bluuebunny/crossref_metadata_2025 huggingface dataset:
Coaxially driven dielectrically sheathed post in a rectangular waveguide
Authors: Keam R. B. , Williamson A. G.
Published: July 2007

The problem of a coaxially excited dielectrically sheathed hollow post in a rectangular waveguide is analyzed. The approach taken treats the electric field in the gap region as the unknown to be found by the solution of an integral equation. Expressions for current distribution on the interior and exterior surfaces of the post, and the input admittance to the junction, are given. The numerical aspects of the solution are discussed briefly and a comparison of theoretical and experimental results shows the theory to be very accurate. © 1993 John Wiley & sons, Inc.
High‐Q‐factor low dielectric loss inverted microstrip YBa2CU3O7‐δresonator for accurateRscharacterization
Authors: Easwar K. , Sarkar B. K. , Pinto R. , Apte P. R.
Published: July 2007

An accurate measurement of the surface resistanceRsbased on a reduced dielectric loss factor inverted microstrip configuration is reported. The inverted microstrip resonator, with a resonant frequency of 2.5 GHz in S‐band, yields a quality factor of 10,000 at 15 K and 5000 at 77 K. This corresponds toRsvalues of 1 and 26 μΩ at 15 and 77 K, respectively. © 1993 John Wiley & sons, Inc.
On the choice of basis functions in quasistatic spectral‐domain analysis of strip‐line‐like transmission lines
Authors: Gentili G. G. , Macchiarella G.
Published: July 2007

The choice of basis functions in the expansion of charge density using spectral‐domain methods is discussed. It is shown that the simple inclusion of the correct singular behavior of charge density close to the edges of the strip is not sufficient to get accurate results with very few basis functions. For best performance, one should be able to model correctly the first terms of the charge density expansion close to the edge. © 1993 John Wiley & sons, Inc.
Electric surface current model for the analysis of the radiation resistance of a spherical circular microstrip antenna
Authors: Tam W. Y. , Tam S. W. , Luk K. M. , Lai K. Y. A.
Published: July 2007

An approach to the analysis of a spherical circular microstrip antenna which is applicable to a relatively thick substrate is presented. Based on the spectral‐domain Green's function formulation, the effect of the dielectric substrate as well as the spherical ground are incorporated. Numerical results for the radiation resistance agree well with the results using the generalized transmission line model (GTLM), which is accurate for a thin dielectric substrate only. © 1993 John Wiley & sons, Inc.
Mutual impedance between circular microstrip antenna
Authors: Bhattacharjee Partha S.
Published: July 2007

This communication describes a solution to the problem of computing mutual impedance of a one‐dimensional array of circular micro‐strip patches fed by coaxial probes. Some experiments have been conducted for mutual coupling between two circular microstrip antennas in the S band. Theoretical results are in good agreement with the experimental ones. © 1993 John Wiley & sons, Inc.
Application of green's theorem approach to symmetrical right‐angled H‐plane rectangular metallic waveguide bend
Authors: Leong M. S. , Kooi P. S. , Yeo T. S.
Published: July 2007

The Green's theorem approach is applied to analyze the transmission properties of a symmetrical right‐angled H‐plane rectangular metallic waveguide bend. The numerical results obtained have been corroborated by actual experiment and Marcuvitz data. It is found, however, that the method suffers from the limitation that the problem matrix condition number increases rapidly with the number of waveguide modes considered in the field matching. © 1993 John Wiley & sons, Inc.
Sensitivity analysis of tuned front‐end receivers for subcarrier multiplexing systems
Authors: Marti J. , Capmany J. , Marin J.
Published: July 2007

We consider the application of Monte Carlo and shadow methods for sensitivity analysis and optimization of tuned front‐end receivers for suhcarrier multiplexing systems. A second step based on the centering design method is also presented. © 1993 John Wiley & Sons, Inc.
Reflecting mode integrated optical temperature sensor
Authors: Liang J. Y. , Wilson M. G. F.
Published: July 2007

This Letter presents a novel type of integrated optical temperature sensor which is based on a single waveguide with a reflecting mirror at the rear end. The experimental results achieve a half‐wave temperature of 0.14 C and an extinction ratio of 76%. The reflecting mode sensor shows advantages over the Mach‐Zehnder structure in terms of high sensitivity and good extinction ratio. © 1993 John Wiley & Sons, Inc.
Thermal resistance of 1.3μm InGaAsP vertical cavity lasers
Authors: Shimizu M. , Babić D. I. , Dudley J. J. , Jiang W. B. , Bowers J. E.
Published: July 2007

The thermal resistance of 1.3μm InGaAsP vertical cavity lasers is calculated using the finite difference method in cylindrical coordinates. Three etched‐well laser structures are compared and the thermal resistance is calculated for a range of active area diameters and a typical cavity size. Using an InP regrown laser structure appears to be most promising for achieving room‐temperature continuous operation of long‐wavelength vertical cavity lasers. © 1993 John Wiley & Sons, Inc.
Probe impedance measurements for millimeter‐wave integrated horn antennas
Authors: Guo Yong , Chiao Jung‐Chih , Potter Kent A. , Rutledge David B.
Published: July 2007

