bluuebunny/crossref_metadata_2025 huggingface dataset:
Low‐impedance matching: The straight stub solution
Authors: Giannini F. , Bartolucci G. , Ruggieri M.
Published: July 2007

The requirement of low impedances in most integrated circuits is solved through the use of straight stubs, treating them as one‐dimensional structures.

The inadequacy of that approach can be overcome by adopting a complete modal theory—and the corresponding synthesis tools—developed to characterize those electromagnetic aspects deriving from the “planarity” of the structure.

The simulations performed adopting both commercial CAD packages and the modal approach have been compared with some experiments and the need for a better characterization for the presently available cross‐junction element models has been pointed out.
Interferometric waveguide modulator with polarization‐independent operation
Authors: Xue‐Feng Huang , Guo‐Xian Yu , Hai‐Ting Zhang
Published: July 2007

A Ti: NiNbO3 polarization‐independent modulator is described, which has two sets of electrodes with approximately equal applied voltages. The drive voltages of TE and TM mode at 0.633 μm are about 15 and 11 V, respectively, with above 95% modulation.
Local reflected millimeter wave power from moving strip illuminated semiconductor panel
Authors: Rahnavard M. H.
Published: July 2007

Moving spot illuminated semiconductor panels are used as millimeter wave image converters. To determine the performance of this system, knowledge of the response of illuminated semiconductor panels is required. In this paper local reflected millimeter power from moving strip illuminated semiconductor panels as a function of scanning velocity, width of the strip, time and so forth, is studied.
Scattering of a tem wave from a time varying SLAB
Authors: Elcrat Alan R. , Foster John D. , Walsh John L.
Published: July 2007

A finite difference method based on characteristic coordinates is applied to Maxwell's equations for scattering of a TEM wave from an infinite slab. The electric properties of the slab are varied with time, and if the permittivity oscillates with high frequency, a resonant type phenomena is observed.
A novel phase‐noise and polarization fluctuations compensating coherent optical system
Authors: Betti S. , Curti F. , de Marchis G. , Iannone E.
Published: July 2007

A novel coherent optical system is proposed that is independent of the received state of polarization and widely insensitive to phase‐noise. It is based on transmission of the phase‐modulated signal and a reference carrier on two orthogonal polarizations and that makes feasible PSK heterodyne systems with phase‐noise affected sources with less than 3 dB penalty.
Scattering by a conformal array of metallic patches
Authors: Ko Wai L. , Mittra Raj
Published: July 2007

The scattering characteristics of metallic patches arranged on a parabolic cylindrical surface are investigated. The induced surface current on each patch is identified as the current induced on the center patch of a planar array, which is tangent to the parabolic cylindrical surface at the patch. Each of these planar‐array problems is solved by the spectral‐Galerkin method. The scattering pattern from the conformal array is obtained by superposition.
Millimeter‐wave in0.17Ga0.83as power mesfets on GaAs(100) substrates
Authors: Shih H. D. , Kim B. , Bradshaw K. , Tserng H. Q. , Wurtele M. , Duncan W. M. , Moore T. M.
Published: July 2007

In0.17Ga0.83As MESFETs were grown on GaAs(100) substrates by molecular beam epitaxy (MBE). The structure comprised an undoped, In0.17Ga0.83As buffer layer grown directly on GaAs and an In0.17Ga0.83As active layer doped to 5 × 10+ 17cm−3. The defect structure was characterized by cathodoluminescence (CL) in a scanning electron microscope. FETs with 0.25‐μm gate length and 50‐μm gate width were fabricated using a standard processing technique. Excellent dc and microwave performance characteristics were obtained. The best device showed a transconductance (gm) of 400 mS / mm and a current‐gain cutoff frequency (fT) of 75 GHz. At 60 GHz, it delivered a power density of 0.50 W / mm with a gain of 4 dB and a power‐added efficiency of 20%, indicating its superior performance over a standard AIGaAs / GaAs HEMT.
Optically excited microwave ring resonators in gallium arsenide
Authors: McGregor Douglas S. , Park Chang Soo , Weichold Mark H. , Taylor Henry F. , Chang Kai
Published: July 2007

Microstrip ring resonators with fundamental frequencies near 3.5 GHz have been fabricated in semi‐insulating GaAs using an electroplating technique for conductor deposition. Test signals were coupled into the resonators by focusing modulated light into a photoconductive microstripline gap. Loaded Q‐factors measured for one of the rings with optical excitation ranged from 54 at the fundamental frequency to 103 at the third harmonic.
Simulation of coupling efficiency between a laser diode and a single‐mode fiber with microlens end
Authors: Ghafoori‐Shiraz H. , Kotsas A. , Maclean T. S. M.
Published: July 2007

A microlens fabricated on the end of a single‐mode fiber (SMF) can increase the coupling efficiency to laser diodes (LDs). A simulation of microlens formation and an analysis of the resulting coupling efficiency have been performed. The results are in good agreement with data obtained experimentally.
Performance criteria for resonant tunneling diodes as millimeter‐wave power sources
Authors: Mehdi I. , Haddad G. I. , Mains R. K.
Published: July 2007

