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Microwave Theory and Techniques, IEEE Transactions on

Issue 5 • Date May 1997

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Displaying Results 1 - 19 of 19
  • Guest Editorial

    Page(s): 709 - 711
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    Freely Available from IEEE
  • Application of the Cauchy method for extrapolating/interpolating narrowband system responses

    Page(s): 837 - 845
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    In this paper, it is shown that Cauchy's method can be used effectively to interpolate/extrapolate narrow-band system responses. The given information can either be theoretical datapoints or measured experimental data over a band. For theoretical data extrapolation or interpolation, the sampled values of the function and, optionally, a few of its derivatives have been used to reconstruct the function. For measured data, only measured values of the parameter are used to create broadband information from limited data as derivative information is too noisy. Cauchy's method assumes that the parameter to be extrapolated/interpolated, as a function of frequency, is a ratio of two polynomials. The problem is to determine the order of the polynomials and the coefficients therein. The method of total least squares (TLS) has been used to solve the resulting matrix equation involving the coefficients of the polynomials. Typical numerical results have been presented to show that reliable interpolation/extrapolation can be done for various system responses. View full abstract»

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  • The application of neural networks to EM-based simulation and optimization of interconnects in high-speed VLSI circuits

    Page(s): 712 - 723
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    In this paper, a neural network based approach to the electromagnetic (EM) simulation and optimization of high-speed interconnects is discussed. Traditional techniques used to model interconnects in high-speed very large scale integration (VLSI) circuits are based on EM-field simulation, and are thus highly demanding on central processing unit (CPU) resources. This limits their suitability for computer-aided design (CAD) and optimization techniques which are, in general, iterative in nature. Neural networks can be used to map the complex relationship between the physical and electrical parameters of interconnect structures in an efficient manner. The models, once developed, operate with minimal on-line CPU resources and are thus ideally suited for use in iterative CAD and optimization routines View full abstract»

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  • An innovative CAD technique for microstrip filter design

    Page(s): 780 - 786
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    An innovative computer-aided design (CAD) technique for efficient and accurate microstrip filter design is presented in this paper. The technique utilizes full-wave electromagnetic (EM) simulation for the individual circuit elements, while interactions between nonadjacent elements are emulated by introducing circuit components to form extra signal paths. Designs can be accomplished with the accuracy of complete circuit EM simulation while keeping the computational efforts at a cascading simulation level which is crucial for design optimization. The technique has clear physical interpretations and is easy to implement. The authors have successfully applied this technique to design several microstrip filters. Very good filter performance was achieved with good correlation between predicted and measured results View full abstract»

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  • A systematic optimum design of waveguide-to-microstrip transition

    Page(s): 803 - 809
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    In this paper, a systematic optimum design method is introduced, which consists of the finite-element method (FEM), design sensitivity analysis (DSA), and the steepest descent algorithm. A waveguide-to-microstrip (W/G-to-M/S) probe-type transition is designed by using the proposed method. In the FEM as a full-wave analyzer, eigenvalue and eigenvector calculations in the two-dimensional (2-D) FEM precede the three-dimensional (3-D) FEM, in order to terminate the W/G-to-MIS transition model into an electrically small model. The analysis results of this approach are compared with ones of a commercial FEM software high-frequency structure simulator (HFSS). The total derivative required in the steepest descent algorithm is calculated numerically by the DSA based on the FEM. The additional time needed for this proposed method is only one more calculation of a sparse matrix equation. The return loss is chosen as the objective function to be minimized, and the backshort length and probe length are selected as the design variables in the transition design. The proposed method gives a good convergence characteristic and the optimized results show its usefulness View full abstract»

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  • Full-wave analysis of packaged microwave circuits with active and nonlinear devices: an FDTD approach

