bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new approach to broadband matching for P‐I‐N photodiodes
Authors: Zhu Zhimin , Gillon Renaud , Vorst André Vander 
Published: July 2007

AbstractMicrowave transmission‐line theory has been applied to calculate p‐i‐n photodiode systems in which the carrier transit time, the geometric configuration, and the transmission‐line characteristics were considered. The thickness of the intrinsic layer has been optimized to obtain a wide 3‐dB bandwidth and a maximum gain‐bandwidth product. A simulated result of 40‐GHz bandwidth has been obtained for a device with a 20 × 20 μm2 p‐i‐n area.
Modal cutoff conditions for a chirowaveguide with a chiral core of large annular cross section bounded by dielectric media
Authors: Ganguly Sonali , Singh Kh. S. , Ojha S. P. , Khastgir P. 
Published: July 2007

AbstractA chirowaveguide with an annular cross section where the chiral region is bounded by dielectric media has been analytically studied for cutoff conditions. The annular guiding region can be looked upon as a bent slab waveguide with a circular curvature. The origin of this curvature may be deliberate or the result of warping due to fabricating defects. The effect of changing chiral admittance on the cutoff conditions is also discussed.
A first‐order, hybrid FEM/MoM approach for the analysis of two‐dimensional structures
Authors: Pekel Ü. , Mittra R. 
Published: July 2007

AbstractThere exist various hybrid techniques that combine the finite element method (FEM) and surface integral equation‐type (SIE) techniques to solve Maxwell's equations for objects located in unbounded regions. In this article a novel first‐order hybrid approach is considered, which combines the conventional FEM and MoM techniques in two distinct phases by using the field solution initially obtained by FEM to modify the incident field expression of the subsequent MoM analysis part.
Scattering from a periodic inhomogeneous medium with a rough interface
Authors: Freni A. 
Published: July 2007

AbstractA hybrid technique that utilizes the finite‐element method (FEM) and an analytic solution is presented for the analysis of the scattering of a plane wave from a periodic inhomogeneous medium, having arbitrary geometry and material properties. This medium is overlaid with a homogeneous one that presents a rough interface with the space from which the incident plane wave originates. The rough interface is studied with a perturbative method, whereas the inhomogeneous medium is examined with the finite‐element procedure. The two methods are matched imposing the continuity of the fields into the homogeneous medium.
A sparse‐matrix canonical‐grid method for scattering by many scatterers
Authors: Chan C. H. , Tsang L. 
Published: July 2007

AbstractA new efficient algorithm based on the decomposition of strong and weak interactions among scatterers is proposed. The weak interactions, which account for the majority of the required CPU time and memory, are calculated using a canonical grid with a translation addition theorem. This facilitates the use of FFT and results in an N log N‐type efficiency for CPU and O(N) for memory.
Design of a matrix amplifier using FET‐gate‐width tapering
Authors: d'agostinos Stefano , Paoloni Claudio 
Published: July 2007

AbstractA MMIC matrix amplifier design based on FETs with tapered gate width is proposed. The Tschebyscheff filter theory is applied to each of the artificial transmission lines composing the matrix amplifier. The improvement of the input and output reflection coefficient and the reduction of the FET's width in comparison to a conventional matrix amplifier with equivalent performance demonstrates the effectiveness of the presented approach.
Analysis of the microstrip yagi antenna by an iterative MPIE formulation
Authors: Bokhari S. A. , Costache G. I. 
Published: July 2007

AbstractThe Letter presents a method for the rigorous analysis of the microstrip Yagi antenna. Using the mixed potential integral equation (MPIE) for patch antennas, the FFT algorithm and the biconjugate gradient iterative method, the solution for the unknown current distribution on the patch is obtained in an efficient manner without requiring the storage of large matrices that typically arise in moment‐method computations. Consequently, the scheme can deal with patches of arbitrary shapes and can handle a very large number of unknowns. Numerical results of input impedance and radiation patterns are compared with measured results.
A technique for solving 2D method‐of‐moments problems involving large scatterers
Authors: Mittra Raj , Varadarajan V. 
Published: July 2007

