bluuebunny/crossref_metadata_2025 huggingface dataset:
Rigorous solutions of problems of electromagnetic resonators loaded with high‐loss dielectrics
Authors: Xu Yansheng , Bosisio Renato G.
Published: July 2007

In this paper, free oscillations in a rectangular cavity loaded with a high‐loss dielectric slab are analyzed and calculated. By means of the transformation of the complex characteristic equation into an ordinary differential equation and the application of suitable initial conditions, this problem is solved with both simplicity and high accuracy. The behavior of resonant frequencies (both the real and imaginary parts) of various modes is demonstrated and discussed. Our theoretical results will be helpful to computer simulation of heating and cooking processes in microwave ovens and applicators; our method of analysis may also be used in the calculation of microwave components and devices loaded with high‐loss dielectrics or magnetic materials.
Multifrequency antenna system for propagation experiments at 12.5, 20, and 30 GHZ
Authors: Herben M. H. A. J. , de Maagt P. J. I. , van de Goor W. A. , Casper A. C. A.
Published: July 2007

A multifrequency antenna system for future propagation experiments, at 12.5, 20, and 30 GHz with the Olympus satellite, is described. This antenna system consists of a 5.5 m Cassegrain reflector antenna and a multifrequency feed system.
Addition to spectral domain analysis of a microstrip thin superconducting line laid on GaAs substrate
Authors: Huret F. , Kinowski D. , Pribetich P. , Kennis P.
Published: July 2007

Our letter was published in the June, 1989 issue.* We would like to add additional curves to this letter in order to clarify the curves exhibited on Figure 4 with a too extensive caption. Furthermore, some mistakes have been introduced in the curves due to this bad representation. But the main purpose of this addition is to make some comments on the determination of σ1 and σ2 for new high Tc superconductor YBaCuO, especially for thin film.
A technique for reducing mutual coupling between rectangular microstrip antennas by frequency scaling
Authors: Gupta B. , Chaudhuri S. R. Bhadra , Mukherjee A. , Poddar D. R. , Chowdhury S. K.
Published: July 2007

A significant reduction of mutual coupling between E‐plane coupled rectangular microstrip antennas by frequency scaling is presented. Compactness in the design may also be achieved by this technique.
An envelope description of the RCS of complex scattering bodies
Authors: Pistorius C. W. I.
Published: July 2007

A new method whereby the radar cross section (RCS) of complex scattering bodies can easily and rapidly be estimated is described. The RCS envelope of a scatterer is found by extracting and adding the envelopes of the component canonical shapes acting as the scattering centers of the body.
Parameters of shielded modified coupled microstrip lines
Authors: Hanna Victor Fouad
Published: July 2007

Analytic closed‐form expressions for even‐ and odd‐mode characteristic impedance and effective dielectric constant for shielded coupled microstrip lines, either having or not having a tuning slit in their back metallization, are obtained using conformal mapping techniques. The effect of the existence of this tuning slit as well as that of the upper shielding is studied.
Theoretical investigation on the effects of nonmatching loads upon the impedances of millimeter wave oscillators
Authors: Hong Wei
Published: July 2007

In this paper the effects of nonmatching loads on the impedances of millimeter wave oscillators are analyzed. For a special case of matching load, the numerical results are in agreement with Doring's experimental data and Wu's theoretical results. The impedance variations due to the nonmatching loads are first presented and some useful conclusions are followed.
Millimeter‐wave detection using resonant tunnelling diodes
Authors: Mehdi I. , Kidner C. , East J. R. , Haddad G. I.
Published: July 2007

A lattice‐matched InGaAs/InAlAs resonant tunnelling diode is studied as a video detector in the millimeter‐wave range. Tangential signal sensitivity and video resistance measurements are made as a function of bias and frequency. A tangential signal sensitivity of — 37 dBm (1 MHz amplifier bandwidth) with a corresponding video resistance of 350 Ω at 40 GHz has been measured. These results, to the best of our knowledge, are the first millimeter‐wave tangential signal sensitivity and video resistance results for a resonant tunnelling diode.
Complex permittivity of lanthanum aluminate in the 20 to 300 K temperature range from 26.5 TO 40.0 GHZ
Authors: Miranda F. A. , Gordon W. L. , Bhasin K. B. , Ebihara B. T. , Heinen V. O. , Chorey C. M.
Published: July 2007

Dielectric constants of microwave subtrales are required in the design of superconducting microwave circuits at various temperatures. In this paper, we report the results of a study of the complex permittivity of the newly developed lanthanum aluminate (LaAIO3) substrate, in the 20 to 300 K temperature range at frequencies from 26.5 to 40.0 GHz. The value of the complex permittivity was obtained by measuring the sample scattering parameters using a microwave waveguide technique. It is observed that, while the dielectric constant did not change appreciably with frequency, its value decreased by approximately 14 percent from room temperature to 20 K.
A new evaluation method for rf characteristics of varactor diodes
Authors: Imaoka Toshikazu
Published: July 2007

A new evaluation method used for RF characteristics of varactor diodes has been developed using an S‐parameter measurement technique for packaged MESFETs and their simulation. This method can measure accurately the characteristics under any given frequency and any bias conditions.
Total reflected millimeter‐wave power from moving‐strip‐illuminated semiconductor panel
Authors: Rahnavard M. H. , Habibzadeh A.
Published: July 2007