    Page(s): 819 - 826
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    This paper presents a comprehensive full-wave analysis of packaged nonlinear active microwave circuits by applying the extended finite-difference time-domain (FDTD) method. Based on the approach of using equivalent sources, the device-wave interaction is characterized and incorporated into the FDTD time-marching scheme. As a consequence, analysis of linear and nonlinear properties, including harmonic generation and intermodulation, can be accomplished by employing a large-signal device circuit model. The implementation is first validated by comparing results of FDTD and HP MDS simulation of the circuit without the packaging structure. The analysis then goes beyond the capability of the circuit simulator to include the packaging effect. This analysis is useful in circuit design involving electromagnetic compatibility/electromagnetic interference (EMC/EMI) problems View full abstract»

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  • Automated design of waveguide components using hybrid mode-matching/numerical EM building-blocks in optimization-oriented CAD frameworks-state of the art and recent advances

    Page(s): 747 - 760
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    Fast hybrid mode-matching/boundary-contour (MM/BC) and mode-matching/finite-element (MM/FE) waveguide building blocks are described for the optimization-oriented use in powerful circuit computer-aided design (CAD) tools and the automated design of waveguide components. The efficient electromagnetic (EM) CAD technique allows the accurate design of a comprehensive class of rectangular and circular waveguide components including realistic structures of higher complexity. The efficiency and flexibility of the hybrid CAD method is demonstrated at advanced EM design examples, such as broad-band circular-to-rectangular waveguide transitions including octagonal cross sections, waveguide resonator filters with rounded corners, optimum-shaped bends, dual-mode filters with coupling sections without tuning screws, ridged waveguide filters with rounded corners, and multiplexers. The designed components are directly amenable to cost-efficient fabrication techniques like computer-controlled milling methods. The theory is verified by available measurements View full abstract»

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  • Simple and effective EM-based optimization procedure for microwave filters

    Page(s): 856 - 858
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    A simple and effective computerized optimization procedure for microwave filters is discussed. The basic idea is to integrate a fast and accurate electromagnetic (EM) solver, a filter design strategy, and two different optimization algorithms. The structural parameters to be modified are then chosen with the objective of improving the interaction between the EM solver and the optimization process. A simple example is discussed in detail indicating how the procedure is very simple and effective View full abstract»

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  • Microwave filter analysis using a new 3-D finite-element modal frequency method

    Page(s): 810 - 818
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    A new finite element modal frequency method is presented and shown to be advantageous for the analysis of microwave filters. The method analyzes a finite-element model of a filter by first computing the eigenmodes of the three-dimensional (3-D) structure. The computed eigenvalues are shown to reliably determine all of the resonant frequencies in a frequency range; the filter design can be changed until the desired resonant frequencies are computed. Finally, the eigenvectors are used as basis functions to compute the frequency response of the filter, thereby achieving a speedup that increases with the number of frequencies analyzed. Two filters analyzed in this paper show speedups ranging from 1.39 to 4.01, and their computed S-parameters agree closely with measurements View full abstract»

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  • Electromagnetic optimization of 3-D structures

    Page(s): 770 - 779
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    This paper discusses novel techniques and methodologies suitable for automated electromagnetic (EM) design of arbitrary three-dimensional (3-D) structures. In the context of parameterization of arbitrary 3-D structures, the authors outline the concept of the geometry capture technique. The authors present efficient response interpolation with respect to optimizable parameters-the key to effective automation. The authors' formulation is based on the maximally flat quadratic interpolation (MFQI) technique and provides gradient estimation essential to efficient optimization. The authors address the issue of storing the results of expensive EM simulations in a dynamically updated database, integrated with the interpolation technique. The automated EM optimization process is illustrated by the design of waveguide mitered bends. The authors also apply the aggressive space mapping (SM) technique to the optimization of multistep waveguide transformers View full abstract»

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  • Artificial neural networks for fast and accurate EM-CAD of microwave circuits

