bluuebunny/crossref_metadata_2025_split huggingface dataset:
Über die existenz und eindeutigkeit einer lösung für ein randwertproblem für eine gleichung vom gemischten typ in einem rechteck
Authors: Müller‐Rettkowski Andreas , Schneider Manfred , Wendland W. 
Published: March 2007

AbstractIn the paper a boundary value problem is studied for the equation of mixed typek(y)uxx+uyy+r(x, y)u=f(x, y)in the rectangular domain {(x, y)| −1 <x< +1,yc<y<yH} withyc< 0,yH> 0,k(y)= signy|y|m,m> 0 (and more generally for a functionk = k(y)withk(O) = 0,k(y)y> O fory≠ O). Specific for the stated problem is that no data are prescribed on the line {(x, yc), −1 <x< +1}. It is proved that the formulated problem is well‐posed in the sense that there is at most one quasi‐regular solution and that a generalized solution exists. The energy‐integral‐(abc‐)method is used to show uniqueness and to obtain an apriori estimate for the solution of the adjoint problem whence the existence statement follows.
Half‐stable solution branches for ordinary bifurcation problems
Authors: Beyn W.‐J. , Kirchgassner K. 
Published: March 2007

AbstractIt is shown that second order bifurcation problems with a positive, autonomous nonlinearity have a smooth branch of positive solutions which tends to infinity. Moreover, this branch satisfies a stability rule saying that the solutions are stable if the branch turns to the right and unstable if it turns to the left.
The sommerfeld half‐plane problem revisited, II the factoring of a matrix of analytic functions
Authors: Heins A. E. , Mmeister E. 
Published: March 2007

AbstractA half‐plane under plane wave excitation obeys a Dirichlet boundary condition on one side and a Neumann boundary condition on the other. These boundary conditions contrast the ones used by A. Sommerfeld in his classical paper. The present problem leads to a system of integral equations of the Wiener‐Hopf type which may be solved by a matrix factoring method suggested by A. E. Heins in 1950.
Dual‐band patch antenna on magnetic substrate for WLAN communication
Authors: Encheng Wang , Shaojun Fang 
Published: March 2007

AbstractThis article introduces a novel dual‐band patch antenna printed on organic magnetic substrate for WLAN communication, operating at 2.45 and 5 GHz. The dual‐band operation is obtained through embedding a pair of L‐shaped slots. The antenna has smaller size for the use of magnetic material, compared with rectangular microstrip antennas on normal dielectric substrate. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1445–1447, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22405
Analysis of multilayer substrates by multilayer contribution of wave concept iterative process
Authors: Hajlaoui El Amjed , Trabelsi Hichem , Zairi Hassen , Gharsallah Ali , Baudrand Henri 
Published: March 2007

AbstractAn efficient iterative technique based on the concept of wave is presented for computing multilayer substrates. This article presents an extensible approach of the iterative method to study substrates with n layers. To validate our theory, we intend to study multilayer dielectric substrates. The approach involves the mixed magnetic and electric filed equation technique and the multilayer contribution of wave concept iterative process, which involves S‐parameters extraction technique based on a simple form of Matched Load Simulation. In this sense, a program in FORTRAN has been elaborated to determine different parameters Sijcharacterizing the studied structure. The numerical results are compared with the published data. Good agreement will be important to establish the validity and usefulness of the iterative method given in this article. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1439–1445, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22406
A wideband circularly polarized 2 × 2 sequentially rotated patch antenna array
Authors: Lu Y. , Fang D. G. , Wang H. 
Published: March 2007

AbstractA wideband circularly polarized 2 × 2 sequentially rotated patch antenna array is presented. This array applies the wideband circularly polarized elements to the sequential rotated feeding to realize wide bandwidth by a simple structure. A measured −10‐dB return loss bandwidth of 102% and an AR < 3‐dB bandwidth of 43.7% are obtained. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1405–1407, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22409
Characterization of on‐human‐body UWB radio propagation channel
Authors: Zhang Y. P. , Bin Li , Qi Cao 
Published: March 2007

