bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of the fast recursive algorithm to a large inhomogeneous scatterer for TM polarization
Authors: Wang Y. M. , Chew W. C. 
Published: July 2007

AbstractA fast recursive algorithm has been developed to solve for the scattering solution of a large 2‐D inhomogeneous body for TM waves. The inhomogeneous body is first divided into N subscatterers. The algorithm uses an aggregate T̄ matrix and translation formulas to solve for the solution of n + 1 subscatterers from the solution for n subscatterers. The computational complexity of the algorithm is of O(NMP2), where NM is the number of unknowns and P is the number of harmonies required in the translation formulas. The memory requirement is proportional to the number of unknowns. The algorithm has been used to solve for the scattering solution of a 10‐λ‐diameter two‐dimensional scatterer with about 12,000 unknowns, taking about 30 s on a CRAY‐2 supercomputer.
Application of cubic‐phase theory to galindo‐williams subreflector
Authors: Rahnavard M. H. , Rusch W. V. T. 
Published: July 2007

AbstractA JPL Fortran program for designing the main reflector and the subreflector of a Galindo‐Williams system with a constant intensity over the aperture of the main reflector was modified for use on our computer system. Geometrical optics and conservation of energy are the basic laws used for designing this type of surface. The basic computation is a numerical solution of three simultaneous differential equations. The resulting subreflector is a type of inflected surface. Analysis of the fields scattered from such a surface using physical optics yields adequate results. Cubic‐phase theory is numerically applied to the Galindo‐Williams surface. Although the technique appeared to yield results accurate to within 10%‐15%, the nearness of the edge to the turning point caused a coupling of the edge and turning‐point solutions, which prevented higher accuracy.
Mutual impedance between two parallel thin linear antennas in chiral medium
Authors: Bhattacharyya Asoke K. 
Published: July 2007

AbstractThe problem of mutual coupling between two parallel thin linear antennas in chiral medium is addressed in this article. Expressions for self‐ and mutual impedances are presented. The effect of chirality of the radiating medium on the mutual resistance and reactance is discussed. It is found that with proper choice of parameters the chirality of the medium may considerably reduce the mutual impedance effect. Also discussed is the role of chirality on the projected values of the self‐ minus mutual resistance of the antenna, which is important in antenna array design. It may be concluded that under certain conditions the self‐ minus mutual resistance is considerably smaller than in the achiral case, so that an array made with chiral antenna elements may produce higher gain.
Computations of the diffraction effect and the nonlinear effect on spatial solitons in nonlinear planar waveguides
Authors: Bian Jie‐Ren , Chan Andrew K. 
Published: July 2007

AbstractThe nonlinear effect and the diffraction effect on a spatial soliton are isolated by rewriting the nonlinear Schrödinger equation into a form of the linear Schrödinger equation with a nonlinear potential. Numerical results on these effects are obtained for a fundamental spatial soliton, a second‐order spatial soliton, and two coupled solitons in a parallel‐plate waveguide. The effects of waveguide loss are also included.
A quasilumped six‐port reflectometer for cellular radio use
Authors: Riddels G. , Fusco V. F. 
Published: July 2007

AbstractThis article describes the design, construction, and performance of a six‐port reflectometer which operates at 925 MHz and is designed for on‐line cellular radio RF component measurement. The effects that reflectometer subcircuit performance have on overall six‐port operation are discussed in terms of the six‐port constants. Due to the conservative bandwidths required by the application, narrow‐band quasilumped hybrid and power splitter circuits are employed throughout. The final design is suitable for ultimate implemenation in MMIC form.
Synthesis of far‐field patterns of circular cylindrical arrays
Authors: Narasimhan M. S. , Rao R. Srihari 
Published: July 2007

AbstractAn analytically simple and numerically efficient procedure to synthesize the far‐field patterns of a cylindrical array of point dipoles with uniform spacing is presented. FFT is employed to determine the excitation currents. A numerical example is presented to validate the synthesis procedure suggested.
Holographic photoelectro‐chemical etching of submicron gratings in n‐InP for DFB/DBR lasers
Authors: Wu Jie , Liu Ruitang , Lin Senmao 
Published: July 2007

