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This paper investigates the structural evolution in a magnetic fluid microstrip under external magnetic fields parallel to the strip surface. It is shown that as the field strength increases, the structure evolves from an originally monodispersed state to a disordered magnetic chain state, and then to a one-dimensional ordered structure of chains. For the ordered structure state, the chain spacing is reduced with an increase in field strength, because more columns form under higher fields. Thus, a tunable one-dimensional ordered structure can be achieved in magnetic fluid films under parallel magnetic fields. The manipulations of the tunability of the ordered structure under various control parameters, such as the sweep rate of the magnetic field, the fluid concentration, and the strip width, are also discussed. [ABSTRACT FROM AUTHOR]

The importance of synthesizing carbon nanotubes with iron nanowires inside (Fe-MWNTs) via microwave radiation lies in the fact that it allows to improve aspects such as selective and uniform heating of the sample, reduction of the time of synthesis, avoiding complex experimental procedures and lowering the cost of production. In this paper we synthesize and characterize carbon nanotubes with iron nanowires inside using a mixture of graphite and iron acetate powders as starting materials and a 900 W domestic microwave oven used as power source. A mixture of the starting materials inside a vacuum sealed quartz ampoule was subjected to radiation for 7 min. As a result straight Fe nanowires are obtained with lengths between 5 and 15 microns, and a wide variety of partially Fe filled nanotubes with diameters in the 30-80 nm range. Samples were characterized with scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

The U-slot patch antenna, a single-layer single-patch antenna on a relatively thick substrate (~ 0.08 [lambda].sub.o), is a wide-band antenna with an impedance bandwidth in a range of 20%-30%, which is about an order of magnitude larger than that of the regular patch antenna. Recently, it was shown that a half U-slot patch antenna, with half of one of the dimensions of the U-slot patch, maintains similar wide-band behavior. The half-structure was also successfully applied to the U-slot with shorting wall. In this paper, new results on half structures, not previously published, are presented. First, the shorting pin technique is used to reduce the size of the half U-slot patch antenna. By both simulation and experimental studies, it is concluded that the impedance bandwidths, radiation patterns, radiation efficiencies and gains of the half-structures are comparable to the corresponding full structures. Bandwidth of 28.6% and radiation efficiencies exceeding 90% are obtained for the half U-slot patch with shorting pin. Radiation patterns are stable across the matching band. Second, it is shown that a structure obtained from halving the E-shaped patch, which is a derivative of the U-slot patch, also maintains its wide-band behavior. Index Terms--Broadband antennas, microstrip antennas.

Novel compact parallel-coupled microstrip bandpass filters are proposed by using additional lumped inductors to realize K-inverters between coupled-line sections to achieve an equivalent to the quarter-wavelength ([lambda]/4) resonator filters. As a resuit, the filter order can be doubled without increasing the circuit area, and no repeated passband is observed at twice the center frequency. In addition, by introducing the cross-coupling effect, two transmission zeros at upper and lower stopbands may be created. Simple equivalent-circuit models are also established as effective design tools. Specifically, several compact fourth-order microstrip bandpass filters with good stopband rejection are implemented and carefully examined. Index Terms--Bandpass filter, coupled line, lumped element, microstrip.

Quadruplet microstrip filters with source-load coupling are proposed to achieve similar skirt selectivity and/or in-band flat group delay as that of a sixth-order canonical form or an extracted pole microstrip filter. The diagnosis method of unwanted effects such as asynchronous resonant frequencies and unwanted couplings, which often occurs in the microstrip's open environment, is described in detail. A systematic design flow to implement a quadruplet microstrip source-load coupled filter with proper filter response is also provided. Two trial filters exhibited quasi-elliptical and flat group-delay response are designed and fabricated. Both theoretical and experimental results are presented. Index Terms--Diagnosis, flat group delay, microstrip quadruplet filter, source-load coupling.

