bluuebunny/crossref_metadata_2025 huggingface dataset:
A model for timing jitter estimation in optical‐fiber PPM
Authors: Elmirghanl Jaafar M. H. , Cryan Robert A. , Clayton F. M.
Published: July 2007

An original model for timing jitter estimation in optical‐fiber PPM is developed and used to examine the performance impairment due to imperfect slot synchronization. An original expression that predicts the spectral properties in the presence of jitter is presented. The extracted slot clock timing variance is evaluated in terms of the PPM parameters such as the number of slots and the modulation index, and the effects of the other parameters such as the phase‐locked loop (PLL) bandwidth and the fiber bandwidth are examined and used to optimize the slot clock timing variance. Original results are presented for the system wrong slot error (WSE) probability due to imperfect synchronization. The results indicate that this probability can be maintained well below the 10−9system operating error rate. The model enables the identification of the set of optimum PPM, PLL, and fiber parameters for a given required performance. © 1994 John Wiley & Sons, Inc.
Signal splitting using the traveling‐wave principle
Authors: Desclos Laurent , Floc'h Jean Marie , Bernick Philip
Published: July 2007

In this article we will describe a concept that we call active splitting. It is based on an extension of an existing structure. The primary advantages to active splitting are that it provides large frequency bandwidth and cascadability. Additionally, active splitting produces gain rather than loss. This feature allows us to design cells with multiple (more than two) in‐phase outputs and to adjust gain by using bias points on the same coplanar structure. © 1994 John Wiley & Sons, Inc.
On the simplified expression of realistic raindrop shapes
Authors: Li L. W. , Kooi P. S. , Leong M. S. , Yeo T. S.
Published: July 2007

The Pruppacher‐and‐Pitter (PP) raindrop model has been well accepted as a realistically distorted raindrop model. To employ this model for the investigation of radio wave attenuation by rain requires tedious numerical calculations. In this Letter a simple mathematical formula is used to simplify and improve the expression of the nonaxisymmetric distorted raindrop shapes, enabling the scattered field by rain to be derived analytically. The coefficients in the formula are determined for different raindrop sizes by translating the polar coordinates vertically and fitting the shapes of the Pruppacher‐and‐Pitter‐form raindrops to the shapes discussed in this Letter. Using the least‐squares method, a general expression for the coefficients in terms of the raindrop sizes is obtained. A comparison of the raindrop shapes obtained from the Pruppacher and Fitter expression and the expression in this Letter demonstrates the validity of the simplified formula for realistically distorted raindrops. © 1994 John Wiley & Sons, Inc.
On stability in the MMIC distributed amplifier
Authors: D'Agostino Stefano , Paoloni Claudio
Published: July 2007

A study aimed at avoiding the high‐frequency oscillation phenomenon in the MMIC distributed amplifier is presented. The results obtained are applicable to both the design simulation step and the bias tuning phase on the realized amplifier. The analysis of a five‐section MMIC distributed amplifier confirms the validity of this research. © 1994 John Wiley & Sons, Inc.
Fiber ring resonator with fringe shape stabilization
Authors: Mouroulis Pantazis , Narayanan S. Anantha
Published: July 2007

We describe a fringe shape stabilization scheme for a birefringent fiber ring resonator with power exchange between the birefringent axes. It is shown that this type of resonator provides an easy way of deriving an error signal in order to stabilize the fringe shape. The system uses piezoelectric control of the fiber birefringence along a short portion of the loop, which counteracts environmentally induced changes in the fringe shape. The system is suitable for use in sensing and spectrum analysis applications requiring high accuracy and scale factor stability. © 1994 John Wiley & Sons, Inc.
Cavity stabilized Gunn oscillator at 35 GHz
Authors: Nag B. R. , Saha P. K. , Ghosh G. , Biswas S. K.
Published: July 2007

The performance characteristics of a 35‐GHz cavity stabilized Gunn diode oscillator is presented. The frequency variations are found to be reduced by a factor of 66 when the oscillator is locked to the cavity. © 1994 John Wiley & Sons, Inc.
Asymptotic evaluation of the Green's functions for a biased n‐type semiconductor
Authors: Shanker Balasubramaniam
Published: July 2007

The dyadic wave matrix is derived for propagation in a biased n‐type semiconductor and an asymptotic expression for the dyadic Green's function is obtained. © 1994 John Wiley & Sons, Inc.
A gamma distribution of raindrop sizes and its application to Singapore's tropical environment
Authors: Li L. W. , Kooi P. S. , Leong M. S. , Yeo T. S.
Published: July 2007

The use of a gamma distribution of raindrop sizes in the calculation of microwave rain attenuation is gaining acceptance. A method of calculating the general gamma distribution of raindrop sizes based on the rain attenuation relation aRb has been developed in this article using the measured microwave attenuation data with respect to the rain rates. The method, which has been tested using the CCIR model, overcomes the common problems of instability and does not suffer from the possibility of multiple solutions. The parameters of the gamma distribution suitable for the moderate climatic region are computed from the calculated attenuation data provided by CCIR model. Comparison of the calculated results with the data from the CCIR model shows that the method provides the ideal modeling of raindrop size distribution (DSD). As an application, the two‐year experimental data recorded in Singapore have been used to obtain another set of parameters of the gamma DSD function for the tropical region. © 1994 John Wiley & Sons, Inc.
EM plane‐wave diffraction by a material‐coated perfectly conducting half‐plane‐ oblique incidence
Authors: Ly H. C. , Rojas R. G.
Published: July 2007

