bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency dependent finite‐difference–time‐domain [(fd)2td] formulation applied to ferrite material
Authors: Melon C. , Leveque Ph. , Monediere T. , Reineix A. , Jecko F.
Published: July 2007

When subjected to a constant magnetic field, ferrites exhibit anisotropic constitutive parameters. This anisotropy can be described in the frequency domain by using a permeability tensor [μ(ω)] instead of the usual scalar permeability. This article introduces a new method to analyze saturated ferrite structures by a FDTD algorithm where the convolution between the permeability tensor [μ(t)] = F−1 ([μ(ω)]) and the magnetic field H(t) = F−1 (H(ω)) are to be calculated. Results are obtained for a two‐dimensional problem and are compared with those given by direct differential FDTD algorithm [1] and a mode‐matching method [2]. © 1994 John Wiley & Sons, Inc.
Effect of four‐wave mixing on the performance of subcarrier multiplexing (scm) catv systems
Authors: Betti S. , De Marchis G. , Matera F.
Published: July 2007

The effect of four‐wave mixing on the performance of CATV‐SCM systems, in which the optical carrier is either amplitude or phase modulated, has been evaluated, considering both direct and coherent detection. Four‐Wave‐Mixing is a nonlinear phenomenon arising in single‐mode fibers when input optical power is too high and / or channel spacing is excessively narrow. The penalty induced by this phenomenon on the carrier‐to‐noise ratio has been evaluated assuming the FWM as a noise process that affects the amplitude and phase of the useful signal. © 1994 John Wiley & Sons, Inc.
Characteristics of row withdrawn surface acoustic wave reflective dot dispersive delay lines
Authors: Tuli Suneet , Bhattacharyya A. B.
Published: July 2007

The effect of row withdrawal in surface acoustic wave reflective dot array dispersive delay lines has been investigated, and the simulated multifrequency, constant fractional chirp bandwidth operation of such a device has been experimentally validated. Utilizing appropriate input/output interdigital transducers, the approach enables higher frequency and increased time‐bandwidth product operation of reflective array devices, with relaxed mask‐making and lithography constraints. © 1994 John Wiley & Sons, Inc.
An explicit time‐domain method using three‐dimensional whitney elements
Authors: Todd Elson J. , Sangani H. , Chan C. H.
Published: July 2007

A new three‐dimensional time‐domain method is proposed. The computational domain consists of a union of tetrahedrons with electric fields assigned on the edges. Fields are updated from the integral form of Maxwell's equations in conjunction with the use of Whitney two‐form elements. A rectangular waveguide is modeled as an example. © 1994 John Wiley & Sons, Inc.
Self‐timed p‐i‐n‐hbt ppm receivers
Authors: Elmirghani J. M. H.
Published: July 2007

An original analysis and results are presented for the sensitivity and self‐timing of a hybrid p‐i‐n, heterojunction bipolar transistor pulse position modulation (p‐i‐n‐HBT PPM) strategy at 622 Mbit/s and λ = 0.85 μm. The results indicate a significant performance improvement over a comparable p‐i‐n‐HBT PCM system. The proposed strategy can find application in optical signal distribution at high bit rates in areas such as optical back planes and multiprocessor systems. The self‐timing of the hybrid is addressed and original results are presented for the extracted slot clock timing variance and the associated jitter wrong slot error (WSE) probability, resulting in specifications on the optimum PPM order, fiber bandwidth, and phase‐lock loop (PLL) bandwidth under self‐timing. © 1994 John Wiley & Sons, Inc.
Cross‐polarization characteristics of spherical annular‐ring microstrip antennas
Authors: Chen Horng‐Dean , Wong Kin‐Lu
Published: July 2007

The cross‐polarization characteristics of a probe‐fed spherical annularring microstrip antenna excited in the TM12 mode are investigated. The analysis is performed by using a Green's‐function formulation and a Galerkin's moment‐method calculation. Numerical results of the copolarized and cross‐polarized radiated fields for various sphere radii are calculated and presented. The cross‐polarization level for different feed locations is also discussed. A great dependence of the feed location on the cross‐polarization level is observed. © 1994 John Wiley & Sons, Inc.
Classical forces on solitons in finite and infinite nonlinear planar waveguides
Authors: Ramos J. I. , Villatoro F. R.
Published: July 2007

Conservation equations for the mass, linear momentum, and energy densities of solitons propagating in finite, infinite, and periodic nonlinear planar waveguides and governed by the nonlinear Schrödinger equation are derived. These conservation equations are used to determine classical force densities that are compared with those derived by drawing a quantum mechanics analogy between the propagation of solitons and the motion of a quantum particle in a nonlinear potential well. © 1994 John Wiley & Sons, Inc.
A new aperture‐coupled rectangular dielectric resonator antenna array
Authors: Loos G. D. , Antar Y. M. M.
Published: July 2007

A new type of planar subarray composed of rectangular dielectric resonators fed by a microstrip‐line / aperture combination has been devised and investigated. Good performance has been achieved, including a 10‐dB impedance bandwidth of 18% and excellent radiation patterns. Results for impedance bandwidth, radiation patterns, and mutual coupling effects are presented. © 1994 John Wiley & Sons, Inc.
Complex modes and wave interaction in lossless shielded waveguiding structures
Authors: Kezai T. , Vander Vorst A.
Published: July 2007

Complex modes, singular value decomposition, shielded microstrip, fin line.