    Page(s): 794 - 802
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    A novel approach for achieving fast and accurate computer-aided design (CAD) of microwave circuits is described. The proposed approach enhances the ability to utilize electromagnetic (EM) analysis techniques in an interactive CAD environment through the application of neurocomputing technology. Specifically, a multilayer perceptron neural network (MLPNN) is implemented to model monolithic microwave integrated circuit (MMIC) passive elements using the element's physical parameters. The strength of this approach is that only a minimum number of EM simulations of these passive elements are required to capture critical input-output relationships. The technique used to describe the data set required for model development is based on a statistical design of experiment (DoE) approach. Data generated from EM simulations are used to train the MLPNN which, once trained, is capable of modeling passive elements not included in the training set. The results presented indicate that the MLPNN can predict the s-parameters of these passive elements to nearly the same degree of accuracy as that afforded by EM simulation. The correlations between the MLPNN-computed and EM-simulated results are greater than 0.98 for each modeled parameter View full abstract»

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  • Automated optimization of a waveguide-microstrip transition using an EM optimization driver

    Page(s): 861 - 864
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    An electromagnetic (EM) optimization driver is introduced which makes optimization of electromagnetic components fully automatic. The driver is composed of an EM simulator and an optimizer. As a test example, an optimum design of a waveguide-microstrip transition using the driver is demonstrated. The numerical design is verified by the measurement View full abstract»

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  • Design optimization of interdigital filters using aggressive space mapping and decomposition

    Page(s): 761 - 769
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    This paper presents a new electromagnetic (EM) design methodology which combines two powerful techniques in a coherent strategy: space mapping (SM) and decomposition. An accurate but computationally intensive fine-resolution EM model is used sparingly only to calibrate a less accurate, but computationally much more efficient “coarse model.” Applying this new approach to interdigital filter design, the authors exploit structural decomposition to construct a highly efficient coarse model using a combination of EM models with a coarse grid and empirical models for the noncritical substructures. The authors employ the aggressive SM optimization technique to obtain a rapidly improved design after each fine-model simulation while the bulk of the computation is carried out using the coarse model. To avoid possible oscillation in the iterative process, a penalty function is introduced. Fast and stable convergence to a desirable interdigital filter design is achieved after only three EM fine-model simulations View full abstract»

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  • Spiral super-quadric generatrix and bodies of two generatrices in automated parameterization of 3-D geometries

    Page(s): 864 - 866
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    Most of the methods that solve the surface integral equation (SIE) by the method of moments (MoM) use triangles and flat quadrilaterals for geometrical modeling. Many complex structures can be easily modeled by quadrilaterals combining spiral super-quadric generatrices and the concept of the body of two generatrices (BoTG). A BoTG is any body that can be obtained from two generatrices by applying a certain rule. Four simple rules for obtaining BoTG's are: (1) generalized rotation; (2) translation; (3) constant cut; and (4) connected generatrices. Spiral super-quadric generatrices enable efficient modeling of circles, arcs, ellipses, squares, rectangles, spirals, etc. Thus, a simple but fairly general algorithm for geometrical modeling is obtained, convenient for implementation in electromagnetic-field solvers View full abstract»

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  • Improved design of passive coaxial components using electromagnetic 2-D solver in an optimization loop

    Page(s): 858 - 861
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    In this paper a new approach to the design of passive coaxial components, based on finite-difference time-domain (FDTD) electromagnetic (EM) analysis in an optimization loop is presented. A specialized coaxial EM solver has been modified for combined use with three optimization methods. Algorithms proved to be accurate and effective producing significantly improved circuits designs in a reasonable computing time. Practical examples illustrate advantages of the present approach View full abstract»

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  • Methods of using commercial electromagnetic simulators for microwave and millimeter-wave circuit design and optimization

    Page(s): 724 - 746
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    Efficient utilization of commercial electromagnetic (EM) simulators for design and optimization of microwave (MW) and millimeter-wave (MMW) circuits is achieved by classifying design problems into three categories-characterization of circuit elements, optimization of circuit elements, and creation of circuit element libraries such as scalable libraries. Practical aspects of the methods are illustrated by several examples. An equivalent circuit extraction technique suitable for n-port coupled structures is provided. The derived equivalent circuit is useful for extrapolating data, optimization, and deriving scalable models View full abstract»

