bluuebunny/crossref_metadata_2025_split huggingface dataset:
A note on the use of a beam‐waveguide feed system as a phase shifter for high power microwave dual‐reflector antennas
Authors: Knop C. M. 
Published: July 2007

AbstractA diffraction analysis and associated computations of the transmission loss of a typical BWFS (beam‐waveguide feed system) used to excite an HPM (high power microwave) DRA (dual‐reflector antenna) are reported and show that the use of a BWFS as a phase shifter, as proposed by Hansen and Palaith in early 1989 [1], is reasonable since this phase‐shift action increases this loss by an acceptably low amount.
Analysis of microstrip‐like transmission lines with finite metallization thickness
Authors: Tan Chung‐Hsing , Chang The‐Nan 
Published: July 2007

AbstractThe transverse modal analysis (TMA) method is used for deriving the dispersion characteristics of microstrip‐like transmission lines with finite metallization thickness. Instead of using strip currents as source quantities, the aperture fields are employed for applying the Galerkin method. Numerical results show that the metallization thickness will decrease the propagation constant of both shielded microstrips and suspended strip lines. To verify the accuracy of the present method, the results are also compared with those obtained by other methods.
Ka‐band monolithic GaAs mesfet amplifier design
Authors: Rollman J. A. , Wahid P. F. 
Published: July 2007

AbstractThree designs, a single‐stage, a parallel‐stage, and a two‐stage amplifier, for medium power monolithic GaAs MESFET amplifiers at Ka‐band are presented. The results obtained are consistent with other performances reported at these frequencies.
Reflection and transmission in second harmonic generation of light in KDP crystal
Authors: Bhanthumnavin V. , Lee Chi H. 
Published: July 2007

AbstractThe intensity of second harmonic light beams generated in potassium dihydrogen phosphate (KDP) crystals immersed in the optically denser fluid I‐bromonaphthalene has been observed as a function of the incident angle of the fundamental beam of the neodymium‐glass laser. The laser pulses are polarized in the [110] direction with respect to the KDP crystallographic axes. We observed for the first time that there is no transmitted second harmonic light at normal incidence when the nonlinear polarization PNLS(2w) lies in the direction [001] along the crystal face normal. Furthermore, the noncollinear phase‐matching condition where the two incident fundamental beams are on the opposite side of the face normal is demonstrated. The results agree well with the theory of Bloembergen and Pershan.
A statistical approach for calculating the concatenated connector loss in fiber‐optic links
Authors: Uhing Jim , Thomas Steve , Christodoulou C. G. 
Published: July 2007

AbstractThe insertion loss contribution of concatenated connectors in fiber‐optic links is analyzed. A statistical approach based on the loss distribution of single connectors with a method for numerical convolution is developed. The predicted insertion loss is less than the sum of the “worst case” connector loss values. An avionics short‐haul fiber‐optic example illustrates the new approach.
Cutoff frequencies of dielectric waveguides using the multifilament current model
Authors: Altman Z. , Cory H. , Leviatan Y. 
Published: July 2007

AbstractA new approach for finding the cutoff frequencies of a dielectric waveguide based on the multifdament current model is presented. In this approach, the boundary conditions on the fields are taken in the cutoff limit. The method is applied to an elliptic dielectric waveguide.
On the various forms of the coupled‐mode theory for optical waveguides
Authors: Chang Hung‐Chun , Huang Horng Shou , Wang Yeong‐Cheng 
Published: July 2007

AbstractWe review the various forms of the coupled‐mode theory for optical waveguides. One subtle distinction between two different formulations of the conventional coupled‐mode theory is pointed out. Comparison of accuracy between them and the recently formulated new theory is conducted for the two‐ and three‐slab waveguide structures.
Total field evaluation near the edge shadow of an idealized inflected surface
Authors: Rahnavard M. H. , Rusch W. V. T. 
Published: July 2007

AbstractThe conventional Kouyoumjian transition function cannot be used to evaluate the diffracted field for a converging wave because its argument is imaginary, and the total field is not continuous at reflection and shadow boundaries. In order to find the diffracted field near the edge shadow of the inflected surface, Rusch's proposed edge‐diffraction transition function for a converging wave is used. The argument of this transition function is real and produces a continuous total field at the boundaries. The diffracted field is then added to the geometrical optics field and compared favorably with physical optics.
Optical effects in hemts
Authors: de Sailes A. A. 
Published: July 2007

