bluuebunny/crossref_metadata_2025 huggingface dataset:
Chip‐scale microscopy imaging
Authors: Zheng Guoan
Published: May 2012

Chip‐scale microscopy imaging platforms are pivotal for improving the efficiency of modern biomedical and bioscience experiments. Their integration with other lab‐on‐a‐chip techniques would allow rapid, reliable and high‐throughput sample analysis for applications in diverse disciplines. In typical chip‐scale microscopy imaging platforms, the light path can be generalized to the following steps: photons leave the light source, interact with the sample and finally are detected by the sensor. Based on the light path of these platforms, the current review aims to provide some insights on design strategies for chip‐scale microscopy. Specifically, we analyze current chip‐scale microscopy approaches from three aspects: illumination design, sample manipulation and substrate/imager modification. We also discuss some opportunities for future developments of chip‐scale microscopy, such as time multiplexed structured illumination and hydrodynamic focusing for high throughput sample manipulation. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimum culture medium composition for rhamnolipid production by pseudomonas aeruginosa AT10 using a novel multi‐objective optimization method
Authors: Eswari Jujjavarapu Satya , Anand Mohan , Venkateswarlu Chimmiri
Published: May 2012

BACKGROUND: Rhamnolipid is a biosurfactant that finds wide applications in pharmaceuticals and beauty products. Pseudomonas aeruginosa is a producer of rhamnolipids, and the process can be implemented under laboratory‐scale conditions. Rhamnolipid concentration depends on medium composition namely, carbon source concentration, nitrogen source concentration, phosphate content and iron content. In this work, existing data7 were used to develop an artificial neural network‐based response surface model (ANN RSM) for rhamnolipid production by pseudomonas aeruginosa AT10. This ANN RSM model is integrated with non‐dominated sorting differential evolution (DE) to identify the optimum medium composition for this process.

RESULTS: Different strategies for optimization of culture medium composition for this process were evaluated, and the best determined to be an ANN model combined with DE involving a combination of Naïve and Slow and ε‐constrained techniques. The optimal culture medium is determined to have carbon source concentration of 49.86 g dm−3, nitrogen source concentration of 4.99 g dm−3, phosphate content of 1.42 g dm−3, and iron content of 17.12 g dm−3. The maximum rhamnolipid activity was found to be 18.07 g dm−3, which compares favorably with that previously reported (18.66 g dm−3), and is in fact closer to the experimentally determined value of 16.50 g dm−3.

CONCLUSION: This method has distinct advantages over methods using statistical regression models, and can be used for optimization of other multi‐objective biosurfactant production processes. © 2012 Society of Chemical Industry
Long‐term administration of AMD3100, an antagonist of SDF‐1/CXCR4 signaling, alters fracture repair
Authors: Toupadakis Chrisoula A. , Wong Alice , Genetos Damian C. , Chung Dai‐Jung , Murugesh Deepa , Anderson Matthew J. , Loots Gabriela G. , Christiansen Blaine A. , Kapatkin Amy S. , Yellowley Clare E.
Published: May 2012

Fracture healing involves rapid stem and progenitor cell migration, homing, and differentiation. SDF‐1 (CXCL12) is considered a master regulator of CXCR4‐positive stem and progenitor cell trafficking to sites of ischemic (hypoxic) injury and regulates their subsequent differentiation into mature reparative cells. In this study, we investigated the role of SDF‐1/CXCR4 signaling in fracture healing where vascular disruption results in hypoxia and SDF‐1 expression. Mice were injected with AMD3100, a CXCR4 antagonist, or vehicle twice daily until euthanasia with the intent to impair stem cell homing to the fracture site and/or their differentiation. Fracture healing was evaluated using micro‐computed tomography, histology, quantitative PCR, and mechanical testing. AMD3100 administration resulted in a significantly reduced hyaline cartilage volume (day 14), callus volume (day 42) and mineralized bone volume (day 42) and reduced expression of genes associated with endochondral ossification including collagen Type 1 alpha 1, collagen Type 2 alpha 1, vascular endothelial growth factor, Annexin A5, nitric oxide synthase 2, and mechanistic target of rapamycin. Our data suggest that the SDF‐1/CXCR4 signaling plays a central role in bone healing possibly by regulating the recruitment and/or differentiation of stem and progenitor cells. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1853–1859, 2012
Effect of maturation and cold storage on the organic acid composition of myrtle fruits
Authors: Mulas Maurizio , Fadda Angela , Angioni Alberto
Published: May 2012

BACKGROUND: The effect of maturation and senescence on the chemical composition of two myrtle cultivars was studied in mature, overripe and cold‐stored fruits in order to find the most appropriate harvesting period and best storage technology for industrial purposes.

RESULTS: After cold storage at 10 °C for 15 days, berry weight loss ranged from 12.5 to 18.4%, with the highest losses in less mature fruits. Titratable acidity decreased during maturation and cold storage in both cultivars. Reducing and total sugars increased during maturation. Anthocyanin concentration increased during maturation but decreased in overripe berries. The major organic acids in myrtle fruits were quinic, malic and gluconic acids. In fresh and cold‐stored fruits, malic acid rose to 3 g kg−1 and decreased thereafter. Quinic acid peaked at 90 or 120 days after bloom and decreased thereafter to reach low concentrations in mature fruits.