Moving‐spot‐illuminated semiconductor panels are used as millimeter‐wave image converters. To determine the performance of this system, it is required to know the response of illuminated semiconductor panels. In this paper total reflected' millimeter power from moving‐strip‐illuminated semiconductor panels as a function of attenuation, scanning velocity, width of the strip, etc., is studied.
Active devices for microwave distributed amplification
Authors: D'Inzeo Guglielmo , Giusto Roberto , Petrachi Claudio
Published: July 2007

The theoretical results presented in this letter demonstrate the possibility of growing waves' propagation along MESFET electrodes, through a distributed interaction mechanism based on the active characteristics of the transistor. The analysis proves that a T cross‐section gate is necessary to obtain amplification, moreover this gate configuration allows a remarkable reduction of the electrode gate resistance. In the validity range of the analysis used, the main feature of the new device is a wide bandwidth, deriving from a fully distributed component. This device could result in a valid substitute for low power TWTs.
Multidomain gunn diodes
Authors: Tsay Jenngang , Schwarz S. E. , Raman Shankar , Smith J. S.
Published: July 2007

A technique for obtaining multidomain operation of Gunn diodes is proposed. Device impedance is increased, leading to large potential increases in output power. The precision required of the doping profile has been estimated by simulation and appears to be within the capabilities of molecular beam epitaxy. Estimates of output power, taking thermal effects into account, indicate that in many cases an N‐domain diode can produce N2 times as much power as a single‐domain diode. For example, it should be possible to obtain 1.8 W from a three‐domain device oscillating at 30 GHz.
A GaAs directional coupler
Authors: Choudhury Debabani , Mahapatra S.
Published: July 2007

The performance of a monolithic microwave integrated circuit directional coupler fabricated on semi‐insulating GaAs substrate has been presented in this paper. The coupler characteristics were measured to investigate the effect of introducing tapered section terminations at all the ports of the coupler.
An optimized forward‐coupling microstrip hybrid for millimeter‐wave circuits
Authors: Ikäläinen Pertti
Published: July 2007

A forward‐coupling microstrip hybrid with optimized coupling variation is described. The advantages of the new structure are its suitability for use at millimeter waves, high directivity, and relaxed fabrication tolerance. Experimental results from a 36‐GHz coupler are presented.
Performance of convolutional codes in noisy optical channels using an APD‐viterbi decoder receiver
Authors: Fares Doaa A.
Published: July 2007

In this analysis, performance evaluation of orthogonal convolutional coded pulse position modulation (PPM) in a typical binary‐asymmetric optical channel is presented. Then, the system performance is compared to that of the Reed‐Solomon coded PPM model, where high background noise affects the channel behavior. Using an avalanche photodetector for detection, threshold decision technique is used. This treatment for the PPM orthogonal convolutional coding is more comprehensive than that described in reference 1.
Broadband design of ring type microstrip power divider
Authors: Roy Jibendu Sekhar , Poddar Dipak Ranjan , Chowdhury Santosh Kumar
Published: July 2007

The broadband design of a ring type microstrip power divider with any desired power division ratio is described. The improvement in bandwidth is obtained by the addition of a fifth port to the conventional four‐port power divider design. The present design provides good device performance over a wide range of frequency. For a minimum isolation of around 30 dB, the coupling coefficients remain about constant over a band of frequency that is 30% of the design center frequency. This design technique is applicable to both equal and unequal power divisions. This broadband design of power divider is very useful for the basic power divider of the feeding network in microstrip antenna arrays including phased arrays.
Performance evaluation of two passive mmic components
Authors: Choudhury Debabani , Mahapatra S.
Published: July 2007

An important part of the monolithic microwave integrated circuits (MMICs) are the passive circuit elements which outnumber the FETs. In this article, design procedures and techniques for realizations of two passive components (viz., power divider and interdigital capacitor) on the semiinsulating GaAs substrates are indicated. Performances of the components are described and commented on.
Solutions to the electrostatic problems of a dielectric sphere resting on a conducting plane by inversion transformation method
Authors: Lin Weigan , Jin Hang
Published: July 2007

The analytic solutions to the electrostatic problems of a dielectric sphere resting on a conduction plane are obtained by the inversion transformation method and the field enhancement at the apex of a dielectric sphere is evaluated.
Changes in the band structure pattern of microstrip filters due to gap capacitive effects
Authors: Faria J. A. Brandão
Published: July 2007

Simulation results are presented for a transversally symmetric three‐line microstrip half‐wave filter structure, showing the effect of taking into account the finite series‐gap capacitances associated with existing internal strip discontinuities.
A novel very wideband 2‐port S‐parameter calibration technique
Authors: Soares R. , Gouzien P. , Meszaros S.
Published: July 2007

In this article explicit formulas are presented permitting the de‐embedding of two‐port S‐parameter data in the case of the through‐reflect family of calibration techniques. The readily programmable algorithm developed is applied to a novel through‐attenuate‐reflect method (TAR) which, unlike the through‐reflect‐line method, has no inherent bandwidth limitation.
Effect of a parasitic mode on the performance of a serpentine waveguide mode converter
Authors: Kasraian Masoud , Seshadri S. R.
Published: July 2007

A cylindrical waveguide with an axis having a weak harmonic variation about a straight line in a plane can be used to convert selectively the TEpq mode to the TEp+1,r mode. The performance of this waveguide converter in the presence of a parasitic mode is examined and certain aspects of the optimization of this distributed mode converter are discussed.
A design technique for minimizing the electromagnetic interference induced along a microstrip line by external sources
Authors: Bernardi Paolo , Cicchetti Renato
Published: July 2007