Integrated‐circuit probe‐excited horn‐antenna arrays made in silicon are well developed. They are a very promising class of antenna arrays for millimeter‐ and submillimeter‐wave applications. Further development of this technology involves integrating mixers and amplifiers into antenna arrays. In an effort to develop an horn‐antenna‐mixer array based on the existing technology, various antenna probes inside the pyramidal horns have been examined on scaled model horns at microwave frequencies. Modeling results and design principles of these antenna probes are presented. © 1993 John Wiley & Sons, Inc.
Study of stacked microstrip phased arrays
Authors: Arts M. J. , Smolders A. B.
Published: July 2007

A study of phased arrays of rectangular stacked microstrip patch antennas is presented. Two theoretical methods are discussed, i. e., a finite array theory and an infinite array theory. Both theories give almost the same results for a 7 × 7 array, except for edge array elements and for large scan angles. Measured coupling coefficients of a 7 × 7 array are compared with calculations and agree fairly well. © 1993 John Wiley & Sons, Inc.
Optical implementation of localized interconnected neural network
Authors: Zhang Li , Zhang Jiajun , He Anzhi , Yan Dapen
Published: July 2007

The localized interconnected neural network (LINN) provides for a smaller interconnection weight matrix (IWM). It is possible to construct a large‐scale optical neural network using commercially available spatial light modulators (SLMs). In this article, optical implementation of one‐dimensional (ID) LINN for associative memory is discussed, in which three optoelectronic architectures are proposed. In the proposed optoelectronic correlation system, the IWM is generated by a TV monitor, while input data are displayed on a liquid crystal television (LCTV). Experimental demonstrations are also provided. © 1993 John Wiley & Sons, Inc.
An efficient analysis of anisotropic multiconductor‐multilayered mics using the spectral‐domain‐block‐transfer‐matrix method
Authors: And Yinchao Chen , Beker Benjamin
Published: July 2007

In this article the spectral‐domain approach and the transfer matrix technique are extended to analyze multilayered‐multiconductor anisotropic microwave and millimeter‐wave integrated circuits. The spectral‐domain formulation only uses two components of the electric field that are tangential to interfaces between adjacent layers. A 2×2 block matrix is defined for every interface to relate the coefficients of the fields in all stratified layers of the guiding structure. The use of the proposed spectral‐domain‐block‐transfer‐matrix method is illustrated for both single and coupled three‐layer bilateral transmission lines. In addition, a detailed material parameter study is performed to examine the effects of individual anisotropic layers on the propagation characteristics of the line. © 1993 John Wiley & Sons, Inc.
Complex propagation constants for nonuniform optical waveguides: Calculations
Authors: Gallawa R. L
Published: July 2007

A method of calculating the complex propagation constant of a planar optical waveguide under very general but weakly guiding conditions is derived. The method, based on Galerkin 's formalism using Hermite‐Gaussian basis functions, allows a nonuniform and complex refractive index profile. The real and imaginary parts of the index are allowed to vary independently and arbitrarily as a function of position. The planar waveguide is used so the results can be compared with exact solutions. The method is more general than this, however, and can be used with any geometry. The results are inherently stationary. © 1993 John Wiley & Sons, Inc.
Optimization of substrate dielectric and mode of microstrip ring antenna for high efficiency and directivity
Authors: Iyer S. M. Vaitheeswaran , Joshi A. W. , Karekar R. N.
Published: July 2007

Theoretical formulation using the Green's function in conjunction with the reflection coefficient matrix approach (instead of potentials) is used for calculations of fields of microstrip ring antennas. Different TM modes are studied using the magnetic cavity wall model for obtaining ring sheet currents. The results show that the ring antenna is superior to disk and rectangular patch antennas and has optimized performance for the TM12 mode, with a substrate dielectric constant of 6 with high gain, broad lobe width and no side lobes. The better performance at higher r may be of importance for array synthesis in MMIC. The theoretical approach used is simpler for calculation and is easily extendable to other situations and higher substrate thicknesses. © 1993 John Wiley & Sons, Inc.
A unidirectionally conducting screen is a super‐brewster screen
Authors: Lakhtakia Akhlesh
Published: July 2007

Expressions for the plane‐wave response of a unidirectionally conducting screen (UCS) embedded in a linear, homogeneous, bianisotropic substance are obtained. The ratio of the complex amplitudes of the two reflected plane waves is shown to be always independent of the ratio of the complex amplitudes of the two incident plane waves; likewise, for the transmitted plane waves. Thus, a UCS is a super‐Brewster screen. © 1993 John Wiley & Sons, Inc.
Mutual coupling in finite‐length thin wire chirostrip antennas
Authors: Pelet Philippe , Engheta Nader
Published: July 2007

Here, we theoretically analyze the mutual coupling between two finite‐length thin wire chirostrip antennas. These antennas are defined as thin wires printed on grounded substrate made of chiral materials which exhibit electromagnetic handedness. Chiral materials are circular polarization (CP) birefringent and are described by the constitutive relations ε and ε with εc μc, and ε as material parameters. Mutual coupling for broadside, collinear, and echelon configurations for these antennas is investigated, and it is shown that introducing chirality in the substrate can, under certain circumstances, modify the mutual coupling between the chirostrip antennas. © 1993 John Wiley & Sons, Inc.
Maxwell‐garnett model for composites of electrically small uniaxial objects
Authors: Weiglhofer W. S. , Lakhtakia A. , Monzon J. C.
Published: July 2007