AbstractThe major photoeffects affecting the DC and RF performance of depletion mode Al0.3Ga0.7As/GaAs HEMTs are presented. When photons are absorbed only in the GaAs layer, an increase in the electron concentration of the 2‐DEG channel is estimated (photoconductive effect). When photons are also absorbed in the AlGaAs layer the gate junction photovoltage is calculated (photovoltaic effect).
Microwave circuit modeling for semiconductor lasers under large and small signal conditions
Authors: Elkadi H. , Vilcot J. P. , Maricot S. , Decoster D. 
Published: July 2007

AbstractWe present a new large/small signal equivalent circuit for semiconductor lasers, valid for above‐ as well as below‐threshold operating conditions, based on the monomode rate equations and a polynomial approximation of Fermi integral. The model is thus valid for conditions of large injection. Results obtained by this model match perfectly those obtained by numerical integration of the rate equations. The equivalent circuit is easy to implement and solve on a nonlinear circuit analysis software such as SPICE and consequently allows the study of the parasitic effects as well as the laser behavior in complex circuits. Comparison between this model and previously published models is presented. The model is applied to the study of various heterojunction laser diodes, the experimental results of which have been published elsewhere.
Solution of thin‐wire integral equations by nystrom methods
Authors: Kot John S. 
Published: July 2007

AbstractNumerical solutions to the electric‐field integral equation (EFIE) for a thin wire are obtained by a Nystrom method. The singular EFIE is treated by subtraction of the singularity and a thin‐wire integral equation convenient for numerical solution is obtained. Solutions for exact and approximate EFIE kernels are compared.
Dispersion characteristics of optical dielectric waveguides
Authors: Cheng Yuehua , Lin Weigan 
Published: July 2007

AbstractA new iteratively equivalent index method for the analysis of rectangular dielectric waveguide problems is presented. This analysis is found to be more accurate both than the effective index method and the modified effective index method. The results obtained by this method compare very favorably with those produced by the variational analysis, weighted index analysis, and numerical computation over a large range, but without the complexity of the latter.
A balanced optical interferometric sensor with a wavelength‐dependent offset
Authors: Bernard J. E. , Chrostowski J. , Wartak M. S. 
Published: July 2007

AbstractA Mach‐Zehnder interferometer with dissimilar arms in the form of buried‐rib and ARROW waveguides is considered. The interferometer has a wavelength‐dependent offset because of diferent chromatic dispersion in the two arms. This feature makes it possible to build a balanced interferometric sensor with negligible temperature sensitivity but in which the offset due to an external stimulus can still be determined by varying the wavelength of the source. Dispersion calculations for this interferometer are presented with a possible construction design.
A simple and efficient formulation for the transmission characteristics of generalized suspended striplines
Authors: Rong Ao Shong 
Published: July 2007

AbstractAn efficient numerical procedure based on full‐wave analysis is formulated to compute the transmission characteristics of suspended striplines including the finite metallization thickness and substrate‐holding grooves. The formulation identifies the electric current sheets on the metallic strips and the magnetic current sheets at the apertures of the grooves, instead of the magnetic current sheets at the interfaces between adjacent media, as the unknown source quantities to be determined. The effect of the finite metallization thickness is taken into approximate account by the electric current sheets on the upper and lower surfaces of the metallic strips. This makes the final matrix equation be of the moderate order and calculated with the reasonable CPU time. The validity of the formulation is confirmed by comparing the present results with available data in the literature.
Propagation constant of microstrip leaky‐wave antennas
Authors: Abdallah E. A. F. , Mitkees A. A. , Hamdy S. A. , Elsohly A. A. 
Published: July 2007

AbstractA microstrip leaky‐wave antenna is treated as a microwave network. A transverse resonance method with perturbation technique is applied to the resonance equation to get results in a simple and practical form. The aperture admittance is taken from that of a dielectric loaded parallel plate transmission line radiating into space. Good agreement is obtained between the theoretical and the experimental results.
Submillimeter heterodyne remote sensing of upper atmospheric gases
Authors: Waters Joe W. 
Published: July 2007

