bluuebunny/crossref_metadata_2025 huggingface dataset:
Introduction to the U.S. Geological Survey National Water‐Quality Assessment (NAWQA) of Ground‐Water Quality Trends and Comparison to Other National Programs
Authors: Rosen Michael R. , Lapham Wayne W.
Published: September 2008

Assessment of temporal trends in national ground‐water quality networks are rarely published in scientific journals. This is partly due to the fact that long‐term data from these types of networks are uncommon and because many national monitoring networks are not driven by hypotheses that can be easily incorporated into scientific research. The U.S. Geological Survey (USGS) National Water‐Quality Assessment Program (NAWQA) since 1991 has to date (2006) concentrated on occurrence of contaminants because sufficient data for trend analysis is only just becoming available. This paper introduces the first set of trend assessments from NAWQA and provides an assessment of the success of the program. On a national scale, nitrate concentrations in ground water have generally increased from 1988 to 2004, but trends in pesticide concentrations are less apparent. Regionally, the studies showed high nitrate concentrations and frequent pesticide detections are linked to agricultural use of fertilizers and pesticides. Most of these areas showed increases in nitrate concentration within the last decade, and these increases are associated with oxic‐geochemical conditions and well‐drained soils. The current NAWQA plan for collecting data to define trends needs to be constantly reevaluated to determine if the approach fulfills the expected outcome. To assist this evaluation, a comparison of NAWQA to other national ground‐water quality programs was undertaken. The design and spatial extent of each national program depend on many factors, including current and long‐term budgets, purpose of the program, size of the country, and diversity of aquifer types. Comparison of NAWQA to nine other national programs shows a great diversity in program designs, but indicates that different approaches can achieve similar and equally important goals.
Environmental Impacts and Sustainability of Degraded Water Reuse
Authors: Corwin Dennis L. , Bradford Scott A.
Published: September 2008

Greater urban demand for finite water resources to meet domestic, agricultural, industrial, and recreational needs; increased frequency of drought resulting from erratic weather; and continued degradation of available water resources from point and nonpoint sources of pollution have focused attention on the reuse of degraded waters as a potential water source. However, short‐ and long‐term detrimental environmental impacts and sustainability of degraded water reuse are not well known or understood. These concerns led to the organization of the 2007 ASA‐CSSA‐SSSA Symposium entitled Environmental Impacts and Sustainability of Degraded Water Reuse Out of this symposium came a special collection of 4 review papers and 12 technical research papers focusing on various issues associated with the reuse of agricultural drainage water, well water generated in the production of natural gas from coalbeds, municipal wastewater and biosolids, wastewater from confined animal operations, urban runoff, and food‐processing wastewater. Overviews of the papers, gaps in knowledge, and future research directions are presented. The future prognosis of degraded water reuse is promising, provided close attention is paid to managing constituents that pose short‐ and long‐term threats to the environment and the health of humankind.
Cognitive Tools for Scaffolding Students Defining an Ill-Structured Problem
Authors: Zydney Janet Mannheimer
Published: September 2008

This study assessed the effect of cognitive tools on scaffolding students defining an ill-structured problem. Seventy-nine 10th-grade students used the Pollution Solution software to study an environmental problem. A quasi-experimental, mixed-method design was used. One class received the organization tool, a second class received the higher-order thinking tool, a third class received both tools, and a control group received neither tool. The organization tool group obtained a moderate understanding of the problem, which was significantly higher than the control group. Students who received the organization tool also asked significantly more problem-related questions than the other groups. The higher-order thinking tool prompted students to ask significantly more questions than the other groups. The combination tool group did not perform as well as expected. This study raised some questions about whether combining tools will add the effects of these individual tools.
Implementation and Outcomes of a Laptop Initiative in Career and Technical High School Education
Authors: Mouza Chrystalla , Cavalier Albert , Nadolny Larysa
Published: September 2008

This study examined the design, implementation, and outcomes of a laptop technology initiative in a career and technical education high school, in which many of the students had identified learning disabilities. Quantitative and qualitative data were collected that included teacher and student surveys, classroom observations, teacher interviews, student focus groups, and document analysis. Findings of the study indicated that teachers and students a) exhibited improvements in their technological skills and competence, b) used computers extensively for a range of traditional and innovative tasks, and c) strengthened their beliefs and attitudes toward the role of computers in teaching and learning. Increased access to resources and technical support were factors that facilitated sustained use of laptops. The nature of teacher professional development, the physical set-up of the classrooms, and the lack of accountability mechanisms were factors that hindered the implementation of laptops. Results of the study have implications for researchers and practitioners involved in the implementation of laptop initiatives.
The Impact of Technology Use on Hispanic Students' Mathematics Achievement Within Family and School Contexts: Subgroup Analysis between English- and Non-English-Speaking Students
Authors: Park Hae Seong
Published: September 2008