A figure‐of‐merit expression is derived for resonant tunneling diodes being used as millimeter‐wave sources. It is found that for very high‐frequency applications the most important parameter is the ratio of the peak current to the device capacitance. Results for lattice‐matched and pseudomorphic InP‐based resonant tunneling structures that have a high figure‐of‐merit are presented.
Coherent optical system based on polarization modulation and stokes parameters differential detection tailored for lan application
Authors: Betti S. , Curti F. , de Marchis G. , Lannone E.
Published: July 2007

A novel coherent optical receiver, suitable for LAN applications, is proposed. It is based on Stokes parameters detection and is insensitive to the instantaneous polarization state using a new decision criterion. Moreover, it is widely tolerant to laser phase noise and allows efficient utilization of channel bandwidth.
Transition loss in bent single‐mode optical fibers
Authors: Yamauchi Junji , Nakano Hisamatsu
Published: July 2007

The transition loss in bent fibers is numerically investigated using the phase constant and deformed field obtained by a perturbation method. It is demonstrated that the transition loss is reduced by offsetting the fiber axis. Calculation of the first moment of the transverse field distribution gives an optimum offset value.
Local field analysis of bent optical waveguides
Authors: Cheng Yuehua , Lin Weigan
Published: July 2007

The scalar local field equations are derived from the Maxwell's equation in a bent local coordinate system, and the field transformation function for the TM (or the x‐polarized) modes in our recent papers is corrected as well. It is found that no pure geometry birefringence can be produced if the gradient‐index term of local field equations is neglected when the waveguide we considered is weakly guiding.
symbolic logic processor using cascaded liquid crystal televisions (LCTVs)
Authors: Yu Francis T. S. , Jin Yong , Zhang Chenhua
Published: July 2007

A shadow casting optical logic array processor using cascaded programmable liquid crystal televisions (LCTVs) is described. We have shown that the 16 basic logic operations can be easily achieved with this technique. A technique of performing two‐level logic function using a modified version of this proposed architectures is also given. We have shown that any two‐level logic function can be performed with this technique. The experimental demonstrations of this optical symbolic logic processor are also provided.
New design of flat gain and wideband field effect structure
Authors: Byl Christophe , Crosnier Yves
Published: July 2007

This paper provides a new possibility of realizing in chip form wideband amplifiers with simple wide gate field effect structures, by taking advantage of especially designed electrode terminations to overcome inherent traveling wave losses. Demonstration of these properties is performed through various realizations and is based on distributed equivalent circuit modelling.
Numerical analysis of a multilayered dielectric waveguide with a periodic surface
Authors: Yasumoto K. , Kubo H. , Itoh Y.
Published: July 2007

An accurate numerical approach to study the wave guidance in multilayered dielectric waveguides having a periodic surface is presented. The complex propagation constants of a four‐layered dielectric waveguide with a sinusoidal surface are calculated and compared with those obtained by other numerical methods.
Grating‐surface‐emitting laser arrays with > 1 cm output apertures
Authors: Evans G. A. , Carlson N. W. , Bour D. , Hammer J. M. , Lurie M. , Butler J. K. , Palfrey S. L. , Amantea R. , Bibby T. F. A. , Farkas R. E. , Gilbert D. B. , Truxal D. A.
Published: July 2007

Two dimensional grating‐surface‐emitting laser arrays produce up to 4 W peak power from a 60 μm × 1.2 cm aperture. These arrays consist of up to 10 × 27 laser elements and are based on either single or multiple quantum well laser structures.
Coded multipulse position modulation in a noisy optical channel
Authors: Atkin G. E. , Fares D. A. , Corrales H. P.
Published: July 2007

In this paper, Reed‐Solomon codes are applied to a multipulse position modulation scheme derived from a combinatorial design. Under high noise background radiation level, threshold detection of this system offers a better performance compared to a RS coded standard PPM system, considering the same information efficiency in nats per photon, and a similar bandwidth expansion factor.
Double‐slot‐fed microstrip antennas for circular polarization operation
Authors: Aksun M. I. , Wang Z. H. , Chuang S. L. , Lo Y. T.
Published: July 2007

Using the cavity model theory, simple design formulas are developed for double‐slot‐fed circularly polarized microstrip antennas. Equivalent magnetic current sources are assumed at the slot positions and then the electric field distribution under the patch is obtained in terms of cavity modes. By applying the circular polarization conditions to the far‐field components of the electric field, the loci of the positions of the slots for the circular polarization operations are found. Experimental results are successfully demonstrated based on the theoretical designs.
A rapidly convergent galerkin‐collocation (GC) method for the analysis of electromagnetic scattering from thin‐wire structures
Authors: McNamara Derek A. , van Rensburg Daniël J. Janse
Published: July 2007

Results obtained using a novel technique for computing the electromagnetic scattering from conducting thin‐wire structures and which exhibit Galerkin‐like convergence properties with collocation‐like computational efficiency, are presented.
Q‐factors and designs of CP microstrip antennas
Authors: Choi S. J. , Lo Y. T. , Chew W. C.
Published: July 2007

This paper discusses simple designs for circularly polarized antennas without the need of phase shifters and power dividing networks. In particular, design formulas of several commonly used microstrip antennas are derived and quantitative information on the antenna Q‐factor is presented to facilitate the design. Design examples are given to illustrate the proposed design procedure.
Absorbing boundary conditions for the finite element solution of the vector wave equation
Authors: Webb J. P. , Kanellopoulos V. N.
Published: July 2007

