A Fast Frequency Sweep – Green’s Function Based Analysis of Substrate Integrated Waveguide

In this paper, a fast frequency sweep technique is applied to the analysis of Substrate Integrated Waveguides performed with a Green’s function technique. The well-known Asymptotic Waveform Evaluation technique is used to extract the Padè approximation of the frequency response of Substrate Integrated Waveguides devices. The analysis is extended to a large frequency range by adopting the Complex Frequency Hopping algorithm. It is shown that, with this technique, CPU time can be reduced of almost one order of magnitude with respect to a point by point computation

Krylov subspaces from bilinear representations of nonlinear systems

Purpose – The paper is aimed at the development of novel model reduction techniques for nonlinear systems. Design/methodology/approach – The analysis is based on the bilinear and polynomial representation of nonlinear systems and the exact solution of the bilinear system in terms of Volterra series. Two sets of Krylov subspaces are identified which capture the most essential part of the input-output behaviour of the system. Findings – The paper proposes two novel model-reduction strategies for nonlinear systems. The first involves the development, in a novel manner compared with previous approaches, of a reduced-order model from a bilinear representation of the system, while the second involves reducing a polynomial approximation using Krylov subspaces derived from a related bilinear representation. Both techniques are shown to be effective through the evidence of a standard test example. Research limitations/implications – The proposed methodology is applicable to so-called weakly nonlinear systems, where both the bilinear and polynomial representations are valid. Practical implications – The suggested methods lead to an improvement in the accuracy of nonlinear model reduction, which is of paramount importance for the efficient simulation of state-of-the-art dynamical systems arising in all aspects of engineering. Originality/value – The proposed novel approaches for model reduction are particularly beneficial for the design of controllers for nonlinear systems and for the design and analysis of radio-frequency integrated circuits

Fast Frequency Sweep Technique Based on Segmentation for the Acceleration of the Electromagnetic Analysis of Microwave Devices

[EN] The characterization of communication devices in a certain frequency band can be accelerated if a fast frequency sweep technique is used instead of a discrete frequency sweep. Existing fast frequency sweep techniques are either complex or specific for a certain electromagnetic solver. In this work, a new fast frequency sweep method is proposed that consists in segmenting the device under analysis into simple building blocks. Each building block is characterized with a generalized (multimode) circuital matrix whose elements present a simple and flat frequency response that is interpolated using natural cubic splines with very few points. In this way, the response of each block along the whole frequency band is obtained efficiently and accurately with as many frequency points as desired. Then, the circuital matrices of all the blocks are cascaded and the circuital matrix of the whole device in obtained. The new fast frequency sweep was successfully applied to the analysis of different types of devices (all metallic rectangular waveguide filter, dielectric loaded rectangular waveguide filter, and substrate integrated waveguide filter). The computational times were reduced to 15% or 19%, depending on the device, when compared with a discrete frequency sweep using the same electromagnetic solver.This research was funded by Ministerio de Economia, Industria y Competitividad, Spanish Government, under Research Projects TEC2016-75934-C4-3-R and TEC2016-75934-C4-1-R.Martínez-Zamora, JÁ.; Belenguer Martínez, A.; Esteban González, H. (2019). Fast Frequency Sweep Technique Based on Segmentation for the Acceleration of the Electromagnetic Analysis of Microwave Devices. Applied Sciences. 9(6):1-16. https://doi.org/10.3390/app9061118S11696Erdemli, Y. E., Reddy, C. J., & Volakis, J. L. (1999). Awe Technique in Frequency Domain Electromagnetics. Journal of Electromagnetic Waves and Applications, 13(3), 359-378. doi:10.1163/156939399x00961Reddy, C. J., Deshpande, M. D., Cockrell, C. R., & Beck, F. B. (1998). Fast RCS computation over a frequency band using method of moments in conjunction with asymptotic waveform evaluation technique. IEEE Transactions on Antennas and Propagation, 46(8), 1229-1233. doi:10.1109/8.718579Polstyanko, S. V., Dyezij-Edlinger, R., & Jin-Fa Lee. (1997). Fast frequency sweep technique for the efficient analysis of dielectric waveguides. IEEE Transactions on Microwave Theory and Techniques, 45(7), 1118-1126. doi:10.1109/22.598450Chiprout, E., & Nakhla, M. S. (1995). Analysis of interconnect networks using complex frequency hopping (CFH). IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, 14(2), 186-200. doi:10.1109/43.370425Gustavsen, B., & Semlyen, A. (1999). Rational approximation of frequency domain responses by vector fitting. IEEE Transactions on Power Delivery, 14(3), 1052-1061. doi:10.1109/61.772353Bandler, J. W., Biernacki, R. M., Shao Hua Chen, & Ya Fei Huang. (1997). Design optimization of interdigital filters using aggressive space mapping and decomposition. IEEE Transactions on Microwave Theory and Techniques, 45(5), 761-769. doi:10.1109/22.575598Ros, J. V. M., Pacheco, P. S., Gonzalez, H. E., Esbert, V. E. B., Martin, C. B., Calduch, M. T., … Martinez, B. G. (2005). Fast automated design of waveguide filters using aggressive space mapping with a new segmentation strategy and a hybrid optimization algorithm. IEEE Transactions on Microwave Theory and Techniques, 53(4), 1130-1142. doi:10.1109/tmtt.2005.845685Alos, J. T., & Guglielmi, M. (1997). Simple and effective EM-based optimization procedure for microwave filters. IEEE Transactions on Microwave Theory and Techniques, 45(5), 856-858. doi:10.1109/22.575610Bachiller, C., Gonzalez, H. E., Boria Esbert, V. E., Belenguer Martinez, A., & Morro, J. V. (2007). Efficient Technique for the Cascade Connection of Multiple Two-Port Scattering Matrices. IEEE Transactions on Microwave Theory and Techniques, 55(9), 1880-1886. doi:10.1109/tmtt.2007.904076Interpolación de Splineshttps://www.uv.es/diaz/mn/node40.htmlBachiller, C., Esteban, H., Mata, H., Valdes, M. Á., Boria, V. E., Belenguer, Á., & Morro, J. V. (2010). Hybrid Mode Matching Method for the Efficient Analysis of Metal and Dielectric Rods in H Plane Rectangular Waveguide Devices. IEEE Transactions on Microwave Theory and Techniques. doi:10.1109/tmtt.2010.208395