AbstractThe article demonstrates that a Method‐of‐Moments solution for large, smooth, two‐dimensional scatterers, requiring matrices that are several hundreds to several thousands in size, can be constructed efficiently by using a combination of transformations based upon FFT and partial QR decomposition of off‐diagonal blocks. The primary contribution of the article is to demonstrate that these techniques, applied in tandem, can typically reduce the active RAM requirements by a factor of 60‐100 for moderately large problems, and by as much as 225 (estimated) for matrix sizes around 100,000. It is also estimated that an effective flop rate of about 8‐35 N2 In N to 0.01N3 can be achieved via this transformation. The reduction factors for RAM requirements and the accuracy of the solution are demonstrated for the problem of a 2D elliptic cylinder with a large aspect ratio, requiring matrix sizes up to 10,000.
Sensitivity analysis of the nonorthogonal fdtd method applied to the study of square coaxial waveguide structures
Authors: Navarro Enrique A. , Wu Chen , Chung Paul Y. , Litva John 
Published: July 2007

AbstractThe nonorthogonal finite‐difference‐time‐domain method is applied to the analysis of structures in a square coaxial waveguide to demonstrate the influence of the mesh on the results. The analysis presented provides insight on how best to discretize the computational domain when modeling discontinuities with this method. Three structures, described as 90°, 120°, and 170° bends, are used as examples in our analysis. A comparison is made with results obtained using the FEM method for the 90° bend. The comparison shows good agreement between these two techniques.
A theoretical analysis of a planar, elliptically shaped 3‐dB quadrature coupler
Authors: Bialkowski M. E. , Jellett S. T. 
Published: July 2007

AbstractA planar 3‐dB quadrature coupler in the form of an eight‐port elliptical disc is investigated. The hybrid consists of additional arbitrarily loaded reactive stubs and impedance steps for tuning purposes. A contour‐integral method of analysis is used to obtain the electric parameters of the structure.
Standing waves in scan impedance of finite scanned arrays
Authors: Hansen R. C. , Gammon Daniel 
Published: July 2007

AbstractScan impedance of elements, especially near the edge of a finite array, differs from that of an element in an infinite array. A numerical experiment shows the standing‐wave behavior of scan impedance over the finite array, for a range of scan angles. The standing wave exists even for a broadside beam. © 1995 John Wiley & Sons. Inc.
Studies of stacked electromagnetically coupled patch antennas
Authors: Lee Kai‐Fong , Chen Wei , Lee R. Q. 
Published: July 2007

AbstractTheoretical results illustrating the behavior of stacked electromagnetically coupled patch antennas are presented, using a recently developed rigorous model for probe‐fed microstrip antennas. Examples of design guides are given and the need for comprehensive design guides is noted. © 1995 John Wiley & Sons. Inc.
Modeling of waveguide structures using the nonorthogonal FDTD method with a PML absorbing boundary
Authors: Wu Chen , Navarro Enrique A. , Chung Paul Y. , Litva John 
Published: July 2007

AbstractIn this letter, we combine the nonorthogonal FDTD method with a perfectly matched layer (PML) absorbing boundary condition to analyze waveguide structures. This combination provides a very useful numerical tool for modeling complex waveguide structures. The PML absorbing boundary condition is tested by simulation of propagation in a WR‐75 rectangular waveguide. It easily gives lower than −60‐dB return loss in the frequency band of interest. An E‐plane, U‐bend waveguide transmission line is modeled to demonstrate the usefulness of this technique. © 1995 John Wiley & Sons. Inc.
Coherent optical processor for inverse filter generation
Authors: Abushagur Mustafa A. G. , Riasati Vahid R. 
Published: July 2007

AbstractA new algorithm and system architecture for inverse filter generation using a coherent iterative optical processor is presented. This processor avoids the singularity problem usually faced in inverse filter generation. The algorithm convergence is analyzed and a convergence condition is derived. Computer simulation of the algorithm performance is presented, and the results confirm the theoretical predictions for the convergence. Two optical architectures for the implementation of this algorithm are also introduced, based on space‐ and time‐domain utilization. © 1995 John Wiley & Sons. Inc.
Fast far‐field approximation for calculating the RCS of large objects
Authors: Lu Cai‐Cheng , Chew Weng Cho 
Published: July 2007

