bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microwave dielectric properties of NiFe2O4 nanoparticles ferrites
Authors: Rubinger C. P. L. , Gouveia D. X. , Nunes J. F. , Salgueiro C. C. M. , Paiva J. A. C. , Graça M. P. F. , André P. , Costa L. C. 
Published: March 2007

AbstractNickel ferrite (NiFe2O4) was synthesized by the micelles mixing method, using lyophilized coconut oil. The method leads to the formation of ferrite nanoparticles. Nickel ferrite was prepared in coconut oil suspension and annealed during 4 h, at 400, 600, 800, 1000, and 1200°C. The X‐ray diffraction (XRD) was applied to investigate the nanoparticle size dependence on the annealing temperature. Complex permittivity measurements were carried out in cavity resonators at 5.0 and 9.0 GHz, using the small perturbation theory. The main result is that the real part of the permittivity decreases with increasing annealing temperatures (3.6–2.4), while the imaginary part of the permittivity varies only for the lowest annealing temperatures, remaining low for the other samples (about 10−3). The X‐ray diffractograms indicates that the nanoparticle size increase with annealing temperature, allowed the correlation between the nanoparticle size and the observed microwave dielectric response. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1341–1343, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22402
Efficient analysis of resonator by the unconditionally stable three‐dimensional iterative ADI‐FDTD method
Authors: Ye Z. B. , Du L. , Rui P. L. 
Published: March 2007

AbstractIn this article, the iterative alternating‐direction‐implicit finite‐difference time‐domain (ADI‐FDTD) method is used to simulate the resonator in electromagnetic field. This method is exactly the same as the original Crank–Nicolson (CN) method, while recognizing the ADI‐FDTD method as a special case of a more generalized iterative approach to solve the CN‐FDTD method, which can reduce the splitting error of the ADI‐FDTD method. Numerical results demonstrate that this 3D iterative ADI‐FDTD method can improve the accuracy of the ADI‐FDTD method by using the time step size greatly exceeding the Courant–Friedrich–Levy (CFL) limit within several iterations. As a result, much time is saved compared with CN‐FDTD method. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1473–1477, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22403
Maximizing net light pressure on a chiral sculptured thin film by selection of the vapor incidence angle
Authors: Ross Benjamin M. , Lakhtakia Akhlesh 
Published: March 2007

AbstractThe net light pressure on a chiral sculptured thin film, for normal incidence, can be maximized by appropriately choosing the vapor incidence angle during the fabrication of the film by physical vapor deposition. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1407–1409, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22407
Permittivity characterization from open‐end microstrip line measurements
Authors: Hinojosa J. 
Published: March 2007

AbstractA broad‐band method for measuring the complex permittivity of isotropic film‐shaped materials at low microwave frequencies is presented. The characterized material is the substrate of an open‐end microstrip line used as sample‐cell. Complex permittivity is computed from S11 reflection parameter measurement of open‐end microstrip cell using analytical relationships, which decrease the computation time. Vector network analyzer and high‐quality on‐microstrip test fixture are used for the measurement bench. Measurements over 0.01 GHz–3 GHz frequency range with several nonmagnetic materials show good agreements between measured and predicted results. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1371–1374, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22410
An improved discrete complex image method for Green′s functions in multilayered media
Authors: Zhuang Lei , Zhu Guoqiang , Zhang Yunhua , Xiao Boxun 
Published: March 2007

AbstractThe numerical implementation of traditional discrete complex image method (DCIM) approach for spatial‐domain Green's functions (GFs) is limited to low values of ρ (ρ is the distance between the source and the field points of the GFs). Although recently a direct DCIM was introduced to obtain both near‐ and far‐field region accurately, the direct DCIM was limited to choose the paths of kz plane in free‐space layer. In this paper, an improved DCIM is introduced without any quasistatic and surface‐wave extraction. We choose a novel path of kz plane. The improved DCIM works in both the near‐ and far‐field region for multilayered media as direct DCIM does. And the method is applicable to choose the paths of kz plane in the layer where the source and field points are. The improvement makes it feasible to accelerate the calculation of spatial‐domain GFs of electrically large buried objects in multilayered media. In this paper, the method developed for the computation of GFs is used for planar structures containing both lossless and lossy media. The CPU time used to perform the improved DCIM is less than 1 s for computing the fields, with a horizontal source‐field separation from 1.6 × 103λ0 to 16λ0 (λ0 is the free‐space wavelength). © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1337–1340, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22412
An efficient metamaterial‐inspired electrically‐small antenna
Authors: Erentok Aycan , Ziolkowski Richard W. 
Published: March 2007