This work shows that embedded‐strip microstrip lines may be usefully adopted in microwave integrated circuit applications when minimization of the interference caused by external electromagnetic sources is required. A design procedure for minimizing the interference induced by external sources in the proposed structure is suggested.
A derivation of the vector addition theorem
Authors: Chew W. C.
Published: July 2007

An alternative derivation of the vector addition theorem is presented using the completeness of vector wave functions and integration by parts. The advantage of this derivation is that it leads directly to the simplified results of Bruning and Lo and of Stein. Moreover, the dichotomous results of the addition theorem when a spherical Hankel function is involved can be derived by contour integration.
Space‐variant aberrations: Differential operator
Authors: Ojeda‐Castañeda J. , Ibarra J.
Published: July 2007

A differential operator describes the influence of space‐variant aberrations on a diffraction‐limited image, formed under coherent illumination. To illustrate our general treatment, the Talbot effect for space‐variant defocus is discussed in terms of the eigenfunctions of the differential operator.
Dielectric properties measurement of substrate and support materials
Authors: Wu Te‐Kao
Published: July 2007

In this paper a fast and straightforward waveguide measurement technique is described for the determination of the dielectric constant and loss tangent of many commercially available materials. These dielectric materials include Cuflon, Teflon, Arlon's polyimides, Lockheed's ceramic foams, and Rogers Duroid materials. The effective dielectric constant and loss tangent of Hexsel's honeycomb material is also measured by this method and is compared to the predicted data obtained using the volume averaging theory. The accuracy and other features of this measurement technique are also discussed.
Analysis and optimization of high‐performance antenna feed
Authors: Gupta G. S. , Nguyen D. N. , Huang C. C.
Published: July 2007

Hybrid‐mode feeds exhibit good axisymmetric copolar radiation patterns and low cross polarization. Practical design often relies on an empirical cut‐and‐try approach and is therefore time consuming and costly. A new computer‐aided design, based on an optimization routine, is proposed and presented in this paper. The analysis employs the mode matching technique at approximated step junctions, and the optimization procedure uses the minimax algorithm. Validation of this approach is supported by the excellent agreement between computed and measured data.
Differential detection of optical heterodyne dpsk communication systems with intersymbol interference
Authors: Zhang Xiupu , Jiang Peixuan
Published: July 2007

The system model for differential detection of optical heterodyne DPSK systems is set up, taking into account the effects of the IF filter and its production of ISI, the additive white Gaussian noise in the receiver and the quantum phase noise of lasers as well as the bandwidth‐time product (BT). We derive the probability distribution function of noise statistics for BT ≥ 1. The bit error rates (BER) are investigated in the presence of ISI. Numerical results for a 140‐Mbit /s system are presented for Gaussian IF filters. It is found that the laser linewidth requirement is the same as the system that does not consider the IF filter effect and the ISI it causes.
A UTD formula for H‐polarization plane wave diffraction by a wedge with impedance faces
Authors: Wang Bing‐Zhong , Lin Weigan
Published: July 2007

In this article, by using the surface reflection coefficients to describe the boundary conditions, a simple uniform geometrical theory of diffraction (UTD) formula for an impedance wedge is given by a rigorous analysis under the assumption that both faces of the wedge are illuminated by a H‐polarization plane wave.
Quasi‐tem analysis of a monolithic microwave GaAs phase shifter
Authors: Singh D. R. , Champlin K. S.
Published: July 2007

A simple analytical model is developed for a slow‐wave monolithic microwave variable phase shifter. Propagation characteristics of the phase shifter were evaluated using this model and were found to be in excellent agreement with the experimental results of Neidert and Krowne. The model permits changing various parameters to optimize phase‐shifter performance with relative ease.
Harmonic generation in II‐VI compound semiconductors under hot electron condition
Authors: Dutta A. , Mukhopadhyay D.
Published: July 2007

The second harmonic generation efficiency has been calculated in a number of II‐VI‐compound semiconductors under high‐field condition by approximating the velocity‐field characteristics by a power‐series relation. It is found that the second harmonic generation efficiency is much higher in these materials than in the elemental or IIIV compound semiconductors. Also, because the carrier relaxation times are lower in these materials, they can be used for efficient harmonic power generation in the infrared‐ and millimeter‐wavelength ranges.
The new method of measuring the RCS of a target by means of the six‐port reflectometer
Authors: Jia Sun
Published: July 2007

A new method of measuring the RCS of a target in a general laboratory by means of a six‐port technique and a new error‐correcting model is given. The six‐port reflectometer testing RCS circuit and the experiments used are also given.
Nondiffracting wavefields in grin and free‐space
Authors: Ojeda‐Castañeda J. , Noyola‐Iglesias A.
Published: July 2007

The formal solution to Helmholtz equation is used for finding nondiffracting wavefields in generalized α‐power GRIN and free‐space Two novel solutions contain previously known nondiffracting beams.
High‐frequency resonant‐tunneling oscillators
Authors: Brown E. R. , Parker C. D. , Calawa A. R. , Manfra M. J. , Chen C. L. , Mahoney L. J. , Goodhue W. D. , Söderströom J. R. , McGill T. C.
Published: July 2007