AbstractA fast far‐field approximation (FAFFA) is developed to estimate the RCS of conducting scatterers. This method accounts for the interaction between subscatterers in two ways, depending on the electrical distance between the subscatterers. The interactions of subscatterers separated by a large electrical distance are computed in three stages: (1) aggregation, which computes the total field at a group center due to the subscatterers of the group; (2) translation, which translates the field from one group center to another; and (3) disaggregation, which distributes the field in a group center to each subscatterer in the group. Two strategies are employed to accelerate the computation in the above three stages. One is the use of far‐field approximation to simplify the computation in the translation stage; the other is the use of interpolation and smoothing techniques, which reduces the complexity of aggregation and disaggregation. The overall computational complexity for a matrix‐vector multiplication is of the order of N1.33, and the memory requirement is of order N. Numerical results show that this method can predict a RCS that is very close to exact solution, and that the method can be applied to objects with very large electrical sizes. © 1995 John Wiley & Sons. Inc.
Full‐wave analysis of microstrip Yagi array antennas
Authors: Ke Shyh‐Yeong , Wong Kin‐Lu 
Published: July 2007

AbstractThis article presents a rigorous analysis of microstrip Yagi array antennas using a full‐wave method and a moment‐method calculation. The input impedance of a microstrip Yagi array antenna is formulated and calculated. The obtained input impedance is found to be significantly altered as compared to that of a single driven microstrip patch, due to strong coupling between the driven and parasitic patches. Radiation patterns of the microstrip Yagi array antenna are also calculated and discussed. Both the E‐ and H‐plane coupling cases are considered. © 1995 John Wiley & Sons. Inc.
Microwave model of an optically controlled GaAS mesfet
Authors: Chakrabarti P. , Mishra B. K. , Kumar K. Satish , Shrestha S. K. 
Published: July 2007

AbstractThe effects of optical illumination on the microwave characteristics of a conventional MESFET have been studied theoretically. The effect of the changes in the intrinsic parameters of the device under illumination has been utilized to calculate the Y parameters of the device at microwave frequencies. The small‐signal equivalent circuit of the device in the illuminated condition has been obtained with the various components determined from the Y parameters. The attractive feature of the present model is that it is fully compatible with commonly used circuit simulation packages like SPICE. © 1995 John Wiley & Sons. Inc.
New technology to realize printed radiating elements
Authors: Tarot A. C. , Sharaiha A. , Terret C. , Ganier Y. 
Published: July 2007

AbstractA plating process for low‐cost dielectric substrates (like polypropylene or foam) has been developed by the CNET (Centre National d'Etudes des Télécommunications) in collaboration with LAM (Laboratoire Antennes et Microélectronique). This process allows the realization of printed radiating elements like microstrip antennas. An example of a multilayered printed antenna realized with this technology is presented with its performance. © 1995 John Wiley & Sons, Inc.
Efficient space‐domain analysis of microstrip lines using wavelet transform
Authors: Kunasani Subba R. , Nguyen Cam 
Published: July 2007

AbstractAn efficient method of analyzing microstrip transmission lines is presented. The technique is based on solving coupled integral equations in the space domain using wavelet‐like basis functions. The unique feature of this approach is very fast computation, obtained due to the sparsity of the resultant matrix realized under a two‐dimensional wavelet transform. In the shielded single‐layer microstrip line considered, the computational time is reduced by approximately 40% when compared to the spectral‐domain approach. The computational advantage is expected to be much more pronounced when the dimensions of the matrix are large, a situation that is encountered in complex structures involving multiple layers and strips. The characteristic impedance and effective dielectric constant calculated using this approach are found to be very accurate, as they agree well with those obtained via the spectral‐domain method. © 1995 John Wiley & Sons, Inc.
An energy‐efficient free‐space optical interconnection for clock distribution
Authors: Tamil Lakshman S. , Hsia Kangmin 
Published: July 2007

AbstractAn energy‐efficient free‐space clock‐distribution scheme for intrachip and chip‐to‐chip application is proposed here. The scheme involves two aspheric mirrors in confocal configuration. The length between the mirrors should be equal to the length traversed by an optical ray in one or an integer multiple of the clock period for ghost‐free clock reception. The proposed method reuses the unused optical energy of a clock pulse scattered over the nonphotodetector area of the chip by synchronously combining with the optical energy of the successive clock pulses. Zero clock skew can be achieved by this method. © 1995 John Wiley & Sons, Inc.
Simplified closed‐form expressions for computing the generalized fresnel integral and their application to vertex diffraction
Authors: Capolino F. , Maci S. 
Published: July 2007