Composites consisting of randomly dispersed, electrically small, uniaxial inclusions in an isotropic dielectric‐magnetic host material are homogenized in accordance with the Maxwell‐Garnett approach. The inclusions may be wire‐and‐loop models of helices or acicular bianisotropic bodies. Effective constitutive dyadics for the composites are found for various orientational arrangements of the inclusion objects. Furthermore, the inadequacy of current theoretical models for scattering from electrically small metal helices is discussed. © 1993 John Wiley & Sons, Inc.
A recursive aggregation method for the computation of electromagnetic scattering by randomly distributed particles
Authors: Lu Cai‐Cheng , Chew Weng Cho
Published: July 2007

We develop a new algorithm to expedite the matrix‐vector multiplication in using the conjugate gradient method to solve the linear algebraic equation of scattering by a cluster of particles. We compare this method of solving the scattering problem with two other methods. One is our previously developed method, called recursive aggregate T‐matrix method. The second one is the direct use of the conjugate gradient method. Our new method is shown to have reduced computational complexity as well as memory requirement compared to the use of the conjugate gradient directly to solve the linear algebraic equation of scattering. © 1993 John Wiley & Sons, Inc.
Electromagnetic scattering from skew‐symmetric metallic grids
Authors: Christodoulou C. G.
Published: July 2007

In many applications for reflector antennas, the reflector is made from flexible, conducting material. The wires are weaved together, forming a very complex structure to study. So far, these mesh structures have been approximated by rectangular grids. In this study, the mesh geometry is approximated by a skew‐symmetric grid. The FFT‐conjugate gradient method (FFT‐CGM) is employed to solve the problem of scattering from such grids. A convenient unit cell is chosen and utilized to study the effects of skewness on the reflection coefficients and current densities. Calculated values of the reflection coefficient for different angles of incidence for both the bonded and unbonded skewed gratings are presented and discussed. © 1993 John Wiley & Sons, Inc.
A NOTE ON THE TESTING FUNCTIONS USED IN THE METHOD‐OF‐MOMENTS SOLUTION OF THIN‐WIRE ANTENNA PROBLEMS
Authors: Rynne Bryan P.
Published: July 2007

It was observed in an article by Klein and Mittra that when the method of moments is used to solve thin‐wire antenna problems, erroneous, highly oscillatory solutions can occur when certain wide‐pulse testing functions are used. This article presents a possible explanation of the occurrence of these erroneous solutions. © 1993 John Wiley & Sons, Inc.
A note on the analysis of nonreciprocal phase shifters by the spectral index method
Authors: Shamonin M. , Erdmann A. , Hertel P. , Dötsch H.
Published: July 2007

The spectral index method is applied to nonreciprocal quasi‐TM mode phase shifters based on rib‐type waveguide structures. It compares well with the much slower finite‐difference method. © 1993 John Wiley & Sons, Inc.
An optical fuzzy matrix‐vector processor for implementing fuzzy associative memory
Authors: Zhang Shuqun , Lin Senmao , Chen Caisheng
Published: July 2007

An optical fuzzy matrix‐vector processor is designed to implement fuzzy associative memory. By spatial encoding and thresholding operation, the two basic operations needed by fuzzy associative memory, maximization and minimization, are realized optically. Experimental results are given as well. © 1993 John Wiley & Sons, Inc.
Wave propagation along a closed rectangular chirowaveguide
Authors: Cory H.
Published: July 2007

Wave propagation along a closed rectangular chirowaveguide is studied. The coupled differential equations governing the transverse variation of the transverse components of the electric field have been established and a zero‐order solution has been proposed. This solution provides the corresponding β ‐ ω diagram, whose characteristics are investigated. © 1993 John Wiley & Sons, Inc.
Hybrid analytical technique for waveguide coupling by means of apertures or slots
Authors: Sangster A. J. , Wang Hanyang
Published: July 2007

A hybrid technique which combines the finite element method with the moment method is proposed for the analysis of waveguide coupling by means of irregular apertures or slots. An example is given to verify the validity of the hybrid technique, while the numerical predictions are supported by results obtained using conventional moment methods. © 1993 John Wiley & Sons, Inc.
Polarization properties of plane waves in transversely bianisotropic uniaxial medium
Authors: Koivisto Paivi
Published: July 2007

Transversely bianisotropic uniaxial medium can be constructed by mixing metal helices into anisotropic host medium in such a way that the axes of the helices are perpendicular to a fixed direction in space but randomly oriented in the transverse plane. In general, the host medium can be either reciprocal or nonreciprocal. Eigenwaves, expressions for the plane‐wave fields, and polarization behavior are derived for the plane wave propagating perpendicular to the symmetry axis. The polarization properties of chiral and reciprocal transversely bianisotropic uniaxial medium are studied in order to find a suitable parameter combination for a polarization transformer. Several numerical examples are given to illustrate the propagation properties of the transversely bianisotropic uniaxial medium.
An integrated optical fabry‐perot modulator in LiNbO3
Authors: Liang Jia Yi , Wilson Mike G. F.
Published: July 2007

This letter presents a novel approach to low driving power optical modulation by using a waveguide resonator. A modified technique called etched lift off is used for electrode deposition. A modulation bandwidth of 1 GHz at 1.15 μm was achieved by a driving voltage of 1.5 V for 84% modulation.
A vector finite‐element analysis of complex modes in shielded microstrip lines
Authors: Alam Md. Shah , Hirayama Koichi , Hayashi Yoshio , Koshiba Masanori
Published: July 2007

The finite‐element method is employed to carry out the numerical analysis of complex modes, as well as propagating and evanescent modes in lossless shielded microstrip lines. In this finite‐element calculation, the triangular mixed element is used. The possible electric field distributions of the complex modes are also presented.
Optical‐fiber digital PPM systems employing PIN‐FET receivers
Authors: Cryan R. A.
Published: July 2007

