bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antioxidant effects of supercritical fluid garlic extracts in sunflower oil
Authors: Bravi Elisabetta , Perretti Giuseppe , Falconi Caterina , Marconi Ombretta , Fantozzi Paolo 
Published: February 2016

AbstractBACKGROUNDLipid oxidation causes changes in quality attributes of vegetable oils. Synthetic antioxidants have been used to preserve oils; however, there is interest in replacing them with natural ones. Garlic and its thiosulfinate compound allicin are known for their antioxidant activities. This study assesses a novel formulation, the supercritical fluid extract of garlic, on sunflower oil oxidation during an accelerated shelf‐life test.RESULTSThree quality parameters (free acidity, peroxide values, and p‐anisidine values) were evaluated in each of the six oil samples. The samples included sunflower oil alone, sunflower oil supplemented with BHT, the undiluted supercritical fluid extract of garlic, and sunflower oils supplemented with three levels of garlic extract. The oils were also investigated for their antioxidant properties using the DPPH and the FRAP assays. The results were compared with the effect of the synthetic BHT. Our results underlined that the highest level of garlic extract may be superior, or at least comparable, with BHT in preserving sunflower oil.CONCLUSIONThe oxidative degradation of oily samples can be limited by using supercritical fluid extract of garlic as it is a safe and an effective natural antioxidant formulation. © 2016 Society of Chemical Industry
Design of a DPA based on the dual‐level supply voltage modulation for efficiency improvement
Authors: Cao Xin , Tang Zongxi , Wang Fei 
Published: February 2016

ABSTRACTIn this article, a Doherty power amplifier (DPA) based on the dual‐level supply voltage modulation is proposed. To improve efficiency, the drain of the carrier amplifier in the DPA is supplied with two different voltage levels based on the input RF power. The switching between these two different voltage levels is modulated by a voltage control circuit. The DPA is fabricated using two LDMOSFETs at the working frequency of 2.14 GHz. The measured results show that, compared with the conventional DPA, the power‐added efficiency (PAE) has been enhanced at low RF input power, and the feasibility of the proposed method has been verified. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:759–762, 2016
Gain variation of 60‐GHz patch antennas due to ground plane dimensions
Authors: Seo Haekyo , Hong Wonbin , Gun Kam Dong 
Published: February 2016

ABSTRACTDesigning phased‐array antennas for millimeter‐wave systems becomes difficult because of anomalous gain variation across elements. The performance of each antenna element varies significantly depending on its location on a finite ground plane. Based on simulation and measurement of 60‐GHz patch antennas, we explain which design parameters determine specific gain variations. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:745–747, 2016
Balun‐feed reconfigurable antenna applied for broadband switched beam arrays
Authors: Tsai Jia‐Fu , Row Jeen‐Sheen 
Published: February 2016

ABSTRACTA design for switchable beam linear arrays is described. The radiating element of the array is a balun‐feed reconfigurable antenna and its exciting phase is controlled with two switched‐line phase shifters. By switching the feed points, the reconfigurable antenna can generate dual radiations with the same amplitude and 180° phase differences. Moreover, the delay lines of the two switched‐line phase shifters, respectively provide phase shifts of 45° and 90°. Therefore, the array elements can be excited with the progressive phases of {0°, ±45°, ±90°, ±135°}, and each progressive phase is corresponding to one radiation beam. A 1 × 8 array prototype operating in the range from 1.7 to 2.7 GHz is constructed. Experimental results for the performances of the phased array are shown. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:748–751, 2016
Investigation of four‐arm Archimedean spiral antennas with a built‐in balun for balanced multi‐mode operations in GPS applications
Authors: Mehrabani Ali M. , Shafai Lotfollah 
Published: February 2016

ABSTRACTMulti‐mode four‐arm Archimedean spiral antennas, backed by partially‐filled absorber, are investigated. A low‐profile structure with an embedded balun is realized to produce balanced spiral modes for both broadside and conical radiation patterns over GPS frequency bands. Prototype antennas are developed and measured results are in excellent agreement with computed ones. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:762–767, 2016
Microwave heating of heavy oil reservoirs: A critical analysis
Authors: Oloumi Daniel , Rambabu Karumudi 
Published: February 2016