Time‐harmonic electromagnetic field problems in unbounded space may be solved by the finite element method applied inside a sphere which contains the region of interest, providing a suitable boundary condition is imposed on the surface of the sphere. The boundary condition must have the effect of absorbing out‐going waves. A new second‐order absorbing boundary condition (ABC) is proposed, similar to that introduced by Peterson [1], but capable of being incorporated in a variational principle and consequently leading to symmetric finite‐element matrices.
Optically controlled subsystems at HF and at MM‐wavelengths
Authors: Rosen A. , Stabile P. , Janton W. , Gombar A. , Delmaster J. , Basile P. , Hurwitz R.
Published: July 2007

This paper describes the use of optically controlled devices at HF (2‐30) (MHz) in a narrow band antenna coupler using high voltage PIN diodes as switching devices and at 60 GHz as an attenuator / switch. PIN devices tested in an rf circuit between 2.5 and 30 MHz yielded isolation between 28 and 49 dB in the off state and insertion losses as low as 0.1 dB when illuminated with 180 W of optical power. Measurements made at 60 GHz have shown a 0.9 dB insertion loss in the on state and an isolation value of better than 21 dB in the off state.
Characteristic modes for bodies endowed with mutually orthogonal symmetry planes
Authors: Vescovo Roberto
Published: July 2007

We deal with the characteristic modes of perfectly conducting bodies and of loss‐free dielectric or magnetic bodies, endowed with h mutually orthogonal symmetry planes (1 ≥ h ≥ 3). It is shown that by suitably choosing basis and weighting functions, the moment method transforms the eigenvalue equation defining the modes into a matrix eigenvalue equation involving matrices partitioned into 2h diagonal blocks.
A simple microstrip to dielectric waveguide transition
Authors: Miller Jeffrey A. , Li Ming‐Yi , Chang Kai
Published: July 2007

A simple microstrip to rectangular dielectric waveguide transition has been developed. The transition extends the microstrip strip conductor into one surface of dielectric waveguide. The transition exhibits an insertion loss of approximately 1 dB over a wide bandwidth.
A square multiflare horn with 1‐megawatt CW power‐handling capability
Authors: Hoppe Dan
Published: July 2007

The analysis and low‐power testing of a square miltiflare horn designed‐for 1‐megawatt CW operation is described. Design considerations for the five‐port input section are discussed. The required aperture modes are determined from radiation pattern considerations, and analysis of the multiflare section is carried out using mode matching. Measurements demonstrate that a circularly symmetric beam is produced with relatively low sidelobes.
Dual gate mesfet for flat microwave response of directly modulated laser diode
Authors: Rocco M. T. M. , de Salles A. A.
Published: July 2007

A dual gate GaAs MESFET (DG‐FET) driver is designed to obtain a flat frequency response from a direct intensity modulated semiconductor laser diode. The DG‐FET input and output matching circuits are designed to compensate the laser diode intrinsic frequency response in a band from 0.3 to 2.0 GHz. A frequency response flatness improvement of more than 15 dB is obtained.
Incremental frequency rules for arbitrary resonant cavities
Authors: Kajfez Darko , Wu Wen Liang , Chu Qingxin
Published: July 2007

The Q factor due to resistive losses in conductor walls of resonant cavities can be evaluated by computing the changes in resonant frequency resulting from small perturbations of either magnetic or dielectric material along the cavity wall. Two rules are presented: one in terms of derivatives, suitable for analytic solutions, and the other in terms of incremental changes, suitable for use with computer codes.
Antenna mode and structural mode RCS: DIPOLE
Authors: Hansen R. C.
Published: July 2007

The short‐circuit, match, and antenna components of RCS are examined for a thin‐wire dipole over a range of lengths and incidence angles. Resonances are identified and discussed in terms of current distributions and antenna patterns. The antenna component contains more resonant peaks than the short‐circuit component due to differences in current distribution. The results are useful for RCS understanding and control.
Experimental comparison between four dual‐polarized microstrip antennas
Authors: Levine E. , Shtrikman S.
Published: July 2007

A comparison between four designs of dual‐polarized microstrip arrays is reported. The measured coupling between ports, the cross polarization, and the gain are presented and discussed.
Frequency chirping in semiconductor‐optical fiber ring laser
Authors: Jiangping Zhang , Peida Ye
Published: July 2007

In this letter, a complete small‐signal analysis for frequency chirping in the semiconductor‐optical fiber ring laser is presented. It shows that chirp‐to‐power ratio (CPR) strongly depends on the junction phase shift, the optical coupling, and the phase detuning between two cavities, especially if the modulation frequency is below the gigahertz range.
Microwave noise performance and frequency response of PIN GalnAs photodiodes
Authors: Gouy J. P. , Vilcot J. P. , Decoster D. , Riglet P. , Patillon J. N. , Martin G.
Published: July 2007

We have measured the noise performance of GaInAs PIN photodiodes in the microwave frequency range. We show that the frequency response of the photodetectors can be deduced from their photocurrent shot noise spectra. The noise level has been measured using a setup which is based on heterodyne microwave mixing.
A broadband microwave linear phase modulator made of high Tc superconductors
Authors: Martens J. S. , Beyer J. B. , Nordman J. E. , Ginley D. S.
Published: July 2007

