bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variational analysis and synthesis of stepped ridged waveguide transformers
Authors: Tao J. W. , Baudrand H. , Espes P. 
Published: July 2007

AbstractA multimodal variational approach is presented for the analysis and synthesis of stepped ridged waveguide transformers. The introduction of the notion of active and passive modes allows reduction of the order of the matrices handles in the numerical calculations. Measured data are in good agreement with the predicted performances.
Theoretical and experimental determination of the coplanar line dispersion characteristics
Authors: Stoeva Antoaneta , Urshev Ljubomir , Angelov Llcho 
Published: July 2007

AbstractFor calculating the dispersion characteristics of coplanar lines, “a modified method of lines” is applied, based on the separation of the field into TM or TE type modes. The experimental data for the effective dielectric constant are compared to the theoretical results.
Wave propagation in weakly coupled microstrip lines — an anomalous degenerate quasi‐tem solution
Authors: Faria J. A. Brandão 
Published: July 2007

AbstractCoupled‐mode analysis of multiconductor microstrip lines, based on quasi‐TEM approximations, leads to a wave solution usually obtained by superposition of exponential elementary waves. This paper shows that critical situations exist where such simple exponential waves cannot describe the propagation phenomenon. Particular relationships among the quasistatic parameters of a two‐conductor asymmetrical microstrip line are obtained allowing the synthesis of a physically realizable critical situation where an anomalous wave solution is required.
Analysis of finite dielectric sheets with arbitrarily shaped metallization on both sides using the conjugate gradient‐fast fourier transform method
Authors: Cátedra Manuel F. , Alcaraz José A. 
Published: July 2007

AbstractRadiation and scattering from finite dielectric sheets with arbitrary metallization on both sides is analyzed using the conjugate gradient‐fast Fourier transform (CG‐FFT) method to solve a system of integral equations (SIE), where the unknown functions are electric and magnetic equivalent surface currents. The results obtained indicate that the method is efficient and accurate.
Desktop computer models for cad of coplanar lines laid on semiconductor layers with dielectric cap layer
Authors: Delrue R. , Seguinot C. , Pribetich P. , Kennis P. 
Published: July 2007

AbstractFor CAD simulation, it is necessary to determine the frequency behavior of coplanar lines laid on semiconductor substrates. Exact analyses can be performed using numerical techniques such as SDA or mode matching. However such analyses cannot be included in CA D programs. For this purpose, we present an original model for coplanar lines laid on semiconductor substrates, which takes into account both the influence of thickness metallization and dielectric cap layer. The validity of our model is tested by comparison with mode‐matching and SDA results. The influence of metallic losses is quantified and taken into account for micronic structures.
Theoretical calculation of insertion losses of ferrite Y‐junction circulators
Authors: Xu Yansheng , Miao Jianyong , Zhao Junsheng 
Published: July 2007

AbstractIn this paper the dissipative characteristics of some practical Y‐junction ferrite circulators (waveguide and stub tuned stripline circulators) are calculated. By using field analysis and perturbation methods the calculation is both simple and accurate. The calculated results are compared with the experiments in the literature.
Vector expansion functions for the numerical solution of maxwell's equations
Authors: Tanner David R. , Peterson Andrew F. 
Published: July 2007

AbstractVector fields within triangular domains in two‐dimensional space and tetrahedral domains in three‐dimensional space can be conveniently represented by expansion functions that are linear in the spatial variables and have either zero divergence or zero curl. These expansion functions are developed. Numerical solutions for the resonant frequencies of two‐dimensional cavities are presented to illustrate the use of vector functions.
Chromatic dispersion in nonlinear optical waveguides
Authors: Wartak M. S. , Chrostowski J. 
Published: July 2007

AbstractCompound chromatic dispersion has been calculated for waveguides with nonlinear substrate made of heavy metal oxide and fluoride glasses. Negative dispersion was found in a single‐mode regime for those guides. Crossover value of wavelength is waveguide power‐dependent. Such a behavior offers a very attractive pulse compression scheme in the potentially important 3 μm wavelength range.
Design and performance of finline frequency dividers
Authors: Kosmopoulos S. A. , Uher J. , Hoefer W. J. R. , Eldali S. 
Published: July 2007