ABSTRACTIn this article, microwave heating of the heavy oil reservoir, oil‐sand, is critically studied. The study is carried out based on full wave and multiphysics simulations that are performed at 2.45 GHz using both CST Microwave studio and COMSOL. It is demonstrated that most of the microwave power is deposited in bitumen rather in sand due to the dielectric properties of bitumen. Thermal analysis showed that most of the heat is generated in bitumen and is conducted to sand. Although microwave power is selectively deposited into bitumen of the oil‐sand, the temperature gradient between the bitumen and sand is not able to maintain due to high thermal conductivity of the oil‐sand medium. Microwave heating can play very important role to reduce the tailing ponds and protect the environment by minimizing water usage in the recovery process. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:809–813, 2016
Parameterized indoor propagation model for mobile communication links
Authors: Zyoud Alhareth , Habaebi Mohamed H. , Islam Rafiqul 
Published: February 2016

ABSTRACTIn this letter, a path loss indoor propagation model is parameterized. This model is suitable for application in 4G and wireless networks and maybe applied in both LTE and LTE‐A system level simulators. Measurements were conducted at the most popular frequencies for future LTE networks of 1800 and 2600 MHz. In addition, path loss has been examined in terms of various antenna aspects such as polarization and directivity. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:823–826, 2016
High‐gain polarization‐reconfigurable monopole antenna for GNSS applications
Authors: Cao Y. F. , Cheung S. W. , Yuk T. I. 
Published: February 2016

ABSTRACT:The design of a circular polarization (CP) reconfigurable monopole antenna with enhanced boresight gain for the Global Navigation Satellite System (GNSS) is presented. The antenna is composed of two meandered monopoles perpendicular to each other, a switchable feeding network and a metallic reflector. The switchable feeding network consists of a Wilkinson power divider, a 90°‐phase shifter, a double‐pole double‐throw (DPDT) switch, and a defected ground structure (DGS). The power divider divides the input signal into two signals with equal amplitude and 90°‐phase difference. The two signals arrived at the two monopoles have a phase difference of 90° or −90°, determined by two DC voltage inputs to the DPDT switch hence to generate a right‐ or left‐handed CP signal. Compared with the previous work, the antenna requires only two control DC voltages and so is much simpler. Measured results show that the metallic reflector placed at the back of the antenna increases the boresight gain by 5 dBi. The measured impedance bandwidth (S11< −10 dB) and axial‐ratio bandwidth (AR< 3 dB) are from 1.28 to 1.97 GHz and 1.44 to 1.85 GHz, respectively. Simulated and measured results on S11, AR, radiation pattern, and gain show good agreements. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:791–798, 2016
Design and initial measurements of K‐band FMCW rain radar with high resolution
Authors: Kong Ki‐Bok , Jeong Woo‐Ram , Park Seong‐Ook 
Published: February 2016

ABSTRACT:This paper presents an FMCW K‐band rain radar with the property of high resolution. The radar system was designed for measurement of localized torrential rain. Using DDS and FPGA control, heterodyne modulation was used to generate the FMCW down‐chirp signal with 50 MHz bandwidth, and emitted a K‐band signal with nominal power of 125 mW in the vertical direction. To obtain high resolution for the Doppler spectrum, the radar system used a coherent signal processing method. Several experiments were conducted and the results were compared with data from the meteorological administration. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:817–822, 2016
Design and analysis of miniature planar four‐way equal power divider for 60 GHz wireless home network and 77 GHz automobile radars in 90 nm CMOS
Authors: Lin Yo‐Sheng , Lin Yun‐Wen 
Published: February 2016