AbstractWireless body area network (WBAN) has begun to receive attention recently. Ultra wideband (UWB) is a promising technology for WBAN applications. This article presents the results of UWB radio channel measurements performed on human bodies from 3.1 to 10.6 GHz in indoor environments. The measurements were devised to generate the radiographs of path loss and delay spread for the first time. The radiographs contain both qualitative and quantitative information on the channel. They clearly display the influence of the body on the channel and thus reveal where the network nodes should be strategically placed on the body in the design of the UWB WBAN systems. They directly give such channel parameters as path loss and delay spread. They also reflect variations of the channel on and in close proximity to the body. In addition, the measurements were made in an anechoic chamber to expose the impact of the body and to study the effect of different environments on the channel. It is shown that for the UWB channel on the body the path loss exponent n = 2.7 can be used, while for the UWB channel through the body the path loss exponent increases to n = 3.7. The maximum value of the rms delay spread is 12 ns. The rms delay spread values are less than 6 ns 50% of the time. The number of multipath components increases with the separation between transmit and receive antennas. Because of the nonreflecting mechanism, the path loss is larger and the delay spread is smaller in the anechoic chamber environment. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1365–1371, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22411
A study of printed monopole antenna for ultra wideband applications
Authors: Lee Yi‐Chieh , Sun Jwo‐Shiun , Huang Wei‐Jiun 
Published: March 2007

AbstractA printed monopole with coplanar waveguide‐fed antenna for ultra‐wideband applications is proposed. The proposed antenna includes a rectangle‐shaped patch as a radiator, two ground planes with symmetrical notch, and feed excitation. It covers the all ultra wideband (UWB 3.1–10.6 GHz) and has 7.8 GHz (2.8–10.6 GHz) measured return loss bandwidth. In modifiable design, we choose to design the notches on the ground plane, the height of the proposed antenna, and the width of the radiator, and have to obtain broad impedance bandwidth and accessible measurement parameters. The experiment results have shown acceptable omnidirectional radiation pattern and fine gain in this paper. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1435–1438, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22420
Switchable dual wavelength erbium‐doped fiber laser at room temperature
Authors: Han Young‐Geun , Lee Ju Han 
Published: March 2007

AbstractA simple technique of a switchable dual wavelength erbium‐doped fiber laser based on fiber Bragg gratings is proposed and demonstrated by using both the linear cavity loss controlling and the homogeneous gain broadening of EDF. The single or dual lasing wavelength can be also obtained by controlling of two linear cavity losses at room temperature. The stability response time for the small‐amplitude stability of less than 1% is measured to be less than 0.27 ms. High‐quality EDF laser output with a high extinction ratio of more than ∼40 dB is achieved for all wavelength switching cases. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1433–1435, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22421
Pulse generator based on commercially available digital circuitry
Authors: Chang K. C. , Mias C. 
Published: March 2007

AbstractThe circuitry of a low cost pulse generator based on a commercially available digital integrated circuit is presented. The circuit produces ‘rectangular’ pulses of amplitude 0.77 V and width 362 ps at half amplitude, and 0.688 V peak‐to‐peak monocycle pulses with a −10 dB bandwidth of 1.2787 GHz (0.1191 to −1.3978 GHz). © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1422–1427, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22425
Dual‐frequency antenna for RFID tags with complementary characteristic
Authors: Kuo Jieh‐Sen , Wang Jyun‐Jie , Huang Chih‐Yu 
Published: March 2007

AbstractA novel dual‐frequency Radio Frequency Identification (RFID) antenna with complementary operation mechanisms (two different operation mechanisms: near field and far field operation) is proposed. The proposed antenna is obtained by printing a rectangular‐spiral‐shaped and a meander‐shaped line, which is placed above on a rectangular microwave substrate as a RFID tag's antenna where its ground plane is at the bottom of substrate. The proposed antenna is fed by a 50 Ω microstrip line printed on the same substrate, and the antenna's two resonant frequencies can be excited with good impedance matching. Closer to omni‐directional radiation patterns and the lower cross‐polarization levels (at least 25‐dB) are also obtained. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1396–1398, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22426
Left‐handed microstrip lines with multiple complementary split‐ring and spiral resonators
Authors: Crnojević‐Bengin V. , Radonić V. , Jokanović B. 
Published: March 2007

AbstractNegative‐permeability sub‐wavelength particles, namely split‐ring resonators and spiral resonators, are compared and their performances analyzed for a different number of concentric rings and spiral turns, respectively. Left‐handed lines are designed, fabricated, and measured that use multiple complementary split‐ring and spiral resonators. More compact structures are obtained, with improved characteristics. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1391–1395, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22427
Design of a compact rectangular mono‐cone antenna for UWB applications
Authors: Choi Il H. , Choi Sang S. , Park Jong K. , Song Hyo W. , An Hee S. 
Published: March 2007

AbstractIn this articel, we have designed, fabricated, and measured a compact rectangular mono‐cone antenna for UWB applications. The measured bandwidth is 8.2 GHz from 2.8 GHz to 11 GHz for S11< −10 dB. The path loss S11and phase were measured and discussed. The radiation patterns and antenna gain across the frequency bands are also presented. From the measured results, the proposed antenna shows a good characteristic (almost linear phase, omni‐directional pattern, and very low gain variation). © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1320–1323, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22430
A hybrid FDTD/UTD radiowave propagation modeling: Application to indoor channel simulations
Authors: Reynaud Sébastien , Vauzelle Rodolphe , Reineix Alain , Guiffaut Christophe 
Published: March 2007

