bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of broadside coupled cylindrical striplines
Authors: Reddy C. Jagadeswara , Deshpande Manohar D.
Published: July 2007

This letter presents a method for calculating the even and odd mode impedances of broadside coupled cylindrical striplines using the conformal mapping technique. Closed form expressions are presented for calculating the even and odd mode characteristic impedances. The data for even and odd mode impedances are presented. The analysis can also be extended to warped broadside coupled striplines.
Mode spectrum of waveguides using a generalized mode matching technique
Authors: Gruner L.
Published: July 2007

The mode spectrum of a large number of waveguides having different cross‐section geometries has been determined using a generalized mode matching technique, based on a Fourier expansion in each domain.
Propagation characteristics of superconductive interconnects
Authors: Cangellaris A. C.
Published: July 2007

Under the assumptions of weak magnetic fields and temperatures well below the critical temperature of the superconductors, the propagation characteristics of a set of N coupled superconducting strips are calculated using an integral equation approach. The proposed theory provides accurate results for frequencies up to a few GHz. Magnetic field calculations allow us to predict acceptable values for the currents in the strips. Comparison with the propagation characteristics of aluminum strips demonstrates the major advantages of superconducting transmission lines, namely, negligible losses and dispersion, and higher phase velocities. Such properties are highly desirable in the engineering of fast interconnects for modern high‐speed integrated circuits.
Microwave behavior of electroless microstrip lines on SI GaAs substrates
Authors: Sinha M. P. , Mahapatra S.
Published: July 2007

A technique of fabrication and evaluation of microstrip lines onto undoped semi‐insulating (SI) GaAs substrates is described. The fabrication technique is based on the electroless plating of nickel flashed with gold. The evaluation includes the measurements of transmission and reflection properties of microstrip lines. The measured data for insertion and return loss are encouraging.
Mfsk signal detection using acousto‐optic joint transform correlator
Authors: Yu Francis T. S. , Nagata Toshio
Published: July 2007

A multichannel acousto‐optic joint transform correlator is presented. On‐plane acousto‐optic (AO) cells and a square‐law converter are employed. The AO cells are driven by frequency multiplexed temporal signals to produce spatially modulated signals. The joint transform power spectrum is generated with a square‐law converter. By inverse Fourier transformation with a coherent readout, the cross correlation of input signals can be obtained. Since the architecture can process wideband signals, it may be applied to detect multiple frequency shift keying (MFSK) signals.
Waveguide measurements on dye‐filled hollow‐core fibers as laser systems
Authors: Englert Thad J. , Flohr Mark C.
Published: July 2007

Preliminary measurements of the waveguide properties of hollow‐core glass fibers filled with an index‐matching dye solution indicate that such fibers may be useful as dye laser systems. Efficient guidance of 632.8 nm light is found for various core diameters and lightwave polarization is retained over 1‐m lengths.
Aberration balancing for shade annular pupils
Authors: Ojeda‐Castañeda J. , Gomez‐Sarabia C. M.
Published: July 2007

We report a simple, yet powerful, Fourier optics formalism for balancing wave aberrations with circular symmetry. Our balancing method is valid either for clear annular apertures (the clear circular aperture being a particular case) or for certain shade annular pupils. We relate our method with Maréchal's tolerance treatment.
A fiber optic recirculating memory loop for radar applications
Authors: Koffman I. , Herczfeld P. R. , Daryoush A. S. , Even‐Or B. , Markowitz R.
Published: July 2007

The use of optical fibers as the delay line element in radio frequency memory loops, promises light weight and small size devices with long time delays. This paper presents the experimental results and performance analysis of a 2‐6‐GHz fiber optic recirculating delay line.
A note on a parabolic elliptical prime‐fed offset reflector antenna
Authors: Knop C. M. , Cheng Y. B.
Published: July 2007

An extension of the analysis of the parabolic circular prime‐fed offset antenna to the elliptical prime‐fed offset case is given. An example design with experimental verification is provided. Advantages / disadvantages of this elliptical case are discussed.
Resonant behavior of conducting slotted rectangular shells
Authors: Wang Tai‐Mo , Ling Hao
Published: July 2007

A parametric study of scattering from a slotted rectangular shell is presented. The E‐field integral equation for the TM excitation is solved using the method of moments. Resonance spikes in the scattering width appear at frequencies that correspond to the resonant frequencies of the interior cavity. When the slot size increases, the resonance spikes shift down as well as broaden in frequency. A different set of modes is excited when the slot position changes. For a slot on the shadow region of the incident wave, the resonance spikes do not appear.
Joint fourier transform processor
Authors: Yu F. T. S. , Ludman J. E.
Published: July 2007