Efficient positive-real balanced truncation of symmetric systems via cross-riccati equations

We present a highly efficient approach for realizing a positive-real balanced truncation (PRBT) of symmetric systems. The solution of a pair of dual algebraic Riccati equations in conventional PRBT, whose cost constrains practical large-scale deployment, is reduced to the solution of one cross-Riccati equation (XRE). The cross-Riccatian nature of the solution then allows a simple construction of PRBT projection matrices, using a Schur decomposition, without actual balancing. An invariant subspace method and a modified quadratic alternating-direction-implicit iteration scheme are proposed to efficiently solve the XRE. A low-rank variant of the latter is shown to offer a remarkably fast PRBT speed over the conventional implementations. The XRE-based framework can be applied to a large class of linear passive networks, and its effectiveness is demonstrated through numerical examples. © 2008 IEEE.published_or_final_versio

Efficient and Accurate Design of Passive Devices in Substrate Integrated Waveguide Technology and their Tapered Transitions from Microstrip Lines

[EN] In this paper, a strategy for the efficient design of passive devices in substrate integrated waveguide (SIW) technology is presented and validated with the analysis of several devices and the real design of filters in different topologies. In addition, a procedure for accurately designing tapered microstrip-to-substrate integrated waveguide transitions is described.Díaz Caballero, E.; Miralles, E.; Esteban González, H.; Belenguer Martínez, Á.; Boria Esbert, VE.; Bachiller Martin, MC.; Morro Ros, JV.... (2011). Efficient and Accurate Design of Passive Devices in Substrate Integrated Waveguide Technology and their Tapered Transitions from Microstrip Lines. Waves. 3:76-85. http://hdl.handle.net/10251/55349S7685

An electrical circuit theoretical method for time- and frequency-domain solutions of the structural mechanics problems