Advances in high‐frequency resonant‐tunneling‐diode (RTD) oscillators are described. Oscillations up to a frequency of 420 GHz have been achieved in the GaAs/AlAs system. Recent results obtained with In0.53 Ga0.47As/AlAs and InAs/AlSb RTDs show a greatly increased power density and indicate the potential for fundamental oscillations up to about 1 THz. These results are consistent with a lumped‐element equivalent circuit model of the RTD. The model shows that the maximum oscillation frequency of the GaAs/AlAs RTDs is limited primarily by series resistance, and that the power density is limited by low peak‐to‐valley current ratio.
Capability of schottky‐diode multipliers as local oscillators at 1 THz
Authors: Räisänen Antti , Sironen Mikko
Published: July 2007

Extensive studies on the theoretical performance of Schonky‐varactors and varistors as multipliers of a frequency around 100 GHz to the submillimeter region (400‐1200 GHz) in various direct and cascaded configurations have been carried out using harmonic balance analysis. Because of high circuit losses (≥10 dB) in a multiplier chain producing 1 THz, the output power seems to stay at or below 100 μW even in the best multiplier configurations when the available input power at 100 GHz is 50 mW.
Energy propagation with phase velocity in a waveguide
Authors: Giakos George C. , Ishii T. Koryu
Published: July 2007

Transit‐time measurements of the leading edge of pulse‐modulated microwaves propagating in a waveguide have been performed in time domain. These measurements show that a part of the energy associated with the leading edge of the pulse propagates with a phase velocity exceeding the intrinsic velocity in free space. Calibration techniques and repeated measurements confirm this phenomenon.
Normal‐mode synthesis of N‐coupled coplanar stripline structures
Authors: Faria J. A. Brandão
Published: July 2007

Normal modes of n‐coupled stripline structures can be constructed out of a set of generating modes. For coplanar structures a proper choice of the generating set may be based on tridiagonal symmetric Toeplitz L and C matrices. The relationship between the normal‐mode set and the generating‐mode set is established by resorting to standard first‐order perturbation theory results. A numerical example, involving a shielded coplanar five‐line structure (n = 5) is provided for demonstration purposes.
Thermal behavior of wavelength demultiplexers monolithically integrated on InGaAIAs/InP
Authors: Morasca S. , De Bernardi C. , Rigo C. , Stano A. , Croston I. R.
Published: July 2007

An experimental and theoretical analysis of the thermal behavior of wavelength demultiplexers, based on the two‐mode interference principle, integrated on InGaAlAs epitaxially grown by molecular beam epitaxy on InP, is presented. The tuning characteristics of these devices are determined by the superposition of two mechanisms: a pure thermo‐optic effect an an elasto‐optic effect, caused by induced stress. The former is responsible for a shift in the spectral characteristics of about 0.1 nm °−1, while the latter can lead to a much higher temperature sensitivity, up to 1 nm °−1 or more.
Identification of a target in presence of ground clutter using polarization
Authors: Bhattacharyya Asoke K.
Published: July 2007

This article examines the polarimetric method of identification of a target in the presence of ground clutter. The clutter is modeled as a two‐layer random medium. The complex scattering matrix for the clutter is obtained by using Born approximations carried to the second order to extract the crosspolarized scattered fields. The test target used is a loop of conducting wire oriented arbitrarily. It is found that the choice of polarization is one of the key factors if one has to identify targets in presence of clutter. This work does not take into account the mutual coupling between the target and the clutter sources. The important results are analyzed and discussed.
Optimality of galerkin method for scattering computations
Authors: Wandzura Stephen
Published: July 2007

Practitioners of the method of moments have found empirically that the Galerkin method, when applied to scattering problems, gives more rapid solution convergence than more general moment methods. A simple demonstration of the reason for this is given.
Conversion gain and stability of a resonant tunneling diode harmonic mixer
Authors: Krishnamurthi K. , Conn D. R.
Published: July 2007

Based on the negative differential resistance (NDR) in the current‐voltage characteristic of the resonant tunneling device (RTD), various applications have been proposed. Circuit considerations are, in most cases, the limiting factors for high‐frequency applications. Stability criteria for the RTD subharmonically pumped mixer are investigated in this article. Improvements needed for the RTD devices in subharmonically pumped mixer applications are suggested.
III‐V monolithic resonant photoreceiver using local epitaxy and large lattice mismatch material
Authors: Aboulhouda S. , Vilcot J. P. , Razeghi M. , Decoster D. , Francois M. , Maricot S. , Aboudou A.
Published: July 2007

It is shown that local and large lattice mismatch epitaxies could be useful techniques for the fabrication of optoelectronic integrated circuits. As an example, we fabricated a monolithic resonant photoreceiver which associates a long‐wavelength metal‐semiconductor‐metal photodetector, a GaAs MESFET preamplifier, and an inductor. The GaAs/GalnAs heteroepitaxy needed for the photodetector was selectively grown using a SiO2 mask and the entire circuit was fabricated on a silicon substrate. Compared to a PIN photodiode loaded with a 50‐Ω resistor, more than 10 dB gain was measured at 7 GHz in a microwave optical link.
A transmission phase grating analysis
Authors: Brand Faria J. A. Ão
Published: July 2007