CONCLUSION: Cold storage for 15 days at 10 °C does not affect myrtle fruit quality for liqueur production. Anthocyanin concentration is the best indicator of harvest time for industrial purposes. Gluconic acid concentration is high in mature, overripe and cold‐stored berries. This parameter can be used as a marker of the onset of fruit senescence. Copyright © 2012 Society of Chemical Industry
1,3‐Bis‐dibutylaminopropan‐2‐ol as inhibitor for reinforcement steel in chloride‐contaminated simulated concrete pore solution
Authors: Liu J. P. , Chen C. C. , Cai J. S. , Liu J. Z. , Cui G.
Published: May 2012

An organic compound, 1,3‐bis‐dibutylaminopropan‐2‐ol (BDAP) was prepared and tested experimentally as inhibitor for reinforcement steel in simulated concrete pore solution. The electrochemical behavior of carbon steel electrodes immersed in simulated pore solutions with different concentration of BDAP was investigated by electrochemical measurements. Adsorption isotherm was determined based on the inhibition efficiency. The surface composition was evaluated via X‐ray photoelectron spectroscopy (XPS) as well in order to verify the presence and adsorption property of BDAP. The results showed that BDAP could effectively suppress the anodic process of carbon steel corrosion and the inhibition efficiency was improving with the increase of inhibitor concentration. BDAP could adsorb on carbon steel surface according to Langmuir adsorption isotherm. XPS spectrum certified the existence of BDAP on the steel surface.
Corrosion behaviour of twin belt cast EN AW 7075 alloy
Authors: Birol Y. , Birol F. , Yuksel B. , Duygulu O.
Published: May 2012

The corrosion behaviour of the twin belt cast EN AW 7075 alloy is governed by intermetallic phases, namely Al12(Fe,Cr,Mn)3Si, Mg2Si and CuAl2, and by Mg(Zn,Cu,Al)2 precipitates. The former are responsible for pitting activities while the Mg(Zn,Cu,Al)2 precipitates play a key role in intergranular corrosion. The very fine dispersion of Mg(Zn,Cu,Al)2 precipitates in samples aged to peak hardness undergo coarsening, particularly along the grain boundaries, when the hot band samples are overaged. Overageing improves the resistance to intergranular corrosion while the samples in T6 temper suffer heavy attack along grain boundaries. While ageing treatments hardly produce any change in the features of the intermetallic particles, they nevertheless seem to impact the pitting response. This may be accounted for also by the precipitation activities which in turn, change the chemistry of the solid solution matrix. Overageing to the T73 temper implies a higher purity matrix and thus changes the microgalvanic effects when exposed to neutral chloride solutions.
Poly(3‐octylthiophene) thermally treated as coating for corrosion protection of SS304 in sulfuric acid media
Authors: León‐Silva U. , Nicho M. E. , González‐Rodríguez J. G. , Chacón‐Nava J. G. , Salinas‐Bravo V. M.
Published: May 2012

Poly(3‐octylthiophene) (P3OT) was synthesized by direct oxidation of the 3‐octylthiophene monomer using ferric chloride (FeCl3) as an oxidant. Using the drop‐casting technique, P3OT coatings were deposited onto 304 type stainless steel electrodes. For the purpose of determining the effect of thermal annealing on the corrosion protection of stainless steel with P3OT coatings, the coated electrodes were thermally annealed for 30 h at two different temperatures, 55 and 100 °C. The corrosion behavior of P3OT coated stainless steel was investigated in 0.5 M sulfuric acid (H2SO4) at room temperature using potentiodynamic polarization curves (PPC), linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS). The results indicated that the thermally treated P3OT coatings improved the corrosion resistance of the stainless steel in 0.5 M H2SO4. The best corrosion protection was obtained by the P3OT coating annealed at 100 °C. In order to study the temperature effect on the morphology of the coatings before and after the corrosive environment and compare it with corrosion protection, atomic force microscopy (AFM) and scanning electronic microscopy (SEM) were used.
Cracking investigation of a pressure transmitter tapping line
Authors: Al‐Meshari A. , van Zyl G. N. , Diab M. , Al‐Ghadeer Y.
Published: May 2012

This article describes the findings of an investigation on cracking of ethylene furnace pressure transmitter tapping lines made of stainless steel type 304H. A detailed failure analysis using several characterisation techniques such as visual and metallographic examinations, SEM/EDX, XRF/C&S as well as finite element analysis uncovered that the cracking was caused by polythionic acid stress corrosion cracking that took place due to presence of condensate, sulphides and oxygen in contact with sensitised material. Several corrective measures to prevent similar failures are discussed.
Corrosion of Al 7075 alloy during the production of aeronautic components: Influence of process parameters at the deburring stage
Authors: Faria M. I. S. T. , Robin A. , Prisco L. P. , Puccini M. C. , Gonçalves D. C. , Lourenço J. C.
Published: May 2012