Shrinking device dimensions in integrated circuit technology made integrated circuits with millions of components a reality. As a result of this advance, electrical circuit simulators that can handle very large number of components have emerged. These programs use new circuit simulation techniques and can find solutions accurately and quickly. In this paper, we apply these techniques to structural mechanics problems by adopting electrical circuit equivalents. We first apply finite element formulation to the mechanical problem. The obtained sets of equations are treated as if they are sets of equations of an equivalent electrical circuit which consists of linear circuit elements such as capacitors, inductors and controlled sources. The equivalent circuit is obtained in the form of a circuit netlist and solved using a general purpose electrical circuit simulator. Several examples showing the advantages of the circuit simulation techniques are demonstrated. Asymptotic waveform evaluation technique which is widely used for simulation of large electrical circuits is also studied for the same examples and the speed-up advantage is shown. Copyright © 1999 John Wiley & Sons, Ltd

Addressing Computational Complexity of Electromagnetic Systems Using Parameterized Model Order Reduction

As operating frequencies increase, full wave numerical techniques such as the finite element method (FEM) become necessary for the analysis of high-frequency and microwave circuit structures. However, the FEM formulation of microwave circuits often results in very large systems of equations which are computationally expensive to solve. The objective of this thesis is to develop new parameterized model order eduction (MOR) techniques to minimize the computational complexity of microwave circuits. MOR techniques provide a mechanism to generate reduced order models from the detailed description of the original FEM formulation. The following contributions are made in this thesis: 1. The first project deals with developing a parameterized model order reduction to solve eigenvalue equations of electromagnetic structures that are discretized by using FEM. The proposed algorithm uses a multidimensional subspace method based on modified perturbation theory and singular-value decomposition to perform reduction directly on the finite element eigenvalue equations. This procedure generates parametric reduced order models that are valid over the desired parameter range without the need to redo the reduction when design parameters are changed. This provides significant computational savings when compared to previous eigenvalue MOR techniques, since a new reduced order model is not required each time a design parameter is changed. 2. Implicit moment match techniques such as the Arnoldi algorithm are often used to improve the accuracy of the reduced order model. However, the traditional Arnoldi algorithm is only applicable to first order linear systems and can not directly include arbitrary functions of frequency due to material and boundary conditions. In this work, an efficient algorithm to create parametric reduced order models of distributed electromagnetic systems that have arbitrary functions of frequency (due to material properties, boundary conditions, and delay elements) and design parameters. The proposed method is based on a multi-order Arnoldi algorithm used to implicitly calculate the moments with respect to frequency and design parameters, as well as the cross-moments. This procedure generates parametric reduced order models that are valid over the desired parameter range without the need to redo the reduction when design parameters are changed and provides more accurate reduced order systems when compared with traditional approaches such as Modified Gram Schmidt. 3. This project develops an efficient technique to calculate sensitivities of microwave structures with respect to network design parameters. The proposed algorithm uses a parametric reduced order model to solve the original network and an adjoint variable method to calculate sensitivities. Important features of the proposed method are 1) that the solution of the original network as well as sensitivities with respect to any parameter is obtained from the solution of the reduced order model, and 2) a new reduced order model is not required each time design parameters are varied

Circuit theoretical methods for efficient solution of finite element structural mechanics problems

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent Univ., 1999.Thesis (Ph.D.) -- Bilkent University, 1999.Includes bibliographical references leaves 78-84.Shrinking device dimensions in integrated circuit technology made integrated circuits with millions of components a reality. As a result of this advance, electrical circuit simulators that can handle very large number of components have emerged. These programs use new circuit simulation techniques which approximate the system with reduced order models, and can find solutions accurately and quickly. This study proposes formulating the structural mechanics problems using FEM, and then employing the recent speedup techniques used in circuit simulation. This is obtained by generating an equivalent resistor-inductor-capacitor circuit containing controlled sources. We analyze the circuits with general-purpose circuit simulation programs, HSPICE, and an in-house developed circuit simulation program, MAWE, which makes use of generalized asymptotic waveform evaluation (AWE) technique. AWE is a moment matching technique that has been successfully used in circuit simulation for solutions of large sets of equations. Several examples on the analysis of the displacement distributions in rigid bodies have shown that using circuit simulators instead of conventional FEM solution methods improves simulation speed without a significant loss of accuracy. Pole analysis via congruence transformations (PACT) technique is a recent algorithm used for obtaining lower order models for large circuits. For a further reduction in time, we employed a similar algorithm in structural mechanics problems before obtaining the equivalent circuit. The results are very promising.Ekinci, Ahmet SuatPh.D