A very simple analysis of a transparent transmission phase grating with alternate phase regions is presented, and it is shown how its behavior depends on the imposed phase shift. A possible application as a beam routing device or as a wavelength demultiplexer is suggested.
Evaluation of dispersions penalty in an optical coherent PSK transmission system
Authors: Tang XiongYan , Ye PeiDa
Published: July 2007

A transmission system model suitable for analyzing both chromatic dispersion and polarization dispersion effects on any coherent optical transmission systems is proposed. Applying this model, the waveform distortion due to both dispersions is calculated for a coherent PSK signal. The dispersions penalty in a coherent PSK system and in a coherent CPFSK system is compared.
Analysis of broadside coupled cylindrical suspended microstrip lines using conformal mapping techniques
Authors: Reddy C. Jagadeswara
Published: July 2007

Cylindrical striplines and microstrip lines have recently been investigated due to their applications as feed networks of patch antennas on curved surfaces. This letter analyzes the broadside coupled cylindrical suspended microstrip lines using conformal mapping technique. Closed‐form expressions for even‐ and odd‐mode characteristic impedances are obtained. This analysis can also be extended to warped broadside coupled suspended cylindrical microstrip lines.
AIGaAs/GaAs power MISFET with 0.5 W/mm at 30 GHz
Authors: Bonte B. , Amairi A. , Crosnier Y. , Salmer G.
Published: July 2007

This article deals with the application of the AlGaAs‐GaAs DMT principle to the millimeter wave range. It is based on two technological realizations and related characterizations. An Idss of 700 mA/mm and a 10‐12‐V breakdown voltage are demonstrated. Power measurements indicate an output‐power capability of about 0.5 W/mm at 30 GHz.
Far‐field radiation from step junctions in biaxially anisotropic slab waveguides
Authors: Ho T. Q. , Beker B.
Published: July 2007

In this article far‐field radiation properties of step discontinuities on biaxially anisotropic slab waveguides are examined. The stationary phase method is applied to obtain the asymptotic form of the far‐field expressions, which are derived based on the transmission coefficient of the radiation mode. The analysis yields data that agree well with those previously published for special cases of isotropic slabs. The newly calculated results for far‐field radiation patterns of step junctions between biaxially anisotropic waveguides are presented for several combinations of tensor element parameters.
Simple and efficient analysis for a slot‐coupled patch antenna with a microstrip line feed
Authors: Yang Rugui , Lo Y T. , Aksun M. I. , Chuang S. L.
Published: July 2007

In this paper, a simple and eficient analysis f o r slot‐coupled microstrip antennas with a microstrip line feed is developed, using the cavity‐model theory. The computed results are found in excellent agreement with the experimental data.
Numerical analysis of brillouin amplifiers for use in self‐homodyne detection
Authors: Ronghui Feng , Peida Ye
Published: July 2007

An analysis of Brillouin amplifiers (BA) for use in self‐homodyne detection is given considering the pump depletion and the frequency dependence terms. Numerical calculated results shows that operating a BA in the saturated region will give better performance than in the linear region, and the most economic fiber length and pump power can be selected to obtain optimum characteristics of BA.
The effect of spatial hole burning on FM response in DFB laser diodes
Authors: Jianping Zhang
Published: July 2007

In this article, the factors of aP and δP are introduced to describe the effects of all optical field longitudinal nonuniformity on the threshold condition. The rate equation model, including spatial hole burning, is established. The two factors are calculated from the rate and coupled mode equations and analytical expressions of FM responses are derived. FM responses of DFB laser diodes are also analyzed numerically.
High‐power, low‐recovery‐time switched pin diode duplexer at Ku band
Authors: Sarkar B. K. , Prasadh S. S. , Gupta S.
Published: July 2007

High‐power duplexer consisting of a four‐port ferrite junction circulator and two‐stage switched PIN diode limiter with appropriate driver circuit is designed and developed for a low‐recovery‐time requirement. Insertion loss of 1.5 dB, isolation of 70 dB and recovery time of 40 ns are achieved at a 10‐KW peak, 200‐ns pulsewidth at Ku band.
Investigation of radiation and surface‐wave losses at compensated microstrip T junctions and bends at near‐millimeter‐wave frequencies
Authors: Lin C. C.
Published: July 2007

This article presents the results of an experimental investigation on the radiation and surface‐wave losses at the microstrip discontinuities such as compensated symmetrical T junctions and bends at near‐millimeter‐wave frequencies. Reflection and transmission losses of samples containing those discontinuities with fine geometrical differences have been measured. The reduction of those losses with the use of smooth T junctions and bends is demonstrated.
Wide‐band printed dipole antenna
Authors: Dey Supriyo , Aanandan C. K. , Jose K. A. , Monahan P. , Nair K. G.
Published: July 2007

The design and development of an L‐band printed dipole antenna, optimized for wide‐band applications near first resonance, is reported. This design has achieved more than 48% impedance bandwidth (VSWR 2:1), without degrading its overall radiation efficiency.
Linear analysis of sheet beam planar grating and dielectric cerenkov maser amplifiers
Authors: Joe J. , Chang S. F. , Scharer J. E. , Booske J. H.
Published: July 2007

We consider a planar grating and partially filled dielectric as slow wave structures for a low‐voltage electron sheet beam, moderate power Cerenkov amplifier. The small signal growth rate for both slow wave structures with partially filled sheet beams are evaluated. The results are compared at 35 and 60 GHz. We find that both configurations offer attractive and comparable gain at relatively low beam voltages and can be developed as moderate power sheet beam sources.
Self‐trapping of vibrational energy
Authors: Scott Alwyn C.
Published: July 2007