Aluminum alloys of the 7XXX series are widely used in aircraft applications. During the manufacturing of aeronautic components, the parts pass through four production phases (milling/drilling, deburring/adjustment, non‐destructive testing, and surface treatment) and come into contact with several kinds of fluids such as degreasing and cleaning solutions, which can lead to the occurence of surface defects due to localized corrosion, then requiring reworking or scrapping. The present study aimed at studying the influence of process parameters in the deburring/adjustment stage on the development of surface defects in 7075 alloy parts. The methodology consisted of design of experiments, immersion and drying tests, and surface analysis for quantification of corrosion damage. The results showed that the degreasing bath concentration and temperature, the immersion time of the aluminum parts in the degreasing solution, and the use of solvent pre‐cleaning had no significant influence on the quantity of surface defects. Therefore, these factors do not need to be rigorously controlled in the process. Clean washing water must be preferred and the parts must be dried in the stove at 110 °C in order to ensure a surface free of defects. The immersion and electrochemical tests showed that the occurrence of surface defects is lower in aged degreasing solution than in recently prepared solution.
The efficiency of electrochemical methods for the removal of chloride ions from iron marine archaeological objects: A comparative study
Authors: Coelho J. C. , Oliveira C M. , Carvalho M. D. , Fonseca I. T. E.
Published: May 2012

The conservation of archaeological marine iron artefacts requires chloride ions removal. In this study, the removal of chloride ions was undertaken by two electrochemical methods: the electrolytic and the galvanic reduction in alkaline media. The results were compared with those obtained by the washing and the sulphite reduction methods, under identical conditions. The experiments were performed on samples coming from an 18th century cast iron cannon‐ball, found in the archaeological context of a shipwreck, l'Océan, which sank near the southern Portuguese coast, in 1759. The extraction of chloride ions was monitored by ionic chromatography (IC). The results allow to conclude that the sulphite reduction experiments using the mixture 0.5 M NaOH/0.5 M Na2SO3 presents the higher efficiency in the first week, being further overcome by both electrochemical methods. After 40 days of treatment, the electrolytic reduction is the most efficient method.
Structure‐Property Optimizations in Donor Polymers via Electronics, Substituents, and Side Chains Toward High Efficiency Solar Cells
Authors: Uy Rycel L. , Price Samuel C. , You Wei
Published: May 2012

Many advances in organic photovoltaic efficiency are not yet fully understood and new insight into structure‐property relationships is required to push this technology into broad commercial use. The aim of this article is not to comprehensively review recent work, but to provide commentary on recent successes and forecast where researchers should look to enhance the efficiency of photovoltaics. By lowering the LUMO level, utilizing electron‐withdrawing substituents advantageously, and employing appropriate side chains on donor polymers, researchers can elucidate further aspects of polymer‐PCBM interactions while ultimately developing materials that will push past 10% efficiency.
High‐selectivity dual‐band bandpass filter using folded stepped‐impedance resonators and asymmetric coupling lines
Authors: Cheng Wei , Wang Xin‐Huai , Tuo Yong , Bai Yan‐Fu , Shi Xiao‐Wei
Published: May 2012

A compact microstrip line dual‐band bandpass filter using folded stepped‐impedance resonators (FSIRs) with high selectivity is proposed and implemented. The filter consists of two FSIRs and asymmetric coupling input/output lines. By utilizing resonance characteristics of the FSIRs, a compact filter is designed for WLAN (2.4 and 5.2 GHz). In the new design, asymmetric coupling input/output lines are applied not only to generate two more transmission zeros than the symmetric ones but also to tune the transmission zeros to improve the selectivity. These performances are demonstrated by simulation and measurement. Owing to asymmetric coupling input/output lines, five transmission zeros could be generated near the passband edges to improve the selectivity. Both experimental and simulated results are with good agreement. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1866–1869, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26928
Comment on “Experimental study of electromagnetic band gaps using plasmas as defaults in a metallic photonic crystal”
Authors: Jha Ratneshwar
Published: May 2012

Original article published Microwave Opt Technol Lett 53:1109–1113, 2011. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2006, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26929
Compact conventional phone antenna integrated with wideband multiple‐input‐multiple‐output antenna
Authors: Li Jian‐Feng , Chu Qing‐Xin , Li Zhi‐Hui
Published: May 2012

A compact conventional phone antenna integrated with wideband multiple‐input‐multiple‐output (MIMO) antenna is presented.Within operation band of the MIMO antenna, the effect of mutual coupling between the conventional phone antenna and the MIMO antenna is reduced by etching three slits into the ground plane, and this slits also can relieve the impedance matching degradation caused by the mutual coupling between the conventional phone antenna and the MIMO antenna. A wideband T‐shaped neutralization line without effect on the performance of conventional phone antenna is applied to enhance the isolation for the two MIMO antenna elements. Therefore, high isolation is achieved within the operation band of the MIMO antenna. The two operation bands of the convention phone antenna with VSWR ≤ 3 are 0.89–0.96 GHz and 1.71–2.18 GHz, respectively, and the operation band of the MIMO antenna with VSWR ≤ 1.7 and isolation ≥ 20 dB is 2.4–3.7 GHz. Moreover, the conventional phone antenna has good omnidirectional radiation patterns in H‐plane, and the MIMO antenna has back‐radiation patterns for diversity gain. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1958–1962, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26930
Thermally tunable metamaterial based on thermochromic effect
Authors: Huang Jinguo , Xuan Yimin , Li Qiang
Published: May 2012