Complex waves in shielded lossless inhomogeneous waveguiding structures are investigated. A new theoretical approach for wave interaction, which may result in complex modes, is developed using the theory of coupled modes. It is shown that complex modes may exist in perturbed homogeneous waveguiding structures as a result of the coupling of a pair of degenerate or nearly degenerate modes. Coupled modes, in microstrips and fin lines, are discussed and numerical data are compared. © 1994 John Wiley & Sons, Inc.
Radiation characteristics of an aperture‐coupled hemispherical dielectric resonator antenna
Authors: Leung K. W. , Luk K. M.
Published: July 2007

The radiation characteristics of an aperture‐coupled hemispherical dielectric resonator (DR) antenna excited at the broadside TE111mode is investigated both theoretically and experimentally. The Green's functions of the DR antenna are presented for the evaluation of fields in the upper‐half plane, and the stationary phase technique is used for the back‐lobe radiation. The effect of the slot length on the radiation is studied, and the cross‐polarized fields of the antenna are discussed. © 1994 John Wiley & Sons, Inc.
A new design approach for monolithic transimpedance receivers based on root‐locus techniques
Authors: Cocco Valter , Marietti Piero , Trifiletti Alessandro
Published: July 2007

In this article we present a new design method for monolithic trans‐impedance receivers that is based on a simple model of voltage amplifier and on root‐locus evaluation of closed‐loop transimpedance transfer function. © 1994 John Wiley & Sons, Inc.
Numerical analysis of rectangular waveguide multiple‐slot narrow‐wall couplers using a 2D/FDTD algorithm
Authors: Navarro Enrique A.
Published: July 2007

Slot narrow‐wall couplers are simple but effective directional couplers. A simple and efficient approach to analyze these devices using the FDTD algorithm is presented. The technique uses a synthetic excitation and a second‐order ABC especially designed for the frequencies contained in the incident field. The method is illustrated in the computation of coupling and isolation of a two‐slot ‐20‐dB coupler and is also applied to study a three‐slot coupler. © 1994 John Wiley & Sons, Inc.
A microwave applicator using a rectangular waveguide with two symmetrically placed double L septa for processing sheet materials
Authors: Zhang Henry Z. , Mohan Ananda S. , Beard Geoffrey E. , Belcher W. Rod
Published: July 2007

A microwave applicator using a rectangular waveguide with two symmetrically placed double L septa is proposed for processing dielectric sheet materials. The attenuation caused by the loaded lossy dielectric sheet is obtain by the Ritz‐Galerkin method combined with perturbation theory. The results show that a microwave applicator using the proposed structure can process dielectric sheets with a higher loss factor and/or larger physical dimensions. © 1994 John Wiley & Sons, Inc.
Generalized transmission‐line model for cylindrical‐rectangular microstrip antennas
Authors: Wong Kin‐Lu , Liu Yu‐Hua , Huang Chih‐Yu
Published: July 2007

An analysis using a generalized transmission‐line model (GTLM)for a probe‐fed cylindrical‐rectangular microstrip antenna is presented. The equivalent circuit elements for the microstrip antenna modeled as a transmission line loaded with wall admittances are derived, and the expression for the input impedance is given. Numerical results of the input impedance are calculated and presented as a function of the cylinder radius and the substrate thickness. Excellent agreement of the GTLM solutions with the experimental results is observed. © 1994 John Wiley & Sons, Inc.
A numerical absorbing boundary condition for edge‐based finite‐element analysis
Authors: Boag Amir , Boag Alona , Mittra Raj
Published: July 2007

The numerical absorbing boundary condition (NABC) approach is applied to the problem of deriving the local boundary conditions that can be employed in conjunction with the edge‐based formulation of the finite‐element method (FEM) to s olue electromagnetic scattering and radiation problem. The key step in this approach is to derive linear relationships that link the values of the field along the boundary edges to those at the neighboring ones. These linear relationships are satisfied, to within a certain tolerance, by all of the outgoing wave components. They can thus be used in lieu of the FEM equations employing the usual absorbing boundary conditions for the boundary edges. The NABC approach not only provides a simple way to derive an accurate boundary condition for mesh truncation, but also presemes the banded structure of the FEM matrices. © 2994 John Wiley & Sons, Inc.
Dispersion effect of substrates on the scanning behavior of chirostrip dipole antenna
Authors: Wenyan Yin , Wei Wan , Wenbing Wang
Published: July 2007

The far‐field behavior of a chirostrip dipole antenna on chiroferrite substrates is shown using the generalized spectral domain—exponential matrix technique, and such substrates are made from a nonreciprocal chiral medium and ferrite material. Numerical results show that both beam scanning and pattern reshaping can be achieved by adjusting the constitutive parameters of chiroferrite, and the dispersion effects of substrates are considered in detail. © 1994 John Wiley & Sons, Inc.
Design of two‐layer wave absorbers for metallic cylinders with mirror‐symmetric cross section
Authors: Hashimoto Osamu , Setsu Takanori
Published: July 2007

This article discusses the method for analyzing the reflection characteristics of a metallic cylinder coated with a two‐layer wave absorber. Various design curve and numerical results of the reflection characteristics are shown for wave absorbers that are optimum for masts with elliptical cross sections. © 1994 John Wiley & Sons, Inc.
Some effects of curvature on transmission performance of finite dipole FSS
Authors: Philips B. , Parker E. A. , Langley R. J.
Published: July 2007