The development and testing of a two-dimensional (2-D) prototype detector based on a microstrip gas chamber (MSGC) are reported. The second coordinate is obtained by utilising a plane of wires as pick up electrodes. The detector is operated with the wire plane at such a potential so as not to induce any gain around the wires. This means that the high tolerances normally associated with wire planes in multiwire proportional counters are not necessary, making the manufacture and repair of such a device relatively easier. The detector comprises of 48 individually instrumented channels in both X (MSGC strips) and Y (transverse wire plane). A specially designed encoding module has been constructed which feeds digital addresses for each event to the ISIS data acquisiton electronics (DAE) system. (ISIS is the spallation neutron source at the Rutherford Appleton Laboratory.) An intrinsic detector resolution of ~ 0.5 mm full-width at half-maximum (FWHM) has been measured for both dimensions which is degraded slightly by the digital resolution for the overall system. This readout method is shown to be very tolerant of a poor signal-to-noise ratio in the readout channels (unlike traditional analogue wire chamber readout systems) and permits the operation of the MSGC at moderate avalanche gains (~ 1000) which helps to maximize the rate and lifetime performance of the detector as well as permitting data capture rates in the MHz range. Index Terms--Gas microstrip detector, MSGC, X-ray imaging detector.

This paper presents the design of a novel branch-line coupler that can operate at two arbitrary frequencies. The proposed circuit also features compact size and planar structure. Explicit design formulas of the proposed dual-band coupler are analytically derived. Moreover, practical issues such as the realization of branch-line impedance and optimum choice of circuit topologies are addressed. For verification purposes, both simulated and measured results of a microstrip branch-line coupler operating at 900/2000 MHz are included. Index Terms--Couplers, dual band, planar circuits.

A capillary plate (CP) comprising an assembly of fine glass tubes was applied as a pre-gas-amplification device for a microstrip gas chamber (MSGC) operating under a gas pressure of 3 atm of helium-3 for use in neutron detection. The collection efficiency of the electrons between the CP and MSGC was maximally 17% using neutrons. The effective gas gain of the detector system was ~600 at a gas pressure of 3 atm with a 10% mixture of ethane with helium-3, confirming the feasibility of the CP as a pre-gas-amplification device. Moreover, we demonstrated that the coincidence measurement of the signals between the CP and the anodes of MSGC decreased the background levels of electronics noise, electronic discharges, and gamma-rays, indicating that a detector system with a low background can be constructed using the CP. Index Terms--Capillary plate (CP), gas gain, microstrip gas chamber, neutron detector.

Bandpass filters with an optimal rejection bandwidth are designed using parallel-coupled stepped impedance resonators (SIRs). The fundamental ([f.sub.o]) and higher order resonant harmonics of an SIR are analyzed against the length ratio of the high-Z and low-Z segments. It is found that an optimal length ratio can be obtained for each high-Z to low-Z impedance ratio to maximize the upper rejection bandwidth. A tapped-line input/output structure is exploited to create two extra transmission zeros in the stopband. The singly loaded Q([Q.sub.si]) of a tapped SIR is derived. With the aid of [Q.sub.si], the two zeros can be independently tuned over a wide frequency range. When the positions of the two zeros are purposely located at the two leading higher order harmonics, the upper rejection band can be greatly extended. Chebyshev bandpass filters with spurious resonances up to 4.4 [f.sub.o], 6.5 [f.sub.o], and 8.2 [f.sub.o] are fabricated and measured to demonstrate the idea. Index Terms--Microstrip, microwave filter, spurious response, stepped impedance resonator (SIR), transmission zero.