This study tested a theoretical model explaining the relationship between technology, family context, and school context variables as predictors of mathematics achievement across two language groups: English-speaking and non-English-speaking Hispanic students. It used data from the base year and first follow-up of the Education Longitudinal Study (ELS: 2002/2004). The multigroup analysis of the path model was used to analyze the data. The findings continue to indicate the importance of individual technology usage as a predictor of mathematics performance among non-English-speaking Hispanic students. The study also found that Hispanic parents' direct involvement in their children's schooling has a significant negative effect on their academic achievement.
Human-in-the-Loop: A Feedback-Driven Model for Authoring Knowledge-Based Interactive Learning Environments
Authors: Qiu Lin , Riesbeck Christopher K.
Published: September 2008

While computer-based interactive learning environments can provide authentic and supportive settings for problem-based learning, they are very difficult to build. The traditional development model requires significant upfront development and results in systems that are hard to deploy and customize. In this article, we describe a feedback-driven authoring model that aims to reduce the development difficulty by including teachers in the feedback loop to complement system feedback and incrementally author the content in the learning environment during real use. We discuss the design of INDIE, a learning environment authoring toolkit, for supporting the incremental authoring model. Wepresent empirical results obtained from the development and use of Corrosion Investigator, a learning environment delivered by INDIE, as an example to show how the incremental authoring model is implemented in educational settings.
Improving Psychological and Psychiatric Aspects of Palliative Care: The National Consensus Project and the National Quality Forum Preferred Practices for Palliative and Hospice Care
Authors: Hultman Todd , Reder Elizabeth A. Keene , Dahlin Constance M.
Published: September 2008

As patients with terminal disease enter into the final stage of their illness, psychiatric symptoms and psychological responses to the disease contribute to overall suffering of both patient and family. Until recently, no nationally accepted guidelines or practices had been established to support assessment and management of this type of suffering. In 2007, the National Quality Forum published A National Framework and Preferred Practices for Palliative and Hospice Care Quality that included a list of preferred practices for assessing and treating symptoms of psychiatric illness, anticipatory grief and psychologic distress prior to death, and bereavement after the death, of the patient. While specialized care may be provided to patient and families in the context of advanced disease, all clinicians involved in palliative and end-of-life care are responsible for having a basic understanding of effectively managing psychologic and psychiatric aspects of this care. Evidence from current literature supports these best practices.
Psychological Adjustment to Conjugal Bereavement: Do Social Networks Aid Coping following Spousal Death?
Authors: Somhlaba Nceba Z. , Wait John W.
Published: September 2008

This research sought to investigate the role of social networks in coping and adjustment to spousal bereavement. A total of 198 Xhosa-speaking participants, drawn from the rural areas of the Eastern Cape Province, South Africa, took part in the study. Quantitative data analyses revealed significant correlations between perceived social support on Social Support Appraisals scale and the anxiety scores on the Beck Depression Inventory-Second Edition and the problem-solving coping strategy scale on the Coping Strategy Indicator. Regression analyses revealed that depression contributed to increased social support appraisals, while anxiety was a significant negative predictor of the participants' experience of perceived social support. The authors highlight the need for bereavement intervention programs in the rural areas to be geared toward psycho-educating the conjugally bereaved individuals, within the socio-cultural framework, to continuously evaluate their support structures and strengthen ties with social networks that render support, instrumental assistance, and advice in times of need.
Improving the Maximum Conversion of Ethanol Esterification
Authors: Edreder E.A. , Emtir Mansour , Mujtaba Iqbal M
Published: August 2008

In this study, the (catalysed) esterification process of acetic acid with ethanol producing ethyl acetate and water is modelled using detailed mass and energy balances and thermodynamic properties within gPROMS modelling software (version 3.0.3, 2004). The basic model was taken from Mujtaba and Macchietto (1997) assuming no azeotrope formation in the system. Kinetic (hydrochloric acid as a catalyst at 100 °C) and vapour-liquid equilibrium models are taken from Bogacki et al. (1989) and Suzuki et al. (1970) respectively. Physical properties are calculated using the Ideal Physical Properties Foreign Objective (IPPFO) package interfaced to gPROMS. The performance of the batch reactive distillation is evaluated in terms of the maximum conversion of ethanol to ethyl acetate. Five cases with varying amounts of reactants (including the cases with the reduced amount of water in the feed and keeping the amount of acetic acid and ethanol fixed) are utilized to improve the conversion of ethanol to ethyl acetate. Both piecewise constant and linear reflux ratio profiles (single time interval) are considered as a control variable for the base case while the piecewise constant single reflux ratio strategy is adopted for other optimized cases. The results show that both the maximum conversion and distillate product (base case) are improved using the linear reflux strategy as a control variable compared to those with a constant reflux ratio profile. Increasing the amount of water in the feed leads to a reduction in the conversion and distillate product; moreover, the column was operated at a higher reflux ratio compared to the case without any water in the feed.
Transport properties of PVA/PEI/PEG composite membranes: sorption and permeation characterizations
Authors: Ben Hamouda Sofiane , Roudesli Sadok
Published: September 2008