A high‐frequency solution is developed for the electromagnetic diffraction of an obliquely incident plane wave by a material‐coated perfectly conducting half‐plane. It is assumed that the coating is electrically thin so that it can be modeled by a generalized impedance boundary condition of O(t), where t is the coating's thickness. © 1994 John Wiley & Sons, Inc.
Periodic wavelet expansions for analysis of scattering from metallic cylinders
Authors: Steinberg B. Z. , Leviatan Y.
Published: July 2007

The recent application of wavelet transforms in method‐of‐moments solutions for scattering problems is extended to cases involving metallic cylinders whose periphery contain a variety of length scale features ranging from smoothly varying large‐scale features to rapidly varying small‐scale ones. The basic idea is to first consider a periodic extension of the equivalent current in the arc‐length variable with a period identical to the scatterer circumference, and then to expand this representation, using a set of periodic wavelets derived from a conventional basis of wavelets by a periodic extension. Using a Galerkin method and subsequently applying a threshold procedure, a substantial reduction in the number of elements of the moment‐method matrix is attained without virtually affecting the solution accuracy. The proposed extension is illustrated by a numerical study of TM (transverse magnetic) scattering from a cylinder of elliptic cross section. © 1994 John Wiley & Sons, Inc.
Characterization of single‐mode graded‐index fibers: A new method based on transverse offset splice loss
Authors: Hosain S. I. , de Fornel F. , Goudonnet J. P.
Published: July 2007

A method of characterization has been proposed for single‐mode graded‐index fibers using knowledge of the power transmission coefficient at the splice as a function of transverse offset. The method utilizes an analytical expression for the power transmission coefficient based on a highly accurate variational approximation for the LP01 mode developed earlier. The method accurately predicts the profile shape parameter and the normalized frequency of the fiber. © 1994 John Wiley & Sons, Inc.
An optically preamplified PPM threshold detection receiver for satellite communications
Authors: Cryan R. A. , Phillips A. J. , Senior J. M.
Published: July 2007

A novel scheme for the utilization of optically preamplified (EDFA) PPM receivers in intersatellite laser communications is proposed. Instead of employing a photon counting strategy, we have considered a threshold detection system. Using our model with conservative parameters, we have demonstrated potential receiver sensitivities of 40 photons/bit. This compares well with other results in the field and indicates the great potential of this receiver formation for use in satellite communications. © 1994 John Wiley & Sons, Inc.
Scaling of fields, sources, and constitutive properties in bianisotropic media
Authors: Lakhtakia Akhlesh
Published: July 2007

Scaling relations for time‐dependent and time‐harmonic electromagnetic fields and sources are obtained, and the consequent scaling relations for the constitutive properties of linear bianisotropic materials are also derived. © 1994 John Wiley & Sons, Inc.
Dual‐mode dielectric‐resonator microwave active filters
Authors: Delpino F. , Madrangeas V. , Billonnet L. , Jarry B. , Guillon P.
Published: July 2007

The purpose of this article is to present a new miniature dielectric‐resonator (DR) dual‐mode active filter. Measured results for a two‐pole bandpass active filter using dielectric‐resonator dual HEM118 mode are described. © 1994 John Wiley & Sons, Inc.
Comparison of InGaAs/InP photodetectors for microwave applications
Authors: Peredo E. , Decoster D. , Gouy J. P. , Vilcot J. P. , Constant M.
Published: July 2007

The purpose of this article is to compare the microwave performance of three photodetector types, an InGaAs/InP p‐i‐n photodiode, an interdigitated InAlAs/InGaAs/InP metal‐semiconductor‐metal (MSM) photodiode, and an interdigitated InGaAs/InP photo‐conductor (PC). Static and dynamic characterizations have been carried out at 1.3‐μm wavelength using a directly modulated laser diode. Our experiments show that photoconductive detectors exhibit the best sensitivity for frequencies up to 3 GHz. © 1994 John Wiley & Sons, Inc.
Use of correlation functions to assist the experimental validation of numerical modeling techniques
Authors: Duffy A. P. , Woolfson M. S. , Benson T. M.
Published: July 2007

Numerical modeling has an important role to play in optical, microwave, and EMC design. An objective assessment of the accuracy of such numerical modeling tools using experimental data is often hampered by the general complexity of the data to be compared. It is therefore difficult to quantify the resulting comparisons. This communication suggests that three parameters derived from correlation functions can prove useful in assessing validation comparisons. © 1994 John Wiley & Sons, Inc.
Resonance frequency of a superstrate‐loaded annular‐ring microstrip structure on a spherical body
Authors: Chen Horng‐Dean , Wong Kin‐Lu
Published: July 2007

We report on the resonance problem of a superstrate‐loaded annular‐ring microstrip structure on a spherical body. This study is performed by using a Green's‐function formulation in the spectral domain and a moment‐method calculation. Numerical results of the resonant frequency and quality factor of the structure are presented. Both cases of the structure, used as a radiator at TM12 mode and as a resonator at TM11 mode, are studied. A great superstrate loading effect is observed for the structure excited at the TM12 mode as a radiator. Details of the results are presented. © 1994 John Wiley & Sons, Inc.
Annular ring microstrip antenna on a spherical body
Authors: Tam W. Y. , Lai A. K. Y. , Luk K. M.
Published: July 2007

