Showing papers in "IEEE Transactions on Microwave Theory and Techniques in 1985"
TL;DR: The basic algorithm for simulating wave propagation in two- and three-dimensional transmission-live networks is derived and the introduction of boundaries, dielectric and magnetic materials, losses, and anisotropy are discussed in detail.
Abstract: This paper presents an overview of the transmission-line matrix (TLM) method of analysis, describing its historical background from Huygens's principle to modem computer formulations. The basic algorithm for simulating wave propagation in two- and three-dimensional transmission-live networks is derived. The introduction of boundaries, dielectric and magnetic materials, losses, and anisotropy are discussed in detail. Furthermore, the various sources of error and the limitations of the method are given, and methods for error correction or reduction, as well as improvements of numerical efficiency, are discussed. Finally, some typical applications to microwave problems are presented.
678 citations
TL;DR: In this paper, a technique for measuring the effective surface resistance R/sub s/ of the conducting plates is proposed to allow the accurate measurement of the loss tangent tan delta.
Abstract: Improvements both in accuracy and speed are described for the technique of measuring the microwave dielectric properties of low-loss materials by using a dielectric rod resonator short-circuited at both ends by two parallel conducting plates. A technique for measuring the effective surface resistance R/sub s/ of the conducting plates is proposed to allow the accurate measurement of the loss tangent tan delta. By means of the first-order approximation, the expressions are analytically derived for estimating the errors of the measured values of relative permittivity epsilon/sub r/, tan delta, and R/sub r/, for measuring the temperature coefficient of epsilon/sub r/, and for determining the required size of the conducting plates. Computer-aided measurements are realized by using these expressions. It is shown that the temperature dependence of R/sub s/, should be considered in the tan delta measurement. The copper plates used in this experiment have the relative conductivity of 91.0+-2.7 percent at 20°C, estimated from the measured R/sub s/ value. For a 99.9-percent alumina ceramic rod sample, the results measured at 7.69 GHz and 25°C show that epsilon/sub r/,= 9.687+-0.003 and tan delta = (1.6+-0.2)x 10/sup -5/. The temperature coefficients measured between 25 and 100°C are 112x10/sup -6//°C for epsilon/sub r/, and 23x10/sup -4//°C for tan delta.
605 citations
TL;DR: In this article, a nonlinear equivalent circuit model for the GaAs FET has been developed based upon the small-signal device model and separate current measurements, including drain-gate avalanche current data.
Abstract: A nonlinear equivalent circuit model for the GaAs FET has been developed based upon the small-signal device model and separate current measurements, including drain-gate avalanche current data. The harmonic-balance technique is used to develop the FET RF load-pull characteristics in an amplifier configuration under large-signal operation. Computed and experimental load-pull results show good agreement.
402 citations
TL;DR: In this paper, the exact Green's function of the grounded dielectric slab is used in a moment method procedure, so surface waves as well as space-wave radiation are included.
Abstract: A solution is presented for the characteristics of microstrip open-end and gap discontinuities on an infinite dielectric substrate. The exact Green's function of the grounded dielectric slab is used in a moment method procedure, so surface waves as well as space-wave radiation are included. The electric currents on the line are expanded in terms of longitudinal subsectional piecewise sinusoidal modes near the discontinuity, with entire domain traveling-wave modes used to represent incident, reflected, and, for the gap, transmitted waves away from the discontinuity. Results are given for the end admittance of an open-ended line, and the end conductance is compared with measurements. Results are also given for the reflection coefficient magnitude and surface-wave power generation of an open-ended line on substrates with various dielectric constants. Loss to surface and space waves is calculated for a representative gap discontinuity.
273 citations
TL;DR: In this article, the problem of anisotropy in substrate materials for microwave integrated-circuit applications is addressed, and several quasi-static, dynamic and empirical methods employed to obtain the propagation characteristics of microstrip, coplanar waveguides, and slotlines on anisotropic substrates are presented.
Abstract: This paper addresses the problem of anisotropy in substrate materials for microwave integrated-circuit applications. It is shown that in modeling the circuit characteristics, a serious error is incurred which becomes larger with increasing frequency when the substrate anisotropy is neglected. Quasi-static, dynamic, and empirical methods employed to obtain the propagation characteristics of microstrip, coplanar waveguides, and slotlines on anisotropic substrates are presented. Numerical solutions such as the method of moments and the transmission-line matrix technique are outlined. The modified Wiener-Hopf, the Fourier series techniques, and the method of lines are also discussed. A critique of the aforementioned methods and suggestions for future research directions are presented. The paper includes new results as well as a review of established methods.