Poly(vinylalcohol)/poly(ethyleneglycol)/poly(ethyleneimine) blend membranes were prepared by solution casting followed by solvent evaporation. The chemical structure of the prepared membranes was analyzed by FTIR and DSC. The sorption behavior as well as the permeabilities of the membranes for pure CO2 and N2 were investigated. The results show that the PVA/PEI/PEG membranes possess a higher permeability of CO2 and a lower permeability of N2. The membrane displays a CO2 permeability of 27 Barrer, and a N2 permeability of 3 Barrer at 25°C and 1 bar. CO2 sorption behavior of the composite membrane, which can be classified as a dual-mode sorption model, and N2 sorption behavior of the copolymeric membrane is in agreement with the Fickian diffusion model.
The Henry reaction: spectroscopic studies of nitrile and hydroxylamine by-products formed during synthesis of psychoactive phenylalkylamines
Authors: Guy Michelle , Freeman Sally , Alder John , Brandt Simon
Published: September 2008

A clandestine two-step route to psychoactive racemic phenylalkylamines utilises the Henry reaction. In the first step an aromatic aldehyde reacts with a nitroalkane to give the nitrostyrene intermediate. In the second step the nitrostyrene is reduced to the phenylalkylamine. An impurity profile of both steps was evaluated through the synthesis and analysis of common street derivatives. The formation of nitrile impurities in the nitroaldol reaction and hydroxylamine impurities in the reduction step were shown by NMR spectroscopy and GC-MS. A selection of reducing agents has been used to give the phenylalkylamines, together with variable quantities of the partially reduced hydroxylamine product. GC-MS analysis of the hydroxylamines showed heat-induced disproportionation which led to the detection of the corresponding oximes.
Impact of selected supramolecular additives on the initial electrochemical lithium intercalation into graphite in propylene carbonate
Authors: Walkowiak Mariusz , Waszak Daniel , Gierczyk Błażej , Schroeder Grzegorz
Published: September 2008

Impact of silicon tripodand-type electrolyte additives and graphite pre-treatment agents on the electrochemical intercalation of lithium cations into graphite was investigated. Addition of Si-tripodand-type silanes to propylene carbonate-based electrolytes was found to suppress detrimental solvent co-intercalation and graphite exfoliation. Similar effects were observed for graphite pre-treated with the reported silane agents. It was observed that the presented supramolecular additives allow for the formation of effective passive layers on graphite during first charging, and thus can be considered as novel low-cost film-forming components for rechargeable lithium batteries.
Density and temperature effect on hydrogen-bonded clusters in water - MD simulation study
Authors: Swiatla-Wojcik Dorota , Pabis Anna , Szala Joanna
Published: September 2008

Molecular dynamics NVE simulations have been performed for five thermodynamic states of water including ambient, sub-and supercritical conditions. Clustering of molecules via hydrogen bonding interaction has been studied with respect to the increasing temperature and decreasing density to examine the relationship between the extent of hydrogen bonding and macroscopic properties. Calculations confirmed decrease of the average number of H-bonds per molecule and of cluster-size with increasing temperature and decreasing density. In the sub-and supercritical region studied, linear correlations between several physical quantities (density, viscosity, static dielectric constant) and the total engagement of molecules in clusters of size k > 4, Pk>4, have been found. In that region there was a linear relationship between Pk>4 and the average number of H-bonds per water molecule. The structural heterogeneity resulting from hydrogen bonding interactions in low-density supercritical water has been also discussed.
Instability analysis of Gaussian beam propagation in a nonlinear refractive index medium
Authors: Zhao Chaoying , Tan Weihan
Published: September 2008

In this paper, we use a thin filament two dimensional Gaussian beam to model the self-trapping filament. The instability of the propagation of a Gaussian beam through a nonlinear refractive index media is investigated, theoretically and numerically. Specifically, the small scale instability of the beam is examined. The numerical results show that the propagation of the two dimensional Gaussian beam presents one or more nonlinear focal points.
The charge exchange reaction dp → (pp)n
Authors: Glagolev Viktor , Martinská Gabriela , Mušinský Jan , Piskunov Nikolaj , Urbán Jozef
Published: September 2008

The ratio of the differential cross section of the charge exchange reaction of the deuteron to that of the nucleon, at small transferred momenta, has been discussed in order to estimate the spin-dependent part of the np → pn charge exchange amplitude.
Shedding new light on the regulation of complementary chromatic adaptation
Authors: Montgomery Beronda
Published: September 2008