The current status of Davydov's soliton mechanism for the storage and transport of vibrational energy in biomolecules is reviewed. It is concluded that this mechanism should be viable under normal physiological conditions. Davydov's analysis is extended to the discrete self‐trapping (DST) system which is a convenient model for exploring the relations between classical anharmonic effects (solitons, local modes, chaos, etc.) and their quantum descriptions.
Stability and soliton via modified nonlinear schrödinger equation
Authors: Li Guifang , Seshadri S. R.
Published: July 2007

The evolution of nonlinear dispersive waves in weakly and cubically nonlinear media is shown to be governed by a modified nonlinear Schrödinger equation. The linear stability of the plane‐wave solution and the soliton solution are investigated using the modified governing equation. The height of the new soliton is a function of both its width and velocity.
Coupled‐mode formulation of parallel dielectric waveguides using singular perturbation technique
Authors: Yasumoto Kiyotoshi
Published: July 2007

A new coupled‐mode formulation for parallel dielectric waveguides is presented by using a singular perturbation technique. The theory is applied to two parallel, planar dielectric waveguides and the coupled‐mode equations that are asymptotically correct are obtained.
Crystal‐clad fiberoptic polarizer
Authors: Wang Zi Hua , Wang Dao Gang , Seshadri S. R.
Published: July 2007

Theoretical analysis, design considerations, and manufacturing techniques of a fiber‐optic polarizer made of crystal‐clad single‐mode fiber are discussed. The measured extinction ratio exceeds 30 dB over a wide bandwidth and is 37 dB at 1.53‐μm wavelength. The excess loss is less than 1 dB. The device is 3x3x20 mm in size.
On the performance of different types of MESFET‐mixers
Authors: Angelov I. , Zirath H.
Published: July 2007

In this article, performance of different types of MESFET mixers is compared by using one and the same transistor. The impact of different circuit parameters on the mixer performance were investigated theoretically and compared with practically obtained results.
The implementation of a high accuracy optical measurement technique of particular interest to miniature optics
Authors: Ghafouri‐Shiraz H. , Mcloughlin Ian Vince
Published: July 2007

This letter details an implementation of optical coherence domain reflectometry (OCDR) which is capable of resolving distances of less than 10μ. Simulated and experimental data have been used to evaluate the effects of different parameters on a future system, allowing the prediction of OCDR capabilities under different arrangements, and the determination of its suitability in different application areas.
Thermal analysis of etched‐well surface‐emitting diode lasers
Authors: Nakwaski Wlodzimierz , Osiński Marek
Published: July 2007

A new self‐consistent thermal‐electrical model of etched‐well GaAs/ AlGaAs vertical‐cavity surface‐emitting lasers is developed. The model features a realistic distribution of heat sources and two‐dimensional current‐ and heat‐flux spreading. It is shown that the P‐AlGaAs layer represents a major source of Joule heating that may easily exceed the active‐region heating. A moderate increase of the P‐AlGaAs layer doping is shown to be very effective in reducing the excessive heating.
Field approximations at thin‐wire junctions for the finite‐difference time‐domain method
Authors: Boonzaaler J. J. , Pistorius C. W. I.
Published: July 2007

Approximations for the circumferential magnetic fields at right‐angled junctions are derived and validated by computing the radiation patterns of a square‐loop antenna by means of the finite‐difference time‐domain (FD‐TD) method. The radiated time‐domain fields are transformed to the frequency domain and then compared to the frequency domain results obtained from the method of moments.
Radiated fields of microstrip patches at arbitrary angular positions
Authors: Wahid P. F. , Christodoulou C. G. , Rutkowski K. A.
Published: July 2007

This article investigates the radiation characteristics of microstrip patch antennas located at arbitrary angular positions. The aperture method was employed to determine the radiated far field of the patch. A circular arrangement of the patch antennas was studied. The effect of the array configuration on the radiation characteristics are presented and analyzed.
Analysis of second harmonic generation in organic crystal‐cored fibers for various cladding materials
Authors: Ghafouri Shiraz H. , Ozsoy S.
Published: July 2007

The second harmonic power generation efficiency (SHPGE) obtained under phase‐matching conditions in organic crystal‐cored fibers having different cladding materials have been investigated. It has been found that a very high SHGPE can be obtained under certain conditions.
Analysis of waveguide‐to‐microstrip transition
Authors: Li Dawei , Wang Rongjie
Published: July 2007

The analysis method for the antipodal finline waveguide‐to‐micro‐strip transition is presented in the article. The revised empirical expressions for the transition from nonoverlapped antipodal finline to overlapped one are given. We design a Ka‐band broadband waveguide‐to‐microstrip transition using this method. The experimental results have a good agreement with the theoretical ones.
Characteristic features of a leaky‐wave microstrip antenna on cylindrical surfaces
Authors: Mitkees A. A. , Abdallah E. A. , Hamdy S. M. , Elsohly A. A.
Published: July 2007

Antenna parameters of microstrip leaky‐wave antennas are highly affected by the complex nature of the propagation factor. Beam direction, beamwidth, gain, side‐lobe level, efficency, and input impedence for different lengths and linewidths are investigated. The antenna showed good performance and promising features. Efficiency up to 90%, – 18‐dB side‐lobe level, 9‐dB gain, and 20° beamwidth can be obtained.
How does atmospheric turbulence affect threshold detection in optical channels?
Authors: Fares Doaa A.
Published: July 2007