AbstractThis article presents an inexpensive, efficient, and electrically‐small antenna design that is based on a metamaterial‐inspired structure driven by an electrically‐small semi‐circular loop antenna, which is coaxially‐fed through a finite ground plane. The proposed antenna system is linearly scalable over a wide frequency spectrum. The design details and radiation characteristics of the antenna system at 300, 1580, and 6000 MHz are reported. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1287–1290, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22415
Design of a 5‐bit time delay module with left‐handed and right‐handed transmission line
Authors: Chen Lijun , Zhu Qi , Han Lu , Xu Shanjia 
Published: March 2007

AbstractA 5‐bit time delay module with left‐handed and right‐handed transmission line is designed and fabricated, which can realize a minimum time delay of 100 ps and a maximum time delay of 3100 ps in 9–10 GHz frequency range. Compared with traditional transmission line time delay module, the present 5‐bit left‐handed transmission line time delay module has shown its compactness and low losses. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1256–1259, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22416
New band‐pass filter design with tapped‐line using J/K‐inverter
Authors: Yun Tae‐Soon , Hong Tae‐Ui , Lee Byungje , Choi Jin‐Joo , Kim Jin‐Young , Kim Ki‐Byoung , Lee Jong‐Chul 
Published: March 2007

AbstractIn this letter, a novel design method of tapped‐line gap‐coupled half‐wavelength band‐pass filter (BPF) using J‐ or K‐inverter is proposed. A model of tapped‐line is composed of shunt stub and the additional transmission line that has the electrical length of the negative value. The electrical lengths of the stub and line are functions of the line's impedance and the inverter that has a variable of filter's bandwidth. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1253–1256, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22417
Input impedance‐tuning slots of PIFA antennas
Authors: Wang Hanyang 
Published: March 2007

AbstractInput impedance‐tuning methods are proposed for antenna designs of mobile communications devices. The proposed method can be applied to input impedance‐tuning of single‐band, dual‐band, and multiband planar inverted‐F antenna. The prominent feature of this impedance‐tuning method is to use an inductive‐tuning slot or a capacitive‐tuning slot, rather than the width of the grounding and feeding strips and the gap between the grounding and feeding strips, to get desirable impedance matching and bandwidth. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1464–1467, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22419
Small broadband disk‐loaded monopole antenna with a vertical ground plane
Authors: Kim Myungbum , Khang Nguyen , Woo Insang , Choo Hosung , Park Ikmo 
Published: March 2007

AbstractA small broadband monopole antenna with a vertical ground plane and an electromagnetically coupled feed is presented in this paper. The antenna was formed by positioning a probe with a folded stripline under a shorted square disk. A resonance of the shorted square disk was coupled to a resonance of the probe with a folded stripline, so that the antenna had a wide bandwidth of about 37% at the center frequency of 2.313 GHz based on a VSWR ≤ 2. The antenna had dimensions of 11 mm × 11 mm × 11 mm and rectangular slits were inserted into the vertical ground plane to improve distortion of the radiation pattern. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1401–1405, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22422
A 1‐V, 6‐mA, 3–6 GHz broadband 0.18‐μm CMOS low‐noise amplifier for UWB receiver
Authors: Chang C.‐P. , Yen C.‐C. , Chuang H.‐R. 
Published: March 2007

AbstractA 3–6 GHz broadband CMOS single‐ended LNA fabricated with the 0.18 μm 1P6M process for UWB and WLAN receiver is presented. Due to its noncascode circuit architecture, the proposed LNA can operate under 1V supply voltage and 6mA current consumption. In the UWB low band (3.1–5.15 GHz), the broadband LNA exhibit a gain of 11.7–13.7dB, noise figure less than 4.9 dB and input return loss better than 13.2 dB, respectively. From 5–6 GHz range (covering Hiperlan, 802.11a, and MBOA group B), the LNA exhibit a gain of 12.4–12.7 dB, noise figure less than 5.5 dB and input return loss better than 15.7 dB, respectively. The input P1dB and IIP3 are −20 dBm and −10.9 dBm, respectively. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1358–1360, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22428
Design of a compact dual‐band bandpass filter using trisection stepped impedance resonators
Authors: Chang Sheng‐Hsiung , Weng Min‐Hang , Kuan Hon 
Published: March 2007

AbstractWe propose a compact dual band bandpass filter (BPF) using trisection stepped impedance resonators (SIRs). By appropriately selecting the impedance ratio (K) and length ratio (α) of the SIR, the harmonic frequencies can be tuned for generating the dual‐passband response. The BPF has good dual‐passband performances at 2.4/5.2 GHz and has a very smaller area in comparison of previous works. Good agreement is also shown between full‐wave electromagnetic (EM) simulation and measurement. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1274–1277, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22432
2 × 2 Array with UC‐EBG ground for low RCS and high gain
Authors: He Wei , Jin Ronghong , Geng Junping , Yang Guoming 
Published: March 2007