Finite curved dipole frequency‐selective arrays are analyzed using an integral equation to solve for the current distribution in the array elements. This article studies the effect of finiteness and curvature on the current distribution in the dipoles and on the transmission performance of the array. Results obtained are compared with measured values. © 1994 John Wiley & Sons, Inc.
Microwave small‐signal equivalent circuit model for multielectrode lasers
Authors: Elkadi H. , Hamelin R. , Vilcot J. P. , Decoster D.
Published: July 2007

A small‐signal equivalent circuit model of the multielectrode lasers with saturable absorbers based on a modified formulation of the rate equations is presented. The Auger recombinations are taken into consideration because they largely modify the carrier lifetime at the high carrier densities that occur in such structures. An analysis of the bistability of the power‐current characteristic is presented. The model predicts an extremely high resonance amplitude as well as a very large bandwidth up to the millimetric range, which can be very interesting for microwave optical links. The results obtained using this model are comparable to those obtained using a large‐signal equivalent circuit model implanted on SPICE, the results of which are published elsewhere. The equivalent circuit obtained is a tool suitable for the study of the behavior of the multielectrode laser within a microwave optical system. © 1994 John Wiley & Sons, Inc.
Interferometric refractive index profile measurement of an optical fiber
Authors: Das Kamal K. , Arif Muhammad , Halder A. F. M. Yusuf , Alam Mohammad S.
Published: July 2007

We present a simple and inexpensive interferometric technique for mapping the refractive index profile of an optical fiber. This technique also enables one ot determine whether a fiber is a step index fiber or a graded index fiber. Experimental results are presented to verify the effectiveness of the proposed technique. © 1994 John Wiley & Sons, Inc.
Dynamic simulation of doppler spectra of targets with rotating parts
Authors: Bhalla Rajan , Ling Hao , Lee Shung‐Wu , Andersh Dennis J.
Published: July 2007

We present the dynamic simulation results of the Doppler spectra of targets containing rotating parts based on first‐principle electromagnetics computation. Our simulation examples include an inlet duct with a rotating compressor and a model helicopter with rotating blades. Such simulation results allow a detailed interpretation of the various scattering phenomenologies for radar target identification applications. © 1994 John Wiley & Sons, Inc.
Transient electromagnetic modeling with the generalized K‐space (GkS) method
Authors: Liu Qing‐Huo
Published: July 2007

A centralized k‐space (GkS) method is developed for transient electromagnetic modeling. This method consists of the solution of two equations: (1) the scattering equation in the spectral‐time < k − t) domain, and (2) the constitutive equation in the spatial‐time (r − t) domain. Both are derived as local algebraic equations, and therefore can be solved with O(N) operations. The connection between the r − t domain and k − t domain is obtained by the spatial FFT algorithm. Therefore, in each time step, the number of complex multiply‐add operations is O(N Iog2 N), and the storage requirement is O(N). Because it treats the spatial derivatives by Fourier transform, the k‐space method, compared to the finite‐difference method, provides a high‐order accuracy for the same discretization. It is shown that with the same accuracy requirement, the GkS method requires much fewer unknowns than the conventional finite‐difference method. © 1994 John Wiley & Sons, Inc.
Isotropic chiral composite modeling: Comparison between analytical, numerical, and experimental results
Authors: Mariotte F. , Tretyakov S. A. , Sauviac B.
Published: July 2007

Electromagnetic properties of artificial isotropic chiral composites are calculated based on the analytical antenna model for the polarizabilities of small bianisotropic wire‐and‐loop particles and on a numerical simulation technique. Averaged media parameters are estimated using the Maxwell‐Gamett model. Theoretical results are compared with the transmission coefficients for a composite slab measured at microwave frequencies. The analytical model is seen to provide an accurate description in the area of the first resonance of the structure and at lower frequencies, which corresponds to the approximations made in the theoretical modeling. © 1994 John Wiley & Sons, Inc.
Analytic solutions for the ac resistance and internal inductance of a superconductive circular two‐wire transmission line
Authors: Wang Bing‐Zhong
Published: July 2007

In this article, under the quasi‐TEM assumption, using the two‐fluid model and the London equations, and through an exact electromagnetic field analysis, we get an analytic solution for the current density inside the superconductors of a superconductive circular two‐wire transmission line. Finally, the analytic solutions for its ac resistance and internal inductance are obtained.
Determinations of normalizing input/output impedances to apply to parameter conversions for terminated microwave transistors
Authors: Bor Sheau‐Shong , Yeh Shu‐Ming , Liu Ji‐Chyun
Published: July 2007

We propose a practical technique to determine the normalizing input/output impedances by a couple of terminated conditions. The realized quantity of the normalizing input/output impedances could be applicable in the design and implementation of microwave amplifiers.
A higher‐order surface boundary condition for a dielectric substrate backed by a nonperfect conductor
Authors: Cicchetti Renato
Published: July 2007

A higher‐order surface impedance boundary condition (HOIBC) for a dielectric substrate backed by a nonperfect conductor is presented. The boundary condition is derived first in the spectral two‐dimensional Fourier domain, and later in the space domain. It is shown that in the space domain such a condition is expressed by a dyadic operator acting on the tangential components of the magnetic field. Finally, in order to demonstrate the qualities of the proposed HOIBC, a comparison of the field radiated by a horizontal electric dipole (HED) placed on the considered structure, computed using the exact and the approximated (higher‐order) impedance boundary condition (IBC), has been presented.
Accurate analysis of modal capacitances in coupled coplanar waveguides
Authors: Costamagna Eugenio , Fanni Alessandra
Published: July 2007