AbstractClassical theories such as the uniform theory of diffraction use analytical expressions for diffraction coefficients. These methods are convenient for canonical problems and objects much greater than the wavelength and enable to rise in frequency. For more complex and smaller scattering structures, rigorous methods as the finite difference time domain method is more suited. In this article, we present a new look on radiowave propagation prediction, combining the advantages of these two complementary methods. This article presents several studies aiming to evaluate the validity domain of this hybrid method in terms of far‐field propagation conditions. Finally, an application to indoor channel modeling is presented. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1312–1320, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22431
Design of a V‐shaped surface‐mounted monopole array antenna for DCS/PCS operations
Authors: Floc'h Jean‐Marie , Rmili Hatem 
Published: March 2007

AbstractIn this paper, a surface‐mountable, reconfigurable monopole antenna was designed for array antenna operations in the DCS‐1800 and PCS‐1900 bands. First, the elementary structure was obtained by folding a metallic strip into a V‐shape, and then soldered to a 50‐Ω microstrip feed line printed on a metallized substrate. For the optimized structure, an impedance bandwidth of 22.7%, corresponding to the frequency range 1560–1960 MHz, was obtained. Measured radiation patterns are similar to that of a monopole antenna, and the maximum measured gain is about 1.8 dBi at 1.6 GHz. Next, this elementary antenna was used for realization of both linear‐ and planar‐array antennas. The linear‐array shows a dual and wideband behavior with good impedance matching and asymmetric radiation patterns, whereas the planar‐array presents a unique resonant band with moderate adaptation and symmetric radiation patterns. The measured gain for the two arrays is about 5 dBi. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1486–1491, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22437
Remote optically controllable antenna array using a single optical fiber for RoF reception
Authors: Ritosa P. , Vidmar M. 
Published: March 2007

AbstractA novel technique for remote antenna array steering and control using a single optical fiber is described. The system is designed to be combined with radio‐over‐fiber (RoF) transmission of medium range (10–30 km) on standard G.652 optical fiber using standard optical components. System characteristics and performance are presented. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1349–1353, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22444
Doppler‐invariant pulse compression for targets moving in an arbitrary direction
Authors: Yang J. , Sarkar T. K. 
Published: March 2007

AbstractIt can be shown that a hyperbolic frequency‐modulated waveform is Doppler‐invariant only when the Doppler factor is a constant number, i.e., the target has a constant velocity and along the direction from the radar to the target. If the target moves in an arbitrary direction, the degradation of the pulse compression caused by the mismatch between the reflected signal and the matched filter may still exist. In this paper, we demonstrate that the Doppler effect caused by the moving target in an arbitrary direction can be approximated by a target with an initial velocity and a constant acceleration along the direction from the radar to the target, which results in a frequency shift in the reflected waveform. Therefore, a bank of matched filters with preselected values of frequency shifts can be utilized to compensate for the Doppler effect. Numerical examples, with target moving in an arbitrary direction, are presented to illustrate this effect, which has been successfully compensated by shifting the frequency response of the matched filter. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1449–1453, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22454
Wideband microstrip‐fed planar monopole antenna
Authors: Tseng Ching‐Fang , Huang Cheng‐Liang 
Published: March 2007

AbstractThe design of a multiband planar monopole antenna with a RF/battery shielding metal case is described. The prototype of the proposed antenna with 0.8 mm in height and 50 mm in length has been fabricated. The proposed antenna exhibits sufficient bandwidth of 915 MHz (1525–2440 MHz) with a voltage standing wave ratio (VSWR) lower than 2:1, which covers global positioning system (1575.42 MHz), digital communication system (1710–1880 MHz), personal communication service (1850–1990 MHz), universal mobile telecommunications system (1920–2170 MHz), and International Mobile Telecommunications‐2000 (1900–2025 MHz) bands. At the upper band, the measured impedance bandwidth (2:1 VSWR) of the designed antenna is about 770 (4310–5080 MHz) MHz. This antenna could be applicable for the mobile communication systems. Details of the proposed antenna design and the experimental results are presented and discussed. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1377–1383, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22458
Novel distributed circuit model for transition between coplanar waveguide and microstrip by using the generalized telegrapher equation method
Authors: Hong Jing‐song , Zhang Guang‐Ming , Wang Bing‐Zhong 
Published: March 2007