ABSTRACTA millimeter‐wave (MMW) miniature planar dual balun (i.e. single‐to‐dual‐differential four‐way equal power divider) in 90 nm CMOS technology is reported. The dual balun can be applied to a star mixer for converting the single RF (or LO) input signal to dual differential RF (or LO) signals, or a four‐way power amplifier (PA) for four‐way equal power dividing. In contrast to the traditional four‐way PA that uses three Wilkinson power dividers for four‐way equal power dividing, the proposed PA achieves smaller chip area, higher output power and higher power‐added‐efficiency The dual balun occupies a small chip area of 0.14 mm×0.18 mm (i.e. 0.0252 mm2) and achieves S11 smaller than −10 dB for frequencies of 50–110 GHz. For frequencies of 55–65 GHz, the dual balun achieves S21 of −7.6 to −7.9 dB, S31 of −7.9 to −9 dB, S41 of −7.5 to −7.9 dB, S51 of −7.8 to −8.9 dB, magnitude of amplitude imbalance (MAI) of 0.34–1.1 dB and phase difference (PD) of 179.22–180.78° for ports 2–3, and MAI of 0.3–1 dB and PD of 178.83–180.48° for ports 4–5. For frequencies of 75–85 GHz, the dual balun achieves S21 of −9.1 to −10.5 dB, S31 of −10.7 to −12.7 dB, S41 of −9.1 to −10.5 dB, S51 of −10.7 to −12.6 dB, MAI of 1.7–2.2 dB and PD of 179.42–180.59° for ports 2–3, and MAI of 1.6–2.1 dB and PD of 179.93–180.73° for ports 4–5. The state‐of‐the‐art results of the proposed dual balun indicate that it is suitable for 60 and 77 GHz communication systems. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:850–860, 2016
A comparative study on switchable frequency‐selective surfaces
Authors: Mahmood Suhair M. , Denidni Tayeb A. 
Published: February 2016

ABSTRACTA comparative study guide for several variant switchable frequency‐selective surfaces (SFSS) with different geometries is introduced. The unit cells are designed for the first realized frequency band to study the transmission coefficient bandwidth. Maximum transmission coefficient bandwidth obtained in the transparent state is around 9.62 GHz while the maximum bandwidth obtained in the reflective state is around 5.46 GHz for the solid interior triangle and square frequency‐selective surface, respectively. The maximum joint bandwidth for both transparent and reflective states is 5.46 GHz in the square‐solid‐interior unit cell. Practical results are compatible with simulated results and the obtained results are summarized in a table to provide a clear comparison between the proposed SFSS unit cells in terms of frequency bandwidth. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:839–844, 2016
Compact fan shaped circularly polarized microstrip patch antenna
Authors: Kumar Saurabh , Vishwakarma Dinesh Kumar 
Published: February 2016

ABSTRACTA novel compact single‐feed fan shaped microstrip patch antenna for circular polarization is proposed and investigated. The compact size is achieved by insetting four equally spaced sectoral slits to the periphery of the circular patch which lowers down the resonant frequency of the circular patch. By carefully selecting sectoral slit pairs of different length along the axis of the patch, the lowered dominant mode resonant frequency splits into two close‐degenerate distinct resonant frequencies resulting in circular polarization. The performance of the antenna for different sectoral slit lengths is also studied. The proposed antenna with 48.53% miniaturization as compared to the conventional standard‐size circularly polarized design is fabricated and measured. The antenna exhibits an overall size of 0.3λ0×0.3λ0×0.009λ0 at 1.8 GHz with measured 2.05% 10‐dB impedance bandwidth and 0.44% 3‐dB axial bandwidth. The antenna is simple, easy to fabricate, and suitable for GSM applications. Its measured and simulated results are in well agreement. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:882–886, 2016
Miniaturized band‐notched UWB MIMO antenna with high isolation
Authors: Kang Le , Li Hui , Wang Xin‐Huai , Shi Xiao‐Wei 
Published: February 2016

ABSTRACTA compact multiple‐input multiple‐output (MIMO) antenna is presented for band‐notched ultra‐wideband (UWB) applications. Miniaturization of the proposed antenna is realized by employing the asymmetric coplanar strip (ACS)‐fed structures. To obtain the band‐notched function, open stubs are introduced on the radiators. In addition, an H‐shaped slot is etched on the ground to reduce the mutual coupling between the antenna elements. The designed antenna with an overall size of 28 × 22 × 0.8 mm3 was fabricated and tested. Measured results show the antenna operates over a frequency band of 2.9–11.8 GHz with reflection coefficient less than −10 dB, except at the rejection band of 4.9–6 GHz. Within the operating band, measured port isolation is better than 20 dB. Radiation characteristics and diversity performance of the antenna are also investigated through measurement. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:878–881, 2016
Isolated dual‐band meander line antenna loaded with U‐slot and modified CSRR for WLAN applications
Authors: Deepak  , Kaur Jaswinder 
Published: February 2016