A theoretical analysis on the radiation pattern and the radiation resistance of an annular ring microstrip antenna mounted on a spherical body using an electric surface current model is presented. The effects of the dielectric layer and the metallic sphere are rigorously taken into account by the Green's functions in the spectral domain. Results for the antenna operating in the TM01 (wraparound antenna) and TM12 modes are given. © 1994 John Wiley & Sons, Inc.
A low‐cost etched linear slotted waveguide array
Authors: Roberts A. R. , Joubert J.
Published: July 2007

Chemical etching and deposition techniques have been used to fabricate longitudinal slots for a linear slotted waveguide array operating at 15 GHz. A comparison between computed and measured data for the antenna radiation pattern demonstrates the success of this low‐cost and accurate fabrication method. © 1994 John Wiley & Sons, Inc.
Analysis of shielding effects on the microstrip effective dielectric constant by the finite‐element method
Authors: Medina José L. , Javier Mendieta F. , Ku Walter H.
Published: July 2007

Structures having symmetrically centered microstrip lines enclosed in a metallic waveguide are analyzed by the finite‐element method. Single and combined shielding effects on the microstrip effective dielectric constant due to a top cover and two side walls are investigated. A finite‐element computer program has been written in Fortran for a supercomputer to obtain very accurate numerical results by means of the solution of a very large system of linear equations. In addition, a new set of accurate empirical equations adequate for CAD to take both effects into account has been developed. Results are compared with other numerical and empirical methods, and discussions are also presented. © 1994 John Wiley & Sons, Inc.
Binary‐encoded matrix‐matrix multiplication architecture based on correlation by shadow casting
Authors: Zhou Changhe , Liu Liren
Published: July 2007

A new binary‐encoded matrix‐matrix multiplication architecture based on correlation by shadow casting is presented. It can perform a binary‐encoded matrix‐matrix multiplication in a fully parallel manner to gel the mixed‐binary output matrix in the focal plane of the lens. Both the advantages and the disadvantages of the proposed architecture are carefully discussed. The proof‐of‐principle experiments demonstrate the effectiveness of the proposed architecture. © 1994 John Wiley & Sons, Inc.
Exact expressions for the ac resistance and internal inductance of a lossy circular two‐wire transmission line
Authors: Wang Bing‐Zhong
Published: July 2007

In this article, under the quasi‐TEM assumption, through an exact electromagnetic field analysis, we give an analytic solution for the current density inside the conductors of a lossy circular two‐wire transmission line, and finally obtain the exact expressions for the ac resistance and internal inductance at an arbitrary frequency. © 1994 John Wiley & Sons, Inc.
On symmetry in microstrip antenna analysis
Authors: Sǒipusǒ Zvonimir , Bartolić Juraj , Milin Zǒeljka
Published: July 2007

An application of the patch shape symmetry for the basis‐function selection for the Green's function/Galerkin's solution is reported. As a result many impedance matrix elements are equal to zero and the computation time is reduced. The symmetry properties of four commonly used microstrip patch antennas are described as examples. © 1994 John Wiley & Sons, Inc.
A multilevel algorithm for solving a boundary integral equation of wave scattering
Authors: Lu Cai‐Cheng , Chew Weng Cho
Published: July 2007

In the solution of an integral equation using the conjugate gradient (CG) method, the most expensive part is the matrix‐vector multiplication, requiring O(N2) floating‐point operations. The fast multipole method (FMM) reduced the operation to O(N15). In this article we apply a multilevel algorithm to this problem and show that the complexity of a matrix‐vector multiplication is proportional to N (log(N))2. © 1994 John Wiley & Sons, Inc.
Adaptation of the fdtd method to the study of femtosecond electromagnetic soliton
Authors: Reineix A. , Ariaudo M. , Jecko B. , Barthelemy A. , Froehly C.
Published: July 2007

This article introduces a theoretical method based on the resolution of Maxwell's equations in the time domain using an extended version of a FDTD algorithm. This approach allows the modeling of optical pulse propagation in nonlinear media; for this, dispersive and nonlinear models have been introduced in the code. Two versions of the method are proposed, the accuracy of this approach is shown, and then some results on the propagation of a soliton are given. © 1994 John Wiley & Sons, Inc.
An empirical resonant frequency prediction of k‐ and v‐band dielectric resonators
Authors: Desclos L. , Madihlan M.
Published: July 2007

This Letter deals with the optimum design of shielded dielectric resonators, with a dielectric constant around 24, for millimeter‐wave oscillator stabilization. Extending the Itoh et al. and Kaifez models, an empirical formula is devised that explicitly determines the optimum dielectric resonator dimensions and the shield height for a desired resonant frequency under the maximum achievable unloaded quality factor. © 1994 John Wiley & Sons, Inc.
Time‐domain analysis of kerr electro‐optic cells for high‐voltage pulse measurements
Authors: Brandao Farla J. A.
Published: July 2007

The time‐domain behavior of Kerr modulators operating under pulse voltage conditions is analyzed and discussed. Comparison with the ordinary quasistatic approach is established, showing the inadequacy of the latter. © 1994 John Wiley & Sons, Inc.
A method of generation of sum and sls‐type difference patterns
Authors: Sridevi P. V. , Raju G. S. N. , Chakraborty Ajoy , Das B. N.
Published: July 2007

