In this article, an efficient transient analysis method with arbitrary high-order accuracy for nonlinear field-circuit cosimulation problems is proposed. The proposed method combines a local time-stepping (LTS) technique with the discontinuous Galerkin time-domain (DGTD) method based on an arbitrary high-order derivatives (ADER) time integration scheme. The stability of the proposed method is not limited by the global time step size, allowing nonlinear and linear elements to update themselves with individual and optimal time intervals in accordance with the local stability condition. It is shown that the efficiency of the proposed method can be significantly improved when the nonlinear effects increase, which requires a smaller time interval to ensure system convergence. Several field-circuit coupling structures are simulated to demonstrate the accuracy and efficiency of the proposed method, confirming that it represents an effective tool for transient analysis of nonlinear field-circuit structures.

This letter focuses on the propagation characteristics of the electromagnetic wave in the plasma under high-power microwave (HPM) illumination. A multiphysical method coupling the electromagnetic field and plasma fluid field is proposed as the dynamic Drude model. The differences between the method based on dynamic Drude model and traditional static Drude model are discussed theoretically for the first time. Unlike the static Drude model, the dynamic Drude model fully considers the motion of electrons in plasma driven by electromagnetic field. Numerical examples demonstrate that both the dynamic Drude model-based and static Drude model-based method are consistent with each other under low power microwave illumination, where the plasma can be considered as a static media. While under HPM illumination, electrons gradually gather together to hinder the propagation of electromagnetic waves. Hence, the proposed dynamic Drude model is more logical to analyze the characteristics of electromagnetic wave in plasma than the traditional static Drude model under HPM illumination.

This article proposes a high-precision simulation method for transient electro-thermal coupling to characterize the self-heating effect in gallium nitride high electron mobility transistors (GaN HEMTs). The method is based on governing coupled drift-diffusion and heat conduction equations. A time scaling factor is introduced for the first time to accelerate the simulation process of electro-thermal coupling in GaN HEMTs. The technique addresses the cross-scale issue associated with the electrical and thermal response times encountered during the solution of the nonlinear coupling equations for GaN HEMTs. An accurate spectral element time-domain (SETD) method was utilized for the numerical realization of the nonlinear equations. The selection rules for the time scaling factor are discussed and exemplified through numerical simulations. By compared with commercial software, the advantages of the proposed method are demonstrated in terms of efficiency, accuracy, and random access memory (RAM) requirements. Based on its ability to accurately take into account electro-thermal coupling, this technique represents a powerful simulation tool for the design of high-performance devices and heat management.

An efficient discontinuous Galerkin time-domain (DGTD) method with an implementation of generalized periodic boundary conditions (PBCs) is proposed to analyze the electromagnetic scattering from arbitrary skewed periodic structures. The transformed field variable approach and the discontinuous Galerkin technique with nonconformal mesh are presented to implement the generalized PBCs for arbitrary skewed periodic structures under both normally and obliquely incident illuminations. The arbitrary high-order time-stepping scheme, which retains the DGTD feature of high-order accuracy and breaks the Butcher barrier, is extended to a transformed version of Maxwell’s equations introduced by the generalized PBCs implementation. The proposed method enables an efficient modeling of arbitrary skewed arrays with a fixed unit-cell mesh. Numerical examples for skewed periodic structures, such as an infinite gold film, 1-D and 2-D staggered dipole frequency-selective surfaces (FSSs), mechanically reconfigurable FSSs, and skewed nanohole arrays, are presented to demonstrate the accuracy and applicability of the proposed method.

In this letter, a novel high-performance energy-selective surface (ESS) is demonstrated for enabling defense against extremely high power microwaves. The meta-surface is designed with periodic metallic textures and loaded nonlinear PIN diodes. The ultra-high shielding performance is achieved through cascades of combined resonant circuits and an optimized coupling scheme. The scheme based on a backward propagation neural network algorithm, which is introduced into the mapping of the equivalent circuit and electromagnetic structures. Simula-tions and experiments show that the proposed ESS can achieve an insertion loss of less than 1dB over a bandwidth of 40%. Specially, the shielding efficiency of more than 40 dB has a relative bandwidth of almost 200%. Meanwhile, this design can realize a angular stability of more than 60° under TE/TM dual-polarized electromagnetic wave incidence. Such a design offers an excellent solution for electronic devices protection from ultra-high power microwave with wide incident angles.

In this paper, the electron transport properties of a C ₃ N nanoribbon-based field-effect transistor (FET) in the ballistic regime have been simulated. Using the density-functional theory (DFT) to obtain the band structures, we found that the armchair-edged C ₃ N nanoribbons are semiconductors, and their bandgaps are determined by their widths, while the zigzag-edged ribbons present the metallic properties. We have carried out calculations to study the transport properties of armchair-edged C ₃ N nanoribbon by using DFT combined with the nonequilibrium Green's function. Our simulation results revealed that both bandgap and current on/off ratio are reduced as the width increasing. Moreover, the gate length, channel length, and ribbon's width are found to have prominent influences on the transfer characteristics. The armchair-edged C ₃ N nanoribbon-based FETs have the highest current on/off ratio of 10 ⁶ and the ideal subthreshold swing of 61.2 mV/dec, which make it promising for potential applications of FET.