A composite structure is proposed by combining a thermochromic oxide with a fishnet structure, which is a metamaterial with tunable negative refractive index that is clearly observed for some special wavelength band for the proposed structure. The negative refractive index is attributed to the excitation of internal surface plasmonic polaritons. The spectral negative refractive index can be self‐regulated with the temperature, which is of significant importance to extend the applications of negative index materials. It is also demonstrated that the wavelength region with negative refractive index can be designed to locate at desired position by dexterously tailoring the structural parameters. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1889–1893, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26931
Low‐cost microstrip filter antenna with a monopole‐like radiation pattern for RF front end
Authors: Wu Wei‐Jun , Yin Ying‐Zeng , Xie Jiao‐Jiao , Ren Xue‐Shi , Zuo Shao‐Li
Published: May 2012

A low‐cost microstrip filter antenna with a monopole‐like radiation pattern suitable to be embedded inside a RF front end of wireless communication systems is presented. The filter antenna comprises two square open‐loop resonators, a coupled line, and a microstrip antenna with an impedance transformation line. The microstrip antenna is excited by the coupled line, which is treated as the admittance inverter in filter design. The microstrip antenna performs as not only a radiator but also the last resonator of the bandpass filter. Therefore, the transmission loss between the filter and the antenna is reduced. The patch of the microstrip antenna is stacked above the system circuit board of the RF front end. In this case, the design can fully integrate the circuit board of the RF front end into an internal filter‐antenna solution. The design procedure of the filter antenna follows the circuit approach—synthesis of bandpass filters. The measured results show good agreement with the simulated ones. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1810–1814, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26932
Dual‐band microstrip antenna structure combined with high‐gain dielectric rod and sleeve‐dipole elements
Authors: Batgerel Ariunzaya , Eom Soon‐Young
Published: May 2012

This article presents a dual‐resonator antenna where a stacked microstrip patch antenna uses a protruding dielectric rod for high gain, and a sleeve‐dipole antenna to support the rod as well as to resonate at another frequency.The proposed antenna structure could be optimized at any two frequencies. However, we designed the microstrip patch to resonate at 2.44 GHz while the sleeve‐dipole at 0.859 GHz. Main points of designing considerations and electrical performances of a fabricated antenna were briefly discussed. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1835–1838, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26933
A 1–12‐GHz variable‐gain low‐noise amplifier MMIC using 0.25‐μm SiGe BiCMOS technology
Authors: Chang Woojin , Lee Sang‐Heung , Mun Jae‐Kyoung , Nam Eunsoo
Published: May 2012

This article introduces an 1–12‐GHz differential two‐stage variable‐gain low‐noise amplifier (VGLNA) using 0.25‐μm SiGe:C BiCMOS commercial process technology for ultra‐wideband system.The results of the fabricated monolithic microwave integrated circuit amplifier show 18‐dB gain with a 3‐dB frequency band of 1.3–11.9 GHz and noise figure of less than 5 dB under the bias condition of 2.5‐V supply voltage and 55‐mW total dc power consumption. The gain‐control range is from −17 dB to +18 dB. The chip size of the manufactured VGLNA is 1.1 × 0.9 mm2 including all testing pads for RF and dc probes. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1935–1937, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26936
Estimation of coupling parameters for auto‐motorized fabrication of fused fiber coupler
Authors: Irawan Dedi , Saktioto  , Ali Jalil , Fadhali Mohamed , Erwin
Published: May 2012

A directional fiber coupler with exertion loss 0.03 dB has been successfully fabricated using fusion technique with typical coupling ratio 1–90%. The coupling region of two twisted single mode fiber is heated by injecting hydrogen gas at 2.5 bar. During fusion process, both two sides of fibers are pulled by stages that are automatically motorized in range of 800–4800 μm, and stopped when the desired coupling ratio is reached. The parameters of automated mechanical motion of pulling stages and coupling parameters at fusion region have been calculated by using kinetic model. The effect of heating and elongation reduces the diameter of cross section tapered region with a diameter 6.35 micrometer scale. As the fabrication of fiber couplers described by degree of fusion, which is function of heating and pulling length, it can be seen clearly that the coupling coefficient between the fibers increases exponentially with increasing the degree of fusion. However, by knowing coupling power and mechanical motion parameters, the fabrication of directional fiber coupler can be optimized. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1932–1935, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26937
Meander line‐loaded planar monopole antennas
Authors: Elsheakh Dalia M. , E. Safwat Amr M.
Published: May 2012