An analysis is presented for the optimum detection of digital pulse position modulation employing PIN‐FET receivers. The results demonstrate a sensitivity improvement of 7.2 dB over an equivalent PCM system when operating at a bit rate of 50 Mbits/s. Calculations have also been performed for a causal approximation to the optimum receiver and it is shown that this leads to only a 0.5‐dB reduction in sensitivity. Finally, receiver design implications are examined for higher bit‐rate operation and the results obtained for a 565‐Mbit/s system demonstrate an improvement of 6 dB over PCM.
Microstrip antenna top‐loaded by a dielectric resonator
Authors: Yung Edward K. N. , Lee Wilson W. S. , Luk K. M.
Published: July 2007

A cylindrical dielectric resonator is placed on top of a circular microstrip antenna. The resonant frequency and the input impedance of the antenna are altered. The bandwidth of the microstrip antenna is nearly doubled by the top loading. These changes are dependent on the displacement between the resonator and the patch. © 1994 John Wiley & Sons, Inc.
New photonic device integration by selective‐area MOVPE and its application to optical modulator/laser integration (invited paper)
Authors: Aoki M. , Suzuki M. , Taniwatari T. , Sano H. , Kawano T.
Published: July 2007

This article describes a novel fabrication technology for photonic integrated circuits (PICs) that easily produces a smooth and high‐quality waveguide coupling between interconnected guided‐wave elements. This technique is based on the in‐plane quantum energy control selective area metal‐organic vapor‐phase epitaxy of multiple‐quantum‐well (MQW) structures. Good local quantum energy control over a very wide range is shown for simultaneously grown MQW crystals. Moreover, the crystal quality, well/barrier heterointerface, and flatness and uniformity of these selectively grown MQW crystals are bound to be as good as those of normally grown crystals. This technique is applied to an electroabsorption modulator/distributed feedback laser integrated device. Superior device performance, including a low threshold and high‐efficiency lasing properties, as well as high‐speed, low‐drive‐voltage, and low‐chirp modulator characteristics are attained due to improved optical coupling, easy fabrication, and sufficient crystal quality of selectively grown MQW structures. 2.5 Gbit/s penalty‐free data transmission is demonstrated over an 80‐km normal single‐mode fiber, which, combined with long‐term device reliability, makes this integration technique more attractive for practical fabrication of semiconductor PICs. © 1994 John Wiley & Sons, Inc.
Fabrication of lithium niobate optical channel waveguides by nickel indiffusion
Authors: Wei Pei‐Kuen , Wang Way‐Seen
Published: July 2007

Singly and randomly polarized nickel‐indiffused waveguides in lithium niobate were found when fabricated under different diffusion conditions. The randomly polarized waveguides are verified to have the advantages of no outdiffusion guiding layer and low diffusion temperatures. The linear electro‐optic coefficient was found only slightly decreased when checked using a Mach‐Zehnder interferometer. © 1994 John Wiley & Sons, Inc.
Design and performance of a microstrip flat reflect‐array antenna
Authors: Javor Ronald D. , Wu Xiao‐Dong , Chang Kai
Published: July 2007

A simple method was used to design a microstrip flat reflect‐array antenna. An X‐band, 12‐element array of rectangular microstrip patches was demonstrated for the first time to reflect the main beam 20 degrees off broadside. A redirection efficiency of 65.8% was observed. © 1994 John Wiley & Sons, Inc.
Decoupled planar dipoles for subsurface cw interface radar
Authors: Park Dong‐Kook , Ra Jung‐Woong
Published: July 2007

Wideband decoupled planar dipoles are suggested for a subsurface transmitting and receiving antenna. Design parameters of the conductor‐backed cut‐off dielectric waveguide containing two planar dipoles above a lossy half space are suggested, and a bandwidth of more than 5 to 1, decoupling of ‐90 dB for about one wavelength separation are obtained. © 1994 John Wiley & Sons, Inc.
A simple new technique for the implementation of vertical currents into the SDA
Authors: John A. , Jansen R. H.
Published: July 2007

This contribution presents a new technique for implementing vertical currents into the spectral‐domain approach. Previously published methods require a drastic increase of spatial resolution and thus CPU time when adding vertical elements. Our technique avoids this by using partial Galerkin solutions without vertical expansion functions and by applying continuity conditions. © 1994 John Wiley & Sons, Inc.
A simple model for the gaas hbt high‐frequency performance under optical illumination
Authors: De Salles Alvaro A. , Hackbart Anelise S. , Spalding Luiz N.
Published: July 2007

A simple theory and a model for the GaAs heterojunction bipolar transistor's (HBT's) high‐frequency performance under optical illumination are described. It is assumed that the major contribution to the photocurrent in the HBT is due to the photovoltaic effect in the base‐collector depletion region. Estimations using PSPICE circuit simulator show photoresponse cutoff frequencies of several tens of gigahertz when some HBT parameters are adequately designed. © 1994 John Wiley & Sons, Inc.
Dual polarized, single‐ and double‐layer strip‐slot‐foam inverted patch (ssfip) antennas
Authors: Zürcher J‐F. , Gay‐Balmaz Ph. , Hall R. C. , Kolb S.
Published: July 2007