The article presents a method of realization of useful sum and sidelobe‐suppressed difference patterns using only one array antenna. The method involves the synthesis of phase functions required for the generation of desired patterns. Computed results on radiation patterns are presented both for a continuous line source and an array of radiators © 1994 John Wiley & Sons, Inc.
A 3D perfectly matched medium from modified maxwell's equations with stretched coordinates
Authors: Chew Weng Cho , Weedon William H.
Published: July 2007

A modified set of Maxwell's equations is presented that includes complex coordinate stretching along the three Cartesian coordinates. The added degrees of freedom in the modified Maxwell's equations allow the specification of absorbing boundaries with zero reflection at all angles of incidence and all frequencies. The modified equations are also related to the perfectly matched layer that was presented recently for 2D wave propagation. Absorbing‐material boundary conditions are of particular interest for finite‐difference time‐domain (FDTD) computations on a single‐instruction multiple‐data (SIMD) massively parallel supercomputer. A 3D FDTD algorithm has been developed on a connection machine CM‐5 based on the modified Maxwell's equations and simulation results are presented to validate the approach. © 1994 John Wiley & Sons, Inc.
Design and characteristics of a periodic butterworth‐like blocking filter using an s‐shaped two‐coupler optical fiber ring resonator
Authors: Ja Y. H.
Published: July 2007

We present the design and output characteristics of a periodic Butterworth‐like blocking filter using the transmitted output intensity of an S‐shaped optical fiber ring resonator with two 2 × 2 fiber couplers. Performance parameters of the periodic Buttenworth‐like blocking filter, including the ripple, the contrast, the bandwidth, and the maximum output intensity, are evaluated, and the design procedures are given. © 1994 John Wiley & Sons, Inc.
On the performance of different AR methods in the spectral estimation of FDTD waveforms
Authors: Jandhyala Vikram , Michielssen Eric , Mittra Raj
Published: July 2007

In the past, several extrapolation techniques have been used in conjunction with the finite‐difference—time‐domain algorithm to reduce the computational cost involved in obtaining an accurate representation of the frequency response of the electromagnetic system under consideration. In this article we study the performances of different autoregressive techniques in accurately estimating the spectra of finite‐difference—time‐domain waveforms without resorting to extrapolation. The advantages and disadvantages of these techniques are demonstrated through two examples: a package plane structure and a cavity. © 1994 John Wiley & Sons, Inc.
The chromatic dispersion of optical guiding structures by an approximation of numerical results
Authors: Valentinuzzi Elvio
Published: July 2007

The guiding structures in photonic and integrated optical circuits have complex geometries and refractive‐index profiles so that numerical methods must be used to analyze them. When it is necessary to evaluate parameters such as group delay or dispersion coefficient, which involve first and second derivatives of the numerically calculated propagation constants of the modes, the required accuracy is not easy to obtain. Suitable functions may be used to fit, in a least‐squares sense, the numerical solutions and to easily obtain derivatives from a direct analytical calculation. © 1994 John Wiley & Sons, Inc.
Attenuation and handedness of axial propagation modes in a cholesteric liquid crystal
Authors: Nagle Steven F. , Lakhtakia Akhlesh
Published: July 2007

The interplay of spatial and temporal periodicities in a cholesteric liquid crystal is responsible for the three zones into which axial propagation may be classified. Each of the three zones is marked by specific attenuation and handedness characteristics. © 1994 John Wiley & Sons, Inc.
Tunable fin‐line—microstrip oscillator
Authors: Xue Quan , Xu Jun , Xue Liangjin , Lin Weigan
Published: July 2007

The frequency of a microstrip oscillator is difficult to tune. A new millimeter‐wave microstrip Gunn oscillator is introduced in this Letter. Consisting of fin line and microstrip with microstrip as the output‐port transmission line, this Gunn oscillator can be mechanically frequency tuned. A Ka‐band oscillator of this structure is developed. The tuning bandwidth of this oscillator can reach 7.5 GHz or more with an output power of more than 70 mW. © 1994 John Wiley & Sons, Inc.
Power‐gain and fmax equations based on the T equivalent circuit of high‐frequency bipolar transistors
Authors: Seo Youngseok , Kim Bumman
Published: July 2007

Analytical expressions for the maximum available power gain and fmax of a high‐frequency bipolar transistor are derived from the simple T equivalent circuit model of bipolar transistors. These equations predict the power gain of the state‐of‐the‐art microwave bipolar transistor very well and show that f/max and power gain are proportional to the transconductance and decrease as the resistance‐capacitance charging time and current gain delay time increase. © 1994 John Wiley & Sons, Inc.
Application of the discrete fourier transform in the 2D‐FDTD method
Authors: Chun Joong Chang , Park Wee Sang
Published: July 2007

The discrete Fourier transform of a modal expansion in the 2D‐FDTD method is investigated theoretically to explain the appearance of the magnitude peaks and phase changes in the transform. It is shown that an eigenfrequency exists between two frequencies having a phase difference of 180 degrees. An algorithm using this property is proposed to improve the accuracy in the determination of the eigenfrequency, which is independent of the frequency resolution inherent in the 2D‐FDTD method. An example of a boxed anisotropic microstrip line is treated, and its result is compared with previous numerical ones. © 1994 John Wiley & Sons, Inc.
Design procedure of a 30‐GHz HEMT hybrid gate mixer
Authors: Kolanowski C. , Allam R. , Crosnier Y.
Published: July 2007