257 citations
TL;DR: In this article, a simple and efficient method of GaAs FET amplifier analysis is presented, where the FET is represented by its circuit-type nonlinear dynamic model taking into account the device's main nonlinear effects including gate-drain voltage breakdown.
Abstract: A simple and efficient method of GaAs FET amplifier analysis is presented. The FET is represented by its circuit-type nonlinear dynamic model taking into account the device's main nonlinear effects including gate-drain voltage breakdown. An identification procedure for extraction of the model parameters is described in detail and examples are given. The calculation of the amplifier response to a single-input harmonic signal is performed using the piecewise harmonic balance technique. As this technique is rather time-consuming in its original form, the optimization routine used to solve the network equations was replaced by the Newton-Raphson algorithm. Characteristics calculated with the use of the proposed method are compared with experimental data taken for a microwave amplifier using a 2SK273 GaAs FET unit. Good agreement at 9.5 GHz over wide ranges of bias voltage and input power levels are observed.
246 citations
TL;DR: The spectral domain approach as discussed by the authors is an analytical and numerical technique particularly suited for the solution of boundary-value problems in microwave and millimeter-wave integrated circuits, the mathematical formulation of the analytical part of that approach is described in a generalized notation for two-and three-dimensional strip and slot-type fields.
Abstract: A survey is given of the so-called spectral-domain approach, an analytical and numerical technique particularly suited for the solution of boundary-value problems in microwave and millimeter-wave integrated circuits, The mathematical formulation of the analytical part of that approach is described in a generalized notation for two- and three-dimensional strip and slot-type fields. In a similar way, the numerical part of the technique is treated, keeping always in touch with the mathematical and physical background, as well as with the respective microwave applications. A discussion of different specific aspects of the approach is presented and outlines the peculiarities of shielded-, covered-, and open-type problems, followed by a brief review of the progress achieved in the last decade (1975-1984). we survey closes with considerations on numerical efficiency, demonstrating that spectral-domain computations can by speeded up remarkably by analytical preprocessing. The presented materal is based on ten years of active involvement by the author in the field and reveals a variety of contributions by West German researchers previously not known to the intenational microwave community.
215 citations
TL;DR: In this article, a theoretical approach for the representation of microstrip discontinuities by equivalent circuits with frequency-dependent parameters is presented, which accounts accurately for the substrate presence and associated surface-wave effects, strip finite thickness, and radiation losses.
Abstract: A theoretical approach for the representation of microstrip discontinuities by equivalent circuits with frequency-dependent parameters is presented. The model accounts accurately for the substrate presence and associated surface-wave effects, strip finite thickness, and radiation losses. The method can also be applied for the solution of microstrip components in the millimeter frequency range.
176 citations
TL;DR: Transferal and recursive filter concepts, normally associated with discrete-time applications, are adapted for implementation in the microwave frequency range in this paper, with microwave transistors used as active elements.
Abstract: Transferal and recursive filter concepts, normally associated with discrete-time applications, are adapted for implementation in the microwave frequency range. Principal focus is on microwave active filter designs that permit realization of wide bandwidths, with microwave transistors used as active elements. A transversal-type and a recursive-type experimental filter, both of which exhibit 9-15-GHz bandpass responses, serve to illustrate aspects of physical implementation, while offering a convenient basis for comparing the two different approaches.
173 citations
TL;DR: Two advanced techniques which have been found to be among the most efficient ones for solving matrix equations resulting from the moment method, namely, the coujugate gradient and the pseudo-inverse, are described.
Abstract: This paper reviews one of the most important general methods for solving electromagnetic-field problems, namely, the moment method. It begins with a brief mathematical foundation of the general method. Then, the various specializations are described, accompanied with relevant references to illustrate the pitfalls and shortcomings, as well as the advantages, as compared to other methods. Deterministic and eigenvalue problems are both discussed separately. Finally, two advanced techniques which have been found to be among the most efficient ones for solving matrix equations resulting from the moment method, namely, the coujugate gradient and the pseudo-inverse, are described. A version of their algorithm which is easily programmable on computer is also presented.
162 citations
TL;DR: In this article, a simple expression for the product nZ/sub pi g/, where Z/sub π g/ is the pi-characteristic impedance of the gate line, which minimizes the overall noise figure of the amplifier.