AbstractThe finline technique has been used for the design and realization of a parametric frequency divider with two varactor diodes, and a harmonically synchronized GaAs FET oscillator‐based frequency divider. Their operational characteristics have been tested in the laboratory over the frequency range from 6 to 22 GHz. These results clearly indicate that finline frequency dividers are very promising for millimeter‐wave applications. Performance limiting factors such as mismatched end effects and phase noise are discussed as well.
An N2 algorithm for the multiple scattering solution of N scatterers
Authors: Chew W. C. 
Published: July 2007

AbstractThe scattering solution from N scatterers, each of whose scattered field is approximated by M harmonics is an NM unknown problem. A straightforward solution to this problem can be obtained by casting it into an NM linear algebraic equation. The solution of the linear algebraic equation will involve order N3M3 flouting point operations. However, via the use of a recursive algorithm and the translation formula, an order N2M3 algorithm to solve such a problem is possible.
Gain‐area product limitation of circular aperture
Authors: Luh Howard H. S. 
Published: July 2007

AbstractCircular apertures are synthesized for maximization of the minimum gain over the coverage area. This study develops the gain‐coverage area product limitation for circular apertures. Two conclusions are: (i) The gain‐coverage area product is not directly proportional to the aperture diameter, (ii) The in‐phase field is the proper field to use in small aperture.
Planar integrated 20 GHz receiver in slotline and coplanar waveguide technique
Authors: Güttich U. 
Published: July 2007

AbstractThe design and performance of a planar integrated 20 GHz receiver in a combined slotline and coplanar waveguide technique on PTFE substrate material is descirbed. The receiving antenna is performed as a Vivaldi aerial, for down‐conversion a balanced mixer circuitry with silicon low barrier diodes is applied, and the local oscillator is realized in a slotline technique using a GaAs MESFET.
Quasi‐tem spectral domain technique for multiconductor structures with rectangular and trapezoidal conductor cross sections
Authors: Kollipara R. T. , Tripathi V. K. 
Published: July 2007

AbstractAn efficient technique based on the quasi‐TEM spectral domain analysis is formulated to compute the characteristic parameters of multiconductor‐multilayered structures with finite thickness conductors having trapezoidal and rectangular cross sections. Computed results for typical single and coupled lines on alumina and GaAs substrates are presented and compared with results based on finite and boundary element techniques and measured data for the effective dielectric constant.
The effect of feed on the input impedance of a microstrip antenna
Authors: Chew W. C. , Nie Z. , Lo Y. T. 
Published: July 2007

AbstractThe input impedance of a probe‐fed, annular‐ring‐loaded, circular‐disk microstrip antenna is analyzed using three methods of increasing complexity. The first method uses a new variational formula. The second method uses a mode‐matching method. The third method uses the mode‐matching method with a diaphragm at the coaxial aperture. The mode‐matching methods are identical to the variational formula under the single‐mode approximation. When a diaphragm is present, the singl‐mode approximation is insufficient, implying the variational formula is inaccurate when a diaphragm exists. The theory shows that the effect of the gap capacitance at the coaxial aperture on the input impedance of the microstrip antenna is important when the dielectric substrate is thick. The theories agree well with experiment data with no fudge factors.
Polarization correction of gutman lens with chiral medium
Authors: Viitanen Ari J. 
Published: July 2007

AbstractThe geometrical optics method for polarization correction of inhomoge‐neous lens antennas introduced recently is here applied to the Gutman lens antenna. For small values of the chirality parameter, the main effect of the chirality is rotation of polarization along the ray. This rotation effect may be used to eliminate the polarization rotation due to the curvature of the rays, to obtain the correct polarization in the aperture. In this paper an analytic expression for the chirality distribution is given for the Gutman lens.
A simple x‐band waveguide‐to‐microstrip E‐probe transition
Authors: Dunn D. S. , Dunn G. L. , Christodoulou C. G. 
Published: July 2007

AbstractA low‐cost, easy to fabricate waveguide‐to‐microstrip E‐probe transition for the entire × band is introduced. Experimental data shows the E‐probe transition to be broadband with low insertion loss. The design of a test fixture to characterize accurately a single waveguide‐to‐microstrip transition is also presented.
Compact semi‐lumped element microwave bandpass filter with harmonic suppression
Authors: Cheng K. K. M. , Everard J. K. A. 
Published: July 2007