A superconducting linear phase modulator using a single film device made of Tl‐Ca‐Ba‐Cu‐O for operation at 77 K is presented. The modulator has been analyzed from 300 MHz to about 6 GHz with good linearity for peak phase deviations up to 100 rad. Modulation has been observed for carriers up to 35 GHz.
Photoavalanche effects in a GaAs MESFET
Authors: Madjar Asher , Herczfeld Peter R. , Paollela Arthur
Published: July 2007

This paper describes a photomultiplication effect in microwave MESFETs that occurs when the device is operated close to the avalanche breakdown voltage of the drain‐gate Schottky barrier. The multiplication enhances the optical response of the device, which is important when the MESFET is used in a photodetection mode. However, caution is required when the device is operated at high Vds levels so that premature avalanche breakdown is avoided.
Polarization correction of luneburg lens with chiral medium
Authors: Viitanen Ari J. , Lindell Ismo V. , Sihvola An H.
Published: July 2007

The geometrical optics method for the wave propagation in inhomogeneous chiral media, introduced recently, is here applied to the Luneburg lens antenna. For sufficiently small values of the chirality parameter, the geometrical optics rays can be calculated as for the achiral medium and the main effect of the chirality is rotation of polarization along the ray. This effect can be exploited to correct the polarization in the aperture of a lens antenna. In this paper the cross polarization of the Luneburg lens is eliminated through use of an inhomogeneous chirality distribution.
Organic‐on‐inorganic guided wave modulator
Authors: Ryley J. F. , Herczfeld P. , Brophy T. J.
Published: July 2007

A high speed, integrated optical intensity modulator based on the application of an organic electrooptic active cladding to an otherwise inactive waveguide is proposed. Computer generated data supporting the proposed device configuration and material selections are presented. The future potential of such devices is discussed.
Cutoff attenuator for azimuthally symmetric transverse electric mode in a cylindrical waveguide
Authors: Elaoud Moncef , Seshadri S. R.
Published: July 2007

A theory of the cutoff attenuator for the azimuthally symmetric lowest order transverse electric mode in a cylindrical waveguide is developed. Illustrative numerical results of the insertion loss as well as the frequency response of the attenuator are presented.
An efficient algorithm for solution of a scattering problem
Authors: Wang Y. M. , Chew W. C.
Published: July 2007

An object can always be subdivided into N subobjects. Hence, the scattering solution of an arbitrary‐shape inhomogeneous scatter can be formulated as a scattering solution of N scatterers, each of whose scattered field is approximated by M harmonics. This results in an NM unknown problem. A previously developed recursive operator algorithm, now adapted for wave scattering problems, can be used to solve this N scatterer problem. It is shown that the computational time of such an algorithm scales N2M2P where P is the number of harmonics used in the translation formulas. The scattered field from the same arbitrary shape scatterer can also be conventionally solved by the method of moments, casting it into an N linear algebraic equation. The solution of the linear algebraic equation via Gauss' elimination will involve order N3 floating‐point operations. Hence, the complexity of the recursive operator algorithm is of lower order than the method of moments. It is shown that the recursive operator algorithm is more efficient than the method of moments when the number of unknowns is large.
The utilization of nonuniform spacings for improved two‐section monopulse array performance
Authors: McNamara Derek A. , Jacobs J. Pieter
Published: July 2007

A method is proposed for using array element positions plus the element excitations in order to obtain both acceptable sum and difference patterns for a monopulse array with a two‐section feed network. Preliminary results are discussed.
Very high‐isolation all‐fiber wavelength‐division multi / demultiplexer
Authors: Luo X. B. , Hu L. , Lin W. G.
Published: July 2007

Successive fused‐taper couplers for wavelength‐division multiplexing are proposed as all‐fiber wavelength division multi / demultiplexers with very high isolation. A low‐loss (0.4 dB) multi / demultiplexer providing 41‐dB isolation at 1.300 μm and 50 dB at 1.550 μm is obtained.
Ka‐Band propagation characteristics of microstrip lines on GaAs substrates at cryogenic temperatures
Authors: Romanofsky R. R. , Martinez J. C. , Viergutz B. J. , Bhasin K. B.
Published: July 2007

Effective permittivity and loss characteristics of gold microstrip lines on GaAs substrates were obtained by characterizing GaAs linear resonators at cryogenic temperatures (300 to 20 K) from 30‐40 GHz. A slight decrease in effective permittivity and a significant reduction in loss were observed with lower temperatures.
Power stored in the evanescent modes of a rectangular waveguide generated by a narrow inclined sidewall slot
Authors: Roy Rajat
Published: July 2007

An alternative expression for the internal power storage in the evanescent modes of a rectangular waveguide due to the presence of a narrow inclined slot on its sidewall to that already given by Hsu and Chen is obtained. The expression is in a closed form, thus doing away with numerical integration.
Crosstalk in a dpsk FDM system affected by laser phase noise
Authors: Betti S. , de Marchis G. , Iannone E. , Todaro M.
Published: July 2007

In this paper the crosstalk penalty for a DPSK FDM system is evaluated by an accurate analytical model taking into account the laser phase noise. The results are also compared with those obtained in the presence of phase noise from the Gaussian approximation to assess the conditions under which this simple algorithm can be used to evaluate the crosstalk induced penalty.
A finite‐difference frequency‐domain approach for solving electromagnetic scattering by conducting bodies of revolution
Authors: Joseph J. , Gordon R. K. , Mittra R.
Published: July 2007