AbstractThe generalized Fresnel integral serves as a canonical function for the uniform ray field representation of several high‐frequency diffraction mechanisms. In this article, an example of application of this canonical function is examined, which is concerned with the diffraction at a plane angular sector with soft boundary conditions on its faces. Closed‐form expressions for computing this canonical function are presented, and it is shown that the approximate formulation adopted herein is accurate and very fast to calculate. © 1995 John Wiley & Sons, Inc.
Polarization behavior of spun fiber versus conventional fiber under strong slight twisting
Authors: Hung‐chia Huang , Ying‐chun He 
Published: July 2007

AbstractIn this article, the authors attempt to treat both strong twisting and slight twisting of fiber via a consistent asymptotic approach to the coupled‐mode theory. In strong twisting, an admirably simple and useful asymptotic equation is derived in the form R2τ = const., which relates the minimum required twist rate τ with the minimum allowable radius of curvature R. In slight twisting, an oscillatory pattern of the polarization behavior clearly reveals the advantageous feature of a twist‐spun fiber, which is made by a prior spinning of the fiber before a twisting. © 1995 John Wiley & Sons, Inc.
Complex permittivity and permeability measurements for high‐loss material in a waveguide
Authors: Jiang Cao , Yang Chongfong 
Published: July 2007

AbstractA partially filled waveguide is presented to measure complex permittivity and permeability simultaneously at microwave frequency in this article. The mode‐matching method is used to analyze the higher‐order modes in the waveguide. Experimental results agree well with theoretical results. © 1995 John Wiley & Sons, Inc.
Traveling‐wave semiconductor laser amplifier induced intermodulation distortion for different digital modulation schemes in a subcarrier multiplexing system
Authors: Lee Yang‐Han , Tsai Chao‐Nan , Lee San‐Liang , Wu Jingshown 
Published: July 2007

AbstractWe analyze the intermodulation distcrtion (IMD) induced by four‐wave mixing in traveling‐wave semiconductor laser amplifiers (TWSLA) for different digital modulation schemes in a subcarrier multiplexing (SCM) system, and compare these results with the transmission of pure tones. We find that the IMDs are reduced in the digital modulation system, because the modulated signals disturb the homogeneous property of amplitude (ASK, FSK) or phase (PSK). We conclude that PSK has better performance, and the worst case is the transmission of pure tones. © 1995 John Wiley & Sons, Inc.
TE/TM decomposition of electromagnetic sources in uniaxial anisotropic media
Authors: Lindell Ismo V. 
Published: July 2007

AbstractDecomposition of electromagnetic sources in two parts giving transverse electric (TE) and transverse magnetic (TM) fields with respect to a given direction, previously introduced to isotropic media, is extended to problems involving media with uniaxial anisotropic permittivity and permeability. The decomposition is made with respect to the axial direction of the medium. The fields radiated by the two decomposed sources see the medium as two affine‐isotropic media, which can be transformed to two isotropic media through two affine transformations. The decomposition method can be applied to simplify problems involving boundaries and structures that do not couple the decomposed fields. © 1995 John Wiley & Sons, Inc.
Cavity‐model analysis of a slot‐coupled cylindrical‐rectangular microstrip antenna
Authors: Wong Kin‐Lu , Chen Jin‐Sen 
Published: July 2007

AbstractAn equivalent circuit of a slot‐coupled cylindrical‐rectangular microstrip antenna is constructed by describing the patch admittance seen at the slot position using the cavity‐model method and calculating the slot self‐admittance simply from a short‐circuited slot line. An impedance transformer is also introduced in the circuit to transform the patch admittance and the slot self‐admittance into a series load as seen by the feed line. The input impedance of the antenna is then readily obtained. Typical numerical results of the input impedance are presented and discussed. © 1995 John Wiley & Sons, Inc.
A reed‐solomon coded optically preamplified PPM system
Authors: Cryan R. A. 
Published: July 2007

AbstractA Reed‐Solomon coded optically preamplified pulse‐position modulation system is analyzed. Results are presented at a bit rate of 622 Mbit/s and a wavelength of 1.537 μm, comparing the system with an equivalent on‐off nonreturn‐to‐zero (OOK NRZ) system. The theoretical results demonstrate that the system offers a potential sensitivity of 7 photons/bit, which represents an improvement of 7.5 dB over the equivalent OOK system and is comparable with that of the best coherent systems reported to date. © 1995 John Wiley & Sons, Inc.
Microstrip antennas with multidielectric layers
Authors: Lee K. F. , Chen W. , Lee R. Q. , Luk K. M. , Tong K. F. 
Published: July 2007