A joint Fourier transform processor can be used as a conventional coherent optical processor. In principle, the joint transform processor can perform all the optical data processing that a conventional coherent optical processor can offer. Sample illustrations for signal extraction and image subtraction are given. The major advantages of the joint transform processor must be (1) the avoidance of synthesizing a matched spatial filter, (2) higher space‐bandwidth product, (3) lower spatial carrier frequency requirement, (4) higher output diffraction efficiency, etc.
Concentric ring microstrip antenna
Authors: Nurie N. S. , Langley R. J.
Published: July 2007

A concentric ring element has been investigated as a dual frequency band microstrip antenna. A model is presented for calculating the input impedance properties that include mutual coupling effects. It is shown that the radiation patterns may be computed from the TM12 mode fields for a single ring.
Attenuation coefficient of the guided mode supported by a metal‐clad planar dielectric waveguide
Authors: Seshadri S. R.
Published: July 2007

The attenuation coefficient of the guided mode supported by a metal‐clad planar dielectric waveguide is deduced by a perturbation technique that is commonly used for metallic waveguides for both the transverse electric and the transverse magnetic modes.
Regularization of permittivity profiles reconstructed by a spectral inverse scattering scheme
Authors: Choi Hyun‐Chul , Ra Jung‐Woong , Kim Se‐Yun
Published: July 2007

A spectral inverse technique, applying the moment‐method procedure with a series expansion for the induced field in each enlarged cell, is suggested to reconstruct permittivity profiles of inhomogeneous dielectric objects. In particular, averaging the reconstructed permittivity distribution over each cell with a weighting function becomes an effective tool to regularize the error arising from a Gaussian random noise of the scattered field.
Theoretical analysis of a four‐level single‐mode fiber laser
Authors: Wang Qing‐Hai , Lian Han‐Xiong
Published: July 2007

The relation between the output power and input pump power and then the threshold pump power and slope efficiency of a four‐level single mode fiber laser is analysed in terms of the four‐level rate equations and the numerical results are in good agreement with the available experimental results by M. Shimizu (1987). Meanwhile, the theoretical model of this paper is simpler and more reasonable than that of Shimizu and is applied to design a single mode fiber laser as well as a single mode fiber amplifier with four‐level material.
Optical processors using modular number codes for complex signals
Authors: Baraniecki Anna Z.
Published: July 2007

Techniques are described for implementing an optical matrix‐vector processor for complex signals. A representation of complex numbers based on modular algebra is utilized to decouple real and imaginary channels, thereby simplifying the implementations. The pipelined architecture of an optical matrix‐vector processor is described.
Hybrid‐mode analysis of asymmetrical shielded dielectric resonator
Authors: Duarte Adriao D. N. , Baudrand Henri
Published: July 2007

A rigorous analysis is presented to determine the resonant frequency and Q factor of an asymmetrical resonator. The Galerkin method is used for the resonant frequency calculation, and the computation time is largely reduced by evaluating the integrals analytically. The method is found to converge rapidly by taking different numbers of modes in the dielectric and air regions yielding an excellent characterization of an asymmetrical dielectric loaded cavity. The agreement of the obtained results with experimental data proves the validity of the method.
A spectral domain approach to electromagnetic coupling through apertures in planar conducting surfaces
Authors: Kouki A. B. , Chan C. H. , Mittra R.
Published: July 2007

A spectral domain approach to solving planar aperture type problems is described. The method is first formulated for an arbitrary aperture in a conducting plane separating two half‐spaces, then applied to the case of a fin‐line structure. The formulation is carried out in the spectral domain in terms of the aperture electric field instead of the electric current density on the plane. The TE‐TM decomposition of the fields in the spectral domain is used in conjunction with the transmission‐line equivalent model to construct the Green's functions associated with the problem.
Variational analysis and synthesis of stepped ridged waveguide transformers
Authors: Tao J. W. , Baudrand H. , Espes P.
Published: July 2007

A 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

For 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

Coupled‐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.
IFM receiver with capability of detecting simultaneous signals
Authors: Tsui James B. Y.
Published: July 2007

A method for detecting many simultaneous signals in an IFM receiver is described. The method uses correlation lags to calculate the frequencies of the input signals. Practical considerations and performance are discussed.
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

Radiation 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

For 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.
Morphological transformation using optical symbolic substitution
Authors: Cherri A. K. , Karim M. A.
Published: July 2007