In this paper, the problem of electromagnetic scattering by a conducting body of revolution is solved using the finite‐difference technique in frequency domain. Two coupled partial differential equations, derived based on the coupled azimuthal potentials introduced by Morgan, Chang, and Mei are solved over a domain surrounding the scatterer. Boundary‐fitted curvilinear coordinates, which avoid the problem of staircasing, are used to discretize the domain of computation. Results are presented to demonstrate the accuracy of the method.
Enhanced scheme for the small‐signal physical simulation of mesfets
Authors: Cáceres J. L. , Pérez J.
Published: July 2007

Time domain linear analysis on an improved finite‐difference discretization scheme is proposed as an efficient technique for the small‐signal simulation of semiconductor devices. In particular, we apply the method to the case of MESFETs.
The singular integral equation technique for planar transmission lines
Authors: Huang Yafei , Xue Liangjin , Lin Weigan
Published: July 2007

The analysis of antipodal and asymmetrical bilateral finlines has been developed. In this method, the propagation constant is achieved via the singular integral equation (SIE) technique. Compared with other methods, it is an accurate method and needs less computer time.
Nonstandard variational method for calculating attenuation in optical fibers
Authors: Oksanen Markku , Mäki Hannu , Lindell Ismo V.
Published: July 2007

A new variational functional for lossy open and dielectric waveguides has been derived. Based on the functional, a nonstandard variational method in terms of longitudinal fields has been introduced for calculating attenuation due to material losses. The method has been tested on a round step‐index optical fiber possessing various complex refraction index profiles.
A fast algorithm for solution of a scattering problem using a recursive aggregate τ matrix method
Authors: Chew W. C. , Wang Y. M.
Published: July 2007

An algorithm based on the recursive operator algorithm is proposed to solve for the scattered field from an arbitrarily shaped, inhomogeneous scatterer. In this method, the scattering problem is first converted to an N‐scatterer problem. Then, an add‐on procedure is developed to obtain recursively an (n + 1)‐scatterer solution from an n‐scatterer solution by introducing an aggregate τ matrix in the recursive scheme. The nth aggregate τ(n) matrix introduced is equivalent to a global τ matrix for n scatterers so that in the next recursion, only the two‐scatterer problem needs to be solved: One scatterer is the sum of the previous n scatterers, characterized by an nth aggregate τ(n) matrix; the other is the (n + 1)th isolated scatterer, characterized by τn + 1(1). If M is the number of harmonics used in the isolated scatterer T matrix and P is the number of harmonics used in the translation formulas, the computational effort at each recursion will be proportional to P2M. (Here we assume M is less than P.) Consequently, the total computational effort to obtain the N‐scatterer aggregate τ(N) matrix will be proportional to P2MN. In the low‐frequency limit, the algorithm is linear in N because P, the number of the harmonics in the translation formulas, is independent of the size of the object.
Modelling microstrip resonators with a dielectric protective layer for biomedical applications
Authors: Pribetich J. , Kennis P. , Pribetich P.
Published: July 2007

Previous modelization does not obtain the resonant frequencies of the rectangular microstrip resonator with a dielectric protective layer radiating into the human body (that is, the resonant frequency Fr and the Q factor), whereas this paper does. This analysis is based on the two‐dimensional spectral domain approach (SDA). Comparison with experiment shows that this method improves the previous one‐dimensional modelization.
Modeling and experimental study of breakdown mechanisms in multichannel AIGaAs/GaAs power hemts
Authors: Temcamani Farid , Crosnier Yves , Lippens Didier , Salmer Georges
Published: July 2007

A theoretical and experimental analysis of breakdown in the power HEMT AlGaAs/GaAs single or multiple wells is presented in this article. The two phenomena ionization and tunneling have been considered. The understanding of breakdown mechanisms has led to definition of structures particularly suitable for power applications.
A 16 × 16 microstrip array of electromagnetically coupled patches operating in the high‐gain region
Authors: Lee R. Q. , Lee K. F.
Published: July 2007

A microstrip array at 18.4 GHz consisting of 16 × 16 rectangular electromagnetically coupled patch antennas operating in the high‐gain region is experimentally investigated. The pattern and impedance characteristics of the array are compared with the case when the parasitic elements are removed.
A treatment by the FD‐TD method of the dispersive characteristics associated with electronic polarization
Authors: Kashiwa Tatsuya , Fukai Ichiro
Published: July 2007

In this article, the formulation of dispersive characteristics associated with an electronic polarization is discussed. The formulation is appropriate for use in the finite‐difference‐time‐domain (FD‐TD) method and is based on the equation of polarization. The validity of the formulation is verified by comparing the calculated complex dielectric constant with analytical values.
Accurate solutions for planar transmission lines by an improved singular integral equation technique
Authors: Huang Yafei , Xue Liangjin , Lin Weigan
Published: July 2007

An improved singular integral equation (SIE) technique is proposed which can be used for the analysis of finlines, microstrip lines, coplanar transmission lines, etc. The concepts of regular solution of the SIE and generalized characteristic equation are introduced. Numerical results show that it is an efficient and accurate method.
Achievement of low coupling loss between a 1.55‐μm wavelength laser diode and a high NA MCVD‐single‐mode fiber by conical microlens
Authors: Ghafouri‐Shiraz H. , Cameron K. , Fatah R. M. A.
Published: July 2007