AbstractA compact structure for a microwave bandpass filter which uses both microstrip lines and lumped elements is proposed. These filters exhibit broad low‐spurious stopbands, a highly suppressed second passband, and small size. A 4.3‐GHz 23% bandwidth 5‐section prototype has been tested and shows good performance. These filters could find applications in radar and communication systems.
A comparison of reflector antenna designs for wide‐angle scanning
Authors: Zimmerman M. , Lee S. W. , Houshmand B. , Rahmat‐Samil Y. , Acosta R. 
Published: July 2007

AbstractConventional reflector antennas are typically designed for up to ±20 beamwidths scan. In this paper, we try to stretch this scan range to some ± 300 beamwidths by varying various parameters of single‐ and dualreflector antennas. It is found that a symmetrical parabolic reflector with f/D = 2 and a single circular waveguide feed has the minimum scan loss (only 0.6 dB at θ0 = 8°, or a 114 beamwidth scan). Reduction of antenna size by means of focal length folding (Cassegrain) of cluster feed implementation is discussed.
An accurate numerical technique for the analysis of arrow waveguides
Authors: Tewari R. , Singh Hemant , Pal B. P. 
Published: July 2007

AbstractWe report an accurate and simple numerical matrix technique for the analysis of ARROW (anti‐resonant and reflecting optical waveguides). All the relevant parameters for the structure of the ARROW have been studied. The accuracy of the method has been established by comparing results with previously reported exact results. The technique proves to be a powerful tool for the design of complicated devices on the ARROW, thereby providing an accurate design tool for scaling a large number of devices on the ARROW chip.
Harmonic device line simulation of negative resistance microwave mesfet oscillators
Authors: Ongareau Eric , Ghannouchi Fadhel M. , Bosisio Renato G. 
Published: July 2007

AbstractIn this paper, the effects of harmonic load impedance of the terminating network on the input impedance and the output power of the equivalent one‐port negative resistance MESFET oscillators are investigated. Harmonic balance techniques in conjunction with a nonlinear MESFET transistor model are used to simulate the nonlinear response of such one‐port negative resistance oscillators. An appropriate Fourier development of steady state voltage and a current wave forms obtained for a given amplitude and frequency signal are used to calculate the input negative resistance and reactance in device line simulations. It was found that the output power of a one‐port negative resistance MESFET oscillator can be maximized by optimizing the harmonic load impedances of the terminating network.
Radar cross section reduction of a flat plate by ram coating
Authors: Bhattacharyya Asoke K. 
Published: July 2007

AbstractThe problem of reduction of radar cross section (RCS) of a flat plate coated with a radar absorbing material has been examined using the uniform asymptotic theory of diffraction. The variation and reduction of RCS with different parameters have been studied and theoretical results have been compared with the experiment and the spectral Galerkin method.
Microwave optical characterization of high‐speed photodetectors utilizing mode‐locked, pulse‐compressed 1.3‐micron solid‐state laser
Authors: Kasemset D. , Ackerman E. , Chinn S. , Wanuga S. , Krol M. , Stacy J. 
Published: July 2007

AbstractA system is described which uses 2.3‐ps compressed pulses from a mode‐locked YAG (λ = 1.3 μm) laser and a spectrum analyzer to measure the microwave characteristic of photodetectors to frequencies exceeding 100 GHz. This technique has been successfully applied to measure the 15‐GHz bandwidth of an InGaAs photodetector.
Mesfet small signal transfer functions
Authors: Linden P. A. , Fusco V. F. 
Published: July 2007

AbstractThis article presents a signal flow graph representation for a microwave MESFET equivalent circuit. The model has been found to provide accurate fits to NE71000 MESFET chip scattering parameters; typical results are shown. Four symbolic transfer functions are presented which allow device scattering parameters to be computed. The symbolic transfer functions can be differentiated in order to determine component or device behavior sensitivities; sample formula are presented. The principle advantage of the symbolic transfer function approach is that when used as the function evaluation engine in a numerical optimization scheme computational overhead is small. In addition, having analytical derivatives available allows for rapid gradient and sensitivity evaluations that are not prone to numerical approximation inaccuracies.
A novel application in matrix distributed amplifier: The forward‐feed
Authors: D'agostino S. , D'inzeo G. , Lambertucci G. , Marietti P. , Panariello G. 
Published: July 2007

