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Item type:Publication, Access status: with files , A waveform relaxation solver for transient simulation of large-scale nonlinearly loaded shielding structures(IEEE, 2022-09-22); ; ; ; This article introduces an algorithm for transient simulation of electromagnetic structures loaded by lumped nonlinear devices. The reference application is energy-selective shielding, which adopts clipping devices uniformly spread along shield apertures to achieve a shielding effectiveness that increases with the power of the incident field, thereby blocking high-power interference while allowing low-power communication. Transient simulation of such structures poses a number of challenges, related to their large-scale and low-loss nature. In this work, we propose a waveform relaxation (WR) scheme based on decoupling the linear electromagnetic structure from its nonlinear terminations. In a preprocessing stage, the electromagnetic subsystem is characterized in the frequency domain and converted into a behavioral rational macromodel. Transient simulation is performed by refining estimates of the port signals through iterations. The proposed scheme combines a time partitioning approach with an inexact Newton–Krylov solver. This combination provides fast convergence also in those cases where standard WR schemes fail due to a strong mismatch at the decoupling sections. Numerical results on several test cases of increasing complexity with up to 1024 ports show that the proposed approach proves as reliable as HSPICE in terms of accuracy, with a speedup ranging from one to three orders of magnitude.Publicationtype: Journal Article21 59 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Iteration Dependent Waveform Relaxation for Hybrid Field Nonlinear Circuit Problems(2022-08-01); ; ; ; This article presents a novel waveform relaxation scheme to solve electromagnetically large structures loaded with lumped linear and nonlinear elements. The scheme partitions the problem into a linear electromagnetic structure and a possibly nonlinear lumped circuit, which are coupled using Thévenin interfaces across the steps of an iterative waveform relaxation scheme. The main novel contribution is an adaptive selection of the decoupling resistances used as port references to define incident and reflected scattering signals, whose time-domain samples are refined through iterations. The decoupling resistances are updated through iterations, with the main objective of improving convergence speed and ultimately runtime. The resulting scheme is self-adapting to terminations exploiting high dynamic range in their impedance profiles and is able to provide a suboptimal convergence rate. Three-dimensional shielding structures loaded with nonlinear elements are employed as numerical examples to demonstrate the proposed method.Publicationtype: Journal Article32 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Regularized and compressed large-scale rational macromodeling: Theory and application to energy-selective shielding enclosures(IEEE, 2022-06-07); ; ; ; In this article, we introduce a robust procedure for the extraction of passive rational macromodels of low-loss electromagnetic structures with massive port counts. Such structures pose inherent challenges that make standard macromodeling tools and approaches inadequate, mainly due to complexity and sensitivity at low frequency. The proposed approach involves a preprocessing stage in which port response data from a full-wave electromagnetic solver are regularized and extrapolated to dc using an asymptotic modal representation. The resulting data samples are then processed by a dedicated compression algorithm that represents the full set of input–output responses in terms of a few basis functions, which are constructed by enforcing an exact low-frequency modal asymptotic behavior, possibly including higher order dc zeros. These zeros are preserved in any stage of rational fitting and passivity enforcement, resulting in dc and low-frequency compliant compressed passive macromodels. Numerical results with up to 400 ports demonstrate the superior performance and accuracy of the computed models with respect to state-of-the-art approaches. In particular, the resulting models preserve their accuracy irrespective of the loading conditions, including the limit cases of short and open terminations.Publicationtype: Journal ArticleScopus© Citations 2 50 126 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Low-Frequency Modal Extrapolation and Regularization for Full-Bandwidth Macromodeling of Electromagnetic StructuresThis paper provides a novel strategy for the extrapolation and regularization of low frequency data of low-loss or lossless structures, based on asymptotic modal trajectories. The proposed data-driven strategy is intended as a fundamental pre-processing step to obtain a full-bandwidth reliable macromodel to be used in transient simulations, providing full control of the low-frequency and DC behavior of the system.Publicationtype: Conference Paper21 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Analysis and Optimization of Nonlinear Diode Grids for Shielding of Enclosures With Apertures(2021-12-01); ; ; ; Lumped-element grids provide an attractive option for wave propagation control in electromagnetic compatibility (EMC) engineering. This article investigates the peak shielding effectiveness (SE) of a diode grid used for protection of enclosures with apertures against high-intensity radiation fields (HIRFs). The nonlinearly loaded aperture is investigated with an efficient hybrid field-circuit simulation approach. Numerical experiments show that design aspects, e.g., aperture and enclosure size, grid density, impedance characteristic of lumped loads, play an important role in the field transmission through a diode grid which is nonlinear and time-variant. With a physics-based analysis of the interaction between the grid and the enclosure-backed aperture, nonlinear shielding techniques are identified that allow a control of the peak SE between 0 and 26 dB in novel ways. For the first time, the peak SE curve of a diode grid is demonstrated with four different field intensity dependencies, i.e., intensity low-pass, intensity high-pass, intensity bandpass, and intensity band-stop selectivities from tens V/m to hundreds of V/m. By considering design aspects into a two-step optimization procedure, practical guidelines are provided for the nonlinear shielding implementation.Publicationtype: Journal Article71 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Distributed Nonlinear Shielding in Power Delivery Networks on Printed Circuit BoardsPublicationtype: Conference Paper61 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A multistage adaptive sampling scheme for passivity characterization of large-scale macromodels(IEEE, 2021-03-01); ; ; ; This article proposes a hierarchical adaptive sampling scheme for passivity characterization of large-scale linear lumped macromodels. In this article, large scale is intended both in terms of dynamic order and especially number of input-output ports. Standard passivity characterization approaches based on spectral properties of associated Hamiltonian matrices are either inefficient or nonapplicable for large-scale models, due to an excessive computational cost. This article builds on existing adaptive sampling methods and proposes a hybrid multistage algorithm that is able to detect the passivity violations with limited computing resources. Results from extensive testing demonstrate a major reduction in computational requirements with respect to competing approaches.Publicationtype: Journal Article43