This article reports on a hybrid HEMT gate mixer exhibiting 4 dB of conversion gain and a 15‐dBm third‐order intermodulation intercept point at 28.5 GHz. These excellent performances have been made possible by a special design procedure that allows us overcome the problems inherent in the realization of hybrid circuits in millimeter‐wave ranges particularly the parasitic effects of bonding. © 1994 John Wiley & Sons, Inc.
Optical bistability in a one planar 3 × 3 coupler fiber‐ring resonator with degenerate two‐wave mixing
Authors: Ja Y. H.
Published: July 2007

A theoretical study of optical bistability in a Type 1 one (planar 3 × 3) coupler fiber‐ring resonator with an all‐fiber scheme, Scheme B, of degenerate two‐wave mixing (DTWM) is presented. The bistability is caused by the DTWM, the inherent positive feedback in the fiber‐ring resonator and the nonlinear dependence of the circulating intensity of the fiber‐ring resonator on the DTWM gain. The relations between the bistability and various parameters of the fibers and the planar 3 × 3 coupler are inuestigated. A comparison between the bistability in such a jiber‐ring resonator and that using an equilateral triangular 3 × 3 fiber coupler is also made. © 1994 John Wiley & Sons, Inc.
Tunable interconnection network using a thick photorefractive (PR) crystal
Authors: Wen M. , Yin S. , Yu Francis T. S.
Published: July 2007

A tunable interconnection network using a photorefractive (PR) crystal with an array of diode lasers is proposed. The interconnection data are wavelength multiplexed in a PR crystal reflection‐type hologram. An N × N interconnection network can be realized by N holograms, for which the network can be reconfigured in real‐time mode. © 1994 John Wiley & Sons, Inc.
Optimization of a power pseudomorphic double heterojunction FET
Authors: Gaquière C. , Théron D. , Bonte B. , Crosnier Y.
Published: July 2007

In this article we report the optimization of a power double heterostructure pseudomorphic FET. A ID model is used for charge control calculation and a 2D simulation for breakdown analysis. These simple models have allowed us to determine the suitable doping densities and device structure for maximum current density and breakdown performances. The results have been applied to the design of a 0.3‐μm × 70‐μm device. At 33 GHz it delivers an output power density of 1 W/mm with 5.7‐dB linear gain and 38% power added efficiency. © 1994 John Wiley & Sons, Inc.
Wave‐function solution of plane‐wave scattering by an anisotropic circular cylinder
Authors: Wu Xin Bao , Ren Wei
Published: July 2007

An analytical solution of plane‐wave scattering by an anisotropic circular cylinder is given in terms of the wave functions for anisotropic media. The T matrix of an anisotropic circular cylinder is derived. Numerical results in the low‐frequency range are used to check our calculations, and those in the resonance region are also presented.
Hybrid ppm‐cdma systems utilizing optical orthogonal codes for indoor wireless infrared communication
Authors: Elmirghani Jaafar M. H. , Cryan Robert A.
Published: July 2007

An original hybrid pulse position modulation code division multiple access (PPM‐CDMA) scheme is proposed and studied in the context of the indoor infrared communication network. The use of optical orthogonal codes (OOC) is proposed and original results are presented illustrating the improvement in bit rate achieved by utilizing PPM‐CDMA rather than on/off keying (OOK) CDMA. Results are presented for the maximum number of users that can communicate over the network at a given bit rate and it is shown that there exists an optimum PPM order, at a given number of users, that maximizes the achievable bit rate. Original results are presented for the false‐alarm errors due to the OOC cross correlations, and the optimum system operating parameters that minimize these errors are specified.
Generalized transmission line model for cylindrical‐circular microstrip antennas
Authors: Wong Kin‐Lu , Huang Chih‐Yu , Liu Yu‐Hua
Published: July 2007

The generalized transmission line model (GTLM) analysis has been applied to the study of cylindrical‐circular microstrip antennas. In this study, the equivalent circuit for the circular microstrip antenna excited at TM11 mode is given, and formulation of the input impedance is derived. Numerical results of the input impedance for different feed positions and cylinder radii are calculated and presented, and the accuracy of the GTLM analysis is discussed.
Theoretical analysis of multiple‐phase‐shift‐controlled distributed feedback wavelength tunable optical filters
Authors: Tan P. W. , Ghafouri‐Shiraz H. , Lo B. S. K.
Published: July 2007

A three‐phase‐shift‐controlled wavelength tunable optical filter is proposed. Theoretical calculation based on the transfer matrix method indicates a tuning range of more than 30 Å. The peak gain and bandwidth are almost constant during tuning. The side‐mode suppression is over 25 dB.
Alternative formulations of electric dyadic green's functions of the first and second kinds for an infinite rectangular waveguide with a load
Authors: Li L. W. , Kooi P. S. , Leong M. S. , Yeo T. S.
Published: July 2007

Alternative expressions of the dyadic Green's function for an infinite rectangular waveguide with and without a load are presented for defining the electromagnetic fields due to a microstrip patch, a slot, and an equivalent magnetic surface source placed along the broad and narrow walls. The alternative formulations of the dyadic Green's functions are given in terms of rectangular vector eigenfunctions defined by using the piloting vector y and z instead of the conventional z. The sign change in the z direction involved in the double numerical integration influences the accuracy and stability of the numerical computation. The alternative forms of the dyadic Green's functions can be used to overcome this problem in the practical applications.
Quasistatic solution of a cylindrical microstrip line mounted inside a ground cylinder
Authors: Tsai Ruenn‐Bo , Wong Kin‐Lu
Published: July 2007