Optical communication through the earth's atmosphere offers a great contribution in increasing our data transmission capability. In addition to background radiation and photodetector random gain, the performance of such a channel is highly affected by atmospheric turbulence along its propagation path. In this article, threshold detection for this channel is studied under different turbulence levels, concluding the optimum threshold setting for different alphabet sizes.
Signal power requirements in indoor directive and diffuse infrared communication channels
Authors: Georgopoulos Chris J. , Prentzas Lampros K.
Published: July 2007

This article deals with the calculation of the minimum required emitting infrared (IR) signal power at the presence of background ambient light, taking into account thermal noise and receiver input amplifier noise. A baseband PCM wireless IR system is assumed and results are obtained for both directive and diffuse IR transmission channels.
Measurements of the minimum reflection signature of pmma fiber splices
Authors: Lawson C. M. , Michael R. R. , Finn G. M. , Dressel E. M. , Harmony D. W.
Published: July 2007

The minimum reflection signature of polished plastic fiber splices has been measured using time domain reflectrometry. Predominant splice reflection sources due to surface roughness, inexact index matching, and fiber core misalignment were eliminated. An intrinsic reflection signature on top of the Rayleigh floor is clearly observable in all tested fibers.
Plane wave scattering response of a unidirectionally conducting screen immersed in a bi‐isotropic medium
Authors: Lakhtakia Akhlesh
Published: July 2007

Reflection and transmission of plane waves by a unidirectionally conducting screen immersed in a bi‐isotropic medium is explored.
A broadband dual slant strip grating for elimination of specular reflection of em waves
Authors: Wilson Gomez L. , Ajaikumar V. , Jose K. A. , Mohanan P. , Nair K. G.
Published: July 2007

Conventional corrugated surfaces and strip gratings are used for eliminating specular reflections from a conducting surface for TE or TM polarization waves. This article presents the development of a dual slant strip grating for the elimination of specular reflections from conducting surfaces for both TE and TM polarizations, with an enhancement in bandwidth. Perfect blazing for n= ‐1 spectral order is also provided by the system.
Microwave bandpass filters using series‐cascaded sections of microstrip line
Authors: Bernhard Jennifer Truman , Joines William T.
Published: July 2007

A quarter‐wavelength‐coupled filter with prescribed frequency response is presented which uses a novel configuration of series‐cascaded microstrip lines as its resonating components. Design equations are obtained from ABCD parameters, with approximations taken to account for the double resonance characteristics of the filter's constituent networks. Experimental and theoretical results agree closely.
Simulation of the erbium‐doped fiber amplifier characteristics
Authors: Ghafouri‐Shiraz H. , Shum P.
Published: July 2007

The dependence of the erbium‐doped optical amplifier gain upon the fiber length, output signal, and pump power have been theoretically investigated for two pumping wavelengths of 0.98 and 1.48 μm. The analytical results are in fairly good agreement with the reported measured data.
A study of optically controlled millimeter‐wave propagation characteristics in a metallic rectangular waveguide loaded with double dielectric layers
Authors: Zhiyuan Yu , Welgan Lin
Published: July 2007

This article presents the theoretical analysis of a new optically controlled metallic waveguide structure loaded with double dielectric layers in H face. This structure shows higher optical sensitivity than that loaded with a homogeneous semiconductor dielectric layer. It can give an optically controlled phase shift greater than 4000 deg/cm and an optically controlled attenuation of more than 200 dB/cm.
Lithium niobate traveling‐wave phase modulator with an indium tinoxide buffer layer
Authors: Chang Wen‐Chung , Chuang Wei‐Ching , Wang Way‐Seen
Published: July 2007

Characteristics of traveling‐wave phase modulators fabricated with indium tinoxide (ITO) and silicon dioxide (SiO2) as buffer layers on Z‐cut LiNbO3 substrate are compared at the wavelength 0.6328 μm. For those with an ITO buffer layer, a half‐wave voltage of 8.1 V and a bandwidth of 10 GHz are obtained, whereas for those with an SiO2 buffer layer, a half‐wave voltage of 9.6 V and bandwidth 11 GHz are obtained. Hence the use of an ITO buffer layer may cause a reduction of the driving voltage and be capable of broadband operation.
A closed‐form multidimensional free‐space green's function by the path‐integral method
Authors: Huang Chenhong , Nevels Robert D.
Published: July 2007

A closed‐form multidimensional free‐space Green's function for the Helmholtz equation is obtained by the path‐integral method. The path‐integral method is novel and the general closed‐form free‐space Green's function is a useful expression which is not widely known.
Broadband horizontally polarized omni antenna
Authors: Misra V. C. , Pal Ram , Dey K. K.
Published: July 2007

Horizontally polarized omnidirectional characteristics in planes of arrays have been achieved with a 32 element circular array. The element incorporated is a printed circuit tapered slot radiator in a strip‐line configuration. This array was excited in cophase condition and was evaluated over the 6–18‐GHz frequency band. It was observed that the omni variation in the horizontal plane is within ±3 dB over the frequency band.
FD‐TD analysis of open cylindrical dielectric resonators
Authors: Shen Ying , Bi Zhiqiang , Wu Keli , Litva John
Published: July 2007