Two‐dimensional meander line‐loaded monopole antennas are presented in this article. They provide either multibands or ultrawideband (UWB). For multiband antenna, the total area is 58 × 60 mm2 and it covers the following bands: 0.9, 1.85, 2.1, 2.5, 3.5, and 5.2 GHz. The UWB antenna is achieved by connecting in parallel four meander line‐loaded monopoles with different lengths. Its total area is 150 × 80 mm2 and the obtained bandwidth extends from 0.9 to 10 GHz. The antennas are matched to a 50‐Ω line feed without the need for an external matching network. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1851–1854, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26939
Novel dual‐mode patch band‐pass filters with slit structures
Authors: La Dong‐sheng , Ma Xue‐lian , Wu Ya‐ping
Published: May 2012

Novel microstrip band‐pass filters using dual‐node patch resonators with slit structures are proposed and optimized in this article.By using etched slit defected structures in the square patch resonator and in the circle patch resonator, the filters have remarkable advantages, such as compact size, high selectivity, and simple structure. The proposed band‐pass filters are fabricated and measured. The measured results prove to be largely consistent with the simulated results. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1965–1968, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26941
High efficiency and suppression harmonics oscillator using front coupled tapered CMRC
Authors: Hayati Mohsen , Lotfi Ali
Published: May 2012

This article presents a novel terminating network for microwave transistor oscillator.A front coupled tapered compact microstrip resonant cell (FCTCMRC) is inserted between the transistor and the input fundamental matching network as its terminating resonance. The fundamental frequency from the output can be connected in a positive feedback loop to the input port by tuning the dimensions of the proposed FCTCMRC. This feedback can simultaneously act as a negative feedback for the second harmonic frequency. The output at the fundamental frequency improved due to the second harmonic suppression. The proposed FCTCMRC is used to obtain as high a reflection coefficient as possible, while providing the oscillation condition with the incorporated microwave transistor. The measured results show 63.05% improvement suppression of the second harmonic using FCTCMRC in comparison with the conventional microstrip line. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1862–1866, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26943
Compact Ultra‐Wideband slot antenna with band‐notch property
Authors: Naser‐Moghadasi M. , Asadpor L. , Virdee B.S.
Published: May 2012

A very small and compact ultra‐wideband (UWB) slot antenna is presented, which possesses band‐notch characteristic to eliminate interference signals. The antenna comprises a rectangular aperture (9 × 18 mm2) etched on the ground‐plane of a printed circuit board and a rectangular shaped stub, also total size of the antenna is 19 × 19 mm2. The antenna uses a novel technique comprising of open‐end stubs at the periphery of the ground‐plane in the vicinity of the feed‐line to improve its VSWR performance over the UWB. An effective conductor‐backed plane structure is used to generate the necessary band‐notch characteristic at the WLAN interfering band (5–6 GHz). The antenna exhibits broadband impedance matching with stable and omnidirectional radiation patterns and gain performance despite its very small size across the entire UWB from 3–11 GHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1829–1832, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26944
80–110 GHz MMIC amplifiers using a 0.1‐μm GaAs‐based mHEMT technology
Authors: Kang Dong Min , Yoon Hyung Sup
Published: May 2012

A 80–110 GHz broadband MMIC low noise amplifiers (LNAs) have been developed for W‐band passive image sensors.A monolithic microwave integrated circuit (MMIC) LNAs consists of a four‐stage single‐ended type and a four‐stage balanced type. The chip set was fabricated using a 0.1‐μm gate‐length InGaAs/InAlAs/GaAs metamorphic high electron mobility transistor process based on a four‐inch substrate. The single‐ended type LNA (ver.1) achieved a gain of 20 dB over in a band between 85 and 105 GHz and a noise figure of lower than 5.3 dB in a frequency range of 86.5–100 GHz. The single‐ended type LNA (ver.2) exhibited a gain of 27 dB with a noise figure of 4.3 dB at 94 GHz. The external DC biasing conditions of Vds and Vgs were 1 and −0.2 V, respectively, and the total current consumption of the LNA was 40 mA. The chip size was 2 × 1.2 mm2. The balanced‐type amplifier demonstrated a measured small signal gain of over 18 dB from 80 to 100 GHz. The external DC biasing conditions of Vds and Vgs were 1 and −0.2 V, respectively, and the total current consumption was 82 mA. The chip size was 2.9 × 2.5 mm2. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1978–1982, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26948
A low‐phase noise and wide‐tuning range CMOS voltage controlled oscillator
Authors: Lin Yao‐Chian , Yeh Mei‐Ling
Published: May 2012

A wide‐tuning range and ultra‐low‐phase‐noise 4.28‐GHz voltage controlled oscillator (VCO) is designed in this article. The VCO implemented with the TSMC 0.18 μm 1P6M CMOS technology uses NMOSs only. Source capacitive degeneration technique is used to increase the frequency tuning range. The proposed VCO can have an 18.94% tuning range from 3.53 to 4.34 GHz. The measured phase noise is −131.2 dBc/Hz at 1‐MHz offset from the 4.28 GHz. The corresponding figure‐of‐merit (FOM) and FOMT are calculated to be −191.6 and −197.15 dBc/Hz, respectively. The chip size is 0.571 × 0.822 mm2. The core circuit consumes 16.5‐mW and 1.3‐V power supply. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1941–1944, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26950
Easy fabrication of long‐period fiber grating by winding a wire around an optical fiber fixed to cylindrical ROD
Authors: Lee Cherl‐Hee , Lee Jonghun , Park Jaehee , Taek Kim Kwang
Published: May 2012

