Dr. Wending Mai (26)

IEEE Senior Member, OSA Life Member, ACES Life Member.

Prism-based Discontinuous Galerkin Time Domain Analysis of Frequency Selective Surfaces in Lossy Water

Planar periodic structures are widely utilized in microwave applications. The prism-based Discontinuous Galerkin time domain (DGTD) method is optimal to cope with the modeling challenges associated with these planar structures. In this work, we modified the prism based DGTD to take lossy materials into account. A ring-shaped frequency selective surface (FSS) is studied as a representative numerical example. When submerged into water, the operating frequency of the FSS is lowered dramatically. We test the algorithm with distilled and tap water of different conductivity. Results of both examples compare well with references of commercial software, which validates the accuracy of the…

Research and Applications on Basis Functions of Discontinuous Galerkin Time Domain Method

The Discontinuous Galerkin Time-Domain (DGTD) method has gain great popularity for its capability of obtaining highly accuracy, flexibility, efficiency and parallel-computing. Different basis functions have their own merit in their advantageous applications. In this work, we focus on reseaches of DGTD’s basis functions and their advantageous applications. We firstly designed a nodal high-order based DGTD algorithm and studied its improvement on accuracy. As we known, an ultra-dense-mesh h-refinement will lead to the low-frequency breakdown which has been studied for decades. However, for highorder p-refinement, it is conventionally regarded that the accuracy is only limited by the basis orthogonality. While in…

An improved 2D／3D hybrid discontinuous Galerkin time domain method

Power integrity (PI) problem is essential when analyzing high speed signal passing through power ground. The fundamental mode in power ground is the zero-order parallel plate mode, which is capable for 2D simplification. However, in areas around anti-pads and other z-axis discontinuities, 3D algorithm has to be adopted to improve the accuracy. A hybrid 2D／3D discontinuous Galerkin time domain (DGTD) method has advantage on both accuracy and efficiency, thus is effective to cope with such full wave simulations. The 2D and 3D domains share the same triangular prism mesh. With appropriated basis functions, different domains can couple with each other…

Broadband transparent chiral mirrors: Design methodology and bandwidth analysis

Chiral mirrors are a class of metamaterials that reflect circularly polarized light of a certain helicity in a handedness-preserving manner, while absorbing circular polarization of the opposite handedness. However, most absorbing chiral mirrors operate only in a narrow frequency band, as limited by the causality principle. Instead of absorbing the undesired waveform, here we propose a transparent chiral mirror that allows undesired waves to pass through. In particular, the handedness-preserving band of the transparent chiral mirror is free of the causality limit, thus enabling broadband functionality. Furthermore, since electromagnetic waves outside the handedness-preserving band may transmit through the proposed chiral…

Prism-based DGTD with a simplified periodic boundary condition to analyze FSS with D2n symmetry in a rectangular array under normal incidence

In this letter, we develop a prism-based discontinuous Galerkin time-domain (DGTD) algorithm with simplified periodic boundary conditions (PBCs) to analyze infinite doubly periodic frequency selective surfaces (FSS). Most FSS structures contain patterned planar conductive layers and supporting dielectric layers. These layers are very thin compared to the wavelength. Therefore, general tetrahedral discretization of space will unnecessarily increase the number of mesh elements, as well as the number of unknowns. Instead, we propose using prismatic elements, which are more optimal for planar structures, resulting in less unknowns, less memory usage, and higher efficiency. The accuracy of the proposed prism-based DGTD method…

A predictive criterion for 2D/3D DGTD method based on the CFL condition

The zeroth-order parallel-plates mode dominates in most parts of the power-ground plates pairs. Domains with such mode distribution can be solved by a simplified 2D algorithm, while only higher-order modes require 3D computation. For DGTD method, different domains can be decoupled with each other by the numerical flux. To distinguish 2D and 3D domains properly, the field distribution has to be known before it is actually solved. This paradox is walked around by a predictive criterion which roughly predicts tn's field distribution based on tn-1's results. Here we introduce an adaptive criterion based on the CFL condition to realize such…