A new way of feeding an SSFIP antenna to obtain two orthogonal linear or two circular (RHCP/LHCP) polarizations is presented. The advantages of the method are its simplicity, a perfect symmetry of the structure and of the pattern, and an excellent decoupling between input ports. The enhanced element retains the desirable properties of conventional SSFIP elements: wide bandwidth, low cost, robustness, and low thickness and weight. © 1994 John Wiley & Sons, Inc.
Frequency dependence of the rcs of an arbitrarily shaped simple scatterer
Authors: Zhendong Shi , Hongwei Liu , Pu Tang
Published: July 2007

The frequency dependence of the RCS of an arbitrarily shaped simple scatterer is given, based on which model measurement of RCS can be made with testing equipment unchanged, even though the size of the model is sometimes scaled down with respect to that of the prototype. © 1994 John Wiley & Sons, Inc.
Multioutput logical processor using joint transform correlator
Authors: Alam M. S. , Karim M. A.
Published: July 2007

Joint transform correlation is applied for real‐time optical implementation of logical processor. As an example, a 4–to–2 line encoder is considered. Simulation results for both sequential and parallel implementation techniques are presented. © 1994 John Wiley & Sons, Inc.
A novel highly selective and tunable optical bandpass filter using a fiber grating and a fiber fabry‐perot
Authors: Capmany J. , Laming R. I. , Payne D. N.
Published: July 2007

We present a novel continuously tunable optical bandpass filter composed of a FFP, on an optical circulator, and a fiber grating. The structure combines the high selectivity of the FFT and the bandpass nature of the fiber grating. © 1994 John Wiley & Sons, Inc.
A novel short‐range anticollision radar
Authors: Benlarbi A. , Leroy Y.
Published: July 2007

An original short‐range low‐cost anticollision CW microwave sensor is based on interferometry. It produces triggering signals when a reflective surface approaches the system and reaches predefined distances. In the examples described here, these distances are between several decimeters and a few meters. © 1994 John Wiley & Sons, Inc.
Variable gain amplifier with traveling wave structure
Authors: Floc'h J. M. , Desclos L.
Published: July 2007

This article presents a technique based on distributed structure in order to make a variable gain amplifier. A method to achieve a large dynamic gain range over a large frequency bandwidth is shown. The steps of design are presented and highlight a simple methodology. A two‐stage GCA (gain‐controlled amplifier) over a 2–12–GHz frequency bandwidth is shown and theoretical investigations for more complicated one are presented. © 1994 John Wiley & Sons, Inc.
Cad formulas for resonant frequencies of tm11 mode of circular patch antenna with or without superstrate
Authors: Lee Kai‐Fong , Fan Zhibo
Published: July 2007

Curve‐fitting formulas based on moment‐method results are presented for the resonant frequency of the TM11 mode of a coaxially fed circular patch antenna with or without superstrate. The formulas can be used for a wide range of substrate and superstrate thicknesses and permittivities. Results predicted by these computer‐aided design formulas agree well with moment‐method results and with measurement. © 1994 John Wiley & Sons, Inc.
Modal control of reflector surfaces using far‐field power measurements
Authors: Silverberg Larry , Washington Gregory
Published: July 2007

The far‐field power received from a transmitting reflector antenna was maximized by varying the shape of the reflector surface. The shape of the reflector surface was controlled by a modal autofocus method which deformed the membrane sequentially into the full range of its natural modes of vibrations. The convergence time was shown to depend on the scan time associated with a natural mode of vibration, the number of cycles the algorithm underwent before convergence, and the desired resolution of the surface shape. A numerical example illustrates the method presented. © 1994 John Wiley & Sons, Inc.
A new broadband circular patch antenna
Authors: Dey Supriyo , Aanandan C. K. , Mohanan P. , Nair K. G.
Published: July 2007

A simple technique to improve the impedance bandwidth of a circular microstrip patch antenna using two sectoral slots is proposed. Using this design more than 5% impedance bandwidth is obtained. The added advantage of this new antenna is that it can be fed by a 50‐ω microstrip line. © 1994 John Wiley & Sons, Inc.
Power added efficiency and gain improvement in mesfet amplifiers using an active harmonic loading technique
Authors: Ghannouchi F. M. , Beauregard F. , Kouki A. B.
Published: July 2007

A six‐port‐based multiharmonic load‐pull setup is used to characterize a medium‐power MESFET transistor for the design of microwave amplifiers. Complete load‐pull measurements at the fundamental (1.7 GHz) and the second harmonic (3.4 GHz) are obtained for two bias points in class A and AB operation. It is shown that the power gain and the power added efficiency can vary up 0.6 dB and 6%, respectively, as the phase of the second harmonic load is changed. © 1994 John Wiley & Sons, Inc.
Bistatic scattering width evaluation for nonlinear isotropic infinite circular cylinders
Authors: Caorsi S. , Massa A. , Pastorino M.
Published: July 2007

This Letter presents an approximate solution to the problem of computing the bistatic scattering width (BSW) for nonlinear, isotropic, infinite, circular cylinders illuminated by TM waves. An iterative solution is developed for weak nonlinearities of the Kerr type, within some approximations for the internal field. Some preliminary results are reported, which show the effects of some of the quantities involved in the nonlinear process. © 1994 John Wiley & Sons, Inc.
Direct electro‐optic modulation of lightwaves in fiber
Authors: Agili Sedig S. , Koryu Ishii T.
Published: July 2007

An audio modulating electric field is applied to a small section at one end of a relatively long optical fiber. When a He‐He laser beam is guided through the optical fiber, the lightwaves are directly modulated by the modulating electric field and detected at the other end of the fiber. © 1994 John Wiley & Sons, Inc.
An active load‐pull measurement system using two six‐port reflectometers
Authors: Deshours F. , Bergeault E. , Jallet L. , Huyart B.
Published: July 2007