A new approach is presented for the easy fabrication of wire‐winding long‐period fiber grating based on the periodic winding of a wire around an optical fiber attached to a cylindrical rod. The periodic pressure of the wire induces change of the refractive index of the optical fiber core, and so the resonance wavelengths of the grating can be easily controlled according to the winding‐wire pitch controlled by a microprocessor. At the winding‐wire pitch of 500 μm, the spectra show resonance–wavelength dips corresponding to the LP02, LP03, LP04, and LP05 cladding modes; the resonance wavelengths go to longer wavelengths at the increased winding pitch of 510 μm; these are in good agreement with theoretical values. The polarization dependence of a resonance wavelength shift of 9 nm and transmission power difference of 2.5 dB was shown at the 520 μm grating pitch. When the diameter of the cylindrical metal rod was smaller, or higher tension by the winding pressure was applied, stronger mode coupling resulted in deeper dips in the transmission spectra according to induced higher index variation. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1937–1941, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26951
Dual‐band branch‐line coupler using double‐sided parallel‐strip line
Authors: Lee Jung‐Kyu , Jung Dong‐Jin , Chang Kai
Published: May 2012

In this article, a three branch‐line coupler is proposed for the dual‐band application. The coupler can operate at two arbitrary frequencies and be realized on double‐sided parallel‐strip line (DSPSL). One of the advantages of the DSPSL is easy realization of high impedance transmission line. The circuit design parameters are derived using the even and odd mode analysis. The measured results show a good performance at 3 and 5.77 GHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1898–1900, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26952
Synthesis of frequency selective surfaces using genetic algorithm combined with the equivalent circuit method
Authors: Campos A. L. P. S. , Martins A.M. , Almeida Filho V. A.
Published: May 2012

Genetic algorithms (GAs) are optimization algorithms that use stochastic techniques inspired in the natural evolution theory. They consist of search algorithms that aim to find a set of parameters that minimizes or maximizes a certain cost function. In this article, the problem is to find a set of physical dimensions for a frequency selective surface (FSS) that force it to have some desired properties. The idea is to use the fact that the analysis of the FSS is much simpler than the synthesis. In this article, this is done for two kinds of FSSs, the square loop and the quasi‐square open loop. Representative numerical examples are presented to demonstrate the effectiveness of the method. Finally, the performance of the GA is presented. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1893–1897, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26953
200‐GHz bandwidth on wafer characterization of CMOS nonlinear transmission line using electro‐optic sampling
Authors: Jamshidifar M. , Spickermann G. , Schäfer H. , Bolivar P. Haring
Published: May 2012

A free running electro‐optic sampling system for on wafer characterization of a 65‐nm technology CMOS nonlinear transmission line with the assessment of device performance up to 200 GHz is described. Noise and relative timing jitter between laser and microwave source, as the major limiting factors for the system dynamic range and bandwidth, are studied. Eventually enhancing the system measurement bandwidth using a fast method, and durable against timing jitter, is achieved at the expense of degraded system noise. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1858–1862, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26954
A compact monopole MIMO array for the 5–6‐GHz band
Authors: Pigozzo F. M. , Giltrelli M. , Sacchetto F. , Assalini A. , Capobianco A. D.
Published: May 2012

In this article, a low‐cost compact multiple‐input multiple‐output array composed of three coplanar waveguide‐fed monopoles printed on flame retardant 4 substrate is presented.The particular feeding mechanism of each single element allows for a wideband behavior, and the specific delta (Δ) shape arrangement of the three radiators leads to a remarkably small footprint. The proposed design is capable of operating in the entire 5–6‐GHz spectrum hence resulting particularly attractive for the IEEE 802.11n 5‐GHz standard. A prototype was fabricated and connected to a Ralink 3 × 3 evaluation board to assess the throughput performance in a typical indoor scenario. The effectiveness of the proposed array is confirmed by experimental results. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1854–1858, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26955
A compact tri‐band bandpass filter with adjustable third passband using square open loop resonator embedded by open stubs
Authors: Ma Xing‐Bing , Zheng Hong‐Xing
Published: May 2012

To obtain an adjustable passband filter, some open stubs are embedded into an open loop resonator. The third resonant frequency can be adjusted by changing size of the stub added at the middle. A tri‐band microstrip bandpass filter is designed to verify the proposed topology, and a prototype was fabricated. Measurement results demonstrate that operating frequency of the sample achieves around 0.86, 1.83, and 2.98 GHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1817–1819, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26957
Compact circularly polarized asymmetric‐slotted microstrip patch antennas
Authors: Nasimuddin  , Chen Zhi Ning , Qing Xianming
Published: May 2012