A two-port ring resonator is used to characterize the microwave properties of a microstrip line printed on Ferro A6-S low-temperature co-fired ceramic. The ring and its coupling gaps are simulated using a simple lumped-element model. The coupling gaps are modeled as capacitors, the values of which are extracted using a commercial two-and-one-half-dimensional electromagnetic simulator. The validity of the lumped-element model is assessed by comparing the simulated and experimental resonant frequencies and, for the first time, the simulated magnitudes of both the reflection and transmission coefficients are also compared with those obtained experimentally. A correction for the frequency pushing due to the capacitive loading of the coupling gaps is also presented. The resulting model is then shown to predict the resonant frequencies to within 0.11% from 5 to 40 GHz. The simulated and experimental reflection magnitudes are within 0.5 dB across the band, whereas the transmission magnitudes are within 3.5 dB up to 22 GHz. Experimental results indicate that the loss of the microstrip ranges from approximately 0.11 to 0.42 dB/cm across the band and that the relative permittivity of the substrate is nearly constant versus frequency with an average value of 6.17. Index Terms--Attenuation and permittivity measurements, equivalent lumped elements, resonant frequency, ring resonator.

This paper presents a new impedance matrix interpolation algorithm, in the context of method of moments, for planar microstrip structures. Three different interpolating functions are implemented depending upon the distance between the basis and testing functions. To demonstrate its efficiency, the technique is applied to several planar microstrip structures, viz. a patch antenna fed by microstrip line and a 4 x 4 planar patch array. It is demonstrated that the use of the proposed impedance matrix interpolation scheme can result in significant savings in the computation time with little or no compromise in the accuracy of the solution. Index Terms--Impedance matrix interpolation, method of moments (MOM), microstrip patch antenna, probe-fed square patch array.

This paper describes a full-wave moment-method analysis of an aperture-coupled microstrip coupler using a resonant cavity (rectangular or circular) between the substrate ground planes. Structures of this type are useful for millimeter-wave integrated circuits and phased arrays, as they allow the use of a relatively thick central ground plane to provide isolation, as well as heat dissipation. Both four-port coupler geometries and two-port transitions are treated. Equivalent circuits are derived for each of these problems, and computed results are validated with data from the literature and with independent calculations from commercial computer-aided design (CAD) packages and measured data. These comparisons show that the solutions derived here are accurate and computationally efficient, and have the added advantage over commercial CAD packages in that equivalent-circuit parameters can be obtained directly. The vector Bessel transform is used to derive the required Green's function for the circular cavity. Index Terms--Aperture coupling, cavity coupling, microstrip couplers.

A high dynamic control system for the Alspa VDM 7000 medium-voltage drive was implemented, which provides fast torque response times of a few milliseconds despite the typically low switching frequency of gate-turn-off thyristors which is necessary to achieve high efficiency. The drive system consists of a three-level voltage-source converter with active front end and a synchronous motor. The drive has most recently been applied to a main strip mill. It provides a maximum of 8.3-MW mechanical power with a rated motor voltage of 3 kV. Besides motor torque as the main control objective, the control system has to comply with a number of additional objectives and constraints like dc-link voltage regulation and balancing, current and torque harmonics, motor flux, and excitation. Index Terms--Adjustable-speed drives, converter control, drives, highly dynamic drives, industrial applications, multilevel converters, variable-speed drives, vector control.

A very compact wireless local area network antenna using meander striplines in three low-temperature co-fired ceramic layers is designed and fabricated in this study. This chip antenna has a small volume of only 3.2 × 1.6 × 2 mm3. The measured radiation bandwidths (voltage standing wave ratio ≤ 2) of 2.45 and 5.8 GHz are 110 and 150 MHz, and the peak gains of the two bands are −1.6 and 2.7 dBi, respectively. The resonant frequencies can easily be tuned by adjusting the inner coupling between different patterns and the length of the striplines. Besides, no via-hole was used in this structure, which guarantees the easy fabrication and high production. [ABSTRACT FROM AUTHOR]

A single layer compact size Swastik-shaped microstrip patch antenna is designed and studied. The antenna is designed to cover the frequency band designated for IEEE802.11 b for WLAN applications. The proposed antenna has simulated return loss of -29.5dB at 5.8GHz frequency. The peak gain of this antenna at resonance frequency is 1.6dB. The antenna is probe feeded. The Ansoft HFSS is employed for the antenna design. [ABSTRACT FROM AUTHOR]

The article presents a study on the use of the new defected ground structure (DGS) and capacitively loaded microstrip line in the design of a quasi-elliptic lowpass filter. The incorporation of the capacitively loaded microstrip line or alternative transmission line above DGS was able to improve the insertion loss. The study reveals the realization of the three-pole LPF through the incorporation of the three DGS units of different dimensions under the capacitively loaded microstrip line.