Phase‐only hologram based optical symbolic substitution architecture is used for realizing digital‐optical morphological transformations. Accordingly, symbolic substitution schemes are applied to binary images to perform erosion, dilation, opening, and closing operations.
Theoretical calculation of insertion losses of ferrite Y‐junction circulators
Authors: Xu Yansheng , Miao Jianyong , Zhao Junsheng
Published: July 2007

In 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

Vector 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

Compound 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

The 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

The 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

Circular 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

The 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

An 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

The 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

The 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

A 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

A 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

Conventional 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

We 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.
On the analysis of parallel coupled transmission lines in an inhomogeneous medium
Authors: Nguyen Cam
Published: July 2007

A theoretical analysis of general n coupled transmission lines in an inhomogeneous medium is presented. Explicit solutions for the properties of the coupled‐line system, including the case where all the lines have the same characteristic impedance, are derived. Results for two and three coupled lines are found in agreement with previously published results.
Harmonic device line simulation of negative resistance microwave mesfet oscillators
Authors: Ongareau Eric , Ghannouchi Fadhel M. , Bosisio Renato G.
Published: July 2007

In 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

The 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

A 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.
Application of equivalent transmission line concept to the method of lines
Authors: Urshev Ljubomir , Stoeva Antoaneta
Published: July 2007

A method for calculating the dispersion characteristics of transmission lines with metal strips at several dielectric interfaces is developed, based on the application of the equivalent transmission line concept to the method of lines.
Mesfet small signal transfer functions
Authors: Linden P. A. , Fusco V. F.
Published: July 2007

This 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

This 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

Analysis 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

We 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

A 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

Multipulse 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

The 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

A 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

The 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

A 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

InAlAs/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

There 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

In 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

The 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

The 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

A 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

In 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

A 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.
A spectral‐domain method for the analysis of the fundamental‐mode leakage effect in microstrip lines on uniaxial substrates
Authors: Michalski Krzysztof A. , Zheng Dalian
Published: July 2007

A simplified spectral‐domain integral‐equation method is applied to analyze the recently discovered fundamental mode leakage effect in open microstrip transmission lines with uniaxial substrates.
A series‐biased distributed amplifier for high‐efficiency applications
Authors: Willems David , Bahl Inder , Wirsing Kelly
Published: July 2007

This article presents a novel circuit configuration which combines a high‐voltage dc bias network with a distributed‐amplifier topology. This type of circuit offers multioctave bandwidth and improved efficiency in systems by reducing dc power consumption where the primary dc power is at voltage levels higher than required operating voltage for the active devices.
On‐axis cross‐polarization discrimination of reflector antennas with random surface errors
Authors: Herben M. H. A. J.
Published: July 2007

An approximate formula is derived for the on‐axis cross‐polarization discrimination (XPD) of a symmetrical reflector antenna with random surface errors. This XPD depends on only two parameters, namely, the normalized r.m.s. surface error (ϵ/λ) and the polarization‐loss efficiency (n).
Image classification by the Kittler‐Young transform using A joint transform correlator
Authors: Li John X. , Yu Francis T. S. , Gregory Don A.
Published: July 2007

This article will discuss a two‐category image classification which has been performed on a joint transform correlator (JTC) by using the Kittler‐Young transform. The property of optimally utilizing the class means and variances in the Kittler‐Young transform has enabled a high space‐bandwidth‐product operation. The digitizing effect of the liquid crystal television has been utilized to increase the correlation peaks.
Empirical expressions for the input impedance of rectangular microstrip antennas
Authors: Deb D. , Gupta A. , Das S. , Palit D. , Bhattacharjee A. K.
Published: July 2007

Closed‐form expressions for the input impedance of half‐wavelength rectangular microstrip antennas fed by a coaxial line at the center of one of the radiating edges and open‐circuited at one of the ends are derived. Good agreement between computed and measured data is obtained.
Microstrip resonator on anisotropic substrate in a shielding waveguide
Authors: Cheng Dajun , Xue Liangjin
Published: July 2007

The dyadic Green's function in the Fourier‐transform spectral domain for a microstrip patch on an anisotropic substrate in a shielding rectangular waveguide is presented. Numerical data for resonant frequencies are provided using Galerkin's method in the spectral domain and Parseval's theorem.
Horn antenna with suppressed sidelobe level
Authors: Odendaal J. W. , Pistorius C. W. I.
Published: July 2007