A technique is demonstrated to generate circularly polarized (CP) radiation of the compact diagonally asymmetric‐slotted microstrip patch antennas. Design rules for the single‐feed, compact, circularly polarized microstrip antennas (CPMA) with any arbitrary‐shaped slots along the diagonal directions are first summarized. Four, compact, CPMA with circular‐, square‐, cross‐, and square‐ring‐shaped slots along the diagonal directions are proposed and compared based on a fixed overall antenna size. A compact, CP, cross‐shaped slotted, microstrip antenna is fabricated and measured to verify the proposed technique experimentally. The measured 3‐dB axial‐ratio bandwidth of about 6.0 MHz is achieved with 10‐dB return loss bandwidth of 19.0 MHz while measured gain of the antenna is 4.0 dBic at 930 MHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1920–1927, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26959
Double‐flip trapezium monopole antenna with high gain design using beveling technique
Authors: Jusoh M. , Jamlos M. F. , Kamarudin M. R.
Published: May 2012

This letter presents a compact double‐flip trapezium monopole antenna (D‐FTMA) for ultra wideband (UWB) application. A significant impedance bandwidth improvement of 7:1 can be achieved at a centre frequency of 7.96 GHz compared to the conventional antenna when the dual bevel technique is deployed near the ground plane. The proposed compact antenna consists of 22 mm × 25.8 mm radiating element and 64 mm × 40 mm rectangular ground plane and fed by a 50 Ω coaxial connector. Furthermore, the low cost D‐FTMA is fabricated on the FR4‐PCB. The antenna agrees between simulation and measurement of return loss, which covers the UWB frequency range (3.1–10.6 GHz). The D‐FTMA has a very constant and high relative gain at particular frequency up to 6 dBi. Moreover, the D‐FTMA is observably capable in producing divisive radiation patterns with linear polarization at four different frequencies: 4, 6, 8, and 10 GHz. The parameter optimization analysis has been studied using CST Microwave Studio. The presented simulated results are supported by the measurement as well. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1882–1886, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26960
A wideband linear array with reduced number of antenna elements
Authors: Ren Yu‐Jiun
Published: May 2012

An X‐band linear array antenna with reduced number of elements is presented. To suppress the sidelobe level using fewer array elements, the synthesis of a nonuniform antenna array has been implemented with the matrix pencil method (MPM) that can provide the excitation and location distribution to miniaturize the array dimension. A comparison with the conventional array antennas with uniform and conventional distributions is conducted to demonstrate the performance of the proposed wideband array, which also experimentally verifies the feasibility of the MPM. The developed array antenna is suitable for portable devices, mini mobile platforms, and low‐tier unmanned vehicles. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1846–1848, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26962
Wideband circularly polarized single probe‐fed patch antenna
Authors: Ma Jinping , Kouki Ammar B. , Landry Rene
Published: May 2012

A wideband circularly polarized single‐patch single probe‐fed patch antenna is investigated for applications of GPS L5, L2 and Galileo E5a, E5b bands. The wideband circular polarization (CP) is achieved by corner‐truncated square patch and insertion of a thick air layer between the radiating patch and the ground plane. A conducting circular disc is etched on the back side of the substrate to compensate the long inductive probe. The obtained 3‐dB axial ratio (AR) CP bandwidth for 25 and 28.5 mm air layer are 5.9% (71 MHz) and 6.4% (77 MHz), respectively. The later covers the all lower L bands of GPS and Galileo. The realized antenna gain reaches 6.45 dBi over the 3‐dB AR bandwidth. The measured and simulated results are in excellent agreement. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1803–1808, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26965
Small square monopole antenna having variable frequency band‐notch operation for UWB wireless communications
Authors: Ojaroudi Nasser , Ojaroudi Mohammad
Published: May 2012

A novel printed monopole antenna for ultra wide band (UWB) applications with frequency band‐notch function is presented.By inserting a vertical H‐shaped slot in the ground plane, a new resonance at higher frequencies can be achieved and provides a wide usable fractional bandwidth of more than 110% (3–11.5 GHz). To generate frequency band‐stop performance, we use a horizontal H‐shaped parasitic structure in the ground plane, that with this design, a frequency notched band of 5.1–5.97 GHz has been obtained. Simulated and experimental results obtained for this antenna show that the proposed single band‐notch square monopole antenna has a good antenna gains and radiation behavior within the UWB frequency. The designed antenna has a small dimension of 12 × 18 mm2. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1994–1998, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26966
A multiband antenna with MIMO implementation for USB dongle size wireless devices
Authors: Kulkarni Anup N. , Sharma Satish K.
Published: May 2012

A compact multiband antenna is proposed for future 4G Long‐Term Evolution (LTE) wireless devices of USB dongle. The antenna covers LTE band‐3 (1710–1880 MHz)/DCS1800 and LTE band‐7 (2500–2690 MHZ based on S11 = −6 dB matching criterion. Next the multiple‐input‐multiple‐output configuration of this antenna is investigated. Prototype antennas were fabricated and experimentally verified. Both measured and simulated results are presented. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1990–1994, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26967
Heterogeneous gigabit orthogonal frequency division multiplexing/radio over fiber transmissions of wired and wireless signals using a reflective semiconductor optical amplifier and single‐arm mach–zehnder modulator
Authors: Pham Dung Tien , Hong Moon‐Ki , Joo Jeong‐Min , Han Sang‐Kook
Published: May 2012