Abstract: This paper calculates the intrinsic noise figure of the MESFET distributed amplifier assuming, for simplicity, only the Van der Ziel gate and drain noise sources, and produces an expression for the noise figure of a distributed amplifier containing n identical devices. For large gain and Iarge n, a simple expression exists for the product nZ/sub pi g/, where Z/sub pi g/ is the pi-characteristic impedance of the gate line, which minimizes the overall noise figure of the amplifier. This approximate expression is compared with the corresponding expression for a resonant ampfifier using the same MESFET with the same noise sources and with the optimum source impedance for minimum noise figure. Although the resonant amplifier has a slightly lower noise figure, the need to use a circulator to remove the mismatch associated with the optimum source impedance removes this slight advantage.
TL;DR: In this article, a general multiple coupled line model compatible with standard CAD programs, such as SPICE, is presented, which can be used to analyze and design coupled line circuits with linear, as well as nonlinear/time varying terminations, and to help study the pulse propagation characteristics in high-speed digital circuits.
Abstract: A general multiple coupled line model compatible with standard CAD programs, such as SPICE, is presented. It is shown that the model can be used to help analyze and design coupled line (e.g., microstrip) circuits with linear, as well as nonlinear/time varying terminations, and to help study the pulse propagation characteristics in high-speed digital circuits.
TL;DR: In this paper, an improved finite-element method for the analysis of dielectric waveguides is formulated in terms of all three components of the magnetic field H. In this approach, the spurious, nonphysical solutions do not appear anywhere above the "air-line", and therefore the present formulation is very useful for analysis of the surface-wave modes of Dielectric Waveguides.
Abstract: An improved finite-element method for the analysis of dielectric waveguides is formulated in terms of all three components of the magnetic field H. In this approach, the spurious, nonphysical solutions do not appear anywhere above the "air-line," and therefore the present formulation is very useful for the analysis of the surface-wave modes of dielectric waveguides. The application of this improved finite-element method to the dielectric waveguides with perfect electric and magnetic conductors is also discussed. In particular, the discussion is how to use the conditions on a boundary surface of a perfect electric or magnetic conductor whose normal direction is not coincident with the direction of a coordinate axis. Application of these boundary conditions for perfect conductors to the dielectric waveguides with planes of symmetry reduces the matrix size. The strength of this approach to boundary conditions is not just the economical use of computer memory but the elimination of spurious solutions through rigorous enforcement of boundary conditions as well.
TL;DR: In this article, an arbitrarily-shaped planar circuit is studied and a numerical method of analysis is introduced to verify the results of the theoretical calculations and the measurements of the measurements.
Abstract: A study of an arbitrarily-shaped planar circuit is reported. The theoretical background is presented and then a numerical method of analysis is introduced. Experiments show good agreement between the theoretical calculations and the measurements. The examples of applications concern stripline circuits but the method may be also applied to waveguides.
TL;DR: In this paper, Pb alloy superconducting tunnel junction mixers operating at 4.5 K were used for low-noise receivers for radio astronomy with double-sideband receiver noise temperature between 70 and 200 K.
Abstract: Low-noise receivers for radio astronomy have been built using Pb alloy superconducting tunnel junction mixers operating at 4.5 K. They have been used for 85-115-GHz astronomy with double-sideband receiver noise temperature between 70 and 200 K. Junction fabrication and receiver construction, operation, and performance are described herein.
TL;DR: In this paper, the upconversion of Iow-frequency noise in microwave FET oscillators is investigated and theoretical analysis is presented in two forms, a general and a simplified one.
Abstract: The upconversion of Iow-frequency noise in microwave FET oscillators is investigated. The theoretical analysis is presented in two forms, a general and a simplified one. The latter version yields closed-form expressions for amplitude and phase noise, which are discussed wfth regard to the physics of the upconversion process. Application of the method is demonstrated with an example.
TL;DR: In this paper, the numerical methods for the analysis of the homogeneous and inhomogeneons,isotropic and anisotropic, microwave and optical dielectric waveguides with arbitrarily-shaped cross sections are compared.
Abstract: This paper presents are view of the numerical methods for the analysis of the homogeneous and inhomogeneons,isotropic and anisotropic, microwave and optical dielectric waveguides with arbitrarily-shaped cross sections.The characteristics of various methods are compared,and a set of qualittative criteria to guide the selection of an appropriate method for a given problem is proposed. The main approaches discussed are those of point matching, integral equations, finite difference, and finite element.
TL;DR: In this paper, the parameters of general two-coupled lines and symmetric three coupled lines in an inhomogeneous medium for the lossless case were obtained. And the impedance and chain matrices of one-section spurline bandstop filters with their stopbands centered near 33 GHz were derived.