A method whereby the sidelobe level of the radiation pattern of a horn antenna can be reduced is proposed. The sidelobes are reduced by curving the edges in the aperture of the antenna. Radiation patterns of regular and modified horns were calculated with GTD and compared with measured results.
Hot electron microwave incremental conductivity characteristics of cadmium telluride
Authors: Chakrabarty D. , Mukherjee M. K. , Mukhopadhyay D.
Published: July 2007

The incremental microwave mobility values for electrons in the presence of a large applied dc field have been calculated in cadmium telluride, assuming a displaced Maxwellian distribution function for the energy of the electrons. It is found that both the real and imaginary parts of the parallel and perpendicular microwave mobility decrease monotonically with the applied dc field. The imaginary part of the microwave mobility, which is a measure of the contribution of free carriers to the dielectric constant, is higher in this material than in III‐V compound semiconductors and shows a peak in the submillimeter‐wavelength range.
Frequency‐domain nonlinear analysis of microwave circuits using frequency‐domain diode model
Authors: Liang Han , Yunyi Wang , Sifan Li
Published: July 2007

This article presents a new nonlinear analysis method of the microwave circuits under multitone excitation. A frequency‐domain diode model and an adaptable spectral balance algorithm are first proposed and the full nonlinear analysis is performed entirely in the frequency domain for a microwave mixer driven by multitone signals. Some frequency‐conversion performances of mixer are investigated in detail.
Quasi‐TEM analysis of the generalized microstrip line by using FFT and iterative methods
Authors: Drake Enrique , Medina Francisco , Horno Manuel
Published: July 2007

A quasi‐TEM analysis of a generic microstrip line is carried out by the combined use of iterative methods and FFT. Asymptotic extraction techniques are used in the determination of the Green's function, allowing reduction of memory storage requirements and CPU time. Several iterative algorithms are compared for solving the final system of convolution linear equations. Numerical results are presented and compared with published data.
Efficient implementation of the finite element method for the rigorous analysis of complex boxed planar resonators
Authors: Railton C. J.
Published: July 2007

The accurate analysis of complex planar resonators using the finite element method often requires the evaluation of the elements of a large matrix. This is computationally expensive. In this contribution it is shown that by using the fast Fourier transform together with asymptotic forms of the Green's function the computation time can be greatly reduced allowing the solution of relatively complex problems on a small computer.
High performance MESFET power amplifiers for high volume application in KA band
Authors: Mondal J. , Carlson D. , Pulver C. , Vickberg M. , Geddes J.
Published: July 2007

A very repeatable MBE power MMIC process has been developed for low‐cost and high‐volume Ka‐band applications. The RF yield under power drive has reached more than 60%. The power out in a balanced configuration was 300 mW with 18% power added efficiency at 30 GHz.
Coplanar waveguide‐fed microstrip antennas
Authors: Aksun M. I. , Chuang S. L. , Lo Y. T.
Published: July 2007

A microstrip antenna fed by a coplanar waveguide is investigated using a full‐wave analysis based on the method of moments in the spectral domain. The surface current density on the microstrip antenna and the field distribution in the slots of the coplanar waveguide are represented by entire domain and subsectional basis functions. The reflection coefficient referenced on the coplanar waveguide is calculated and compared to the experimental results.
Thin‐wire Yagi antenna radiation patterns using the finite‐difference time‐domain method
Authors: Boonzaaler J. J. , Pistorius C. W. I.
Published: July 2007

The radiation patterns of thin‐wire Yagi antennas are computed using the finite‐difference time‐domain method. The radiated time‐do main fields are transformed to the frequency domain and then compared to the frequency‐domain results obtained from the method of moments.
Theory of a new type of TEM cell of variable characteristics
Authors: Lin Weigan
Published: July 2007

The special cases of a general coaxial rectangular line with square outer conductor and inner cross conductor of equal arms are solved analytically by means of conformal transformations.
A six‐port technique application of measuring complex permittivity and permeability
Authors: Jiang Cao , Jia Sun , Zhang Qishao
Published: July 2007

A six‐port technique is presented for simultaneous measurement of complex permittivity and permeability of a given material. A dual six‐port network analyzer is employed to measure the scattering parameters. The complex permittivity and permeability are computed from the scattering parameters of a transmission line filled with the material to be tested. Measured ϵr, μr, data for Teflon agree well with known values. The identical samples are measured with a six‐port ANA and an automatic network analyzer, HP8510B. The measured data of the six‐port ANA and the HP8510B agree well with each other by comparison.
Measurement of electro‐optic effects in acrylic plastic
Authors: Ishii T. Koryu , Griffis Andrew
Published: July 2007