Oddand even‐mode capacitances are computed by a variational method. Trial functions for the charge density distributions are supplied by conformal mapping calculations. Comparison is made with values derived from different methods, and resulting accuracies are discussed.
High extinction ratio metal‐clad GaAs/GaAIAs waveguide polarizer
Authors: Saini Mamta , Gupta V. L. , Sharma Enakshi K.
Published: July 2007

We present the design of an extremely high extinction ratio metal‐clad GaAs/GaAlAs TE‐pass polarizer with the buffer layer also of GaAlAs. Our investigations on the effect of the buffer layer index on the extinction of TM modes show that high index buffers corresponding to GaAlAs can give an extremely high TM loss by a suitable choice of Al concentration. The choice of this type of buffer also eliminates the depositon step, during device fabrication, required for materials like SiN and oxide buffer layers reported earlier.
Design, realization, and evaluation of a millimeter‐wave network analyzer using a single six‐port reflectometer
Authors: Abou Chahine S. , Huyart B. , Bergeault E. , Jallet L.
Published: July 2007

This work presents an automatic network analyzer (ANA) using a single six‐port reflectometer in the W frequency band (75‐110 GHz). Its analysis, design, and testing are described. A calibration procedure requiring two standards and a new calibration technique are used to determine the full scattering parameters of the device under test (DUT). Finally, a comparison between experimental results performed with the six‐port network analyzer and the other measurement systems available in the W frequency band is presented.
A simple technique for the design of gaas mmic double side‐band modulators based on the gilbert cell
Authors: Alonso José I. , Sánchez Juan C.
Published: July 2007

A theoretical analysis of the Gilbert cell has been performed in order to accomplish a simple design method that allows us to choose the gate width and the bias point of its MESFET transistors as well as its load resistor RL; also, the frequency dependence on differential output voltage can be analyzed. A wideband (1‐4‐GHz) double side‐band (DSB) modulator has been designed and built using this method. This DSB modulator is comprised of an input differential amplifier, a Gilbert cell, and an output differential amplifier, and it has been implemented with the 0.5‐μm F20 process of GEC‐Marconi. A carrier rejection of 50 dB and a third‐order intermodulation rejection of 48 dB have been measured at 2 GHz. The dc power consumption of the Gilbert cell is 136 mW.
Asymptotic closed‐form representation of the spatial microstrip dyadic green's function
Authors: Popovski Borislav , Toscano Alessandro , Vegni Lucio
Published: July 2007

An asymptotic closed‐form representation of the spatial microstrip dyadic Green's function is developed. This representation is very efficient for a numerical evaluation of the field when the source and the observation points are laterally rather than vertically separated with respect to the interface plane. Numerical examples are presented that indicate that the representations obtained are very efficient even for relatively small lateral separation of the source and field points. This work is especially useful in the moment‐method analysis of microstrip antenna arrays where the mutual coupling effects are important.
Analysis of a microstrip‐line‐fed radiating slot on a cylindrical surface
Authors: Tsai Ruenn‐Bo , Wong Kin‐Lu , Su Hsin‐Cheng
Published: July 2007

This article presents an analysis of a microstrip‐line‐fed radiating slot on a cylindrical surface. The reciprocity theorem is applied in this analysis, and the Green's functions for the structure studied here are derived and used in the moment‐method calculation for obtaining the slot impedance, which can be viewed as an equivalent series impedance at the slot position as seen by the microstrip line. Numerical results of the slot impedance for various cylinder radii are calculated, and the curvature effects on the slot impedance are discussed. The radiation pattern of the radiating slot is also calculated and presented. © 1995 John Wiley & Sons. Inc.
3D FEM simulation and experimental measurements of microwave microstrip dielectric‐resonator filters
Authors: Chuang H.‐R. , Huang J.‐W. , Wei C.‐C. , Chang Jason L. C.
Published: July 2007

Three‐dimensional numerical simulation of the complete structure and experimental measurements of a microstrip dielectric‐resonator bandpass filter (MDR‐BPF) are presented. The numerical simulation was performed by using the 3D finite‐element method (FEM). A bandpass filter using two dielectric resonators (DRs) in a rectangular metallic enclosure coupled through microstrip lines has been realized around 6.55 GHz. Numerical results and measured data are compared. Good agreements are achieved. The change percentage of the filter passband frequency as a function of the DR dielectric constant were investigated. © 1995 John Wiley & Sons. Inc.
An optically preamplified PPM intersatellite system described by a moment‐generating function formulation
Authors: Phillips A. J. , Cryan R. A. , Senior J. M.
Published: July 2007

An original analysis, facilitated by the use of Chernoff bound techniques, is presented for an optically preamplified satellite PPM system employing a receiver that integrates over a time slot and compares the result with a fixed threshold. At 155‐Mbit/s operation we demonstrate a potential receiver sensitivity of 50.7 photons/bit with background noise present. We also compare results with those obtainable from a Gaussian approximation, finding the Gaussian approximation consistently less conservative for the cases considered. © 1995 John Wiley & Sons. Inc.
Simulation of antenna radiation pattern
Authors: Wu Te‐Kao
Published: July 2007