AbstractTechnology is now becoming available to develop submillimeter‐wavelength heterodyne radiometric experiments for remote sensing the upper atmosphere from space. Such experiments can provide many essential measurements for assessing and critically monitoring the depletion of stratospheric ozone by pollution from industrial products. A millimeter‐wavelength experiment for this purpose is now ready for launch on the NASA Upper Atmosphere Research Satellite (UARS). An enhanced version of the UARS experiment, which operates at submillimeter wavelengths, is under investigation for the future NASA Earth Observing System.
Aperture efficiency of integrated‐circuit horn antennas
Authors: Guo Yong , Lee Karen , Stimson Philip , Potter Kent , Rutledge David 
Published: July 2007

AbstractWe have improved the aperture efficiency of silicon integrated‐circuit horn antennas by optimizing the length of the dipole probes and by coating the entire horn walls with gold. To make these measurements, we developed a new thin‐film power‐density meter for measuring power density with accuracies better than 5%. The measured aperture efficiency improved from 44% to 72% at 93 GHz. This is sufficient for use in many applications which now use machined waveguide horns.
A planar dipole array antenna with an elliptical lens
Authors: Skalare A. , De Graauw Th. , van de Stadt H. 
Published: July 2007

AbstractWe describe a planar antenna structure consisting of two half‐wave dipoles, which are backed by a metallic reflector to create an image of two more elements. The array produces rather a wide main beam, and is therefore used with a dielectric lens. The far‐field pattern of the dipole liens antenna has cross‐pol better than −20 dB, and side lobes below −13 dB over an octave band. The impedance at the feedpoint of the antenna is approximately 70 ‐ j10 Ω at the center of the band.
Twin slot antenna structures integrated with microbolometer detectors for 94‐GHz imaging
Authors: Heston John G. , Lewis Jason M. , Wentworth Stuart M. , Neikirk Dean P. 
Published: July 2007

AbstractThe twin slot antenna on a dielectric stack should find application in the far‐infrared spectral region. We present measurements at 94 GHz which show that this antenna will be useful as an imaging element.Based on these results, in combination with a new detector element, a two‐dimensional FIR imaging array is proposed.
Tunnel transit‐time (tunnett) devices for terahertz sources
Authors: Haddad G. I. , East J. R. , Kidner C. 
Published: July 2007

AbstractThe potential and capabilities of tunnel transit‐time (TUNNETT) devices for power generation in the 100‐1000 GHz range are presented. The basic properties of these devices and the important material parameters which determine their properties are discussed and criteria for designing such devices are presented. It is shown from a first‐order model that significant amounts of power can be obtained from these devices in the terahertz frequency range.
Planar doped barrier devices for subharmonic mixers
Authors: Lee T. H. , East J. R. , Haddad G. I. 
Published: July 2007

AbstractMixers are a critical component of most millimeter‐wave and terahertz systems. Often, the front‐end mixer performance determines the overall system performance. At higher millimeter‐wave and terahertz frequencies, mixer performance can be limited by the lack of low‐cost solid‐state sources. A subharmonic mixer with a pumping frequency at half the signal frequency would reduce the source power requirements at these higher frequencies. Typical subharmonic mixers use back‐to‐back Schottky barrier diodes. The resulting structures are difficult to fabricate. The performance can be degraded by unmatched diodes or by parasitics associated with the various connections. One possible solution is to use an integrated Schottky barrier structure. Another possible solution is to use a planar doped barrier (PDB) as a single‐device subharmonic mixer. This article presents an analysis of PDB subharmonic mixer performance.
Noise performance degradation in feedback oscillators with nonzero phase error
Authors: Cheng K. K. M. , Everard J. K. A. 
Published: July 2007

AbstractThe degradation in oscillator noise performance with nonzero phase error is described. Noise measurements on both bipolar and GaAs oscillators are presented. It is shown that phase error is an important parameter in the design of state‐of‐the‐art low‐noise oscillators.
Improved correlation discrimination using joint fourier‐transform optical correlator
Authors: Alam Mohammad S. , Awwal Abdul Ahad S. , Karim Mohammad A. 
Published: July 2007