ABSTRACTA thin, single substrate layered, dual directionally isolated band Meander line antenna (MLA) with connected ends, widened near the feed area, loaded by a U‐slot in the patch layer, and by a modification from complementary split ring resonator (CSRR) in the ground layer, is presented for WLAN applications. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:895–901, 2016
Design of U‐shaped antenna using different substrate with enhanced bandwidth for WLAN/WiMAX applications
Authors: Roy Bappadittya , Chakraborty U. , Chowdhury S. K. , Bhattacharjee A. K. 
Published: February 2016

ABSTRACTA compact single layer coaxially fed wideband microstrip antenna is presented in this letter. The proposed antenna consists of a U‐shaped patch and a rectangular ground plane embedded with two open ended rectangular ground slots (RGS). The antenna is designed for wide band of communication (3.02–6.03 GHZ). It is found that the maximum bandwidth of the antenna is obtained about 66.5% when a rectangular slot is inserted near the lower edge of the U‐shaped patch. The antenna was studied experimentally for impedance bandwidth, and gain. It is shown that the antenna can cover the bands of several applications including IEEE 802.11n (and the older 802.11a) WLANs application (allocate channels between 5.15 and 5.825 GHz) and WiMAX (3.2–3.8 GHz) application. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:959–963, 2016
Compact cross loop resonator based chipless RFID tag with polarization insensitivity
Authors: Sajitha V. R. , Nijas C. M. , Roshna T. K. , Vasudevan Kesavath , Mohanan P. 
Published: February 2016

ABSTRACTA fully printable, passive, compact, and polarization‐independent chipless radio frequency identification (RFID) tag is proposed. A symmetric cross loop resonator is the basic scattering element. The prototype of the tag is fabricated on RT Duroid 5880 substrate with εr = 2.2, tan δ = 0.0008, h = 1 mm. Data is coded in the frequency domain with multiple resonators. A 20‐bit tag of dimensions 4 × 4 cm2 is demonstrated. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:944–947, 2016
Analysis and design of broadband 90° sectoral microstrip antennas
Authors: Deshmukh Amit A. , Phatak Neelam V. 
Published: February 2016

ABSTRACTAnalysis and design of broadband 90° Sectoral microstrip antenna derived from 270° Sectoral patch is proposed. The formulation in resonant length at its fundamental mode and procedure to design 90° patch at different frequencies is presented. The proposed 90° patch yields higher bandwidth with better radiation pattern characteristics as compared to equivalent circular, 270° Sectoral, rectangular and their slot cut variations. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:927–932, 2016
Compact circularly polarized ZOR and for antenna employing crlh transmission lines
Authors: Liu Liang‐Yuan , Wang Bing‐Zhong 
Published: February 2016

ABSTRACTA metamaterial‐inspired dual‐band antenna with circular polarization is presented in this article. To achieve composite right/left‐hand (CRLH) resonance and circularly polarized (CP) properties, three meander lines act as the shunt inductance, and two slots act as series capacitance. The asymmetric CRLH antenna fed by a coplanar waveguide (CPW) realizes zeroth‐order resonance and first‐order resonance. The dual‐band and CP antenna can work in a 3 dB axial‐ratio bandwidth as much as 8.5% (2.26–2.46 GHz), and 3.0% (3.90–4.02 GHz). Compared with the recently reported metamaterial antennas, the proposed antenna achieves a smaller size, wider CP bandwidth, and higher gain. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:964–969, 2016
Comprehensive study of printed antenna with the handset modeling
Authors: Sultan K. S. , Abdullah H. H. , Abdallah E. A. 
Published: February 2016

ABSTRACTThis article presents a comprehensive study on the performance of a compact multiband antenna operating in LTE700, GSM850, GSM 900, DCS1800, PCS 1900, UMTS 2100, most of LTE bands (especially the low‐frequency LTE 700 band), and wireless applications. The antenna consists of a monopole in conjunction with meander line antenna. An EBG structure is used to miniaturize the antenna size and to enhance the gain in the direction away from the antenna to lower the SAR within the human body. The EBG structure also contributes in open the operating bands. The proposed antenna is tested using the four recommended test positions of the CTIA association where the proposed antenna reveals good performance in all test cases. Return loss, radiation patterns, SAR, and efficiency of this antenna are computed in free space, in the presence of handset (keypad, battery, speaker camera, RF circuit, and LCD) in talking position, in standby position, in packaging, and as well as in the presence of head and hand in free space and in a car. The SAR values are taken into account not to exceed the standard safety levels. In addition, radiation efficiencies of these handset antennas are computed in the presence of head and hand. All simulation results are performed using the CST software. Simulation results are in good agreement with the measurement results. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:974–980, 2016
Optically induced conductivity in silicon: An active control technique for antennas
Authors: Collett Michael A. , Gamlath Chris D. , Cryan Martin J. 
Published: February 2016