Complementary chromatic adaptation (CCA) is a light-dependent acclimation process that occurs in cyanobacteria and likely is related to increased fitness of these organisms in natural environments. Although CCA has been studied for over 40 years, significant advances in our understanding of the molecular foundations of CCA are still emerging. In this minireview, I explore recently reported developments that include novel insights into the molecular mechanisms utilized in the photoregulation of pigmentation and the molecular basis of light-dependent changes in cellular morphology, which are central elements of the process of CCA. I also discuss future avenues of study that are expected to lead to additional progress in our understanding of CCA and our general appreciation of light sensing and photomorphogenesis in cyanobacteria.
Erratum: Effect on radio frequency human exposure of mobile phone inside an enclosed metallic elevator
Authors: Tang C. K. , Chan K. H. , Fung L. C. , Leung S. W.
Published: August 2008

Originally published Microwave Opt Technol Lett 50 (2008), 2207–2210.
A low power low noise amplifier with subthreshold operation in 130 nm CMOS technology
Authors: Song Ickhyun , Jhon Hee‐Sauk , Jung Hakchul , Koo Minsuk , Shin Hyungcheol
Published: August 2008

In this article, a 5.8 GHz ISM‐band CMOS low noise amplifier (LNA) operating in a subthreshold region is presented. A conventional source degeneration inductor is eliminated for higher signal gain while providing reasonable input impedance. The LNA is fabricated using 130 nm CMOS technology and measured signal gain, noise figure, and power consumption are 13.4 dB, 5.2 dB, and 980 μW, respectively, at target frequency. Also the LNA achieves the highest figure of merit among the recently published subthreshold LNAs. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2762–2764, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23788
Investigations on microstrip patch antennas with different slots and feeding points
Authors: Bhunia S. , Pain M. K. , Biswas S. , Sarkar D. , Sarkar P. P. , Gupta B.
Published: August 2008

Single layer single feed dual and multifrequency patch antenna is introduced. Resonant frequency can be reduced and frequency ratio can be increased by cutting unequal rectangular slots at the edge. C band and X band operation can be successfully achieved with a size reduction of about 41%. Multifrequency operation can also be achieved by cutting two equal rectangular slots inside the patch. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2754–2758, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23790
A compact trilayer triband bandpass filter using SIR‐DGS and open‐loop resonator
Authors: Hsiao Pai‐Yi , Weng Ro‐Min
Published: August 2008

A compact trilayer triband (TLTB) bandpass filter (BPF) is presented in this article. The proposed TLTB‐BPF consists of three layers which are two transmission lines on the top layer, open‐loop resonator on the middle layer, and the stepped‐impedance resonator (SIR) defected‐ground structure (DGS) on the bottom layer. The center frequencies of the low band and high band determined by the SIR‐DGS are 1.8 GHz and 5.8 GHz, respectively. The center frequency of the middle band which performed by the open‐loop geometry structure is 3.5 GHz. The measurement results of the insertion loss S21 are −0.97 dB, −2.8 dB, and −3.8 dB at 1.75 GHz, 3.48 GHz, and 5.81 GHz, respectively. The return losses S11 are −13.2 dB at 1.75 GHz, −17 dB at 3.48 GHz, and −11.1 dB at 5.81 GHz. The substrate material for fabrication is an FR4 PCB with a dielectric constant of 4.4 and a thickness of 0.8 mm. The etched size is 36.9 mm × 11.5 mm. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2751–2754, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23791
A method for improving broadband phase performance of CS/CG active balun
Authors: Liu Yu , Yang Tao , Yang Ziqiang , Chen Jia
Published: August 2008

A method for improving broadband phase performance of common‐source/common‐gate (CS/CG) active balun is presented. By setting different terminal impedances and DC bias, the phase error of the balun can be controlled within 7° from 1 to 20 GHz in simulation. A fabricated 2–40 GHz balanced MMIC doubler using the designed active balun has the fundamental frequency suppression (FFS) of more than 16 dB. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2777–2780, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23793
Design of microstrip bandpass and lowpass filters using coupling matrix method and a new hairpin defected ground structure
Authors: Boutejdar Ahmed , Omar Abbas
Published: August 2008

In this work, we present a novel compact hairpin defected ground structure (DGS) bandpass and lowpass microstrip filter using two hairpin‐slots etched in the ground plane. A compact microstrip BPF using coupled DGS resonators is designed using coupling matrix method. The designed BPF showed very wide stopband with two transmission zeros. Furthermore, a simple technique to transform the designed BPF to a LPF was presented. The BPF was fabricated and measured. The measurement results showed good agreement with the theoretical and simulation results. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2898–2901, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23794
Soft‐lithography defined coaxial‐like transmission line with 2.5 dimensional features
Authors: Farcich Nick J. , Asbeck P. M.
Published: August 2008