AbstractSecond‐order diffraction gratings for 1.55‐μm DFB/DBR lasers have been formed by holographic photoelectrochemical (PEC) etching directly on n‐InP substrates with high uniformity and reproducibility. In particular, the dependence of PEC etching rate on the biasing voltage is investigated. The optimum biasing voltage is also given.
Determination of circuit parameters in a 10‐GHz microstrip RF squid
Authors: Jackson Charles M. , Hu R. , Burch J. F. 
Published: July 2007

AbstractWe have fabricated and tested RF SQUIDS made of Nb and YBa2Cu3O7 (YBCO), a high‐temperature superconductor, at 10 GHz using TE011 mode cavities and HTS microstrip resonators. Devices were screened at 27 MHz, and subsequently evaluated at 10 GHz. The SQUID circuit parameters, k2Q and β, were determined at different temperatures.
Application of the finite element method to Monte Carlo simulations of random rough surface scattering with Neumann boundary conditions
Authors: Krause K. C. , Lou S. H. , Tsang L. , Chan C. H. 
Published: July 2007

AbstractScattering from a one‐dimensional random rough surface with Neumann boundary conditions is analyzed using a finite element formulation. Results are in excellent agreement with tapered‐wave integral equation solutions after averaging over realizations. Finite element advantages in CPU time, memory storage, and energy conservation tests are illustrated.
Reduction of the RCS of the leading edge of a conducting wing‐shaped structure by means of lossless dielectric material
Authors: Booysen A. J. , Pistorius C. W. I. , Malherbe J. A. G. 
Published: July 2007

AbstractThe radar cross section of the leading edge of a conducting wing‐shaped structure is reduced by replacing part of the structure with a lossless dielectric material. The structure retains its original external shape, thereby ensuring that the aerodynamic properties are not altered by the structural changes needed to reduce the radar cross section.
Design considerations for high‐TC superconductor microstrip lines based on current distributions
Authors: El‐Ghazaly Samir M. , Itoh Tatsuo , Hammond Robert B. 
Published: July 2007

AbstractThe current distributions on microstrip lines with finite conductor thickness and finite conductivity are investigated in the TM mode. It is found that the lower surface of the conducting strip carries significantly more current than the upper surface. The percentage of the current carried by the lower surface increases with increasing dielectric constant of the substrate. Detailed information on current distributions is useful in design of high‐Tc superconductor lines.
Optimal focusing of gaussian beams
Authors: Brand Faria J. A. ÃO 
Published: July 2007

AbstractIt is well known that a thin focusing lens, placed at the waist of a Gaussian beam with spot size wo, produces a new beam with a smaller waist spot size, given approximately by w'o ⋍ wof/zR, located approximately at the lens focus (where zR is the beam Rayleigh range and f is the lens focal length). We show that the worst situation, corresponding to the maximum waist spot size, occurs when the lens is placed such that the waist of the original beam is at the lens focus. For this case, the focused beam has its new waist at the other lens focus and its spot size is exactly equal to wof/zR. To optimize (minimize) the focused beam waist spot size the lens should be placed as far away as possible from the original beam waist.
On the analysis of microwave MESFET mixers
Authors: Nguyen Cam , Christodoulou Chistos 
Published: July 2007

AbstractA new and efficient analysis method for microwave MESFET mixers was developed. The analysis incorporates harmonic balance large‐signal analysis, implemented using robust and fast numerical algorithms, into an extended small‐signal analysis originally developed for diode mixers. Simulated performance of a GaAs MESFET mixer circuit using the developed analysis and the commercially available software LIBRA agree very well.
The harmonic gyrotron with a symmetrical double‐ridge structure
Authors: Jianming Gong , Shenggan Liu , Jianhua Xu , Hongbo Cui 
Published: July 2007

AbstractAnalysis of a gyrotron with symmetrically double‐ridge structure shows that the growth rate and efficiency are high only when high‐order mode is combined with high‐order harmonic. The results illustrate that the ridge TE3301 gyrotron is effective at decreasing dc magnetic field B0, and has a growth rate of 10−2 level, a saturation efficiency of 51%, and an output power of QPw = 1800 MW.
Homodyne detection of polarization modulated optical signals
Authors: Betti S. , De Marchis G. , Iannone E. , Lazzaro P. 
Published: July 2007