Abstract: The parameters of general two-coupled lines and symmetric three-coupled lines in an inhomogeneous medium for the lossless case are obtained. The impedance and chain matrices of spurline bandstop filters are derived. One-section spurline bandstop filters with their stopbands centered near 33 GHz have been designed and tested. There is excellent agreement between the experimental results and those predicted theoretically.
TL;DR: In this article, a general treatise of cascaded discontinuities in inhomogeneous waveguides is given and applied to finline circuits, where a transmission matrix representation is superior to a scattering matrix representation as far as CPU time is concerned.
Abstract: A general treatise of cascaded discontinuities in inhomogeneous waveguides is given and applied to finline circuits. A transmission matrix representation is superior to a scattering matrix representation as far as CPU time is concerned. The scattering matrix is, however, advantageous if the sum of the line lengths separating the discontinuities is large. Numerical examples are given in order to illustrate the effect of increasing the number of modes used to represent the field at both sides of the discontinuity.
TL;DR: In this article, the relationship linking the reflection coefficient to the dielectric properties is obtained from a theoretical analysis of the electromagnetic field in the vicinity of the aperture, including the effects of both cross polarization and higher order modes.
Abstract: The measurement of reflection from an open-ended waveguide is a simple and nondestructive technique for determining the dielectric properties of materials. A flange-mounted waveguide is considered, the flange being pressed on an unknown material which may be of finite or infinite thickness. The relationship linking the reflection coefficient to the dielectric properties is obtained from a theoretical analysis of the electromagnetic field in the vicinity of the aperture. The theory includes the effects of both cross polarization and higher order modes. An integral equation is obtained, the kernel of which is the dyadic Green function in each medium. The method of characteristic modes is used for the numerical computation. The theoretical results are in good agreement with experimental measurements. Futhermore, a simple and handy technique for data inversion is provided.
TL;DR: In this article, a push-push broadband dielectric resonator oscillator was designed for K-and Ka-band operation, which exhibited excellent spectral purity, power output, and suppression of spurious outputs.
Abstract: A novel coupling method is employed in the design of a push-push broad-band dielectric resonator oscillator for K- and Ka-band operation. The oscillators realized with this technique exhibit excellent spectral purity, power output, and suppression of spurious outputs.
TL;DR: In this article, a phase-locked second harmonic Gunn oscillator, mechanically tunable from 65 to 115 GHz, has been developed for use as a Iocal oscillator (LO) in millimeter radio astronomy.
Abstract: A phase-locked second harmonic Gunn oscillator, mechanically tunable from 65 to 115 GHz, has been developed for use as a Iocal oscillator (LO) in millimeter radio astronomy. The oscillator's output power is greater than 2 mW over most of its operating range, and exceeds 10 mW from 80 to 102 GHz. Its frequency can be electronically tuned approximately +-200 MHz by varying the bias voltage on the Gunn diode it is phase locked by exploiting this bias tuning. The oscillator consists of a commercially available, packaged GaAs Gunn diode which is mounted in a coaxial resonator of adjustable length. Descriptions of the mechanical design and phase-lock circuit are given. Extensive experimental measurements of the tuning range and power output for oscillators with different resonator dimensions also are reported.
TL;DR: In this article, a variational expression for eigenvalue problems was derived by using a trial function which satisfies the right-angled edge condition of a ridge. But the analysis of the variational expressions is limited to a single waveguide.
Abstract: Brief expressions of eigenvalue problems, nornral modes, and electric-field profiles for all odd TE and TM modes of ridged waveguides, and the guide wavelength and characteristic impedance for the TE/sub 10/ dominant mode, are presented in this paper. In this analysis, the computation time can be reduced by getting simple approximated variational expressions for eigenvalue equations by using a trial function which satisfies the right-angled edge condition of a ridge. These theoretical results are in good agreement with the experimental results and the several references employed.
TL;DR: The problem of analyzing the stability of periodic equilibrium regimes in nonlinear microwave circuits is tackled by a general-purpose computer-aided approach, and the use of a vector processor allows the computer time requirements to be kept well within reasonable limits, even in the case of large-size problems.
Abstract: The problem of analyzing the stability of periodic equilibrium regimes in nonlinear microwave circuits is tackled by a general-purpose computer-aided approach. By means of a perturbation technique, the search for instabilities is reduced to a generalized eigenvalue equation expressed in matrix form, and is then carried out by Nyquist's analysis. The use of a vector processor allows the computer time requirements to be kept well within reasonable limits, even in the case of large-size problems. In perspective, this could open the way to the complementation of existing nonlinear CAD packages by an on-line facility for automatic stability analysis.