The quadratic electro‐optic effect in commercial acrylic plastics was determined. The induced birefringence in the Plexiglas was measured to be 2.47 × 10−7 and the resultant Kerr constant was 3.52 × 10−14 m/V2 for an electric field intensity of 3.33 × 106 V/m.
A novel approximation method for asymmetrical coplanar lines
Authors: Chang Jiunn‐Jye , Wang Way‐Seen
Published: July 2007

In this article a novel approximation method is proposed to calculate the quasi‐TEM parameters of asymmetrical coplanar lines. The method is based on simulating an asymmetrical coplanar line with two symmetrical ones. The line parameters of asymmetrical coplanar waveguides calculated using the proposed method are presented and a comparison between the calculated and available results shows good agreement.
Conservation of energy for a weakly irregular, open‐ or close‐bounded dispersive medium
Authors: Schill Robert A.
Published: July 2007

A variational technique is used to develop an energy‐conservation theorem for a dispersive, anisotropic medium bounded by a weakly irregular open or closed structure. The weakly active/dissipative medium supports growing/decaying waves. Corrections in wave number and frequency are dependent on the instability properties of the wave for the open structure. New contributions to the power flux density and energy density result. For open and closed structures, the ratio of the corrections in wave number and frequency is dependent on the reactive properties of the structure walls. Effective wall‐resistance contributions for open structures further modify this ratio. Mode‐coupling and growth‐rate relationships are examined.
Application of the extended boundary condition method to monte carlo simulations of scattering of waves by two‐dimensional random rough surfaces
Authors: Tsang L. , Lou S. H. , Chan C. H.
Published: July 2007

The extended boundary condition method is applied to Monte Carlo simulations of two‐dimensional random rough surface scattering. The numerical results are compared with one‐dimensional random rough surfaces obtained from the finite‐element method. It is found that the mean scattered intensity from two‐dimensional rough surfaces differs from that of one dimension for rough surfaces with large slopes.
A microstrip coupler through a narrow slot in the common ground plane of a two‐sided microstrip circuit board
Authors: Lin C. C.
Published: July 2007

An empirical design of a microstrip coupler through a narrow slot in the common ground plane of a two‐sided microstrip circuit board is presented. The power transmission between a microstripline on a high‐permittivity ceramic substrate (εr = 9.8) and one on a low‐permittivity Teflon‐based substrate (εr = 2.2) is measured at near‐millimeter‐wave frequencies for a varying slot length. It is demonstrated that such a contactless transition can successfully be used with an acceptable loss in order to couple the power from one side to the other of a two‐sided microstrip circuit board.
Optical demonstration of the hartline lateral inhibition model
Authors: Zhou Changhe , Liu Liren , Wang Zhijiang
Published: July 2007

The Hartline model is an important neural network model which reveals the lateral inhibition in neural systems. In this article an optoelectronic architecture is proposed for implementing the Hartline model, in which an incoherent optical convolutor is used for the realization of the convolution operation and a polarization‐coding method for the representation of the connection weights in the Hartline model. The subtraction is performed by electronics. Preliminary optical edge‐enhancement experiments for two‐dimensional images illustrate the versatility of the network.
Calculation of characteristic impedance of broadband tem cell (BTEM cell)
Authors: Huang Kama , Lin Weigan
Published: July 2007

The main section of a newly appearing broadband TEM cell (BTEM cell) can be mapped into a cylinder via conformal transformation in three dimensions. Its outer conductor is approached by using an upper rectangular conductor from above and by a lower rectangular conductor from below; then the maximum and the minimum values of characteristic impedance are calculated. The average of the two extreme values is in good agreement with the actual characteristic impedance when the flared angles is small.
A ka‐band low‐noise hybrid amplifier
Authors: Holzman Eric L.
Published: July 2007

The design, fabrication, and performance of a Ka‐band, two‐stage, low‐noise hybrid amplifier (LNA) are discussed. The LNA's extremely wide‐band measured performance is state of the art with a gain exceeding 10 dB from 14 to 37 GHz and a noise figure less than 3 dB from at least 27 to 37 GHz.
High‐power microwave bipolar transistor modeling
Authors: Asensio Alberto , Pérez Félix
Published: July 2007

This article introduces a model for high‐power microwave bipolar transistors and its associated parameter‐measuring strategy, whose inclusion of thermal phenomena in the dc characterization allows a good estimate of the device's thermal resistance to be obtained. This type of model provides important capabilities for solid‐state radar transmitter design.