AbstractThe first homodyne optical receiver for polarization modulated signals is proposed. It is based on the baseband detection of the four quadratures of the electromagnetic field and, from these, the evaluation of the Stokes parameters. The performance is about the same as that of heterodyne ASPSK, so that it seems particularly suitable for high‐bit‐rate systems in FDM environment.
Accuracy of swept‐frequency measurement of optical modulator frequency response
Authors: Zhu Ning Hua , Zheng Xing Shi , Lin Yi Kun 
Published: July 2007

AbstractFormulas explaining the principle of the swept‐frequency technique of measuring modulation depth have been derived for square‐wave distortion. Further investigation shows that when the drive voltage is smaller than 1/3 V/pi the measurement is sufficiently accurate for practical application.
Electromagnetic scattering of waves by random rough surface: A finite‐difference time‐domain approach
Authors: Chan C. H. , Lou S. H. , Tsang L. , Kong J. A. 
Published: July 2007

AbstractMonte Carlo simulation of random rough surface is carried out using the finite‐difference time‐domain (FDTD) method. The solution domain is truncated using a periodic and an absorbing boundary condition. The advantages of using FDTD include (1) matrix inversion is eliminated, (2) time‐domain response is readily available, and (3) scattering intensities for a range of frequencies can be obtained simultaneously.
Concatenated coding for multipulse signaling in noisy optical channels
Authors: Fares Doaa A. 
Published: July 2007

AbstractMultipulse signaling applied to optical communication channels has become known as a bandwidth efficient signaling format [1]. However, to achieve reliable communication in noisy channels we must resort to some sort of coding. In this article, concatenated coding, recommended by the Consultive Committee for Space Data Systems (CCSDS), is investigated [2] and compared to the standard Reed‐Solomon coding of pulse position modulation signaling.
Rectangular microstrip antenna along a helical direction on a cylindrical substrate
Authors: De Castro Lima Antonio Cesar , Giarola Attilio José 
Published: July 2007

AbstractA theoretical analysis of a rectangular microstrip antenna along a helical direction on a cylindrical substrate is shown in this article. The cavity model with magnetic side walls approximation is used for the calculation of the resonant frequency and input impedance. The theory of dyadic Green's functions in conjunction with the saddle point method are used for the evaluation of the far fields. Results are shown for the TM01 mode.
Radiation of elementary time‐harmonic current in chiral half‐space
Authors: Cheng Dajun , Xue Liangjin , Xu Reimin 
Published: July 2007

AbstractThe radiation emitted by an elementary time‐harmonic current placed vertically and in parallel in a chiral half‐space bounded by a perfect conductor is studied using an exact formulation. It is found that the coupled image principle holds for both cases.
Laser‐beam diameter measurement using periodic logarithmic grating
Authors: Awwal A. A. S. , Klemer D. R. , Birt T. A. , Vallapareddy M. R. , Kurek C. G. , Kauffman H. G. , Turumella S. R. V. , Flahive S. P. 
Published: July 2007

AbstractA novel logarithmic grating is proposed for Gaussian laser‐beam diameter measurement. The grating provides accurate measurement of submicron to millimeter diameter laser beams.
Radiation of open‐ended waveguides into stratified media
Authors: Gentili Guido Diffi , Manara G. , Pelosi G. , Tiberio R. 
Published: July 2007

AbstractA hybrid technique for combining the method of moments and ray methods is applied to analyze a rectangular waveguide‐fed aperture radiating into a semi‐infinite medium through an interposed layer. Numerical and experimental results are compared to test the accuracy and the applicability of this method.
Radiation loss due to step discontinuities in symmetric biaxially anisotropic slab waveguides
Authors: Beker B. , Ho T. Q. 
Published: July 2007

AbstractThis paper is an extension of previous work [1] dealing with guided wave propagation through step discontinuities in anisotropic slab waveguides which focused on the radiated fields only. As opposed to the earlier work, this paper deals with radiation power losses suered by a guided mode incident on the junction, with calculation carried out by an approximate perturbation technique. In addition, the radiation mode solutions to Maxwell's equations in a symmetric biaxially anisotropic slab waveguide are presented for both odd and even symmetries. Characteristics of anisotropic guides are discussed and compared to those of their conventional isotropic counterparts.
Scaled‐down RCS study of a rectangular flat plate coated with lossy material
Authors: Zeng Xuegang , Ruan Chengli , Lin Weigan 
Published: July 2007