A novel coaxial‐like transmission line is presented in this article that offers many of the advantages of single‐mode waveguides but is implemented using conventional lithographic methods. On the basis of full‐wave simulations, a prototype “2.5‐D MicroCoax” was fabricated using soft‐lithography techniques with polydimethylsiloxane serving as the substrate material. In addition to width and gap dimensional control, the structure offers an additional degree of freedom by changing the center conductor's height, thus controlling the characteristic impedance and phase velocity—all without having to compromise performance. Simulation and test results confirm the design's single‐mode, low‐loss operation up to the de‐embedded frequency range of 12.0 GHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2827–2830, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23798
Dual band CPW‐fed monopole antenna with asymmetrical ground plane for bandwidth enhancement
Authors: Sim Chow‐Yen‐Desmond
Published: August 2008

The design of a simple coplanar waveguide (CPW)‐fed inverted C‐shaped monopole antenna with symmetrical ground plane is initially proposed. Its dual band operation is able to cover the entire wireless local area network frequency spectrum at 2.4, 5.2, and 5.8 GHz. By simply tuning one of the CPW ground‐plane widths which results in an asymmetry ground plane structure, it is found that the impedance bandwidth for the upper band is doubled to 50.7% (2650 MHz). Furthermore, its lower band centered at around 2.4 GHz is only slightly varied with an impedance bandwidth of 9.2% (220 MHz). © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3001–3004, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23799
Symmetric microstrip interdigital capacitor‐compensated high directivity directional‐coupler
Authors: Baek Donghyun , Kim Youngjin
Published: August 2008

This article describes a symmetric capacitor‐compensated microstrip directional‐coupler design with very high directivity. The compensation capacitors are incorporated between the coupling lines as interdigital type on the PCB board. The prototype directional‐coupler shows 19.6 dB coupling factor and achieves very high directivity of more than 45 dB at 1.9 GHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2801–2803, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23800
Improvement of optical beam‐forming networks based on broadband optical source and chirped fiber grating
Authors: Zhou Bo , Zheng Xiaoping , Ye Yabin , Zhang Hanyi , Guo Yili , Zhou Bingkun
Published: August 2008

We propose a photonic beam‐forming network scheme based on a broadband optical source (BS), double sideband suppressed carrier (DSB‐SC) modulation, and a chirped fiber grating (CFG). The principle and feasibility are proved by both theoretical analysis and experiments. In 20–32 GHz microwave band, experimental results show a good delay time consistency and the ratio of RF signal to noise met the practical application demands. The time consistency errors are smaller than 3 ps in 20–40GHz band. Specially, compared with traditional double sideband (DSB) modulation scheme, in the proposed approach the dispersion‐induced RF power degradation is effectively mitigated over 24 dB at 30 GHz, and the experimental results agree well with the theoretical ones. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2992–2994, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23802
A 1‐GHz GaN HEMT based class‐E power amplifier with 80% efficiency
Authors: Lee Yong‐Sub , Lee Mun‐Woo , Jeong Yoon‐Ha
Published: August 2008

This article reports a highly efficient 1‐GHz class‐E power amplifier based on a GaN HEMT. The compensation elements with a series capacitor and a shunt inductor are used to compensate for the internal parasitic components of the packaged transistor. To improve output power and efficiency by suppressing harmonic powers, an output matching circuit using the transmission lines is used. The peak PAE and drain efficiency of 79.2 and 80.4% with a power gain of 18.14 dB is achieved at an output power of 41.14 dBm for a continuous wave. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2989–2992, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23803
An RF module integrated with a dual‐band DRO oscillating at X‐ and K‐band simultaneously
Authors: Yang Ru‐Yuan , Weng Min‐Hang , Hung Cheng‐Yuan , Wu Hung‐Wei
Published: August 2008

In this article, a high quality vehicle RF module integrated with a temperature stable dual‐band dielectric resonator oscillator (DRO) oscillating at X‐ and K‐band simultaneously is implemented. The DRO shows the first oscillating frequency at 11.545 GHz and the second oscillating frequency at 23.09 GHz using the fundamental TE01 and enhanced TE02 mode of the dielectric resonator (DR), respectively. The used DR is (Zr, Sn)TiO4 ceramic with a dielectric constant (εr) of 36, a quality factor (Q×f) of 60,000 and a temperature coefficient of resonant frequency (τf) of ± 1 ppm/°C. The design procedure is clearly described in this article. The propagation mode behaviors and equivalent circuits of the DRO are used to predict the circuit performances of the RF module. For practical testing, the RF module combining with a horn antenna, the DRO and a surface‐mounted mixer is fabricated and measured. The results are close matched with the circuit simulation. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2961–2965, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23805
Bow‐tie antenna using high‐impedance ground plane
Authors: Lee Yi‐Chieh , Sun Jwo‐Shiun
Published: August 2008