AbstractIn this article, a novel distributed circuit model of coplanar waveguide to microstrip (CPW‐M) transition is presented by using generalized telegrapher equation. In comparison with conventional nonuniform transmission line equation, the generalized telegrapher equation has two additional terms, dependent series voltage and shunt current sources, which represent local radiation effect from discontinuities of the nonuniform transmission line itself. Based on the full‐wave numerical results, the distributed circuit parameters can be extracted by using the generalized telegrapher equation. Since the generalized telegrapher equation coefficients are determined by dynamic numerical methods and the coefficients are invariant with the line excitation and load, the equation is dynamical rather TEM. The numerical experiments show that the novel distributed circuit model for this CPW‐M transition can have broadband characteristics. As a preparatory experiment, an improved CAD method using this model is utilized to model different structures of CPW‐M transition. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1323–1328, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22461
A coupling element‐based quad‐band antenna structure for mobile terminals
Authors: Villanen Juha , Icheln Clemens , Vainikainen Pertti 
Published: March 2007

AbstractA novel internal coupling element‐based antenna structure for quad‐band mobile terminals is presented. The antenna structure comprises of two nonresonant coupling elements, a multi‐resonant matching circuitry, and the chassis of the mobile terminal. The coupling elements occupy an extremely low volume of only 0.7 cm3, and they have a very low profile of only 4 mm. Despite of the low volume and low profile of the antenna structure, it can fulfill the bandwidth requirements of the GSM850/900 and GSM1800/PCS1900 systems with sufficiently high efficiency, thus making it a promising antenna candidate for future mobile terminals. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1277–1282, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22463
Dual bandstop resonator using combined split ring resonator and defected ground structure
Authors: Safwat Amr M. E. , Tretyakov Sergei , Räisänen Antti 
Published: March 2007

AbstractDefected ground structure and split ring resonator are combined to form a compact dual bandstop filter or a dual pole bandstop filter. An equivalent circuit model is developed for the proposed structure and it agrees very well with EM simulation. A dual bandstop resonator was fabricated. Measurements and theoretical predictions are in a very good agreement. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1249–1253, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22464
Ultra wideband folded rectangular monopole
Authors: Thomas K. George , Lenin N. 
Published: March 2007

AbstractThis article describes a folded planar rectangular monopole antenna, which has reasonably low profile and extremely wide impedance bandwidth. A simple formula is also suggested to determine the frequency of the operation of planar structures, in general. Details of the experimental and simulation results for the proposed antenna are examined and analyzed. Impedance characteristics of simple folded and planar configurations of varied dimensions are presented. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1497–1500, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22466
Analyzing longitudinal‐mode of single‐frequency ring fiber laser
Authors: Wang T. S. , Guo Y. B. , Wang K. 
Published: March 2007

AbstractTo realize single‐frequency of the fiber laser, a ring configuration is devised. The single‐frequency operation is realized at 1549.63 nm by using a fiber Bragg grating (FBG) as wavelength‐selective element and a unpumped 1.5 m‐long erbium‐doped fiber, which can produce standing‐wave saturation effects in the cavity. A measurement method based on fiber‐coupling scanning Fabry–Perot (F‐P) interferometer at 1.55 μm is designed. The laser longitudinal‐mode spacing is 11.1 MHz. The single‐frequency is observed by the interferometer with free spectrum range (FSR) of 7.5 GHz. The longitudinal‐mode fabric is analyzed by the interferometer with FSR of 1.5 GHz. As the cavity length increases, the longitudinal‐mode spacing changes to 3.7 MHz. The structures of longitudinal‐modes under different cavity lengths are compared. The longitudinal‐mode linewidth of 20 MHz is measured. Experimental results show that single‐frequency of the fiber laser can be approved accurately, and the effectiveness of the method, which can analyze longitudinal‐mode of the fiber laser with scanning Fabry–Perot (F‐P) interferometer, is improved. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1494–1497, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI.10.1002/mop.22467
Design of a UWB planar 180° hybrid exploiting microstrip‐slot transitions
Authors: Abbosh A. M. , Bialkowski M. E. 
Published: March 2007

AbstractThe article describes the design of a planar 180° hybrid with an ultra wideband (UWB) performance. The device employs two substrates with a common ground plane and various microstrip‐slot transitions to achieve in‐phase and out‐of‐phase signal division over an ultra wide frequency range. At the initial stage, simple design guidelines are used but the final dimensions are determined using a full‐wave analysis and design software package. The simulated and measured results of the proposed device reveal a well balanced power split accompanied by a very good approximation of ideal 180° and 0° differential phase shift across the band 3.1 to more than 11 GHz. Also low insertion losses, good return loss at all of the four ports, high isolation between the input ports and fine isolation between output ports are noted across this frequency band. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1343–1346, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22472