AbstractIn terms of an asymptotic high‐frequency estimation of monostatic far‐field radar cross section (RCS) of the rectangular flat plate coated with lossy material, which is derived here from a UTD formula of the impedance wedge, the scaled‐down RCS is studied in this article, while the lossy material used in a scaled‐down model cannot satisfy the physical equivalence conditions.
Predicting openwork shielding efficiency using waveguide aperture discontinuity model
Authors: Yeo T. S. , Leong M. S. , Kool P. S. 
Published: July 2007

AbstractOpenwork shielding efficiency is predicted using a waveguide aperture discontinuity model. Theoretical results are obtained using modal analysis and are found to agree closely with Chen's [1] formulas for prediction of openwork shielding efficiencies.
Equivalence of electric and magnetic sources: A paradox
Authors: Van Bladel J. 
Published: July 2007

AbstractFormulas exist for replacing an electric current J1 by an equivalent magnetic current K2, and conversely a K2 by an equivalent J3. The latter could therefore be expected to be equivalent to J1. The equivalence, if not handled carefully by “distributional” methods, leads to apparent paradoxes. The resolution of the paradox is based on the use of a formula for the curl of a surface current.
Antenna sheaths in a dusty plasma
Authors: Lonngren Karl E. 
Published: July 2007

AbstractThe region of charge nonneutrality surrounding a metal antenna that is inserted in an infinite homogeneous plasma is called a plasma sheath. Sheaths form in several time scales that are determined by the electron and the ion plasma periods until an eventual steady‐state Langmuir sheath forms. This article describes the sheaths surrounding an antenna in a dusty plasma consisting of electrons, ions, and heavy dust particles to which electrons have attached themselves. Such a plasma is found in active comets and in the rings surrounding several planets in the solar system and in rings around mature stars.
Theory and design of microwave planar electrodes for stochastic cooling of particle beams
Authors: Mcginnis David P. 
Published: July 2007

AbstractStochastic cooling is a broadband microwave feedback system used in particle accelerators to reduce beam size growth. Because stochastic cooling is a random process, the performance of the system is directly proportional to the bandwidth of the system. Electrodes that sense and correct the position of particles in the beam must accommodate octave bandwidths in the range from 1 to 16 GHz. This article will outline the theory, design, and measurements of planar electrodes that achieve these wide bandwidths.
Analysis and design of a planar balun
Authors: Nguyen T. , Beyer J. B. 
Published: July 2007

AbstractThe analysis and design of a planar balun is presented. The balun consists of three closely placed parallel metallic strips situated on a dielectric substrate. The effective dielectric constants and characteristic impedances for the three independent propagating modes supported by the structure are obtained using the spectral domain approach. Design information is extracted from a three‐port admittance matrix derived in terms of these modes.
Characteristic impedance of a soliton‐bearing nonlinear transmission line
Authors: Lin‐Liu Y. R. , Chan V. S. , Degrassie J. S. , Ikezi H. 
Published: July 2007

AbstractThe wave reflection and transmission in a nonlinear LC transmission line terminated with a resistive load are studied numerically. It is found that the soliton signals in the strongly nonlinear transmission line are almost perfectly absorbed by the linear resistor terminating the transmission line.
Propagation of profiled optical beams through kerr media
Authors: Banerjee Partha P. , Misra Raj M. 
Published: July 2007

AbstractThe propagation of profiled optical beams through cubically nonlinear Kerr media is investigated, theoretically and numerically. Specifically, propagation through both thin and thick nonlinear media are examined, and the far‐field pattern after exit from the nonlinear medium are studied. The profiles investigated are Gaussian and sinctype, the latter obtained from the Fourier transform of a rectangular slit.
Smooth saddle rf coil for magnetic resonance imaging
Authors: Vaslow Dale F. 
Published: July 2007

AbstractA new saddle‐shaped radio frequency coil for magnetic resonance imaging is described. Unlike current “saddle‐shaped” coils made from straight‐line segments and circular arcs, this coil is formed from two smoothly continuous loops, each of which is the intersection of an elliptical cylinder and an elliptical cone. Both the Helmholtz and crossed‐ellipse coils are limiting forms of the smooth saddle coil. When compared to the traditional cylindrical saddle and crossed‐ellipse coils, improvements in the homogeneous magnetic field volume are noted. A modest improvement in the signal‐to‐noise ratio is expected.
A superconductive dual‐control active microwave device
Authors: Beyer James B. , Nordman James E. , Hohenwarter Gert K. G. , Martens Jon S. 
Published: July 2007