Adequately modeling the radiation pattern of a high‐performance antenna system usually requires the expensive development of complicated electromagnetic software or the storage of an extremely large number of measured data. An alternative and efficient simulation technique is described in this article using a spherical wave expansion model, which requires the storage of a relatively small number of coefficients to define the function for the antenna's radiation pattern. © 1995 John Wiley & Sons. Inc.
Efficient spectral‐domain analysis of open asymmetrical multiconductor transmission lines
Authors: Coetzee J. C.
Published: July 2007

The dispersion characteristics of open, asymmetrical planar structures may be obtained through the iterative solution of an eigenvalue equation in the spectral domain. During each iteration, a number of terms need to be calculated by means of numerical integration over an infinite range. In this article techniques for the treatment of slow‐converging integrals are described. © 1995 John Wiley & Sons. Inc.
Sheet resistivity measurements at microwave frequencies
Authors: McGinn V. P.
Published: July 2007

Experimental techniques and data manipulation methods that allow highly accurate measurements of sheet resistivity values associated with thin films are presented. The procedure of microwave energy absorption is offered as a time‐efficient, noncontact, and nondestructive investigative means. © 1995 John Wiley & Sons. Inc.
Analysis of a slot‐coupled cylindrical‐rectangular microstrip antenna
Authors: Huang Chih‐Yu , Wong Kin‐Lu
Published: July 2007

The input impedance of a slot‐coupled cylindrical‐rectangular microstrip antenna is studied. Based on an equivalent circuit derived using the generalized transmission‐line model (GTLM) theory and taking into account the impedance transformations proposed previously for the analysis of a slot‐coupled microstrip antenna, the input impedance is readily calculated. Numerical results of the input impedance for some antenna parameters are presented and discussed © 1995 John Wiley & Sons. Inc.
Equivalent edge current technique for reflector antenna patterns in the boresight caustic region
Authors: Rengarajan Sembiam R. , Lyerly Albert E. , Villaseca Eduardo H.
Published: July 2007

It is shown that the equivalent edge currents (EEC) obtained in terms of the uniform geometrical theory of diffraction coefficients (EEC‐UTD) yield accurate values of the radiated far field in the boresight caustic region of a paraboloid. Failure of the equivalent edge current technique to provide the correct values for boresight region fields in a previous article is attributed to the reflector edge representation in that article. Radiation patterns computed by the EEC‐UTD method are found to blend well with the pattern obtained by the UTD technique. © 1995 John Wiley & Sons. Inc.
Poynting's theorem for the finite‐difference–time‐domain method
Authors: De Moerloose Jan , De Zutter Daniel
Published: July 2007

A discretized version of Poynting's theorem is rigorously derived from the standard FDTD equations. By using the correct averaging expressions for the Poynting vector itself, the energy density, and the current power density, the well‐known form of the theorem in continuous space is obtained. The theorem is checked by calculating the radiated power of an antenna in two ways. It is also shown that the use of nonstandard FDTD equations for thin wires violates the theorem. © 1995 John Wiley & Sons. Inc.
Time‐domain analysis of transmission lines with arbitrary nonlinear loads
Authors: Yun Chan‐Eui , Ra Jung‐Woong
Published: July 2007

A direct time‐domain method is presented for calculating voltage waves at terminals and on transmission line terminating in an arbitrary nonlinear load. By utilizing a time stepping of the load voltage with a sufficiently small time interval, one may linearize the nonlinear load in that interval and obtain the convergent voltage responses. Numerical examples show that this is efficient in the computation without the use of the inverse Fourier transform or the Newton‐Raphson method for the lossy transmission line. © 1995 John Wiley & Sons. Inc.
Quasioptical SMMW resonator with extremely high Q factor
Authors: Steup Dominik
Published: July 2007

A quasioptical resonator for the frequency range between 170 and 260 GHz and a Q factor of more than 50,000 has been built. We use a semiconfocal resonator that is tunable in resonance and has a passive temperature stabilization. The coupling in of electromagnetic energy is realized using metallic meshes with quadratic apertures and polarizing wire grids as well. The resonator is tuned by moving the spherical mirror with a piezo driver. © 1995 John Wiley & Sons. Inc.
Design of multilayer frequency‐selective surface for diplexing two closely spaced channels
Authors: Cahill R. , Parker E. A. , Antonopoulos C.
Published: July 2007

A frequency‐selective surface consisting of three arrays of ring elements is analyzed. It is shown that broad transmission and reflection bands can be generated with separation ratios of less than 1.03:1. Measurements confirm that the diplexer performance is relatively insensitive to the angle and plane of incidence. © 1995 John Wiley & Sons. Inc.
A dual‐frequency antenna using a single patch and an inclined slot
Authors: Antar Y. M. M. , Ittipiboon A. I. , Bhattacharyya A. K.
Published: July 2007

Results on a dual‐frequency microstrip patch antenna fed by using an inclined slot in the ground plane of a microstrip line are described. The frequencies of operation are determined by choosing the dimension of the rectangular patch and by adjusting the inclination angle of the slot. The antenna is easy to construct and results obtained from an antenna designed to operate around 9 and 12 GHz are presented. © 1995 John Wiley & Sons. Inc.
Tunable ring resonator filter for OFDM transmission systems
Authors: Vázquez C. , Hernández‐Gil F. , López‐Amo M.
Published: July 2007