Abstract: The objective of the present investigation is to outline some of the more relevant microwave properties of glass-coated amorphous magnetic microwires. The introductory section includes a brief description of the quenching and drawing preparation procedure that determines their cylindrical shape, their amorphous nature and the presence of the glass coating. The shape and magnetoelastic (stresses and magnetostriction) anisotropy terms imposed by those characteristics finally determine the microwave properties. Subsequently, a description is given of the circumferential, parallel and transverse excitation configurations of the electric and magnetic fields in the study of microwave response. The dynamic properties of the microwires are discussed for the three configurations. Particularly, the correlation between giant magnetoimpedance effect and ferromagnetic resonance (FMR) at various working frequencies is analysed for the circular magnetic field configuration. The influence of magnetoelastic anisotropy through mechanical stresses is investigated through the changes in the parallel permeability for microwires with different coating thickness. The role of magnetoelastic anisotropy through the magnetostriction constant is analysed through the scattering parameters and the change of FMR frequency for microwires with different alloy composition. Finally, the electromagnetic properties of microwires embedded in polymeric matrices are envisaged. [Copyright &y& Elsevier]

State-of-the-art RSFQ circuits consist of Josephson junctions, inductances and bias current sources, where the inductances are practically used as functional elements. Even more, their value defines the functionality and therefore the conventional design process requires strict conditions for the wiring between Josephson junctions. The present design and optimization process does not take into account their parasitic capacitances to ground. This becomes an important issue for ultra fast applications above 100 GHz, but also for circuits dedicated to control quantum electronics. We report on a theoretical and experimental investigation of the influence of ground capacitances. The impedance matching between the connecting microstrip lines and the Josephson junction is a key issue for the correct operation of these circuits. We performed circuit simulations and collected experimental data of correct and incorrect operating circuits to derive design criteria. The critical reflection coefficient is found to be 0.35 and the particular design must use a smaller value for transfer and a larger value for storage of SFQ pulses, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a new realization of standards for ac-dc difference at voltages ranging from 1 to 4 V and frequencies of up to 1 MHz. This work has mainly been focused on improving the determination of the components of ac-dc difference that most significantly contributed to the uncertainty of the previous realization. These components are the ac-dc difference due to skin effect, transmission line effect, and the interaction between parasitic inductances and capacitances, which is described here as the LIC effect. As a result, combined 1 - σ uncertainties as low as 4.3 μV/V at 1 MHz have been achieved. [ABSTRACT FROM AUTHOR]

A generalized impedance boundary condition is developed to rigorously model on-chip interconnects in the full-wave surface integral equation by a two-region formulation. It is a combination of the electric-field integral equation for the exterior region and the magnetic-field integral equation for the interior conductive region. The skin effect is, therefore, well captured. A novel integration technique is proposed to evaluate the Green's function integrals in the conductive medium. Towards tackling large-scale problems, the mixed-form fast multipole algorithm and the multifrontal method are incorporated. A new scheme of the loop-tree decomposition is also used to alleviate the low-frequency breakdown for the formulation. Numerical examples show the accuracy and reduced computation cost. [ABSTRACT FROM AUTHOR]

A simple design of a probe-feed microstrip antenna with circular polarization (CP) radiation is presented. By embedding dual slits in a square microstrip and adjusting the sizes of the slits, an H-shaped microstrip antenna with two near-degenerate orthogonal modes for CP radiation can be achieved. This design provides a wide CP bandwidth and relaxed fabrication tolerances. Details of the antenna design are described, and theoretical and experimental results of the CP performance are presented. [ABSTRACT FROM AUTHOR]