AbstractThis article describes a modification of the matrix distributed amplifier, which yields a wider frequency response employing the forward‐feed method. A detailed study has been developed and we have found some original results. A new circuit configuration that optimizes the performance of the device is presented.
Investigations on planar periodic structures with uniform microstrip lines
Authors: Ghaderi M. , Bhattacharyya A. 
Published: July 2007

AbstractAnalysis of a planar periodic structure formed with two different microstrip line sections is presented. Closed‐form expressions for the ABCD parameters of a structure with N unit cells are derived. The input‐output characteristics of the structure are very similar to a bandpass/bandstop filter. Numerical results for the normalized output power provide good agreement with the measured data.
Ray trajectories and caustic: Clairaut's equation
Authors: Ojeda‐Castañeda Jorge , López‐Olazagasti Estela 
Published: July 2007

AbstractWe show that for an aberrated wavefront the ray trajectories and the caustic are, respectively, the general solution and the particular solution of a Clairaut's nonlinear differential equation. As an example, we obtain the analytical expressions for the caustic and the ray trajectories of spherical aberration and coma.
A rigorous analysis of an aperture‐coupled stacked microstrip antenna
Authors: Wu Chen , Wang Jian , Fralich Russell , Litva John 
Published: July 2007

AbstractA rigorous analysis of an aperture‐coupled stacked microstrip antenna is described. Developed from a coupled integral equation set employing spectral‐domain Green's functions, the analysis includes all coupling, radiation, and surface‐wave effects. Proper choice of the path dimensions yielded VSWR bandwidths of greater than 20%. Theoretical and measured responses are shown to be in excellent agreement.
Performance of convolutional codes with multipulse signaling in optical channels
Authors: Fares Doaa A. 
Published: July 2007

AbstractMultipulse signaling has recently become an attractive alternative format to single pulse position modulation (PPM) utilized in optical communication systems [1]. In Ref. 2, the author analyzed the performance of short constraint length convolutional codes (CC) with the standard PPM model. In this article, CC are extended to multipulse signaling applied to both self‐noise limited, and degraded optical channels. Using this scheme, it is seen that gains in bandwidth expansion and peak‐to‐average power ratios are attainable.
Computation of microwave S‐parameters with the symmetrical condensed node 3D‐TLM method
Authors: Uher J. , Hoefer W. J. R. 
Published: July 2007

AbstractThe symmetrical condensed node (SCN) TLM method is used to compute S‐parameters of various microwave components. A spiral inductor with air bridge, a discontinuous ridge waveguide, a resonant iris, and a double plane waveguide transition are analyzed. The conditions which must be satisfied in the S‐parameter computation of such circuits are defined. The validity of the method is verified by comparison with results obtained by experiment and other numerical methods. Very good agreement with those results has been achieved by virtue of the excellent wideband absorbing boundaries implemented in our method.
A technique for the measurement of mutual impedance of monolithic solid‐state quasioptical oscillators
Authors: Shillue William P. , Stephan Karl D. 
Published: July 2007

AbstractA technique for the measurement of mutual impedance of monolithic solid‐state quasioptical oscillators is described. Varying the spacing between one oscillator and its mirror image causes a frequency shift that can be used to calculate mutual coupling. The theory is confirmed through measurements of a 51‐GHz monolithic IMPATT oscillator.
A finite‐difference time‐domain formulation for transient propagation in dispersive media associated with Cole‐Cole's circular ARC law
Authors: Kashiwa Tatsuya , Ohtomo Youichi , Fukai Ichiro 
Published: July 2007

AbstractThe three‐dimensional time‐domain formulation for dispersive media which obey Cole‐Cole's circular arc law is presented using the finite‐difference‐time‐domain (FD‐TD) technique. The validity of the formulation is verified by comparing the calculated complex dielectric constant to analytical values.
Integrated 222‐GHz corner‐reflector antennas
Authors: Gearhart Steven S. , Ling Curtis C. , Rebeiz Gabriel M. 
Published: July 2007