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  • Fast parameter extraction of general interconnects using geometry independent measured equation of invariance

    Page(s): 827 - 836
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    The measured equation of invariance (MEI) is a new concept in computational electromagnetics. It has been demonstrated that the MEI technique can be used to terminate the meshes very close to the object boundary and still strictly preserves the sparsity of the finite-difference (FD) equations. Therefore, the final system matrix encountered by the MEI is a sparse matrix with a size similar to that of integral equation methods. However complicated the Green's function, disagreeable Sommerfeld integrals, and very difficult umbilical meshes for multiconductors make the traditional MEI very difficult (if not impossible) to be applied to analyze multilayer and multiconductor interconnects. In this paper, the authors propose the geometry independent MEI (GIMEI) which substantially improves the original MEI method. The authors use GIMEI for capacitance extraction of general two-dimensional (2-D) and three-dimensional (3-D) very large scale integration (VLSI) interconnect. numerical results are in good agreement with published data and those obtained by using FASTCAP from Massachusetts Institute of Technology (MIT) and some other commercial tools, while GIMEIs are generally an order of magnitude faster than FASTCAP with much less memory usage View full abstract»

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  • Automated design of corrugated feeds by the adjoint network method

    Page(s): 787 - 793
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    Automated full-wave design of corrugated feeds is generally accomplished by repeated numerical analysis of different feed geometries as obtained by slightly varying the geometrical dimensions of the corrugations. Since a corrugated feed contains hundreds of discontinuities, the above procedure is very time-consuming. In order to reduce the numerical effort, the adjoint network method (ANM) has been applied to the design and sensitivity analysis of circular corrugated feeds radiating into free space. By using the ANM, the return loss sensitivities with respect to variations of all geometrical dimensions are obtained with just one analysis of the entire feed. When a geometrical parameter is varied, only the discontinuity containing that parameter needs to be analyzed; the overall sensitivities being computed by means of a simple formula. Corrugated feeds with more than 100 corrugations have been designed by using the ANM. They have been built and measured demonstrating the efficiency of the proposed approach View full abstract»

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  • Physics-based large-signal sensitivity analysis of microwave circuits using technological parametric sensitivity from multidimensional semiconductor device models

    Page(s): 846 - 855
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    The authors present an efficient approach to evaluate the large-signal (LS) parametric sensitivity of active semiconductor devices under quasi-periodic operation through accurate, multidimensional physics-based models. The proposed technique exploits efficient intermediate mathematical models to perform the link between physics-based analysis and circuit-oriented simulations, and only requires the evaluation of dc and ac small-signal (dc charge) sensitivities under general quasi-static conditions. To illustrate the technique, the authors discuss examples of sensitivity evaluation, statistical analysis, and doping profile optimization of an implanted MESFET to minimize intermodulation which makes use of LS parametric sensitivities under two-tone excitation View full abstract»

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Aims & Scope

The IEEE Transactions on Microwave Theory and Techniques focuses on that part of engineering and theory associated with microwave/millimeter-wave components, devices, circuits, and systems involving the generation, modulation, demodulation, control, transmission, and detection of microwave signals. This includes scientific, technical, and industrial, activities. Microwave theory and techniques relates to electromagnetic waves usually in the frequency region between a few MHz and a THz; other spectral regions and wave types are included within the scope of the Society whenever basic microwave theory and techniques can yield useful results. Generally, this occurs in the theory of wave propagation in structures with dimensions comparable to a wavelength, and in the related techniques for analysis and design..

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Editor-in-Chief
Dominique Schreurs
Dominique.Schreurs@ieee.org

Editor-in-Chief
Jenshan Lin
jenshan@ieee.org