In this paper, signal integrity analysis of traces between two parallel planes with an electromagnetic-bandgap (EBG) structure is made. It is shown that, within the stopband, the signal transmission quality is excellent, traces in the EBG structure are free from cavity resonances, and behave as regular standard transmission lines. It is shown that the high-impedance surface behaves as a solid continuous reference plane within the stopband. The impedances of the traces between the high-impedance surface and the reference planes are extracted. It is found that the extracted impedances are exactly the same as striplines with the same parameters. It is shown that the traces between the high-impedance surface and the reference planes are regular standard striplines within the stopband. In addition, a novel four-via EBG structure is proposed to broaden the stopband for simultaneous switching noise suppression in high-speed digital printed circuit boards and packages. This four-via EBG structure has a higher relative bandwidth and lower center frequency. Compared with one-via EBG structure with the same parameters, the stopband is broadened three times and relative bandwidth is increased 1.3 times, while there is very little additional cost since there is no more change than number of vias. Two test boards with four-via EBG structure were fabricated to verify the signal integrity of the traces and the impedances extraction. Good agreements are observed between the simulations and measurements. [ABSTRACT FROM AUTHOR]

XLPE high-voltage underground cables are being extensively used in Arabian Gulf countries. Most of these cables are being manufactured locally. Although XLPE has excellent dielectric characteristics, extensive premature failures have been reported by the local power utilities. The main causes of such premature failures are related to manufacturing defects and insulation degradation mainly caused by water treeing phenomena. In this research work, five types of 15-kV, XLPE-insulated cables were subjected to accelerated aging under simultaneous electrical, thermal, and environmental stresses for periods of 60, 120, and 180 days. After each aging period, partial-discharge (PD), mechanical properties, ac dielectric strength and the extent of degradation due to water treeing of these cables were measured. The results show that PD and mechanical properties show just little variations whereas the ac-retained dielectric strength decreases rapidly in the first 60 days after which the rate of its decrease retards. Correlations are established between the retained dielectric strength and the lengths of the longest water trees. Pros and cons of the insulating materials that are used as well as the role of strippable and bonded semiconducting screens are also discussed. [ABSTRACT FROM AUTHOR]

The design of an equilateral triangular microstrip antenna embedded with dual V-shaped slots and two shorting walls is proposed and experimentally studied. By properly selecting suitable dimensions for this microstrip antenna, dual frequency operated at TM11 and TM21 modes, with frequency ratio ranging from 1.28 to 1.5 can be achieved with a single probe feed. The experimental procedures on achieving such operation with a maximum gain of around 11 dBi are presented and discussed. [ABSTRACT FROM AUTHOR]

A novel double-layer coupled stripline resonator structure is introduced to realize miniature broadband bandpass filters. Filters with relative bandwidth up to 60% and size less than λ/8 × λ/8 × h (λ is wavelength at the midband frequency; h is the substrate height, which is much smaller than λ/8) can be fulfilled using such resonators. Two possible filter configurations are proposed in this paper: combline and interdigital. The filter synthesis procedure follows the classical coupling matrix approach that generates very good initial responses. Optimization by the mode-matching method and fine tuning in Ansoft's High Frequency Structure Simulator are combined to improve the filter performance. Two filter design examples are given to validate the feasibility. Low temperature co-fired ceramic (LTCC) technology is employed to manufacture the filters. Experimental results of the two manufactured filters are presented. The effects of LTCC manufacturing procedure on the filter performance are also discussed. [ABSTRACT FROM AUTHOR]