Different structures of open dielectric resonators (DR), which include isolated DRs, tuning‐screw DRs, and semiopen supported DRs on a microstrip substrate, are analyzed using the finite‐difference time‐domain method with the efficient numerical integration fourier transform. The numerical results are in very good agreement with the available theoretical solutions and the experimental results.
Dispersion characteristics of open microstrip transmission lines printed on biaxially anisotropic substrates
Authors: Chen Yinchao , Beker Benjamin
Published: July 2007

The dyadic Green's function for an open single microstrip line and a coupled stripline, printed on a homogeneous anisotropic substrate characterized by both its biaxial permittivity and permeability tensors, is rigorously formulated in the Fourier‐transformed domain. The dispersion properties of these transmission lines are examined for different material parameters and several sizes of the geometry. The numerical results show that the addition of the magnetic anisotropy to the substrate material has a significant influence on the propagation characteristics of the microstrip transmission line.
A new approach to the analysis of the soliton: Nonuniform finite difference beam propagation method
Authors: Liu Shuh‐Fang , Wei Pei‐Kuen , Wang Way‐Seen
Published: July 2007

A finite difference beam propagation method with nonuniform discretization is presented and validated for the analysis of solitary waves. We verify the accuracy of our nonuniform finite difference beam propagation method by demonstrating the evolution of the well‐known N soliton in nonlinear dispersive medium with and without higher‐order perturbed terms. Comparisons with the standard beam propagation method for calculation of both bright and dark solitons are also given and show that the nonuniform finite difference method is good for saving computing time, while maintaining the desired accuracy.
Fabrication of strip loaded outdiffusion guides on lithium niobate substrate
Authors: Lau Chi‐Sang , Wei Pei‐Kuen , Su Chi‐Wu , Wang Way‐Seen
Published: July 2007

A fabrication method of strip‐loaded waveguide on lithium outdiffused lithium niobate substrate is presented. The fabricated waveguide provides good characteristics, such as single transverse magnetic (TM) or electric (TE) polarization and without having a thick surface guide on the substrate. Also it takes less time to fabricate the waveguide, and hence, less damage on the substrate is expected. A numerical simulation shows that the normalized amplitude contours of the fundamental waveguide mode can be expanded for efficient fiber coupling or condensed for enhancing the electro‐optic effect depending on the refractive index of the loaded strip. The output power profile of the waveguide, detected by a linear array of charge coupled devices, is in good agreement with that calculated numerically. © 1992 John Wiley & Sons, Inc.
Two‐dimensional inner‐product model for auto‐hetero‐associative memory and its new optoelectronic implementation
Authors: Zhang Jiajun , Zhang Li , He Anzhi , Yan Dapeng
Published: July 2007

The associative memory of the two‐dimensional (2‐D) Hopfield model described in terms of inner product is realized by using a multiimaging hybrid system and an incoherent correlation hybrid system, respectively. A new method, in which polarization coding and half wave plate are employed, is proposed to encode the bipolar data in memory masks. Four 8 × 8 images are used in our experiment, and the experimental results agree well with the numerical simulations. On the basis of this, we also present the inner‐product expression of the modified Hopfield model for the heteroassociative memory which can be implemented in the same system described for autoassociation, as long as the first memory mask is changed and the thresholds in the feedback are adjusted accordingly. © 1992 John Wiley & Sons, Inc.
Microstrip spatial filters for the H‐plane pattern control of microstrip antennas
Authors: Bonvin F. , Bokhari S. A. , Zürcher J. F. , Gardiol F. E.
Published: July 2007

A technique for shaping the H‐plane pattern of a microstrip antenna using a passive unequally spaced planar array of printed strips as a superstrate layer is presented. By a proper choice of the number of strips, their widths, and their relative positions, quasiomnidirectional radiation patterns and radiation patterns with a dip on boresight have been realized. A two‐dimensional model for the analysis and design is presented. © 1992 John Wiley & Sons, Inc.
Direct evidence of the quasibound‐state lifetime effect in resonant tunneling from impedance measurements
Authors: Vanbesien O. , Sadaune V. , Lippens D. , Vinter B. , Bois P. , Nagle J.
Published: July 2007

Small‐signal impedance measurements of GaAs/AlGaAs double‐barrier resonant tunneling heterostructures are analyzed in terms of equivalent circuits taking into account the quasibound‐state lifetime. The lifetime values extracted from experiments are in reasonable agreement with those deduced from calculation of quantum transmission probabilities. © 1992 John Wiley & Sons, Inc.
A CAD formula for microstrip dispersion
Authors: Roy Jibendu Sekhar , Jecko Bernard
Published: July 2007

An expression for the effective relative dielectric permittivity of microstrip transmission lines, derived empirically for X‐band of frequency, is proposed for the computer‐aided design (CAD) of micro‐strips in higher microwave frequencies as well, by comparing with other CAD formulas. The accuracy and simplicity of the formula can demand priority in CAD technology. © 1992 John Wiley & Sons, Inc.
Simple expressions for diffraction loss in open resonators
Authors: Arora R. K. , Mongia R. K.
Published: July 2007

In this article simple closed‐form are presented expressions to compute the diffraction loss of open resonators composed of spherical mirrors of circular cross‐section. These expressions, which are based on the numerical results of scalar theory, should be useful in designing mirror size for open resonators. Experiments are conducted at W band to demonstrate the accuracy of the expressions. © 1992 John Wiley & Sons, Inc.