ABSTRACTWe present a technique using a laser diode to actively tune a Franklin Array type antenna. We investigate the effect of directly illuminating the silicon dielectric to generate free charge carriers, increasing the conductivity of illuminated regions. Measurements and simulated results show reconfigurability of radiation patterns, resonant frequencies and polarization. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:994–998, 2016
Orthogonal orientation‐shifted U‐slotted stacked antenna array for dual‐band applications
Authors: Islam I. , Jamlos M. F. , Jamlos M. A. 
Published: February 2016

ABSTRACTA dual‐band orthogonal orientation‐shifted U‐slotted stacked antenna array is presented in this article for long‐term evolution (LTE) and wireless local area network (WLAN) applications covering the frequency of 2.6 and 5.8 GHz. U‐slotted are integrated in radiating patches with one side of the array U‐slot is shifted by orthogonal orientation from its actual position. FR‐4 substrate with 5‐mm air gap from Aluminum (Al) plate ground plane is designed to form the stacked structure. Two main U‐slotted patches are connected with simple quarter wavelength transmission line designed at the reverse side of FR‐4 substrate using copper via with another four U‐slotted patches are coupled parasitically offering simple array structure. It is found that combination of normal and orthogonal orientation‐shifted U‐slotted patches with four parasitic patches assist the antenna array to realize dual‐band operation. Moreover, the unwanted frequency of 3.9 and 4.5 GHz are notched out as well by the presence of parasitic patches. This leaving the proposed antenna with the only two desired frequency band of 2.6 GHz with −16.663 dB reflection coefficient while −22.261 dB at 5.8 GHz. The proposed antenna is simple, compact in size and stated high gain of 8.63 dBi at 2.6 GHz and 7.31 dBi at 5.8 GHz, respectively. The antenna recorded good agreement between the simulation and measurement results for reflection coefficient, E‐plane and H‐plane radiation pattern. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:985–989, 2016
Coupled‐fed antenna with a matching circuit for small size LTE/WWAN tablet computer application
Authors: Jiu‐Sheng Li , Qing‐Hua Fan , Jian‐Zhong Sun 
Published: February 2016

ABSTRACTThe combination of matching circuit and strip provides a new approach to realize wide bandwidth of the antenna. We presented a coupled‐fed antenna with matching circuit for the LTE/WWAN operation in the tablet computer. The total size of the antenna is of 40 × 10 mm2. Furthermore, the matching circuit of a chip capacitor and chip inductor does not increase the antenna's occupied volume. Details of the proposed antenna and its operating principle are presented and discussed. The excited resonant modes of the proposed antenna cover the desired lower LTE/WWAN band operation (698–960 MHz) and the higher band operation (1710–2690 MHz). Good radiation characteristics of the proposed antenna are also obtained. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1002–1006, 2016
Strict lower bounds with separation of sources of error in non‐overlapping domain decomposition methods
Authors: Rey V. , Gosselet P. , Rey C. 
Published: February 2016

SummaryThis article deals with the computation of guaranteed lower bounds of the error in the framework of finite element and domain decomposition methods. In addition to a fully parallel computation, the proposed lower bounds separate the algebraic error (due to the use of a domain decomposition iterative solver) from the discretization error (due to the finite element), which enables the steering of the iterative solver by the discretization error. These lower bounds are also used to improve the goal‐oriented error estimation in a substructured context. Assessments on 2D static linear mechanic problems illustrate the relevance of the separation of sources of error and the lower bounds' independence from the substructuring. We also steer the iterative solver by an objective of precision on a quantity of interest. This strategy consists in a sequence of solvings and takes advantage of adaptive remeshing and recycling of search directions. Copyright © 2016 John Wiley & Sons, Ltd.