AbstractIn this article we review the background material necessary for the understanding of the operation of superconducting flux flow transistors. A new microwave flux flow device is then presented which exhibits behavior analogous to that of a dual‐gate FET. Equivalent circuits and experimental results are presented.
Design and properties of fabricated superconducting microstrip delay lines made with nb, nbn and ybco
Authors: Hohenwarter G. K. G. , Track E. K. , Drake R. E. , Patt R. , Radparvar M. 
Published: July 2007

AbstractWe report on design, computer modeling, and experimental evaluation of delay lines fabricated with Nb, NbN, and YBCO superconducting thin films. Constraints resulting from the need to achieve long delays on small substrates and the unavailability of some directly applicable models for simulations will be addressed.
Second harmonic modulation in potassium niobate
Authors: Boothroyd S. A. , Chrostowski J. , Lian H.‐X. , Rawicz A. , Deen J. 
Published: July 2007

AbstractWe consider potassium niobate as a medium for room‐temperature second‐harmonic generation at 430 nm and electro‐optic modulation in a single crystal. Modulation voltages of the order of 60 V are needed to fully switch the second harmonic for an electric field applied along the crystal c axis and modulation frequencies in the megahertz range. Although the electro‐optic coefficient for a field applied along the crystal b axis is 10 times larger than for the c‐axis modulation, the voltage required is three times higher. A laser‐diode‐pumped source of high‐frequency intensity‐modulated blue laser light may find application for undersea communication.
The radiation characteristics of a resonant meander line section as a monopole
Authors: Rashed‐Mohassel J. 
Published: July 2007

AbstractThe characteristics of a meander line section at resonance is studied and the current distribution along the wire is obtained. The far‐field components and the effect of wire radius are studied, and a transition from a simple meander monopole as a compact radiator to a meander line section is investigated.
The effect of laser chirping on optical subcarrier multiplexed system with high‐bit‐rate baseband signal
Authors: Tsao Hen‐Wal , Ho Keang‐Po , Lee Yang‐Han 
Published: July 2007

AbstractThe mixed transmission of digital and analog signals via single‐mode fiber has potential in future fiber‐optic systems. We have studied the effect of chirping of the baseband digital signal on the analog subcarrier channels using computer simulation. If the location of the subcarriers or the bias of the laser is selected properly, the SNR penalty due to chirping and cross talk will be less than 0.5 dB.
A new type of coaxial line of rectangular and oval cylinders with constant electric intensity on the latter cylinder
Authors: Lin Weigan 
Published: July 2007

AbstractDenoting g(x + iy) = 1/αβ sn2(x + iy, k0) ‐ A/sn2(x + iy, k0) ‐ A/βA = 1 + α/1 ‐ α/β and k20 = (1 ‐ α/β)/(1 + α)2we find an equipotential of constant electric intensity to form a new type of TEM transmission line for industrial applications.
Vectorial far‐field analysis of the fresnel‐zone plate antenna: A comparison with the parabolic reflector antenna
Authors: Leyten L. , Herben M. H. A. J. 
Published: July 2007

AbstractAn analysis of the radiation properties of the Fresnel‐zone plate antenna (FZPA) and the parabolic reflector antenna (PRA) is presented using the Kirchhoff diffraction theory. Expressions are derived for the vectorial far‐field radiation patterns of both antennas. Some computed co‐ and cross‐polar patterns are shown. The most important differences between the radiation properties of the FZPA and PRA are revealed and discussed. The results of the analysis give good insight into future applications of the FZPA.
Single‐screen triband fss with double‐square‐loop elements
Authors: Wu T. K. 
Published: July 2007

AbstractA single‐screen double‐square‐loop (DSL) frequency selective surface (FSS) has been developed and tested for triband applications (i.e., to reflect the X‐band and to pass the S‐ and Ku‐band waves). Good agreement between predicted and measured transmission performance is obtained for the DSL FSS on a 0.001‐in.‐thick Kapton with/without a flat Kevlar honeycomb sandwich panel. It is found that this single‐screen DSL FSS with/without the Kevlar honeycomb has a resonant frequency near 8.4 GHz for incident angle steered from normal to 45° and for both TE and TM polarizations.