We propose and experimentally demonstrate a novel radio over fiber system that provides different gigabit orthogonal frequency division multiplexing (OFDM) signals transmission for wired and wireless networks using a conventional reflective semiconductor optical amplifier and a single‐arm Mach–Zehnder modulator (MZM). To halve sampling speed of electronics and to simplify a radio frequency front‐end design, the proposed scheme adopts Hermitian symmetry to generate the wireless signal. It was reported that using the proposed scheme, 5‐Gbps 16‐quadrature‐amplitude‐modulation‐OFDM wired and 1.17‐Gbps quadrature phase‐shift keying OFDM wireless signals were successfully transmitted through 23‐km standard single mode fiber link. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1954–1958, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26968
Behavior of several antenna topologies near the human head at the 2.4–2.5 GHz band
Authors: Anguera J. , Andújar A. , Picher C. , González L. , Puente C. , Kahng S.
Published: May 2012

The increasing growth of wireless devices operating at the 2.4–2.5 GHz band near the human head forces the antenna community to improve the robustness of the radiating system to the undesired effects caused by the proximity of the human head. In this sense, this study is focused on assessing the electromagnetic performance of several antenna topologies in the presence of the human head with the objective of determining the topology that maximizes the ratio between the radiated power in free space and the power absorbed by the human head. With this aim, the main antenna parameters [radiation efficiency, radiation patterns, and specific absorption rate (SAR)] of several antenna topologies (dipole, loop, slot, and microstrip patch) operating at the industrial, scientific, and medical 2.4–2.5 GHz band close to the human head are measured and compared. The experimental results demonstrate that the best performance is achieved by the microstrip patch antenna because it presents less human head absorption and less SAR, thus maximizing the radiated power. The study also states that the effect of the human head proximity over the radiation pattern increases the directivity in all cases under study except the patch case where the effect is negligible. Hence, it is possible to conclude that the microstrip patch is a good candidate for wireless devices operating close to the human head because it not only maximizes the ratio between the radiated power and the power absorbed by the human head but also contributes to reduce SAR. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1911–1916, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26970
Improved model of pseudopotentials for array elements
Authors: Psarros Ioannis , Kollia Vassiliki , Fikioris George
Published: May 2012

A recent article has proposed a simplified model, based on the quantum‐mechanical concept of the pseudopotential, for certain types of array elements, particularly for short linear dipoles. A modification of that model that works for a large number of cases is presented here. The modification consists of replacing the complex pseudopotential parameter A by a properly defined real value of A, and is expected to greatly enable future analytical studies. The range of the dipoles' parameters for which the modified model is successful and carefully described. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1874–1879, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26971
New design of an ultra compact printed‐circuit antenna
Authors: Mahe Yann , Chousseaud Anne , Brunet Marc
Published: May 2012

This article presents the design of an ultra compact miniaturized antenna operating around 400 MHz (18 × 8 mm2 on FR4 substrate). Different kinds of miniaturization techniques have been developed. Results indicate that any arbitrary real input impedance can be obtained with S11 lower than −15 dB and quasi omnidirectional radiation pattern. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1783–1785, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26973
A compact broadband nonsynchronous noncommensurate impedance transformer
Authors: Zhurbenko Vitaliy , Kim Kseniya , Narenda Kumar
Published: May 2012

Nonsynchronous noncommensurate impedance transformers consist of a combination of high‐ and low‐impedance transmission lines. High‐impedance lines have narrow tracks in strip and microstrip technology, which allows for high flexibility and miniaturization of the layout in comparison to the traditional tapered line transformers. This flexibility of the broadband nonsynchronous noncommensurate impedance transformers is experimentally demonstrated in this article allowing the length reduction by almost three times. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1832–1835, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26975
Design of a fully integrated wideband six‐port network on a single layer microstrip substrate
Authors: Ibrahim Siti Zuraidah , Bialkowski Marek E. , Karim Mohd Nazri A.
Published: May 2012

The design of a novel wideband six‐port network on a single layer microstrip substrate is presented.Two different configurations of the single‐layer six‐port networks, one conventional and the other nonconventional, are designed, fabricated, and measured. The six‐port network based on the conventional configuration is formed by one Wilkinson divider and three couplers, with one unused port terminated with a coaxial match termination. The nonconventional six‐port network, proposed here, is constructed using a similar configuration except one of the couplers is replaced by a quadrature power divider eliminating the need for match termination. To obtain fully planar device with wideband operation, the six‐port networks use double‐stage Wilkinson dividers, disk type couplers, and a wireless via 90° phase shifter. Their performances are assessed via full‐wave electromagnetic simulations and measurements. Both the simulated and the measured results show a wide bandwidth of the two six‐port configurations in terms of amplitude and phase characteristics across the frequency band of 4.5–8.5 GHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1796–1803, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26976