor for suppressing the noise coming from the current source. The STD VCO achieved a wide‐tuning‐range of 10.3% (from 5.26 GHz to 5.802 GHz) with a low‐power dissipation of 3.02 mW. The measured phase noise was −118.25 dBc/Hz at 1‐MHz offset. The corresponding figure‐of‐merit (FOM) was −188.72 dBc/Hz, better than those of the reported state‐of‐the‐art CMOS LC VCOs in 5‐GHz‐band. The chip area was only 508 × 595 μm2excluding the test pads. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2907–29117, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23859
Analysis and experiment for drain bias dependence of IMD sweet spots in GaN HEMT power amplifier
Authors: Lee Yong‐Sub , Lee Mun‐Woo , Jeong Yoon‐Ha 
Published: August 2008

AbstractIn this article, we propose the drain bias dependency on the intermodulation distortion (IMD) sweet spots of a gallium nitride (GaN) high‐electron mobility transistors power amplifier (PA). Using the mathematical approach by the IDS–VGS characteristic curves and two‐tone distortion products, the positions of the IMD sweet spots according to drain bias as well as gate bias and input power are predicted and well‐matched with the measured results. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2836–2839, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23863
Spectrum separation resolves partial‐volume effect of MRSI as demonstrated on brain tumor scans
Authors: Su Yuzhuo , Thakur Sunitha B. , Sasan Karimi , Du Shuyan , Sajda Paul , Huang Wei , Parra Lucas C. 
Published: September 2008

AbstractMagnetic resonance spectroscopic imaging (MRSI) is currently used clinically in conjunction with anatomical MRI to assess the presence and extent of brain tumors and to evaluate treatment response. Unfortunately, the clinical utility of MRSI is limited by significant variability of in vivo spectra. Spectral profiles show increased variability because of partial coverage of large voxel volumes, infiltration of normal brain tissue by tumors, innate tumor heterogeneity, and measurement noise. We address these problems directly by quantifying the abundance (i.e. volume fraction) within a voxel for each tissue type instead of the conventional estimation of metabolite concentrations from spectral resonance peaks. This ‘spectrum separation’ method uses the non‐negative matrix factorization algorithm, which simultaneously decomposes the observed spectra of multiple voxels into abundance distributions and constituent spectra. The accuracy of the estimated abundances is validated on phantom data. The presented results on 20 clinical cases of brain tumor show reduced cross‐subject variability. This is reflected in improved discrimination between high‐grade and low‐grade gliomas, which demonstrates the physiological relevance of the extracted spectra. These results show that the proposed spectral analysis method can improve the effectiveness of MRSI as a diagnostic tool. Copyright © 2008 John Wiley & Sons, Ltd.
k‐space analysis of point‐resolved spectroscopy (PRESS) with regard to spurious echoes in in vivo1H MRS
Authors: Starck G. , Carlsson Å. , Ljungberg M. , Forssell‐Aronsson E. 
Published: September 2008

AbstractThe spurious echo artefact, not uncommon in 1H MRS in the brain, comes from refocusing outer volume signal. Application of MRS in small volumes in susceptibility‐affected regions often results in large shim gradients. The artefact problem is accentuated when the global effect of the shim gradient shifts the water resonance outside the water suppression band in the outer volume. This scenario brings the issue of spurious echoes once again to the fore. In this paper, spurious signals of the point‐resolved spectroscopy (PRESS) sequence are analysed using the concept of k‐space. This new approach facilitates a more geometrical view of the problem, well suited for studying the effect of gradient spoiling and refocusing of signal. Several spoiling options are shown, and the probability of the global effects of shimming being a primary cause of the artefact is discussed. Fourier transform analysis of realistic slice profiles, combined with the k‐space description of spurious echoes, shows that unsuppressed water signal in outer regions greatly increases the demands on spoiling. Gradient spoiling adequate for artefact suppression at a given size of MRS volume may not be sufficient at a smaller size. Several ways to improve PRESS measurements with regard to suppression of spurious signal are discussed. Copyright © 2008 John Wiley & Sons, Ltd.
From acene to graphene spectrum of π electrons with the use of the Green's function
Authors: Malysheva Lyuba , Onipko Alexander 
Published: September 2008

AbstractThe origin of the spectrum of π electrons that results from the coupling of N 𝒩 ‐long acenes via C‐C covalent bonding has been traced with the use of the Green function formalism.Exact expressions of acene and graphene Green's functions, which are useful for analysis of the electronic properties of these macromolecules, are obtained and advanced to a form suitable for instructive applications. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nanomechanical radio transmitter
Authors: Weldon J. , Jensen K. , Zettl A. 
Published: September 2008

AbstractWe explore a design possibility for a highly integrated nanoscale radio transmitter, where the key functional component is a mechanically vibrating electrically charged beam. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)