AbstractAttempts are being made to investigate techniques to improve the cross‐correlation peak heights of a joint‐transform‐based correlator while reducing the corresponding dc peaks. Two such techniques, namely, preprocessing the reference image and postprocessing the joint Fourier‐transform image, are investigated, and the corresponding simulation results are compared.
Transmission‐line model to analyze a multistage polarizer rotator
Authors: Gimeno B. , Such V. , Garcia A. C. , Cruz J. L. , Navarro E. 
Published: July 2007

AbstractA simple transmission‐line model to design a broadband system consisting of a multilayered polarization rotator that rotates the polarization plane of a linearly polarized electromagnetic wave is presented. A simulation program that permits the design of the rotator parameters was implemented, and a prototype was designed, manufactured, and tested. Comparisons between the theoretical results and measurements are given, and a good correspondence is found.
A method for designing microwave broadband amplifiers by using chebyshev filter theory to design the matching networks
Authors: Quirarte José Luis Ramos 
Published: July 2007

AbstractA method for designing microwave broadband amplifiers is presented. In order to obtain broadband operation, the matching networks are designed using filters with Chebyshev characteristics. To make good use of the transistor, the reactive parts of its input and output impedances are used as part of the first resonator in the filters. The method is applied to the design of a low‐noise amplifier in a microstrip substrate operating at frequencies from 4‐6 GHz. The results show that the method is efficient in designing amplifiers having about 40% bandwidth.
Analysis of Unsymmetrical Waveguide Y‐junction circulators
Authors: Dou W. B. , Rong Y. 
Published: July 2007

AbstractThis article analyzes unsymmetrical waveguide Y‐junction circulators whose two arms are connected with H‐plane bends according to the electromagnetic field solutions given in [1, 2]. The scattering matrix and numerical results are given. The results show that the H‐plane waveguide bend has an influence on the performance of the waveguide Y‐junction circulators.
Aspsk with postdetection filtering: An accurate analysis
Authors: Betti S. , De Marchis G. , Iannone E. , Lazzaro P. 
Published: July 2007

AbstractIn this article antipodal Stokes parameters shift keying (ASPSK) performance is analyzed when a postdetection filter is used before decision. This baseband processing allows high insensitiveness to phase noise to be achieved, so that the system can work with a limited penalty even when the laser linewidth is comparable with the bit rate.
Further study on the rectangular coaxial line of simple symmetry
Authors: Lin Weigan 
Published: July 2007

AbstractThe structure of the rectangular coaxial line is of simple symmetry: however, its exact analysis is difficult. Riblet solves this problem by making use of the degenerate Ryperelliptic integral [3]. Here we point out that his results break down when the inner conductor becomes a strip. We solve this latter case and offer the solution of the rectangular line with a general cross‐inner conductor.
Numerical analysis of an optical coupler composed of three‐channel waveguides with different core sizes
Authors: Kubo Hiroshi , Yasumoto Kiyotoshi 
Published: July 2007

AbstractAn optical coupler composed of three‐channel waveguides with different core sizes is analyzed numerically. Dispersion relations and field distributions are presented for the lowest three modes in the coupler. It is shown that the geometric parameter of the coupler can be optimized so as to satisfy the condition for a maximum power transfer efficiency.
An accurate distributed model for MIM capacitors
Authors: Sadhir Virender K. , Bahl Inder J. 
Published: July 2007

AbstractThis article reports an accurate model for metal‐insulator‐metal (MIM) capacitors designed for monolithic microwave applications. The distributed nature of the model presented is valid for different substrate thicknesses. This model has been validated by comparing the simulated results with the measured data for several MIM capacitors on a 125‐μm‐thick GaAs substrate.
New receiver scheme for homodyne and intradyne satellite optical links
Authors: Betti S. , De Marchis G. , Iannone E. , Pietroselli M. 
Published: July 2007

AbstractA new receiver scheme is presented for homodyne and intradyne satellite optical links. It is based on the property that the circular polarization of the transmitted optical signal, required in space communication for platform rotation insensitiveness, detected by a polarization diversity receiver provides in‐phase and in‐quadrature electrical signals.
Some experimental investigations on electromagnetically coupled microstrip antennas on two‐layer substrates
Authors: Roy J. S. , Shaw S. K. , Paul P. , Poddar D. R. , Chowdhury S. K. 
Published: July 2007