This presents a high‐impedance ground plane (HIGP) structure for bow–tie antenna in order to improve its radiation performances. The HIGP is a kind of electromagnetic bandgap (EBG) structure to decrease surface waves and to bring an improvement of side lobe level, and reduce the mutual coupling between the two antennas. As compared to proposed antenna without HIGP, the measurement results show a fairly good antenna gain and a 5–10 dB reduction in the back lobes. Several properties of the proposed antenna for WLAN operation such as impedance bandwidth, radiation pattern, and measured gain have been investigated in detail, numerically and experimentally. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2928–2931, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23807
Compact band‐notched ultrawideband Y‐shaped antenna with dual inverted‐L slots
Authors: Choi By Sun‐Ho , Jeong Gye‐Taek , Park Ho‐Hwan , Lee Hwa‐Choon , Kwak Kyung‐Sup
Published: August 2008

In this work, a novel band‐notched ultrawideband (3.1–10.6 GHz) Y‐shaped microstrip patch antenna with dual inverted‐L slots is presented. The proposed antenna consists of a wideband Y‐shaped monopole antenna and dual inverted‐L slots, producing band‐notch characteristics. To obtain sufficient bandwidth when the return loss (RL) < −10 dB, but still generate band‐notch characteristics, we propose that a partial ground plane, a coaxial probe source, and two inverted‐L slots can be used. The measured bandwidth of the fabricated antenna is from 2.96 to 4.85 GHz (from 6.05 to 12.65 GHz when the RL < −10 dB), and the frequency notch band is from 5.15 to 5.825 GHz. The measured gain is 3.66–4.58 dBi, which drops to −3.80 dBi in the notch band. The azimuth and elevation of the experimental 3‐dB beam width (HPBW) are 72.58° and 88.59° at 7.0 GHz, respectively. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2797–2799, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23814
Ultra‐wide bandpass filters with sharpened roll‐off skirts, extended upper‐stopband, and controllable notch‐band
Authors: Wong Sai Wai , Zhu Lei
Published: August 2008

This article presents a novel ultra‐wide bandpass filter on microstrip line with sharpened roll‐off skirts, extended upper‐stopband, and controllable notch‐band. A shunt stub structure with two split symmetrical open end stubs is purposed, aiming to create a pair of transmission zeros at the lower and upper ends of the concerned ultra‐wideband range from 3.1 to 10.6 GHz. Then, this open stub loaded with dissimilar low‐impedance sections is studied to create a notch band that is located at 5.6 GHz. To further widen the upper‐stopband and sharpen the roll‐off skirts, an electromagnetic‐bandgap structure is inserted between the two identical coupled lines. Finally, a filter prototype with notch band are designed, fabricated, and tested. Its overall size is only about 0.19λ2. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2958–2961, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23818
Design of ultra‐wideband bandstop filter with three transmission zeros
Authors: Kanti Mandal Mrinal , Krishna Velidi Vamsi , Sanyal Subrata , Bhattacharya Amitabha
Published: August 2008

In this article, a compact microstrip coupled‐line configuration has been presented to design a wideband bandstop filter with three transmission zeros. These transmission zeros are utilized to obtain sharp rejection characteristics. A loss‐less transmission line model is used to obtain the filter design parameters. To validate the theoretical prediction, a single section sharp‐rejecting, compact, bandstop filter having a 20‐dB rejection bandwidth of ∼100% at 1.5 GHz has been fabricated. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2955–2957, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23819
A new design method of microstrip dual‐band bandstop filters
Authors: Kikuchi Katsunori , Ma Zhewang , Anada Tetsuo
Published: August 2008

A generic lumped‐element circuit of dual‐band bandstop filter (DBBSF) is proposed based on novel composite shunt resonators, and its design method is developed with closed‐form formulas. As an example, a DBBSF with center frequencies of 1.7 and 2.3 GHz is designed and fabricated using microstrip lines. The measured frequency response agrees excellently with the theoretical predictions, validating well the proposed design theory and filter structure. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2888–2892, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23822
Magneto‐dielectric properties of the Y3Fe5O12 and Gd3Fe5O12 dielectric ferrite resonator antennas
Authors: Fechine P. B. A. , Moretzsohn R. S. T. , Costa R. C. S. , Derov J. , Stewart J. W. , Drehman A. J. , Junqueira C. , Sombra A. S. B.
Published: August 2008