A low coupling loss of ‐1.34 dB has been achieved between a laser diode emitting at around 1.55 μm wavelength and a high numerical aperture MCVD single‐mode fiber by fabricating a conical microlens on the end surface of the fiber. Also for the same source a coupling loss of about ‐3dB has been achieved when a conventional MCVD single‐mode fiber with a core diameter of 7.3 μm was used.
Effects of multi‐pump beam coupling on intensity enhancement of a probe beam in photorefractive two‐wave mixing
Authors: Gilbreath G. C. , Davidson F. M.
Published: July 2007

The effects of three‐beam coupling are studied when two pump beams are photorefractively coupled to a probe beam of weaker intensity. Our work indicates that gain per unit effective length in the probe beam is affected by multiple‐pump beam interaction. Our work further indicates that reduced gain in the probe due to such interaction may be ameliorated by geometry, beam ratio, and material parameters. Experimental verification is presented using BaTiO3 and 514.5 nm.
Theoretical prediction of nonlinear brewster angle in ADP
Authors: Bhanthumnavin V. , Ampole N.
Published: July 2007

The intensity of reflected second harmonic light from the ADP (NH4H2PO4) crystal immersed in the optically denser liquid 1‐bromo‐naphthalene has been theoretically calculated, with the theory of Bloem‐bergen and Pershan, as a function of incident angle of the fundamental beam of Nd:YAG laser. A nonlinear Brewster angle θiNB of 43.32° is predicted.
A hybrid near‐optimum impedance transition with one discontinuity
Authors: Coetzee Jacob C. , Malherbe Johannes A. G.
Published: July 2007

A near‐optimum impedance transition with one discontinuity consisting of a combination of the techniques proposed by Hecken and Klopfenstein is described. The aim is to utilize the attractive features of the two methods and to combine them in an alternative impedance matching technique that might be used in the design of wideband antenna elements with low return loss.
Prediction of harmonic distortion in semiconductor lasers driven below threshold
Authors: Haldar M. K. , Mendis F. V. C. , Kooi P. S.
Published: July 2007

Simple equations, supported by experimental measurements, are derived for the second and third harmonic distortion resulting from a semiconductor laser driven below threshold.
The stability of nonlinear TE, guided waves revisited
Authors: Zabeu A. C. P. , Souza J. R.
Published: July 2007

The propagation of nonlinear TE, guided waves is simulated numerically using a new algorithm based on variational and finite‐difference methods, and their stability properties are investigated. The results indicate that portions of the solutions are not only unstable but may follow a route to chaos through period doubling as the guided‐wave power increases.
Performances of superconducting interconnections
Authors: Kinowski D. , Huret F. , Seguinot C. , Pribetich P. , Kennis P.
Published: July 2007

Pulse propagation and crosstalk phenomena in metallic and superconducting coupled microstrip lines laid on semi‐insulating substrate are analyzed. Propagation characteristics of the studied lines are obtained through the well‐known spectral domain approach. Time domain results are determined by a fast Fourier transform. Effects of the nature of the strips are investigated.
Effect of a parasitic mode on the characteristics of a cylindrical waveguide mode converter with harmonically varying radius
Authors: Kasraian Masoud , Seshadri S. R.
Published: July 2007

A cylindrical waveguide with harmonically varying radiius can be used to convert selectively the TEmq mode to the TEmp mode. The characteristics of this waveguide mode converter in the presence of the parasitic TEmr mode are treated, and a modified design for the improvement of the performance of this mode converter is presented.
A new spatial slice theorem for microwave imaging
Authors: Suh Kyoung‐Whoan , Kim Se‐Yun , Ra Jung‐Woong
Published: July 2007

The Fourier slice theorem, which was widely used in microwave radar imaging, is modified to be compatible in the spatial domain. Compared with the previous scheme, interpolation is not requisite for this spatial slice theorem. Numerical simulation for simple test targets is presented and its validity is discussed.
Normal mode analysis of asymmetrical two‐line microstrip circuits using a perturbation approach
Authors: Faria J. A. Brandão
Published: July 2007

Normal modes of an asymmetrical two‐line microstrip structure are interpreted as the result of a system perturbation producing mode coupling between the odd and even modes that would primarily characterize the microstrip structure if the system asymmetry were absent.
Tunability of cascaded grating used in distributed feedback laser
Authors: Moheimany O. R. , Rahnavard M. H. , Abiri H. , Alehassin M.
Published: July 2007

Reflectivity of cascaded gratings with phase shifts is studied. It is shown that this structure has wavelength tunability. The effects of phase shift, length of different stages of the gratings, and total length of grating for two and three cascaded grating stages on tunability are studied in this article.
Influence of tem waves on dielectric encapsulated semiconductor devices
Authors: Huang Kama , Lin Weigan
Published: July 2007

The influence of transverse electromagnetic (TEM) waves on dielectric encapsulated semiconductor devices is not attracting engineers' attention. It is found that the parameters of dielectric encapsulated semiconductor devices may degrade when these devices are radiated by TEM waves even though they are open circuited. Our experimental data exhibit that parameter degradations depend on the electric field strength and radiation time. Some discussions on these results are also given in this article.
Effect of metallization edge shape on conductor loss of open coplanar waveguide
Authors: Barsotti Edward L. , Kuester Edward F. , Dunn John M.
Published: July 2007