AbstractThe results of some experimental investigations on electromagnetically coupled microstrip antennas on two‐layer substrates are reported in this article. The variation of input impedance of electromagnetically coupled square and circular microstrip patches, with the degree of overlapping between the patch and feedline, is studied. Also presented is the percentage shift of resonance frequency due to the change of this overlapping. A method of increasing the 1:2 V.S.W.R. bandwidth of the patch antenna is also indicated.
Finite element analysis of semiconductor laser arrays
Authors: Zhao An Ping , Cvetkovic Srba R. 
Published: July 2007

AbstractThis article presents the analysis of semiconductor laser arrays based on the finite element method, with emphasis on nonuniform structures where the channel width and/or refractive index can vary across the array. The results show that the variation of channel width will have the same effect on the near‐field intensity profile as the variation of channel refractive index. Based on this finding, a laser array structure devised to achieve a highly desirable uniform intensity distribution for the lowest‐order mode is also presented.
Mutual coupling between skewed microstrip patch antennas
Authors: Wahid P. F. , Dunn G. L. , Dunn D. S. 
Published: July 2007

AbstractThis article considers mutual coupling as a function of the skew angle between rectangular microstrip patch antennas configured in a two‐element array. Reflection and transmission data for antenna arrays are presented with emphasis on the measured mutual coupling between the elements for varying skew angles.
Two models of optical waveguide modulators independent of polarization
Authors: Zhu Ning Hua , Lin Yi Kun 
Published: July 2007

AbstractTwo novel models of optical waveguide modulators with polarization‐independent operation are created in this article. The efficiencies and the fabricational tolerances of these devices using Z‐cut or Y‐cut LiNbO3 substrate are discussed in detail and the comparison between two models is made.
Accurate computation of mode characteristics for open‐layered circular cylindrical microstrip and slot lines
Authors: Nosich Alexander I. , Svezhentsev Alexander Ye. 
Published: July 2007

AbstractThe results of a highly effective numerical analysis of fundamental and higher‐order modes on open circular cylindrical microstrip and slot lines filled with layered dielectric are presented. The results could be used to optimize the bandwidth and mode‐purity characteristics of the lines.
BI‐isotropic constitutive relations
Authors: Sihvola Ari H. , Lindell Ismo V. 
Published: July 2007

AbstractThe constitutive relations of general bi‐isotropic media, requiring four material parameters, can be written in different ways to describe their electromagnetic behavior. This communication contains a two‐way “dictionary” between a proposed formulation of the constitutive relations with three other sets of relations, generalized from relations used for chiral materials.
Polarimetric scattering characteristics of simple radar targets using Hertz's vector potentials
Authors: Bhattacharyya Asoke K. 
Published: July 2007

AbstractHertz's vector potential is used to compute the co‐and cross‐polarized scattered fields due to simple targets like an arbitrarily oriented wire, an arbitrarily oriented loop of wire, and an infinite cylinder. The monostatic cross‐polarization properties of these targets are studied with different radar and target parameters. Important conclusions are summarized. It is found that under certain combinations of parameters, the cross‐polarization radiation is significant even for simple targets.
Application of the Green's function technique in microstrip patch antenna analysis
Authors: Lehtola Antero , Nikoskinen Keijo I. , Lindell Ismo V. 
Published: July 2007

AbstractMicrostrip structures are now widely used in microwave systems because of their geometrical simplicity, small size, and ease of fabrication. The microstrip structure is inhomogeneous along several directions, which makes the accurate analysis of the electromagnetic fields very difficult. Hence, the design of microstrip devices is mostly done with approximative and empirical methods of limited accuracy. In this report the Green's function technique is used to analyze rectangular microstrip patches. Scalar Green's functions corresponding to the microstrip geometry were derived earlier by the authors. With the aid of these functions, surface currents and resonance frequencies of a patch located in the air/dielectric interface can be computed using the method of moments (MoM). To make the implementation of MoM as simple as possible, numerical approximations for scalar Green's functions are developed. These approximations are functions of permittivity, the frequency, and the thickness of the substrate. Examples of computed results for resonance frequencies of a microstrip patch are given in the present article.