A new configuration of a cylindrical microstrip line mounted inside a ground cylinder is studied. Quasistatic expressions of the effective dielectric constant and characteristic impedance for such a microstrip line are derived. Numerical results are also calculated and compared with those obtained for a corresponding planar microstrip line. It is also found that the quasistatic characteristics for such a microstrip line with various curvatures are in contrast to the case of a cylindrical microstrip line mounted on a ground cylinder.
Input impedance and radiation pattern of a probe‐fed cylindrical annular‐ring microstrip antenna
Authors: Chen Horng‐Dean , Wong Kin‐Lu
Published: July 2007

Analysis of a probe‐fed annular‐ring microstrip antenna mounted on a cylindrical surface is presented. The analysis is performed by using cavity‐model theory. Expressions of the input impedance and far‐zone radiated fields are formulated and given. Numerical results for the antenna excited at the TM12 mode are also calculated and presented, and the effects of different feed positions and cylinder radii on the input impedance and radiation pattern are analyzed.
On the accuracy of analytical expressions for calculating the parameters of coplanar strips on a finitely thick substrate
Authors: Zhu Ning Hua , Wang Zi Qian , Lin Weigan
Published: July 2007

Analytical expressions for calculating the quasistatic parameters of coplanar strips and modified coplanar strips on a finitely thick substrate were derived through analyzing the structure with the complementary electrodes on the same substrate [1, 2]. In this Letter we use conformal mapping techniques to investigate the accuracy of these expressions.
Novel approach to contiguous band multiplexer design for satellite applications
Authors: Chahine Mohamed Khaled , Carrer Gérard
Published: July 2007

A novel and general technique for the optimization of contiguous band multiplexers using sensitivity analysis is presented. The method utilizes exact partial derivatives of circuit responses with respect to all design parameters. The equivalent circuit includes channel filters, waveguide spacings, and three‐port waveguide junctions. A 12‐channel contiguous multiplexer at Ku band has been designed. Utilization of an efficient modelization and automatic decomposition approaches resulted in an excellent simulation performance of the presented multiplexer.
Feasibility study of a new heterodyne technique based on HgCdTe varactor photodetectors for space‐borne wind lidars
Authors: Chaubet M. , Mollier J. C. , Sage J. P. , Roizes A. , Aubry Y.
Published: July 2007

Doppler Lidar is a good candidate for wind velocity measurement. But the total Doppler shift experienced by the backscattered laser pulses with a conical scanning instrument varies in a wide frequency range. Narrowing intermediate frequency bandwidth could provide better performances for both detection and low noise amplification. Therefore, optical mixing and parametric amplification in the same device have been investigated with HgCdTe photodetectors cooled at liquid nitrogen temperature. The optical and microwave setup needed for simulating Doppler and testing these detectors is described. Some experimental results, which demonstrate the feasibility of this new heterodyning process, are given. © 1995 John Wiley & Sons. Inc.
ISOMOM: A new method for reducing storage and execution time of moment‐method solutions in electromagnetics
Authors: Volakis John L. , Krestianinov Sergey V.
Published: July 2007

A new method, referred to as ISOMOM, is presented for reducing storage and execution time of standard moment‐method solutions. ISOMOM isolates the dominant elements of the moment‐method matrix using a smooth filter function on the integral equation kernel, and this leads to sparse matrix systems with about 20% or less nonzero elements. The method is applied to the metallic strip electric field integral equation for illustrative purposes. © 1995 John Wiley & Sons. Inc.
Optimum design of an optical waveguide modulator in a fin line
Authors: Chen Shu‐Qiang , He Yu‐Xin , Ye Pei‐Da
Published: July 2007

In this article an optimum design of optical waveguide modulator in a fin line is given using the spectral‐domain method and the spectral‐domain immittance approach. It takes into account the thickness of the lithium niobate (LiNbO3) plate, the width of the slot, and the position of the optical waveguide. An example at 3‐cm wave band is given. © 1995 John Wiley & Sons. Inc.
Shorted annular patch antenna
Authors: Di Massa Giuseppe , Mazzarella Giuseppe
Published: July 2007

A new type of annular patch antenna is presented. At variance of classical annular patch antenna the inner edge is shorted by a cylindrical conducting wall. Therefore this antenna radiates as a circular patch but has a smaller stored energy, which allows a larger bandwidth, and the feed point can be chosen to have an easy matching. © 1995 John Wiley & Sons. Inc.
Mode degeneracy in quasioptical resonators
Authors: Monahan G. P. , Heron P. L. , Steer M. B. , Mink J. W. , Schwering F. K.
Published: July 2007

Fabry‐Perot resonators and beam waveguides are used in quasioptical systems to refocus electromagnetic fields. These fields are described by Laguerre Gaussian or Hermite Gaussian quasi‐TEM mode families depending on whether the aperture is rectangular or circular. It is shown that certain lower‐order Laguerre Gaussian and Hermite Gaussian modes are identical. This has implications for the design of quasioptical systems for mode selection. © 1995 John Wiley & Sons. Inc.
Proposal and experiment of a novel Er‐doped fiber‐ring laser to suppress mode instability induced by polarization fluctuation
Authors: Shi Chao‐Xiang , Yamashita Shinji , Hotate Kazuo
Published: July 2007