The main objective of this work was to study the magnetic and dielectric properties of Y3Fe5O12 and Gd3Fe5O12 garnets resonator antennas obtained from a new procedure in the solid state ceramic technique. These ferrite resonator antennas (FRAs) had the ability to change their characteristics as a function of the applied magnetic field. The Y3Fe5O12 resonator was able to increase the antenna frequency range with application of external magnetic field. Some of the properties of dielectric resonator antennas (DRAs) can be actively controlled by using low‐loss ferrite materials. When unbiased, these ferrite resonator antennas (FRAs) exhibit similar behavior to DRAs. However, when a DC magnetic bias is applied, the tensor nature of the ferrite permeability is invoked, and various parameters can be controlled electronically. We also studied the magnetic behavior of the antennas and did a numerical study of the gain and directivity of the ferrite resonator antennas. These results can be important to develop wideband third‐generation (3G) cellular phones and other wireless products. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2852–2857, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23824
Dual‐mode filters based on substrate integrated waveguide by multilayer LTCC technology
Authors: Wei Qi‐Fu , Li Zheng‐Fan , Shen Hai‐Gen
Published: August 2008

This letter presents the design and experiment of a single‐cavity dual‐mode bandpass filter and a double‐cavity dual‐mode bandpass filter realized by substrate integrated waveguide (SIW) structure. Both the filters are designed and simulated by network theory and high frequency structure simulator (HFSS), and fabricated using multilayer low‐temperature co‐fired ceramic (LTCC) technology. The measured results show good agreement with the simulated results and validate the structures of the proposed dual‐mode filters. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2788–2790, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23829
A small RFID tag antenna using proximity‐coupling to identify metallic objects
Authors: Choi Wonkyu , Kim Jungsuk , Bae Ji‐Hoon , Choi Gilyoung
Published: August 2008

This article presents the design of a small‐ and low‐profile radio frequency identification tag antenna in the UHF band that can be stuck to metallic objects. The designed tag antenna, which uses a ceramic material as an antenna substrate, consists of a radiating patch and microstrip lines for a proximity‐coupled feeding structure. Impedance matching can be simply obtained between the antenna and tag chip without any matching network using the antenna structure. The return‐loss bandwidth for S11 < 10 dB and radiation efficiency are about 9.5 MHz and 40% at 911 MHz, respectively. The read range is approximately from 3 to 3.5 m when the tag antenna is mounted on a metallic surface. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2978–2981, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23831
Inverse class‐F power amplifier using the metamaterial structure on the harmonic control circuit
Authors: Kim Hyoungjun , Seo Chulhun
Published: August 2008

In this study, the inverse class‐F power amplifier at 1.8 GHz using the harmonic control circuit based on a metamaterial structure is proposed and experimentally tested. The harmonic control circuit has been used with transmission line and metamaterial structure to open the 2nd harmonics, to short the 3rd harmonics, and to match the fundamental frequency to 50 Ω. The interesting properties of the metamaterial structure allow a size reduction of the harmonic control circuit as well simplification of the design. A detailed analysis of the metamaterial structures based on the equivalent circuit model is provided. The proposed harmonic control circuit has been used to design the inverse class‐F power amplifier with maximum PAE of 70.4%. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2881–2884, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23836
A novel low‐cost multisensor‐tag for RFID applications in healthcare
Authors: Catarinucci Luca , Cappelli Mauro , Colella Riccardo , Tarricone Luciano
Published: August 2008

Healthcare represents one of the most promising sectors for future RFID applications. RFID, indeed, candidates as a natural solution to a large amount of biomedical problems, from care giving to telemedicine. For a large scale introduction into this market, the integration of RFID systems with a sensor network could be the turnpoint. We focus here on the implementation of a multisensor RFID system able to send information about the physiological status of a patient by simply exploiting its intrinsic characteristics. Without changing the digital design of the chip (hence its basic cost), it is possible to transmit extra‐information on sensor parameter variations. Results proposed with respect to the wireless remote monitoring of the patient temperature demonstrate the quality of the proposed technology, and the possibility to be extended to many other biomedical sensors. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2877–2880, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23837
Low numerical dispersion locally one‐dimensional FDTD method based on compact higher‐order scheme
Authors: Liang Feng , Wang Gaofeng , Ding Wen
Published: August 2008

A two‐dimensional (2D) locally one‐dimensional finite‐difference time‐domain (LOD‐FDTD) method with low numerical dispersion is introduced by virtue of a parameter‐optimized compact fourth‐order scheme. The numerical dispersion error and anisotropy of numerical phase velocity of this new method are proven to be significantly reduced compared with the original second‐order method. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2783–2787, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23842
An ultra‐wide stopband low‐pass filter using dual reverse U‐shaped DGS
Authors: Hsiao Pai‐Yi , Weng Ro‐Min
Published: August 2008

On the basis of the characteristics of defected ground structures (DGSs), a low‐pass filter (LPF) with a sharp rejection and an ultra‐wide stopband is constructed. The proposed LPF comprises of a dual reverse U‐shaped DGS along with two H‐shaped patterns on the ground plane and a microstrip line on the top layer. The attenuations are 2 and 32.8 dB at 3.7 and 3.85 GHz, respectively. The maximum attenuation rate is 205 dB/GHz. The proposed LPF achieves an ultra‐wide stopband with overall 20 dB attenuation from 3.75 GHz up to 20 GHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2780–2783, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23843
Single probe fed cavity backed circularly polarized antenna
Authors: Luo Guo Qing , Sun Ling Ling , Dong Lin Xi
Published: August 2008