AbstractA high‐gain monolithic millimeter‐wave antenna has been designed, fabricated and tested at 222 GHz. The structure consists of a traveling‐wave antenna integrated on a 1.2‐μm dielectric membrane and suspended in a longitudinal cavity etched in a silicon wafer. A new traveling‐wave antenna design yields a wideband input impedance and a low cross‐polarization component in the E‐ and quasi‐H‐plane patterns. A directivity of 17.7 dB and a main‐beam efficiency of 88.5% are calculated from the 222‐GHz pattern measurements. The integrated corner‐reflector antenna is well suited for millimeter‐and submillimeter‐wave imaging applications in large f‐number systems.
Diode multipliers for submillimeter‐wave InAlAs/InGaAs heterostructure monolithic integrated circuits
Authors: Kwon Y. , Pavlidis D. 
Published: July 2007

AbstractInAlAs/InGaAs heterostructures are studied as multiplier elements for submillimeter‐wave monolithic integrated circuits. The designs considered for this purpose are based on the principle of conventional HEMT, HEMT with n+bottom layer and a new proposed scheme of quantum‐confined modulated charge (QCMC). The QCMC diode is analyzed theoretically and experimentally showing its potential operation capability at 1.5 THz.
Planar schottky barrier mixer diodes for space applications at submillimeter wavelengths
Authors: Bishop W. L. , Crowe T. W. , Mattauch R. J. , Ostdiek P. H. 
Published: July 2007

AbstractThere is great interest in the development of planar diodes for space‐based applications at submillimeter wavelengths for reasons of ruggedness, reliability, and simplicity of receiver assembly. The inherent problems of developing such a device are outlined and a new structure that combines low parasitic capacitance and ease of manufacture is described.
Accurate quasi‐tem analysis of modified coupled suspended microstriplines and its application to directional coupler design
Authors: Masot F. , Medina F. , Horno M. 
Published: July 2007

AbstractIn this article an efficient and accurate quasi‐TEM analysis of a pair of boxed coupled microstrips with slotted ground plane is carried out. The properties of directional couplers based on this structure are theoretically studied. A synthesis program has also been developed, and an example of graphic design charts is provided for a low permittivity substrate.
Some investigations on the effect of the location of feed on the impedance of a rectangular microstrip antenna operated in the first higher‐order mode
Authors: Paul Pranab , Roy Jibendu Sekhar , Poddar Dipak Ranjan , Chowdhury Santosh Kumar 
Published: July 2007

AbstractThe variation of input impedance of a rectangular microstrip antenna with the change of location of feed point is studied. An improvement in the 1:2 VSWR impedance bandwidth is achieved by exciting the antenna at the first higher‐order mode.
A new transducer for thermography to observe the electric field distributions in a microwave oven
Authors: Kashiwa Tatsuya , Naya Hidemitsu , Fukai Ichiro 
Published: July 2007

AbstractThe electric field pattern in a microwave oven is often observed as a heat pattern using thermography by using an appropriate transducer. In this article, a new type of observing plate is proposed as a transducer of the electric field into heat.
A comparison of the boundary‐integral method without using green's function and the field matching method
Authors: Dou W. B. 
Published: July 2007

AbstractA new boundary‐integral method without using Green's function for solving Dirichlet‐ and Neumann‐type boundary‐value problems of a two‐dimensional scalar wave equation has been recently proposed. In the present article we compare this new method with the field matching method. It has been found that the eigenvalue equation derived from the new boundary‐integral method is identical to that derived from the field matching method.
Mixing efficiency in a coherent optical receiver
Authors: De Marchis G. , Lannone E. , Matera F. 
Published: July 2007

AbstractIn this article the mixing efficiency of an optical coherent receiver is calculated using the Stokes parameter representation for the involved fields. It allows us to obtain formulas of immediate interpretation and computation that can be useful for optical coherent communication system performance evaluation and for the analysis of optical coherent sensors. Moreover, a new scheme for active polarization tracking based on the obtained results is presented that is useful for fiber coherent optical communications.
Prediction of the harmonic and intermodulation distortion in semiconductor laser diodes
Authors: Abuelma'Atti Muhammad Taher 
Published: July 2007

AbstractA simple technique is presented for predicting the harmonic and intermodulation performance of semiconductor laser diodes driven by multisinusoidal current signals. This technique requires only simple hand calculations for predicting amplitudes of harmonics and intermodulation products of any order and thus avoids the use of accurate circuit models and sophisticated methods of analysis.