A novel tunable filter is theoretically demonstrated. It is based on a ring resonator with an amplifier and a noise filter in the loop. This optoelectronic device has potential as a high‐sensitivity receiver and as a tunable demultiplexer in OFDM transmission systems. © 1995 John Wiley & Sons. Inc.
Overcoming the onset of ill conditioning at interior resonances by using generalized formulations
Authors: Leviatan Yehuda , Baharav Zachi
Published: July 2007

Generalized formulations, in which instead of solving for the actual surface current one solves for an equivalent fictitious current flowing on a mathematical surface enclosed inside the body, have been used for analysis of many scattering problems. This article explains how inaccuracies occurring at frequencies corresponding to interior resonances of the conducting surface can be avoided by using generalized formulations. A numerical study of TM scattering by a circular cylinder at such resonant frequencies is carried out. The advantage gained by using generalized formulations instead of standard surface formulations in eliminating internal resonances is demonstrated. It is also shown that even if the shape of the interior mathematical surface, when covered by a perfect conductor, forms a resonant cavity, no problem is encountered. © 1995 John Wiley & Sons, Inc.
Comparison between GaAs and AllnAs/GalnAs MSM PDs for microwave and millimeter‐wave applications using a two‐dimensional bipolar physical model
Authors: Ashour I. S. , Vilcot J. P. , Harari J. , Decoster D.
Published: July 2007

Using a 2D bipolar physical model a comparison is made between GaAs and AllnAs/GaInAs MSM PD performance (cutoff frequency and quantum efficiency) as a function of the device parameters. This covers the applied potential, electrode spacing, absorbing layer thickness, and heterojunction effect. We also reported that for millimeter‐wave applications we can expect higher operating frequency using an AlInAs/GaInAs MSP PD, whereas we can expect higher quantum efficiency using a GaAs MSM PD. © 1995 John Wiley & Sons, Inc.
Rigorous hybrid‐mode analysis of an asymmetric coupled shielded dielectric image guide
Authors: Pradhan Lalat K. , Biswas Animesh
Published: July 2007

A rigorous hybrid‐mode analysis based on the mode‐matching technique is used for computing the propagation characteristic of a general symmetric coupled shielded dielectric image guide. The validity of the theory is confirmed by comparing the data for a symmetric coupled line as a special case with the reported data available in literature. Then, illustrative numerical results are presented for the coupling characteristics of various cross‐sections of dielectric guides for suitable wideband coupler applications. © 1995 John Wiley & Sons, Inc.
Influence of the background light on the time‐bandwidth product measured on electroabsorption modulators used as soliton sources
Authors: Brindel P. , Hamaide J. P. , Devaux F. , Carenco A.
Published: July 2007

Twenty‐picosecond soliton pulses are experimentally generated by an electroabsorption modulator at a 10‐GHz repetition rale. By taking into account the unavoidable background light and the voltage‐dependent chirp parameter, a good agreement between theoretical and experimental results is found. It also appears that the usual time‐bandwidth product specifying such sources must be interpreted with care. © 1995 John Wiley & Sons, Inc.
Modeling and testing of a light‐induced spatial light modulator in hybrid optoelectronic systems
Authors: Wysokiński Tomasz W. , Rawicz Andrew H. , Lȩtowski Stanislaw
Published: July 2007

An adaptive filter/photosensitive detector array system is analyzed for use in image acquisition. Different transmittance characteristic adaptive filter models are investigated and a possible application is suggested. The use of photochromes for passive adaptive filter implementation is postulated. Glass and plastic photochromic adaptive filters are tested to confirm some modeling results. © 1995 John Wiley & Sons, Inc.
Analysis of microstrip discontinuities on suspended and grounded anisotropic substrates
Authors: Cain Jeffrey , Beker Benjamin
Published: July 2007

This article presents a comprehensive numerical study of resonant and nonresonant microstrip discontinuities that are printed on anisotropic substrates. The approach employs the method of moments (MoM), which is implemented for the gap, step, and stub discontinuities for the first time in MICs with other than biaxial anisotropic substrates. Numerical results include the variation of the normalized gap admittances with respect to different material parameters, insertion and transmission loss of step discontinuities, and shifts in resonant frequencies of tuning stubs due to rotation of the principal axes of the substrate. Computed data are validated for every structure against results in previously published literature. © 1995 John Wiley & Sons, Inc.
Led spectral slicing strategies for enhanced dual‐wavelength referencing of intensity sensors
Authors: Senior John M. , Murtaza Ghulam
Published: July 2007

A new concept of wavelength thermal matching is described that can be applied to LED‐based dual‐wavelength referenced intensity sensors to achieve compensation for both optical source output fluctuations and variable optical propagation losses. © 1995 John Wiley & Sons, Inc.
Stable transmission of a modulated soliton‐pulse train with soliton transmission control
Authors: Wang Hong , Ye Peida
Published: July 2007

The evolution of the amplitude‐modulated and phase‐modulated soliton‐pulse train in the time and frequency domains under transmission control is numerically investigated. Some discussion and interpretation about the DTS effects are presented. Also some useful conclusions are obtained. © 1995 John Wiley & Sons, Inc.
A finite‐element‐method frequency‐domain application of the perfectly matched layer (PML) concept
Authors: Pekel Ü. , Mittra R.
Published: July 2007