The effect on conductor loss of metallization edges with a trapezoidal shape instead of rectangular, as commonly occurs from ordinary fabrication techniques, is examined for the case of open coplanar waveguide. Depending on the geometric parameters, this can increase conductor loss by a significant amount.
Spectral domain analysis of microstrip antennas with an airgap
Authors: Tam W. Y. , Luk K. M.
Published: July 2007

The circular disk microstrip antenna with an airgap between the dielectric substrate and the ground plane is formulated using the spectral domain method. The complex resonant frequencies of the structure is determined using Galerkin's procedure. Some available experimental data are compared with the present method.
Analysis of a gaussian model for the far‐field intensity pattern of laser diodes
Authors: Ghafouri‐Shiraz H. , Gong J.
Published: July 2007

A Gaussian model for the far‐field intensity pattern (FFIP) of semiconductor laser diodes is proposed based on a curve‐fitting technique. The analysis is carried out for different values of relative refractive index difference Δ and active layer thickness d ranging from 3% to 10% and 0.1 to 0.3 μm, respectively. The model is sufficiently accurate to be used in analyzing the coupling efficiency between laser diodes and single‐mode fibers.
Quasicomplex modes on lossy substrate boxed microstrip lines
Authors: Huret F. , Pribetich P. , Kennis P.
Published: July 2007

In this letter, by using a spectral domain approach improved by asymptotic expansions, we show by means of coupling integral values that the notion of quasicomplex modes can be introduced for lightly lossy substrates. The quasicomplex modes are particular modes with behavior similar to lossless structure complex modes.
Quantum‐well and quantum‐barrier diodes for generating submillimeter wave power
Authors: Grönqvist Hans , Kollberg Erik , Rydberg Anders
Published: July 2007

Quantum‐well diodes have been used for generating power at millimeter and submillimeter waves, both in negative resistance oscillators and in multipliers. In this article, we will first discuss the power versus frequency and the maximum frequency of oscillation of “ordinary” quantum‐well oscillators. Possible methods of improving the power output and the maximum frequency of oscillation will be suggested. Quantum‐well diode multipliers will also be discussed. Realizing the importance of the nonlinear capacitance for the quantumwell diode multiplier efficiency, we have investigated a quantum‐barrier diode in multiplier applications.
GaAs Schottky barrier varactor diodes for submillimeter wavelength power generation
Authors: Crowe T. W. , Peatman W. C. B. , Winkler E.
Published: July 2007

There is interest in the development of heterodyne receivers for submillimeter wavelengths, particularly for space‐based remote sensing of the Earth's upper atmosphere. These receivers require solid‐state local oscillator sources. This article considers the fundamental design tradeoff that limits the cutoff frequency of varactor diodes. Recent results demonstrate a maximum cutoff frequency of 5 THz. and significant power to frequencies as high as 640 GHz.
A simple approach to a four‐way hybrid ring power divider design
Authors: Wang Jian , Spenuk Mike , Fralich Russell , Litva John
Published: July 2007

A straightforward method is proposed for the design of a novel hybrid ring power divider that is compatible with stripline circuits. This configuration is analyzed using standard commercial CAD software TOUCHSTONEtm. Theoretical and experimental results show a return loss of better than −30 dB at the resonant frequency of the hybrid ring circuit and a transmission coefficient of −6.20 ± 0.15 dB in the band of interest (1.633‐1.666 GHz) with a maximum insertion loss of 0.35 dB (including connector effects).
Integrated active antenna using annular ring microstrip antenna and gunn diode
Authors: Miller Richard E. , Chang Kai
Published: July 2007

A Gunn diode has been integrated with an annular ring microstrip antenna to form an active antenna. The location for the diode placement was calculated based on a theoretical analysis for impedance matching. Over 70‐mW output power was achieved at 6.8 GHz.
Polarization dispersion in single‐mode optical fibers: A simpler formulation based on pulse envelope propagation
Authors: De Marchis G. , Iannone E.
Published: July 2007

A new and simpler formulation of the theory of polarization delay and dispersion due to single‐mode optical fiber birefringence and coupling is presented. Exploiting its possibilities it is demonstrated that the polarization delay is the maximum delay between pulses injected into the fiber with orthogonal SOPs, and a relationship is found between the dispersion experimented by a pulse and the delay between this pulse and a pulse with the orthogonal SOP.
Anomalous microwave propagation in open space
Authors: Glakos George C. , Ishii T. Koryu
Published: July 2007

It has been observed in the far radiating zone that at a certain receiver antenna position and orientation the transit time of the arriving pulse‐modulated microwaves in open space was constant regardless of the distance between the receiver and the transmitter. The apparent phase velocity exceeded the intrinsic velocity. Calibration techniques employed and repeated time‐domain measurements done at different frequencies and distances confirmed this phenomenon.
Variation of gate and drain contact positions along the width of MESFETs and its influence on millimeter wave oscillator performance
Authors: Ongareau Éric , Bosisio Renato G.
Published: July 2007