AbstractIn this paper, by exploiting surrounding fractal UC‐EBG ground plane, a 2 × 2 microstrip array capable of X‐band operation is studied. Result of comparison shows that this microstrip array proposed has much lower RCS than that of 2 × 2 array with the standard ground at frequencies outside operating band within 2–18 GHz while its gain is improved in the operating band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1418–1422, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22440
Super‐hyper singularity treatment for solving 3D electric field integral equations
Authors: Tong Mei Song , Chew Weng Cho 
Published: March 2007

AbstractThe super‐hyper singularity treatment is developed for solving three‐dimensional (3D) electric field integral equations (EFIE). EFIE usually takes two forms: one of which includes a super‐hyper singular kernel generated by the double gradient of the Green's function. So far, there is no way to evaluate these super‐hyper singular integrals needed for constructing the pertinent matrix equation. We apply the series expansion of the Green's function to the super‐hyper singular kernel and derive closed‐form expressions for their evaluations in the Cauchy principal‐value sense. The derivation is based on the constant current approximation over a flat triangle patch, but it can be extended easily to higher‐order approximations of the current. The scheme can be used to accurately calculate the near and self interaction terms in the impedance matrix for the method of moments (MoM), Nyström method or boundary element method (BEM). © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1383–1388, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22443
Inverse formula of coupled‐striplines by synthetic asymptote
Authors: Wang Ke , Shi Xiangquan , Tang Wanchun 
Published: March 2007

AbstractThe inverse formula for the ratio of the elliptic integral of the first kind is obtained by synthetic asymptote in this paper. Then calculate the relative dimensions of the structures of broadside‐coupled and edge‐coupled striplines. The average errors of the characteristic impedance for the two cases are less than 1.5%. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1309–1312, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22446
Retro‐directive array with beam steering capability, made by coupled, self‐oscillating mixers
Authors: Christodoulou Michail G. , Chrissoulidis Dimitrios P. 
Published: March 2007

AbstractA novel, phase‐conjugator array for active, retro‐directive operation has been made by use of three dual‐gate, self‐oscillating mixers (SOM's), mutually locked by use of 6 dB hybrid couplers. The coupling network incorporates the load of the oscillators. Reduced LO penetration has been achieved at the RF and IF and ports by trapping the LO signal within the dc bias lines of each SOM. Injection of two external signals at the LO frequency, each at a marginal SOM, with phase difference ΔΦ between them, allows for retransmission at angles other than the angle of arrival of the incident signal. Measured results are presented for a retro‐directive array designed for nominal operation at 900 MHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1303–1309, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22447
Wideband fractal printed monopole antennas
Authors: Lee Yi‐Chieh , Sun Jwo‐Shiun , Lin Syuan‐Ci 
Published: March 2007

AbstractStudy of CPW‐fed monopole antenna with circular and rectangular fractal shape radiator element is proposed. By using fractal slot, new design antennas have the wide measured return loss bandwidth. In addition, the omnidirectional radiation patterns of the design antennas covering the entire frequency range have been obtained. Several properties of the antennas such as impedance bandwidth, radiation patterns, and gain have been investigated numerically and experimentally in detail. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1267–1272, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22448
All‐optical mm‐wave generation by using direct‐modulation DFB laser and external modulator
Authors: Chen Lin , Pi Yazhi , Wen Hong , Wen Shuangchun 
Published: March 2007

AbstractWe proposed and experimentally demonstrated a novel method of optical mm‐wave generation using only one Mach‐Zehnder modulator and a direct‐modulator, based on the method of optical carrier suppression. Using this proposed method, the 2.5 Gb/s data channel was successfully transmitted over 20 km for downstream with less than 1‐dB power penalty. Therefore, the system configure of mm‐wave generation can be further simplified and be more cost effective. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1265–1267, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22449
Nonlinear actuation model for lateral electrostatically‐actuated DC‐contact RF MEMS series switches
Authors: Lázaro A. , Girbau D. , Pradell L. , Nebot A. 
Published: March 2007

AbstractIn this work, a nonlinear model to predict actuation characteristics in lateral electrostatically‐actuated DC‐contact MEMS switches is proposed. In this case a parallel‐plate approximation cannot be applied. The model is based on the equilibrium equation for an elastic beam. It is demonstrated that the contribution of fringing fields is essential. The model relies on finite‐difference discretization of the structures, applying boundary conditions and is solved with a Gauss‐Seidel relaxation iteration scheme. Its usefulness is demonstrated in a series MEMS switch with lateral interdigital electrostatic actuation. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1238–1241, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22450
Gap coupled rectangular microstrip antennas for dual and triple frequency operation
Authors: Ray K. P. , Sevani V. , Kulkarni R. K. 
Published: March 2007