A novel Er‐doped fiber‐ring laser having less mode instability due to polarization fluctuation is proposed and experimentally investigated. The Er‐doped fiber is twisted to form a fiber‐ring laser. The right‐hand‐ and the left‐hand‐rotated circular waves preserved in the twisted fiber are exchanged by a fiber type ½ element placed in the fiber ring. This configuration can fix the separation between two polarization resonances (i.e., two ESOPs' resonances) and suppress the polarization‐mode instability. Both theory and experiment are presented conducted; the experiment his confirmed our design. In addition, the temperature effects on this fiber‐ring laser have been measured © 1995 John Wiley & Sons. Inc.
Interpolation of shaped reflector surfaces by cubic pseudosplines
Authors: Bergmann J. R. , Hasselmann F. J. V.
Published: July 2007

A recent study demonstrated the superior stability of quintic pseudosplines, when compared with usual oscillatory series expansions, for global interpolation of numerically defined reflector surfaces presenting critical behavior of their principal curvatures. Although interpolating functions with continuous derivatives up to second order are necessary for ray‐optical field evaluations, C‐class surface descriptions are sufficient when the antenna secondary field is calculated by integration of physical‐optics‐induced currents. In this connection, the applicability of cubic pseudosplines is explored via numerical comparison with previously obtained results from the implementation of the quintic ones. © 1995 John Wiley & Sons. Inc.
Realization of first‐order monotonic butterworth‐type low‐pass and high‐pass optical filters: Experimental verification
Authors: Ngo Nam Q. , Dai X. , Binh Le Nguyen
Published: July 2007

We present an experimental implementation of the first‐order monotonic Butterworth‐type low‐pass and high‐pass optical filters, using a coherent all‐zero fiber‐optic filter (AZFOF), as a verification of our previously proposed theory [1]. The filter realization technique shows that the all‐fiber Mach‐Zehnder interferometer (AFMZI) belongs to a special class of the first‐order monotonic Butterworth‐type optical filter. The phase‐modulated AZFOF is shown to be a potential candidate as a tunable optical blocking filter. © 1995 John Wiley & Sons. Inc.
A useful fractional linear transformation for the riccati equation for reflection coefficients
Authors: He Sailing
Published: July 2007

The conventional Riccati equation for the reflection coefficient involves the spatial derivative of the refractive index, and thus it is not suitable for use when the refractive index is nondifferentiable and/or discontinuous. In the present article we introduce a fractional linear transformation to obtain a Riccati equation that does not involve the derivative of the refractive index. The transformed reflection coefficient is continuous everywhere in space for any refractive index profile. The transformed Riccati equation is also used to obtain an explicit solution for a multi‐layered structure in a straightforward way. © 1995 John Wiley & Sons. Inc.
Radar cross‐section reduction by polarization rotation
Authors: Ongareau Eric , Roussaud Alain , Marouby Eric , Levrel Jean‐René
Published: July 2007

A system formed by a cascade connection of meander‐line strip grating surfaces that rotates the polarization plane of a linearly polarized wave is reported and measured. Reflectivity measurements of the system shaped on a reflector‐backed metallic ground plane have shown reflectivity levels smaller than –20 dB over the 10.5–17‐FHz band. © 1995 John Wiley & Sons. Inc.
A collocation‐type method for the solution of inverse problems in dispersive scattering theory
Authors: Razzaghi Mohsen , Ahmad Falih
Published: July 2007

This article introduces a numerical technique for solving the inverse problem in dispersive scattering theory. The inverse problem is first formulated as a relationship between the impulse response R and the susceptibility kernel G. Using the Legendre‐Gauss‐Lobatto nodes we construct the Nth polynomial interpolation to approximate the solution of G for a given R. This method is efficient and yields very accurate results. Illustrative examples are included to demonstrate the accuracy of the proposed method. © 1995 John Wiley & Sons, Inc.
Superresolved time‐frequency processing of wideband radar ECHO using esprit
Authors: Moore J. , Trintinalia L. C. , Ling H. , Xu G.
Published: July 2007

A time‐frequency superresolution procedure is presented for processing wideband backscattered data containing both scattering center and natural resonance information. In this procedure, the ESPRIT algorithm is used as the processing engine. The windowed superresolution procedure is performed twice—once in the frequency domain to extract the scattering centers and once in the time domain to extract the resonances. Parametrized models for both scattering centers and resonances are obtained by a weighted average of the results for each segment. The resulting time‐frequency image from the present superresolution procedure is not constrained in resolution by the Fourier limit. Superior noise performance is also demonstrated against a similar Prony procedure reported earlier. © 1995 John Wiley & Sons, Inc.
A numerical absorbing boundary condition for 3D edge‐based finite‐element analysis of very low‐frequency fields
Authors: Boag Amir , Mittra Raj
Published: July 2007

The numerical absorbing boundary condition (NABC) approach in conjunction with the three‐dimensional edge‐based formulation of the finite‐element method (FEM) is applied to the problem of very low frequency (VLF) electromagnetic radiation and scattering. The key step in the NABC approach is to derive linear relationships that link the values of the field along the boundary edges to those at the neighboring ones. Derived via a robust SVD‐based scheme, these linear relationships are satisfied, to within a certain tolerance, by all of the outgoing weve components. They can thus be used in lieu of the FEM equations employing the usual absorbing boundary conditions for the boundary edges. Although the NABC approach provides a simple way to derive an accurate local boundary condition for mesh truncation at an arbitrary frequency, it appears to be the only viable absorbing boundary condition at VLF, because the conventional absorbing boundary conditions are almost as reflecting as perfectly conducting magnetic walls at these frequencies. © 1995 John Wiley & Sons, Inc.
Miniaturization method for matched MIC LNA design at low microwave frequencies
Authors: Bayar Esen
Published: July 2007