AbstractResults based on spectral‐domain full‐wave analysis are presented for several microstrip antennas with multidielectric layers. The geometries include (a) rectangular patch with two superstrates, (b) rectangular patch with a superstrate and an unwanted air space, and (c) rectangular patch with a superstrate and two substrates. Comparison with measurement is given. © 1995 John Wiley & Sons, Inc.
Effect of linear gain saturation on large‐signal dynamics of quantum‐well lasers
Authors: Chen Y. , Wartak M. S. 
Published: July 2007

AbstractDynamical characteristics of separate confinement heterostructure (SCH) quantum‐well lasers with carrier transport effects under large‐signal modulation are investigated numerically. Realistic logarithmic dependence of material gain on carrier density is used. It is shown that both the relaxation oscillation frequency and chirping are reduced due to linear gain saturation. The effect of carrier transport across SCH on transient response is also examined. © 1995 John Wiley & Sons, Inc.
Analysis of biaxially anisotropic waveguides using tangential vector finite elements
Authors: Peng Guanghua , Lee Jin‐Fa 
Published: July 2007

AbstractProblems of biaxially anisotropic waveguides with arbitrary cross section are formulated in terms of vector and scalar potentials. By using the tangential vector finite elements, electromagnetic characteristics of propagating modes in the waveguides are obtained without the occurrence of any spurious modes. Numerical results are verified and agreements with other published results are achieved. © 1995 John Wiley & Sons, Inc.
I.F. Filter bandwidth optimization of coherent heterodyne analog FM optical receiver
Authors: Wu Jingshown , Tsao Hen‐Wai , Lee Yang‐Han , Ho Keang‐Po , Chin Le Pond 
Published: July 2007

AbstractThe performance of the coherent heterodyne optical FM receiver employing a discriminator has been simulated under different i.f. filter bandwidths to find the optimal bandwidth. The value of the signal‐to‐noise ratio has been obtained under different values of i.f. filter bandwidth, modulation index, and signal power. The phase noise linewidth is fixed at Δv = 10 kHz. Even for very small linewidth, the performance of the coherent optical FM receiver is mainly dominated by phase noise. The advantage of FM modulation exists only when received signal power is small. © 1995 John Wiley & Sons, Inc.
Transmission equations for soliton amplification in erbium‐doped optical fibers
Authors: Zhao Y. , Chan K. T. 
Published: July 2007

AbstractThe transmission equation for describing soliton amplification in Er3+‐doped optical fibers is derived from the semiclassical theory. To the best of our knowledge, excited‐state absorption is considered for the first time in such an equation. The doping shape, pump and signal lightwave modes, and spectral‐broadening function are also included. This equation is a general one that is widely applicable to the analysis and optimization of doped fibers for soliton amplification. © 1995 John Wiley & Sons, Inc.
Nonlinear distortion analysis in optically prefiltered SCM systems
Authors: Marti J. , Capmany J. , Mangharam H. 
Published: July 2007

AbstractWe consider nonlinear distortion due to the optical source and the cross talk produced in optically prefiltered SCM systems. Optimum values for the optical modulation index are calculated and power penalties due to intermodulation distortion are obtained depending on the number of channels and the laser linewidth. © 1995 John Wiley & Sons, Inc.
An FFT T‐matrix method for 3D microwave scattering solutions from random discrete scatterers
Authors: Chew W. C. , Lin J. H. , Yang X. G. 
Published: July 2007

AbstractAn efficient method to solve the scattering by a cluster of randomly located discrete scatterers is described. The scatterers can have an arbitrary shape, and only their T matrices need be known. An iterative method is suggested to solve this problem. To expedite the matrix‐vector multiply, we first aggregate the random scattering centers of the scatterers into centers that reside on a regular array. Then, the FFT method is used to perform the matrix‐vector multiply in O(N log N) operations. This method can solve a problem with a large number of unknowns, involving thousands of discrete scatterers, on a workstation. © 1995 John Wiley & Sons, Inc.