The uniform finite-ground microstrip line (FGMSL) and its constituted circuit elements are thoroughly characterized via self-calibrated method of moments for innovative design of a stopband-enhanced and size-miniaturized low-pass filter (LPF). Firstly, an offset FGMSL is modeled and extracted to quantitatively exhibit its capacity in achieving higher characteristic impedance compared to the infinite-ground microstrip line (MSL) counterpart. Secondly, the finite-extended FGMSL section with equally widened strip/ground or offset narrow strip/ground conductors is studied in terms of an equivalent T- or π-network, thereby constructing the modified MSL shunt capacitive or series inductive element. By making effective use of enlarged series inductance of an offset FGMSL with shorter electrical length, two novel LPF blocks are designed on a basis of cascaded circuit networks. Predicted S-parameters show widened and deepened stopband beyond the low passband. Furthermore, it is confirmed by measurement. [ABSTRACT FROM AUTHOR]

Floating strip conductors printed on the backside of the substrate are shown to be useful to suppress the spurious transmission band appearing at twice the central frequency of coupled-line microstrip filters. It is shown that proper adjustment of the dimensions of the floating conductors yields equal even and odd electrical lengths. An attractive feature of this design is its flexibility because the equalization of the modal electrical lengths can be achieved with various geometries. Additionally, the floating conductor provides an extra coupling mechanism that relaxes tolerances of strip width and spacing in those cases where tightly coupled sections are required. A fast quasi-TEM analysis is used to find the structure yielding equal mode phase velocities. Fine tuning to equalize the modal electrical lengths for each coupled stage is based on the use of a commercial electromagnetic simulator. Experimental verification is finally provided. [ABSTRACT FROM AUTHOR]

This paper presents multifunctional microstrip transmission lines for designing a high port-isolation dual-frequency orthogonally polarized rectangular patch antenna and the antenna-integrated power amplifier. The proposed lines were realized through the integration of defected ground structures (DGSs) with conventional microstrip lines. A spiral-shaped DGS-integrated microstrip line enhances the port isolation of the antenna, while feeding the 2.0-GHz excitation to the antenna and filtering out the 2.5-GHz receiving signal from the other port. High-order harmonic signal suppression of the power amplifier at the 2.5-GHz port was accomplished by the dumbbell-shaped DGS, thereby improving the efficiency of the amplifier. Measurements show an improvement of 20 dE in port isolation and 3% in power-added efficiency relative to an identical RF front-end, but integrated with a conventional patch antenna. An image impedance of the DGS-integrated microstrip lines can be controlled by the integrated DGS geometries. Relatively high-impedances lines, i.e., 150 and 100 Ω, are effectively implemented using microstrip lines with 75- and 50-&Ohm; linewidths by incorporating the spiral- and dumbbell-shaped DGSs, respectively. [ABSTRACT FROM AUTHOR]

A small H-shaped microstrip patch antenna (MPA) with enhanced bandwidth is presented. The H-shaped antenna is first studied by a transmission line model and then is fully analyzed with a MoM code. A stacked patch configuration is proposed to increase the narrow bandwidth, radiation efficiency and directivity. The stacked H-shaped MPA is studied using Chu's fundamental limit for electrically small antennas. [ABSTRACT FROM AUTHOR]

In this paper, we report on the results of an investigation into dual-mode operation of microstrip triangular patch resonators and their applications for designing dual-mode bandpass filters. It has been found theoretically that the dual modes can result from the rotation and superposition of a fundamental mode. The characteristics of the dual modes and their mode splitting are described. The applications of this new type of dual-mode microstrip patch resonator in the design of microwave planar filter are presented. A circuit model for operation of this type of filter is proposed. Two- and four-pole filters of this type are demonstrated for the first time. Both theoretical and experimental results are presented. [ABSTRACT FROM AUTHOR]

Quasi-TEM propagation, appropriate for a linearly tapered microstrip line is modeled, and known microstrip impedance behavior is approximated directly. The telegraphist's equations and the resulting ABCD matrix are solved in terms of Airy functions. The theoretical model, which includes conductor and substrate losses, has been verified experimentally. [ABSTRACT FROM AUTHOR]

In this paper an equation for the force between current elements is derived from the new Gaussian equation for the force between moving charges. The new equation is compared with the equations previously derived from the Weber equation and from the classical equation for the force between moving charges. [ABSTRACT FROM AUTHOR]

Describes a simulation of microwave characteristics of high-temperature superconducting microstrip lines by using an empirical two-fluid model. Fabrication of useful devices on microwave cryoelectronics; Measurements of microwave surface impedance; Microwave properties of superconducting materials.