A miniaturization technique is described, based on multiple function assignments to a single component or a small set of discrete components. This approach provides considerable substrate reduction without compromising electrical performance. The effectiveness of the technique is illustrated with a miniaturized L‐band LNA designs of outstanding electrical performance. © 1995 John Wiley & Sons, Inc.
On the design of multifunctional microwave (sub)systems for signal and noise performance
Authors: Rizzoli Vittorio , Costanzo Alessandra , Mastri Franco
Published: July 2007

The conventional approach to microwave system design based on the separate optimization of individual nonlinear functional blocks may result in a strongly suboptimal electrical and noise performance of the assembled system. This is due to nonlinear interactions among the interconnected subsystems, which are unpredictable by conventional means. The state equations of the individual building blocks change after the connection, and this may strongly modify the system electrical and noise performance with respect to the predictions. In order to meet the design goals it may thus be necessary to carry out a simultaneous numerical optimization of the entire assembly for electrical and noise performance, which is currently made possible by state‐of‐the‐art harmonic‐balance‐based numerical techniques. The optimized system performance may exceed the predictions based on the interconnection of noninteracting individually optimized subsystems, thanks to a better exploitation of the available degrees of freedom. © 1995 John Wiley & Sons, Inc.
An on‐wafer method for C‐V characterization of heterostructure diodes
Authors: Stake Jan , Grönqvist Hans
Published: July 2007

An on‐wafer method using coplanar probes for characterizing heterostructure diodes is proposed. Parameters are extracted by fitting a circuit model to a measured reflection coefficient over a broad frequency range. The test structure can be easily fabricated. © 1995 John Wiley & Sons, Inc.
Analysis of some coplanar transmission lines: Coplanar coupled lines, coplanar coupled striplines, and coplanar coupled lines with rectangular microshield
Authors: Yuan Naichang , He Jianguo , Yao Demiao , Dai Qin , Lin Weigan
Published: July 2007

Two types of coplanar transmission lines, rectangular microshield coplanar coupled lines (RMCCL) and coplanar coupled rectangular microshield lines (CCRML), are proposed for MMIC applications. These are developed from coplanar coupled lines (CCL) and coplanar coupled strip lines (CCS). Analytic formulas are presented for calculating the quasistatic TEM parameters of these coupled lines by means of exact conformal mapping techniques. Numerical results are also presented to illustrate the properties of these coplanar transmission lines. © 1995 John Wiley & Sons, Inc.
Space ‐ spectral‐domain approach for the resonant characteristics of fin lines
Authors: Gupta Nisha , Singh Mahendra
Published: July 2007

A simple method for calculating the resonant characteristics of unilateral fin‐line cavity is presented. The present method, called the space—spectral‐domain method, is found to be superior to several other methods in terms of computer memory and time, and can be easily implemented on any other arbitrarily shaped resonators. The results obtained are compared with the results available in the literature, and are found to be in good agreement. © 1995 John Wiley & Sons. Inc.
Mutual coupling computation of probe‐fed circular microstrip antennas
Authors: Huang Chih‐Yu , Wong Kin‐Lu
Published: July 2007

The mutual coupling between two probe‐fed circular microstrip antennas computed using the generalized transmission‐line model (GTLM) theory is presented. Theoretical results of the E‐ and H‐plane mutual coupling coefficients are calculated and compared with the measured data. Effects of the substrate loss tangent on the mutual coupling are also described. © 1995 John Wiley & Sons, Inc.
Optimized performance of erbium‐doped fiber lasers
Authors: Giraldi Maria Thereza Miranda Rocco , Celaschi Sergio
Published: July 2007

A figure of merit and an optimization procedure are defined, with the aim being to maximize the output power of erbium‐doped fiber lasers. Two tunable erbium‐doped fiber‐ring lasers are assembled as examples. The calculated results well agree with the experimental data, confirming the validity of the model. © 1995 John Wiley & Sous, Inc.
On the efficient representation of the electrodynamic green's function using multiresolution wavelet concepts
Authors: Kim Hyeongdong , Ling Hao
Published: July 2007

A multiresolution wavelet concept is applied to efficiently represent the electrodynamic Green's function. In the joint spectral‐spatial representation, the multiscale feature of the spectral‐domain Green's function is clearly revealed. Due to this multiscale feature in the spectral domain, a wavelet application in the spectral domain (KDWT) is more appropriate in representing the Green's function than the wavelet transform applied in the space domain (SDWT). We present a multiresolution implementation of the KDWT and show that the KDWT representation results in a sparser moment impedance matrix than the SDWT representation. © 1995 John Wiley & Sons, Inc.
Analysis on waveguide cross‐section‐plane microstrip probe
Authors: Xue Quan , Xu Jun , Xue Liangjin , Lin Weigan
Published: July 2007

An analysis and optimum method of a microstrip probe is presented. The input impedance is derived through the dyadic Green's function in a dielectric loaded waveguide. A wideband impedance match optimum process is employed to realize good return loss and insert loss of the microstrip probe. A Ka‐band microstrip probe has been designed and tested. Experiment shows good coupling efficiency and return loss. © 1995 John Wiley & Sons, Inc.