The concept of a novel single probe feed cavity backed circularly polarized antenna based on substrate integrated waveguide technique has been investigated in this article. The proposed antenna provides high circularly polarized radiation performance and keeps advantages of low profile and convenient fabrication. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2996–2998, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23848
New THZ excitation of planar Goubau line
Authors: Treizebré Anthony , Bocquet Bertrand , Xu Yansheng , Bosisio Renato G.
Published: August 2008

Quite recently, it has been found that conducting wires lying on a flat dielectric substrate can propagate Terahertz (THz) waves in the same way as conducting wires entirely coated with a dielectric (Goubau line). This phenomenon is interesting because it is a basic requirement to fabricate integrated circuits at THz frequencies. The excitation of planar Goubau line (PGL) waves was found to have a very strong Goubau mode on conducting wire. The excitation was made with a coplanar waveguide transition fed with a THz signal obtained from a vector network analyzer. The Goubau mode on PGL was excited with high efficiency (up to 75%.). This is a first step in the design of THz BioMEMS dedicated to living cell investigations. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2998–3001, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23850
Novel diplexer using composite right/left‐handed transmission lines
Authors: Hu Xin , He Sailing
Published: August 2008

A new type of notch filter based on a balanced composite right/left‐handed (CRLH) transmission line is proposed. Combining such two notch filters with a Y‐junction divider, a novel diplexer is designed and studied. The diplexer has a wide and flat‐top pass‐band and very good isolation between the two outputs. Both theoretical analysis and experimental results are given and they agree with each other. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2970–2973, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23851
A microstrip grid array antenna optimized by a parallel genetic algorithm
Authors: Xing Chen , Kain Chen , Kama Huang
Published: August 2008

In this article, a novel microstrip grid array antenna is presented. For achieving a high gain and good impedance match, its structural parameters were optimized by a parallel genetic algorithm. A prototype antenna measures a gain of 18.3 dBi with an input return loss of −15.0 dB at its working frequency of 2.45 GHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2976–2978, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23856
Novel UWB BPF design using modified trisection MMR
Authors: Chen Lian‐Yu , Lee Ching‐Her , Hsu Chung‐I G.
Published: August 2008

A novel ultrawideband (UWB) bandpass filter (BPF) is proposed and designed using a multimode resonator (MMR) that is modified from a conventional trisection stepped‐impedance resonator (TSSIR). With the first five resonant modes of the TSSIR and the coupling peaks of the input/output interdigital parallel‐coupled lines properly located in the UWB passband, a seven‐transmission‐pole UWB BPF was realized. Open stubs were embedded in the MMR to produce a transmission zero for improving the upper‐stopband rejection. A prototype of the proposed UWB BPF has been fabricated and measured for performance verification. Besides a measured return loss of higher than 11 dB between the lowest and highest transmission poles, the measured results show a minimum insertion loss of 0.3 dB and a group delay variation of less than 0.07 ns in the UWB passband. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2904–2907, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23860
Design of a new dual‐band microstrip bandpass filter with multiple transmission zeros
Authors: Li Lin , Li Zheng‐Fan
Published: August 2008

A novel dual‐band microstrip bandpass filter with multiple transmission zeros has been proposed in this article. Dual‐band resonators composed of one shunt short‐circuited stub and one shunt open‐circuited stub are connected by dual‐band admittance inverters (J‐inverters) to create dual‐passband responses. The three transmission zeros brought by the resonator plus the transmission zero resulted from the inverter will produce sharp attenuations near the passbands, and large isolations between the passbands. Design formulas of this type of filters are also provided in detail. To verify the presented concept, a filter with a dual‐band response has been designed and fabricated with microstrip technology. The measured results are in good agreement with the full‐wave simulation results. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2874–2877, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23861
Properties of mixed‐mode S‐parameters
Authors: Zhou Yonggang , Chen Yinchao
Published: August 2008

The paper explores the properties of mixed‐mode (MM) S‐parameters, which are widely used in computer PCB and wireless RF industries and have not received serious discussion in the current literature. In this paper, to compare these MM S‐parameter properties to the corresponding ones of the conventional single‐ended S‐parameters, we have developed the symmetric and unitary properties in terms of the mixed‐mode S‐parameter matrix. Also, we have developed a method to deal with the reference plane shift, which is expressed in a mixed‐mode S‐parameter fashion for the cases of both the coupled and uncoupled transmission lines. To validate the developed mixed‐mode S‐parameter properties, we have herein analyzed a 10‐dB coupled line‐directional coupler constructed by a pair of coupled transmission lines. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2869–2874, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23862