This article describes the average power handling capability (APHC) of multilayer microstrip lines, including the effect of mismatch at the terminations. The data presented herein are validated by considering an example of a 12-W monolithic microwave integrated circuit power amplifier fabricated using multilayer low-loss microstrip technology. The calculated value of APHC for a 50-Ω line of a 75-μm-thick GaAs substrate is 1445 W at 10 GHz, whereas the corresponding value for a multilayer microstrip that has 10-μm-thick polyimide is only 44 W. At 40 GHz, these values are reduced by a factor of 2. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 385–395, 2001. [ABSTRACT FROM AUTHOR]

An approach is developed for 3D microstrip discontinuities using the finite element method (FEM) and the perfectly matched layers (PML). It is shown that iterative solvers are not suitable for this problem since the matrix equations from the PML-used FEM modeling are rather ill-conditioned and lead to a very slow or nonconvergent result. A newly developed package SuperLU of the sparse LU decomposition solver is incorporated into our developed approach running on a PC-based parallel platform. Various implementation techniques are detailed. Numerical experiments clearly show that the developed approach is reliable, efficient, and suitable for modeling 3D microstrip discontinuities. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 38–47, 2001 [ABSTRACT FROM AUTHOR]

Presents an active image-rejection filter which applies actively coupled passive resonators. Description of the filter; Elimination of using a low-noise amplifier in front-end applications; Diameter of the GaAs monolithic-microwave integrated-circuit; Insertion gain, image rejection and noise figure of the filter; Power dissipation.

Transmission-line modeling (TLM) has been applied extensively to simulate microwave circuits and electromagnetic compatibility (EMC) problems. The introduction of special nodes has allowed us to model complex wire structures. However, so far, all of the problems have dealt with the use of models of nodes with wires considered straight wires oriented along one of the principal directions of the x-, y-, and z-axes. The particular structure of the node with the interface wire model permits us to model inclined wires and other more complex wire structures. In this paper, we present novel applications of this model, allowing its generalization to model wires with arbitrary orientations. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 137–141, 1999. [ABSTRACT FROM AUTHOR]

The influence of intrapulse Raman scattering (IRS) by the conservation of momentum on a dark soliton transmission system is studied. The results show that the IRS leads to a deviation of equilibrium point, the combined role of IRS and amplifier spontaneous emission noise increases the time jitter in arrival, and it reduces the capacity and propagation distance of a dark soliton transmission system. The nonlinear gain can suppress the influence effectively. © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 16: 397–400, 1997. [ABSTRACT FROM AUTHOR]

The mode-matching technique is used to quantify the inaccuracy, especially at high frequencies, of an equivalent network model of a stripline T junction, with a branch-line coupler used as a representative example of devices consisting of T junctions. Experimental results are also presented to verify the accuracy of the mode-matching technique. [ABSTRACT FROM AUTHOR]

Simulated and experimental data on mixer performance of semiconductor alloy ramp heterostructure diodes are presented. The results indicate that these devices are excellent candidates for use in microwave and millimeter-wave mixer circuits. In addition, they possess several significant advantages over contending Schottky harrier diodes, the microwave industry workhorse for mirrors and detectors. [ABSTRACT FROM AUTHOR]

A lumped capacitance equivalent circuit is used to characterize the asymmetric edge-coupled microstrip discontinuity in the case in which the conducting strips are embedded in a multilayered anisotropic medium. The Galerkin method in the spectral domain is employed to determine the excess charge density on the strips of the discontinuity. Original results are provided for the general asymmetric discontinuity in conventional and suspended configurations. [ABSTRACT FROM AUTHOR]