TL;DR: In this article, the effects of losses in the loading elements on the circuit parameters are determined and design factors affecting bandwidth are discussed, utilizing a phasor diagram representation of the line to identify its loading modes.
Abstract: Circuit design procedures for the loaded-line phase shifter are presented, utilizing a phasor diagram representation of the line to identify its loading modes. The effects of losses in the loading elements on the circuit parameters are determined and design factors affecting bandwidth are discussed.
TL;DR: The planar-circuit approach to the analysis and design of microwave integrated circuits (MIC's), with specific reference to microstrip circuits, is reviewed in this paper, where the analysis of planar elements is formulated in terms of an N-port circuit and results in a generalized impedance-matrix description.
Abstract: The planar-circuit approach to the analysis and design of microwave integrated circuits (MIC's), with specific reference to microstrip circuits, is reviewed. The planar approach overcomes the limitations inherent to the more conventional transmission-line approach. As the operating frequency is increased and/or Iow-impedence levels are required, in fact, the transverse dimensions of the circuit elements become comparable with the wavelength and/or the longitudinal dimensions. In such cases, one-dimensional analyses give inaccurate or even erroneous results. The analysis of planar elements is formulated in terms of an N-port circuit and results in a generalized impedance-matrix description. Analysis techniques for simple geometries, such as the resonant mode expansion, and for more complicated planar configurations, such as the segmentation method, are discussed along with planar models for accounting for fringing fields effects and radiation loss.
TL;DR: In this paper, two approaches due to the complex frequency and to the perturbation theory are described to compute accurately the Q-factors of the circularly-symmetric TEO modes for dielectric rod resonators placed between two parallel conductor plates and in a conductor cavity.
Abstract: Two approaches due to the complex frequency and to the perturbation theory are described to compute accurately the Q-factors of the circularly-symmetric TEO modes for dielectric rod resonators placed between two parallel conductor plates and in a conductor cavity. These techniques allow us to estimate separately the Q-factors due to radiation, conductor, and dielectric losses from only the computation of resonant frequencies by means of the mode-matching method. Validity of the theories is verified by experiments. The influence of the conductor shields on the Q-factors is discussed from the computed results. A possibility of realizing high-Q dielectric resonators is suggested.
TL;DR: In this article, a variational formulation of the skin effect problem for calculating the losses as well as the inner inductances of components in planar integrated circuits is described, and the first numerical results of the method are discussed.
Abstract: During the last years, monolithic integrated circuits have been used more and more in microwave techniques. As a result, the metallization thickness of the planar circuits became of the order of the skin depth even at very high frequencies, so that the approximate methods for loss calculations used until recently must be revised. In this paper, a variational formulation of the skin-effect problem for calculating the losses as well as the inner inductances of components in such circuits will be described, and the first numerical results of the method will be discussed.
TL;DR: In this paper, the design formulas for capacitively coupled bandpass filters using dielectric-filled coaxial resonators are derived and experimentally verified, and the most important advantage of this filter is its ability to provide wide stopband characteristics for harmonics suppression.
Abstract: Design formulas for capacitively coupled bandpass filters using dielectric-filled coaxial resonators are derived and experimentally verified. The most important advantage of this filter is its ability to provide wide stopband characteristics for harmonics suppression. Its features can be obtained from the configuration using both quarter-wavelength uniform impedance resonators (UIR's) and stepped impedance resonators (SIR's).
TL;DR: In this article, the authors analyzed the transition waveguide to shielded and dielectric image guide by the rigorous hybrid-mode field expansion technique where higher order mode coupling effects are taken into account directly, also below the corresponding cutoff frequency.
Abstract: The transition waveguide to shielded and dielectric image guide is analyzed by the rigorous hybrid-mode field expansion technique where higher order mode coupling effects are taken into account directly, also below the corresponding cutoff frequency. The solution of the related eigenvalue problem includes waves with a complex propagation constant although the guide is assumed to be lossless. Calculated diagrams of the propagation constant as a function of frequency, as well as of the permittivity, illustrate the complicated mode conversion between evanescent modes, complex waves, backward waves, and propagating waves. For the three-dimensional scattering problem, the calculated magnitude of the input reflection coefficient agrees well with measurements, whereas the transmission-line theory applied to this structure leads to wrong results.