The effects of gate and drain wave propagation of the contact positions along the electrodes of a GaAs MESFET oscillator are studied using a linear and distributed circuit analysis technique. Each distributed device element is considered as a combination of two pairs of coupled coplanar strips and a GaAs intrinsic MEFSET circuit. The distributed equivalent circuit is then analyzed using Touchstone with a chosen terminating load. The input impedance and reflection coefficient of the equivalent one‐port negative resistance MESFET oscillator are calculated as a function of input and output contact positions along the gate and drain of the device width. The results show, for a single gate MESFET of 600‐micron width, that the properties of transmission lines have some effect on the oscillator performance. Added power delivered by the negative resistance one‐port device also depends on gate and drain electrode contact position for a given load and terminating network. The drain contact position can be easily controlled by a circuit designer in MMIC such that the added power efficiency is obtained at no extra cost.
A microwave equivalent circuit model for semiconductor alloy ramp heterostructure diodes
Authors: Tait Gregory B. , Newman Harvey S.
Published: July 2007

The microwave impedance of a current‐rectifying Alx, Ga1‐x, As ramp heterostructure is measured from 0.1 to 12 GHz over a temperature range of 20 to 300 K. The elements of a small‐signal equivalent circuit model are optimized to fit the experimental impedance data over the full temperature and dc bias ranges. These circuit elements are identified with the physical structures and carrier transport mechanisms in the device.
Photopolymer hologram formation theory
Authors: Adhami Reza R. , Lanteigne David J. , Gregory Don A.
Published: July 2007

A backward‐difference technique for the numerical solution of a nonlinear diffusion equation describing photopolymer hologram for mation is described. The monomer concentration, the net polymerization, and mass density changes are calculated and plotted as a function of the hologram's extent.
Analysis of a series‐fed aperture‐coupled patch array antenna
Authors: Wu Chen , Wang Jian , Fralich Russell , Litva John
Published: July 2007

A full‐wave spectral domain model of a series‐fed, traveling‐wave aperture‐coupled patch array antenna is presented. This configuration allows for performance optimization by adjustment of the aperture size, aperture location, and patch size. The theory successfully predicts the input impedance and far‐field patterns of various C‐band configurations.
The electrostatic problem of a portion of a multilayer dielectric sphere in a uniform field
Authors: Lin Weigan , Liu Yuanan , Zhao Yushen
Published: July 2007

We develop a general multilayer dielectric sphere model in the toroidal coordinates and give the analytical electrostatic solution when it is excited by a uniform field. The special case of the electrostatic result of an incomplete conducting sphere can be obtained simply. It is in agreement with the published result. We have also found that the coating dielectric film on the conducting sphere surface can remarkably reduce distortion on the external homogeneous field when the normalized dielectric constant is from 1–5.
Theoretical and experimental determination of the power deposition of a microstrip‐microslot applicator for biomedical applications
Authors: Dubois L. , Bera J. , Pribetich J. , Chive M.
Published: July 2007

We propose to investigate printed circuit applicators for biomedical applications and especially the microstrip‐microslot applicator laid on multilayered lossy media and covered or not with a superstrate. Particular interest is focused on the power deposition inside biological tissues. The theoretical analysis is based on the spectral domain approach (SDA) method. In addition, experimental measurements were performed on phantom models of human tissue, which validate the theoretical study.
Anomalous acousto‐optic effect in glass
Authors: Taalbi Mustapha , Ishii T. Koryu
Published: July 2007

A He‐Ne laser beam in glass plate is modulated by transversely applied audio frequency sound waves. The observed photodetected current showed phase shift in audio signals and frequency doubling depending on the location of the photodetector. The component of elliptical polarization showed modulation frequency sensitive transmission in glass.
Application of the fast recursive algorithm to a large inhomogeneous scatterer for TM polarization
Authors: Wang Y. M. , Chew W. C.
Published: July 2007

A fast recursive algorithm has been developed to solve for the scattering solution of a large 2‐D inhomogeneous body for TM waves. The inhomogeneous body is first divided into N subscatterers. The algorithm uses an aggregate T̄ matrix and translation formulas to solve for the solution of n + 1 subscatterers from the solution for n subscatterers. The computational complexity of the algorithm is of O(NMP2), where NM is the number of unknowns and P is the number of harmonies required in the translation formulas. The memory requirement is proportional to the number of unknowns. The algorithm has been used to solve for the scattering solution of a 10‐λ‐diameter two‐dimensional scatterer with about 12,000 unknowns, taking about 30 s on a CRAY‐2 supercomputer.
An experimental technique for increasing the bandwidth of printed slot antennas
Authors: Rabbaa A.
Published: July 2007

A simple printed slot antenna is derived from an earlier and more complex one. Experimental data show that the modified antenna, like the original one, has the same performance, mainly a large bandwidth.
Application of cubic‐phase theory to galindo‐williams subreflector
Authors: Rahnavard M. H. , Rusch W. V. T.
Published: July 2007

A JPL Fortran program for designing the main reflector and the subreflector of a Galindo‐Williams system with a constant intensity over the aperture of the main reflector was modified for use on our computer system. Geometrical optics and conservation of energy are the basic laws used for designing this type of surface. The basic computation is a numerical solution of three simultaneous differential equations. The resulting subreflector is a type of inflected surface. Analysis of the fields scattered from such a surface using physical optics yields adequate results. Cubic‐phase theory is numerically applied to the Galindo‐Williams surface. Although the technique appeared to yield results accurate to within 10%‐15%, the nearness of the edge to the turning point caused a coupling of the edge and turning‐point solutions, which prevented higher accuracy.