The perfectly matched layer (PML) concept, introduced by Berenger with the aim of synthesizing an absorbing boundary condition (ABC) for the finite‐difference‐time‐domain (FDTD) method, is modified and extended to the frequency domain for FEM applications. The governing equations that characterize this approach require neither the splitting of the field components of interest, nor do they involve negative conductivity parameters. © 1995 John Wiley & Sons, Inc.
Analysis and design of a multichannel HEMT gate mixer
Authors: Allam R. , Kolanowski C. , Théron D. , Crosnier Y.
Published: July 2007

The analysis of the operation of a HEMT gate mixer is presented below. We study the effect of the HEMT nonlinearities on mixer performance by using the nonlinear model in CAD. In particular, the tailoring of an adequate transconductance profile is used to optimize mixer performance for millimeter‐wave realization. © 1995 John Wiley & Sons, Inc.
The effects of biasing and harmonic loading on mesfet tripler performance
Authors: Zhao Guoxiang , El‐Rabaie S. , Ghannouchi Fadhel M.
Published: July 2007

The effects of biasing and harmonic loading on GaAs MESFET tripler performance are studied. The Tajima large‐signal nonlinear model and the harmonic balance approach are used for this purpose. The output power, gain, and efficiency of a 5 ∼ 15‐GHz tripler, as functions of the fundamental and second harmonic load impedances, as well as the gate‐bias voltages, are investigated. Design guidelines for MESFET triplers are deduced. It is recommended, for any biasing, that the fundamental frequency load impedance be an inductive reactance away from the open‐circuit region, and that the second harmonic termination be in the short‐circuit region. © 1995 John Wiley & Sons, Inc.
Phase velocity equalization in microstrip couplers by partial dielectric overlays
Authors: Kouki Ammar B. , Khebir Ahmed , Ghannouchi F. M.
Published: July 2007

The effects of a partial isotropic dielectric overlay on the isolation, coupling, and impedance of a microstrip 10‐dB coupler are studied. Results as functions of the overlay's width, height, and dielectric constant are presented. It is found that a better coupler design can be achieved through proper choice of these three parameters. © 1995 John Wiley & Sons, Inc.
The aperture admittance of a flanged dielectric‐filled waveguide antenna
Authors: Tian M. , Ligthart L. P.
Published: July 2007

The aperture admittance is formulated for a slice dielectric‐filled (ϵr ≥ 1) rectangular waveguide antenna. By considering the specific media discontinuity at the aperture, the formulation is able to predict aperture admittance of the waveguide with various dimension ratios and dielectrics. The summarized results are new in the sense that they have rarely been found in the literature. Calculations and supporting measurements show that the filled dielectric has an important influence, in addition to waveguide height, on the aperture admittance. The proposed approach permits a good simulation of aperture characteristics and impedance matching. © 1995 John Wiley & Sons, Inc.
Performance of a suboptimum PPM presynchronization filtering network
Authors: Hussain A. , Elmirghani J. M. H. , Cryan R. A.
Published: July 2007

An optimum presynchronization filter for the pulse‐position‐modulation (PPM) signal is derived and shown to be comprised of a matched filter in cascade with a derivative network. An original investigation of the performance of the filtered PPM system is presented. The matched filter is realized from a time‐domain specification on the received pulse shape and an RC combination derivative network is used to shape the pulse. The results demonstrate that there exists an optimum value of the differentiating capacitor resulting in performance that is close to the true derivative. The results obtained illustrate a significant improvement in both the timing variance and jitter wrong slot error (JWSE) probability compared to that for the matched filter. © 1995 John Wiley & Sons, Inc.
Inverse scattering of biaxial cylinders
Authors: Chiu Chlen‐Ching , Yang Rong‐Hwa
Published: July 2007

The inverse scattering of inhomogeneous biaxial dielectric cylinders is investigated. Assume that an incident wave is incident upon anisotropic cylinders of unknown dielectric constant distribution, and the scattered field is measured outside. By properly processing the scattered field, the dielectric‐constant distribution of the object can be reconstructed. For the theoretical formulation, based on the proper arrangement of the direction and polarization of the incident field, a set of integral equations that can be solved by the moment method and an unrelated illumination method is derived. Numerical results are given to demonstrate the capability of the inverse algorithm. Good reconstruction is obtained even in the presence of additive random noise in measured data. In addition, the effect of noise in the reconstruction result is also investigated. © 1995 John Wiley & Sons, Inc.
Electrical characteristics of coplanar waveguide devices incorporating nonlinear dielectric thin films of SrTiO3 and Sr0.5Ba0.5TiO3
Authors: Findikoglu A. T. , Jia Q. X. , Reagor D. W. , Wu X. D.
Published: July 2007

We have studied voltage‐tunable (0–200 V) broadband (0.1–5.1 GHz) microwave properties at room temperature and the liquid nitrogen temperature of two coplanar waveguide devices made from a Au / Sr0.5Ba0.5TiO3 bilayer and a YBa2Cu3O7‐x / SrTiO3 bilayer, respectively. The experimental results agree well with the predictions of simple quasistatic and quasi‐TEM models. © 1995 John Wiley & Sons, Inc.
Elimination of the spurious root in the SDA solution to the shielded microstrip problem
Authors: Amari Smain , Børnemann Jens
Published: July 2007