This article presents a microwave active Load‐Pull measurement system, using two wide‐band six‐port junctions in order to have nonlinear characterization of power transistors. Experimental results performed on a 900‐μm MESFET for different operating classes are reported and discussed. © 1994 John Wiley & Sons, Inc.
Interference imagery: Variable lateral shear
Authors: Tepichín Eduardo , Ramírez Gustavo
Published: July 2007

We present an optical setup that produces simultaneously spatially filtered images and lateral‐shear interferometry. Our device uses two gratings. One grating is a computer‐generated hologram that acts as a spatial filter. © 1994 John Wiley & Sons, Inc.
Microwave correlation temperature of an isothermal lossy material
Authors: Waro Philippe , Leroy Yves
Published: July 2007

A microwave correlator is connected to the inputs of an isothermal passive two port made of two antennas placed on both sides of an isothermal lossy material. We verify in which way the output signal of the correlator depends on the scattering matrix of the two port, on the temperature and reference temperature of the radiometer, and on the delay time of the correlator. © 1994 John Wiley & Sons, Inc.
A new compact ring hybrid and its use in a singly balanced mixer
Authors: Nguyen Cam
Published: July 2007

A new miniaturized 180—degree ring hybrid was developed. Its circumference is only one wavelength, as compared to the one and a half wavelengths of the conventional ring hybrid. Simple formulas for its scattering (S) parameters along with design information were derived. The obtained S parameters and measured performance of the ring at X band (8–12 GHz) confirm the 180—degree hybrid feature. A microstrip singly balanced diode mixer using the new ring was also developed at X band band with less than 6.5 dB of conversion loss and more than 25 dB of LO‐rf isolation. © 1994 John Wiley & Sons, Inc.
Transverse conduction current and radiation pattern of an arbitrarily shaped symmetrical patch antenna coupled with a director
Authors: Aksas R. , Vorst A. Vander
Published: July 2007

We describe a new model that yields the transverse component of the conduction current as well as the radiation pattern of the cross‐polar component of a multilayered radiating structure. The structure is com‐posed of a microstrip patch antenna with an arbitrary shape, associated with a director having the same shape and the same axes of symmetry. Losses, dispersion, strip thickness and roughness, and edge diffraction are taken into account. Calculated results agree very well with experimental results previously obtained for a circular shape. © 1994 John Wiley & Sons, Inc.
Propagation‐loss prediction for numerical terrain model using uniform theory of diffraction
Authors: Legendre J. F. , Chassay G.
Published: July 2007

In this article, the uniform theory of diffraction (UTD) is applied to the problem of predicting propagation loss in the frequency range of UHF‐VHF using a numerical terrain model. A ray optical model with automatic ray‐tracing algorithm for a two‐dimensional piecewise‐linear terrain profile and field computation method are presented in this contribution. The predicted results are compared with measured data and with the results of other propagation prediction models. © 1994 John Wiley & Sons, Inc.
Effects of superstrate loading on the mutual coupling between rectangular microstrip antennas
Authors: Ke Shyh‐Yeong , Wong Kin‐Lu
Published: July 2007

The mutual coupling of rectangular microstrip antennas covered with a lossy or lossless dielectric superstate is analyzed by using a full‐wave approach. Numerical results are obtained by using a moment‐method calculation. Both the E‐ and H‐plane coupling cases are studied. Results indicate that the level of the coupling between microstrip antennas due to the superstate thickness variation is small. However, with the introduction of loss into the superstate layer, a noticeable reduction in the coupling level can be observed. © 1994 John Wiley & Sons, Inc.
Mode characteristics in a lossy parallel‐plate uniaxial chiro‐omega waveguide
Authors: Wenyan Yin , Wei Wan , Xiaowei Sun
Published: July 2007

The dispersion characteristics of propagating modes in a lossy parallel‐plate uniaxial chiro‐omega waveguide are examined, and numerical results are presented to show the influences of bianisotropy, chirality, and omega parameter on the propagation constant and attenuation rate of different hybrid modes. Furthermore, the field distributions of one‐ and three‐order modes are demonstrated, and the lossy effect is taken into consideration. © 1994 John Wiley & Sons, Inc.
Effect of dielectric coatings on parabolic reflector antenna performance
Authors: Lo K. W. , Bird T. S.
Published: July 2007

The effect of a dielectric coating on the gain, co‐polar radiation pattern, and cross‐polarization level of a linearly polarized parabolic reflector antenna is investigated for both dry and wet surface conditions using a physical optics analysis of the equivalent surface currents. By choosing the correct thickness, the effect of a dielectric coating can be minimized, and, at the same time, an equivalent metal‐reflector representation shows that the antenna gain is less sensitive to the coating surface accuracy.
Solving microstrip discontinuities with a combined mode‐matching and method‐of‐lines procedure
Authors: Meyer P.
Published: July 2007

A novel technique combining two‐dimensional method‐of‐lines (MOL) analysis with a mode‐matching procedure to analyze microstrip step discontinuties is presented. The MOL is used to calculate the propagation constants and field distributions at discrete points for a number of modes on both sides of a discontinuity. These modes are matched using a modified discrete mode‐matching procedure to produce a generalized S‐parameter description of the discontinuity. The method uses memory sparingly. Results for two microstrip steps are presented.
Analysis of a broadband slot‐coupled dielectric‐coated hemispherical dielectric resonator antenna
Authors: Chen Nan‐Cheng , Su Hsin‐Cheng , Wong Kin‐Lu , Leung Kwok‐Wa
Published: July 2007