AbstractA rectangular microstrip antenna is gradually divided into equal smaller elements along the width, and lengths of these smaller strips are varied to increase the separation between the resonances to obtain dual and triple frequency operation. Likewise, configurations consisting a maximum of five strips have been investigated. For configurations with two strips only dual frequency operation has been obtained, whereas for configurations with more than two strips both dual and triple frequency operation has been obtained. With increase in number of elements, the separation between different resonances is more and the radiation pattern is also similar in two frequency bands. Experiments have been performed and the results are in agreement with the simulations. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1480–1486, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22452
A CMOS LC‐tank frequency divider with 3D helical inductors
Authors: Jang Sheng‐Lyang , Lee Shao‐hua , Wu Yen‐Ruei 
Published: March 2007

AbstractThe design of a frequency divider (FD) employing 3D helical inductors fabricated in the 0.18‐μm 1P6M CMOS technology is reported. The LC resonators consist of two 3D helical inductors and varactors. The aim of using 3D inductor is to reduce chip size, the inductance of inductor is designed to be 2 nH, and the size of the inductor is 155 × 155 μm2. The divide‐by‐2 LC‐tank injection locked FD is performed by adding an injection nMOS between the differential outputs of the divider with the structure of cross‐coupled n‐core VCO that contains a tapped LC resonator. The measurement results show that at the supply voltage of 1 V, the divider free‐running frequency is tunable from 2.496 to 2.04 GHz, and at the incident power of 0 dBm the locking range is about 1.31 GHz (30%), from the incident frequency 3.84–5.12 GHz. The core power consumption is 2.59 mW. The die area is 0.664 × 0.731 mm2. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1477–1480, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22453
A high‐efficiency class‐E power amplifier using SiC MESFET
Authors: Lee Yong‐Sub , Jeong Yoon‐Ha 
Published: March 2007

AbstractThis article reports a high efficiency class‐E power amplifier using a SiC MESFET, which is designed and tested at 2.14 GHz. To improve output power and efficiency by suppressing harmonic powers, an output matching circuit using the transmission lines is used. From measured results for a single tone, the harmonic power levels are maintained below −58 dBc at a whole output power level. The peak power‐added efficiency of 72.3% with a power gain of 10.27 dB is achieved at an output power of 40.27 dBm. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1447–1449, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22455
Novel defected ground structure element with triple transmission zeros and its application for multispurious suppression of microstrip parallel‐coupled‐line bandpass filter
Authors: Ting Sio‐Weng , Tam Kam‐Weng , Martins Rui 
Published: March 2007

AbstractA novel compact defected ground structure (DGS) element with triple transmission zeros is proposed. The zeros can be tuned individually by the DGS geometry and the overall etched area is kept as compact as that of the conventional structure with single zero. The traditional microstrip parallel‐coupled‐line bandpass filter cascading this new element, not only achieves the multispurious suppression but also its basic design formulation is retained. A prototype DGS filter was designed and tested to validate its performance. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1409–1412, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22457
1.9‐GHz low noise amplifier using high‐linearity and low‐noise composite‐channel HEMTs
Authors: Cheng Zhiqun , Cai Yong , Liu Jie , Zhou Yugang , Lau Kei May , Chen Kevin J. 
Published: March 2007

AbstractMonolithic integrated 1.9‐GHz low noise amplifier (LNA) using 1 μm‐gate high‐linearity and low noise composite‐channel Al0.3Ga0.7N/Al0.05Ga0.95N/GaN HEMT (CC‐HEMT) device is designed, fabricated and characterized. The LNA exhibits a noise figure of 1.3 dB, an associated gain of 17 dB, an input return loss of −5.5 dB and an output return loss of −15 dB at 1.9 GHz. The IIP3 and IIP5 of the LNA are 15 and 12 dBm at 1.9 GHz. The LNA with 1 × 100 μm2 device shows high‐dynamic range with decent gain and noise figure. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1360–1362, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22459
Space‐mapped neuro‐fuzzy optimization for microwave device modeling
Authors: Hinojosa J. , Doménech‐Asensi G. 
Published: March 2007

AbstractFour modeling methods of microwave devices using multiple neuro‐fuzzy inference systems (MANFIS) based on space‐mapping (SM) approach are presented. In contrast with previous works using conventional mathematical tools and artificial neural networks, the proposed SM‐based neuro‐fuzzy modeling methods can construct nonlinear multidimensional mapping functions based on both human knowledge in the form of fuzzy if–then rules easy to understand by human beings and stipulated input–output data pairs, without employing precise quantitative analyzes. Optimization by microgenetic algorithm is used to find nonlinear multidimensional mapping functions for the modeling methods that present a singular system. These methods are applied to a shielded microstrip line and the obtained models are discussed. These space‐mapped neuro‐fuzzy models could be integrated in a toolbox of any commercially available computer‐aided design tools for radio frequency/microwave circuits. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1328–1334, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22460