We report that the spurious root that appears in the spectral‐domain approach solution to the shielded lossless and infinitely thin microstrip is eliminated when enough basis functions to accurately describe the transverse current density are used. A fast algorithm based on the observed simple behavior of the minimum singular value of the characteristic matrix as a function of β2 instead of β is presented. For lossless microstrip lines, with small values of the dielectric constant and at relatively low frequencies, two evaluations of the characteristic matrix are sufficient to determine its dispersion properties, when the longitudinal current density is assumed Maxwellian, thus achieving a considerable reduction of CPU time. © 1995 John Wiley & Sons, Inc.
Beam‐propagation‐method analysis of a three‐waveguide nonlinear directional coupler
Authors: Yasumoto Kiyotoshi , Maeda Hiroshi , Nakamura Kouichi
Published: July 2007

The power‐transfer characteristics of a three‐waveguide nonlinear directional coupler (NLDC) are investigated with the beam‐propagation method based on the finite‐difference scheme. The coupler consists of two outer linear waveguides and a center waveguide with a nonlinear Kerrlike medium. It is shown that the three‐waveguide NLDC is useful for constructing a power‐dependent power divider, a power‐dependent power combiner, and an optical logic element. © 1995 John wiley & Sons, Inc.
Design of metal‐semiconductor‐metal photodetector array with uniform 3‐dB bandwidth
Authors: Liu Qing Z.
Published: July 2007

Detailed computer simulations were carried out in order to fully understand the position‐dependent 3‐dB bandwidth variation of an metal‐semiconductor‐metal photodetector (MSM‐PD) array in bus configuration. It was found that the 3‐dB bandwidths of the detectors in the array are different, mainly due to the equivalent inductance of the bus metal trace. It is shown that there exists an optimal length of metal trace between two consecutive MSM‐PDs, which results in an equal 3‐dB bandwidth of the MSM‐PD array. © 1995 John Wiley & Sons, Inc.
An alternate form of the MUR second‐order absorbing boundary condition
Authors: Rahhal‐Arabi Ahmad , Mittra Raj
Published: July 2007

The Mur absorbing boundary conditions (ABCs) are used very widely for the truncation of the finite‐difference mesh. The purpose of this note is to present an alternate form of the second‐order Mur absorbing boundary condition. It has a more compact form and can be viewed as a special case of the second‐order dispersive boundary condition. This compact form is not only simple to implement, but also requires less computational time. © 1995 John Wiley & Sons, Inc.
TE‐TM source decomposition for general uniaxial bianisotropic media
Authors: Olyslager Frank , Jakoby Bernhard , Lindell Ismo V.
Published: July 2007

In the present contribution we study the decomposition of a source into transverse electric (TE) and transverse magnetic (TM) parts in general uniaxial, bianisotropic media. We use a spatial Fourier transform with respect to the axial direction to derive the decomposition in the Fourier domain first. In a next step an analytical inverse transform is performed to obtain the space‐domain result. It is shown that in general the decomposition of a source that occupies a finite region fills up the whole space. It is further shown that our results contain the previously published results for uniaxial anisotropic materials as special cases. © 1995 John Wiley & Sons, Inc.
A new modulation technique based on digital pulse interval modulation (DPIM) for optical‐fiber communication
Authors: Ghassemlooy Z. , Kaluarachchi E. D. , Reyher R. U. , Simmonds A. J.
Published: July 2007

A novel digital pulse time modulation (PTM) technique called digital pulse interval modulation (DPIM) is presented, in which the input signal information is transmitted by the time intervals between two succeeding pulses. DPIM has simplicity of circuit configuration combined with other attractive features of digital pulse position modulation (DPPM) for optical‐fiber communications. This article derives theoretical expressions for transmission capacity, code characteristics, and power spectral density (PSD), and the analytical results are compared with experimental data. © 1995 John Wiley & Sons, Inc.
Efficiency of lossless power combiners
Authors: Eccleston K. W.
Published: July 2007

This article will examine the combining efficiency of a lossless power combiner where port mismatch and interinput port coupling are considerable. A derived lower bound for combining efficiency is compared with simulation results. It is shown that the combining efficiency of a lossless combiner is maximized when the combiner output match is optimized. © 1995 John Wiley & Sons, Inc.
Finite‐difference — time‐domain analysis of a high‐frequency microwave connector
Authors: Chen Yinchao , Shimony Yuval , Harms Paul , Mittra Raj
Published: July 2007

In this study, the finite‐difference‐time‐domain method (FDTD) is used to analyze a complex packaging component, namely, a high‐frequency microwave connector. Because the FDTD technique is easy to use and very flexible, it can be employed to analyze packaging components whose geometrical configurations are highly complex. In contrast, other approaches, for example, the method of moments (MoM), the method of lines (MoL), and the finite‐element method (FEM), are more difficult to apply to complex geometries. In this article we employ the FDTD method to investigate the scattering parameters of a microwave connector and validate the numerical results by comparing them with measured data. © 1995 John Wiley & Sons, Inc.
An improved gaussian approximation for optically preamplified PPM systems including the effect of timing jitter
Authors: Phillips A. J. , Cryan R. A. , Senior J. M.
Published: July 2007

The effect of timing jitter is evaluated using an improved Gaussian approximation for an optically preamplified PPM receiver. For the parameters considered a potential sensitivity of 23.6 photons/bit is demonstrated in the unjittered case with the jittered optimum at worst only 1 dB less sensitive. Both these results surpass the fundamental sensitivity limit of an OOK NRZ system. The analysis predicts that wrong‐slot and jitter errors first become dominant at a coding level higher than that suggested by an earlier model. © 1995 John Wiley & Sons, Inc.