Dielectric‐coated hemispherical dielectric resonator (DR) antennas fed by a microstrip line through a coupling slot are analyzed. The broadside TE111 mode is studied, and the reciprocity theorem is applied in this analysis. In this case the dielectric‐coated DR antenna can be viewed as a series load at the slot position as seen by the microstrip line. The impedance of this series load is calculated by using a Green's‐function formulation, and the input impedance of the slot‐coupled DR antenna can then be obtained using transmission‐line theory. Numerical results for the input impedance are calculated and presented, and the antenna bandwidth is discussed. It is observed that the antenna bandwidth of a dielectric‐coated DR antenna can be as high as two times that of a DR antenna without a coating.
W‐band dual‐frequency circulators
Authors: Dou W. B. , Sun Z. L.
Published: July 2007

W‐band dual‐frequency circulators have been develoved. The dual‐frequency circulator resulting from a dual higher‐order mode is used as stated in [3, 4]. The calculated properties of the dual modes, especially the mode‐change frequency point between the dual higher‐order modes, have been verified experimentally.
Influence of the conducting support on the coupling between two microstrip antennas
Authors: Aubreton Th. , Dufrane Ph. , Vaudon P. , Jecko B.
Published: July 2007

In this article we show that, when the direct coupling between antennas is very weak, the limited support, on which two microstrip patches lie, can be the source of an important parasitic coupling. We consider also the influence of the dimensions and the shape of this support. The theoretical results and the measurements are in a very good agreement in the validity domain of the method.
Scattering of electromagnetic waves by vegetation based on the wave approach and the stochastic lindenmayer system
Authors: Chen Zhengxiao , Tsang Leung , Zhang Guifu
Published: July 2007

Wave scattering from the trees generated by the stochastic Lindenmayer system is studied by Monte Carlo simulations in this article. The scattering coefficients are calculated in three ways: wave approach, tree‐independent scattering, and independent scattering. It shows that the results of tree‐independent scattering agree well with that of wave approach for medium to high frequency. However, independent scattering is not a good approximation except for very high frequency.
Simple closed‐form expressions for microstrip green's functions in a magneto‐dielectric substrate
Authors: Hoorfar Ahmad
Published: July 2007

By invoking a thin substrate approximation, accurate spatial‐domain expressions for the Green's functions, G, and Gm, of microstrip structures in a magneto‐dielectric substrate are derived. The expression for Gm is given in terms of a quasidynamic solution corresponding to a point source and its partial images, while that of Ge is derived in terms of a quasidynamic contribution plus a correction term. It is demonstrated that the addition of the correction term is needed in order to accurately calculate Ge in the near field.
A comparison of two FFT‐based methods for dielectric scattering problems
Authors: Tran T. V. , McCowen A.
Published: July 2007

The performance of two FFT‐based methods for solving dielectric scattering problems is investigated. The first method is associated with van den Berg's integrated‐squared‐error algorithm, where the variational basis function is based on a generalized Neumann series (GNS) expansion of the inverse of the defining integral operator. The second method is the biconjugate‐gradient FFT (Bi‐CGFFT) for symmetric indefinite systems. Both methods are applied to a variety of dielectric problems encompassing both homogeneous and inhomogeneous material compositions in twoand three‐dimensional spaces. Particular emphasis is placed on the identification of the class of problems that yield nonconvergence for the Bi‐CGFFT and the alleviation of this undesirable behavior.
Analytic study of mode locking with a nonlinear mirror
Authors: Bai Yingxin , Zhang Zhuhong , Fan Dianyuan , Wang Zhijiang , Zhang Guoqing
Published: July 2007

In the steady state, a simple mode‐locking equation including the gain saturation is derived for a mode‐locked laser with a nonlinear mirror. Its analytic solution and mode‐locking conditions are obtained. Ignoring the gain saturation, the analytic pulse width is very close to the numerical results.
Self‐programming optical parallel logic
Authors: Zhang Siming , Shao Lan , Liu Liren
Published: July 2007

Based on dual‐rail spatial coding, in this article a self‐programming optical logic concept is proposed. The self‐programming is formulated by different coding of input images. Thus all 16 binary logic operations can be realized optically in parallel. Experimental results are demonstrated.
A microstrip antenna on a conical surface operating in the TM10 mode
Authors: Barbosa Wagner Gomes , Giarola Attílio José
Published: July 2007

A theoretical development for the analysis of a microstrip antenna on a conical surface operating in the TM10 mode is described here. It consists of using the cavity model with magnetic side walls for the calculation of the resonant frequency and input impedance. The dyadic Green's‐function formulation is used for the calculation of the radiated far fields. Particular antennas are examined and numerical results are shown for the TM10 mode.
A semiglobal radiation boundary condition for the finite‐difference‐time‐domain method
Authors: De Moerloose Jan , De Zutter Daniel
Published: July 2007

In the analysis of antennas and scattering problems by the finite‐difference‐time‐domain (FDTD) method, the dimensions of the problem space are primarily determined by the quality of the radiation boundary condition (RBC) that is used to truncate the computational grid. The performance of the recently proposed higher‐order boundary conditions in cases of practical importance is often worse than the standard Mur‐second‐order condition. In the present article we will show that the reason for this unexpected result is the inability of this type of one‐way wave equation to deal with the evanescent or inhomogeneous plane‐wave part of the field. On the basis of this consideration we have constructed a new semiglobal operator that does have the required property. By combining this operator with the unusual Mur‐second‐order condition one arrives at an RBC with a much better performance. The novel RBC can also be used to analyze static problems.
Polarization‐optical morphological processor with programmable structure elements
Authors: Peng Haifeng , Liu Liren , Yin Yaozu , Wang Zhijiang
Published: July 2007

Based on programmable polarization‐optical neighborhood interconnection, which is a stacked integration of rotatable crystal plates for beam splitting the controllable wave plates for polarization direction controlling, a kind of morphological processor with real‐time programmable structure elements is developed. It is compact in structure and effective as well as stable in performance.
Electromagnetic wave propagation in a chiral‐material‐filled rectangular waveguide
Authors: Samant Abhay R. , Whites Keith W.
Published: July 2007

The analysis of wave propagation in a chiral‐filled rectangular waveguide is presented. The validity of our formulation is established and hence corrects a statement in the literature regarding the longitudinal component of the magnetic field at the four corners of the chiral waveguide. Using this formulation and a finite‐difference numerical method, some of the salient features of this device are described.
Nonlinear performance of a reflective fiber‐optic mode converter
Authors: Shi Chao‐Xiang
Published: July 2007

The optical bistability in a nonlinear fiber‐optic LP01 mode converter by a reflective fiber grating is theoretically investigated. Both the transmissive and reflective properties of the device are analyzed. The output‐versus‐input function of the device exhibits the optical bistability property. The switching power and the bistable hysteresis are also discussed. In addition, a comparison between the nonlinearly reflective mode converter (LP01 ↔ LP02) and the nonlinear fiber Bragg grating reflector (i.e., LP01 and counterpropagating LP01 modes) is also presented. Our results show that the former has much lower switching power than the latter.
Surface‐mode suppression in a thick microstrip antenna by parasitic elements
Authors: Lee Choon Sae , Nalbandian Vahakn , Schwering Felix
Published: July 2007

Reduction of the surface‐wave excitation is achieved by placing parasitic elements next to the radiating edges of a rectangular microstrip antenna. A new experimental technique is introduced to measure the effect of the parasitic strips in reducing the surface‐wave excitation.
An indium‐phosphide self‐oscillating mixer for a 90‐GHz millimeter‐wave receiver application
Authors: Gund C. F. , Lazarus M. J.
Published: July 2007

Indium‐phosphide Gunn diodes are applied as self‐oscillating mixers at frequencies in the region of 90 GHz. Sensitivities for signal equals noise are = ‐80 dBm (10 pW) for 48‐MHz bandwidth of i.f. A mathematical theory using the electron velocity‐field curve provides a good prediction of the conversion efficiency.
Asymptotic methods for the analysis of wave propagation in nonlinear, lossless transmission lines and equivalent circuits
Authors: Ramos J. I.
Published: July 2007

Perturbation methods are employed to determine the small‐signal behavior of an LC‐ladder nonlinear, lossless transmission line. It is shown that a straightforward, regular perturbation analysis results in nonuniformly valid expansions, which can be rendered uniformly valid by stretching the time variable. Perturbation methods are also used to show that, when dispersion effects are accounted for, solitons may propagate along the nonlinear, lossless transmission line. The dispersion characteristics of some equivalent circuits derived from a lossless transmission line are also analyzed. © 1995 John Wiley & Sons. Inc.
Analysis of soliton propagation in an optical fiber using a fourier‐series approach
Authors: Ghafouri‐Shiraz H. , Shum P.
Published: July 2007

A novel technique that is based on a Fourier‐series approach has been proposed to analyze the propagation behavior of solitons in an optical fiber. In the analysis both the fiber loss and the third‐order dispersion have been considered. The results compare well with the commonly used split‐step Fourier method [1]–[3]. © 1995 John Wiley & Sons. Inc.
2D microwave imaging using TLS‐ESPRIT with matrix enhancement
Authors: van der Merwe A. , Odendaal J. W. , Botha E. C.
Published: July 2007

In this article TLS‐ESPRIT [1] will be used to generate two‐dimensional high‐resolution microwave images. To enable the utilization of the 1D algorithm, a two‐dimensional data matrix is decoupled into two one‐dimensional sequences by forming an enhanced data matrix [2]. Pairing of the two 1D estimates is also addressed. To demonstrate the performance of the 2D algorithm, a microwave image was generated for a target measured in a compact range. © 1995 John Wiley & Sons. Inc.
Bandpass/bandstop filter design in circular waveguide
Authors: Clark P. R. , James G. L.
Published: July 2007

We show that a multiiris bandpass filter used in conjunction with a ring‐loaded slot bandstop filter in circular waveguide exhibits a considerably extended stop band with high localized attenuation. The results of an accurate analysis of the complete filter give exceptionally good agreement with measured data. © 1995 John Wiley & Sons. Inc.
Characteristic impedance of quadruple‐ridged square waveguides
Authors: Garb Khona , Kastner Raphael
Published: July 2007

The characteristic impedance of the fundamental mode in a quadruple‐ridged waveguide is computed using the finite‐element method. The method is validated by comparison with available results for double‐ridged waveguides, and results for quadruple‐ridged waveguides are given for possible use in the design process of quadruple‐ridged waveguides. © 1995 John Wiley & Sons. Inc.