Finite Element Analysis of Antennas and Arrays

Topology optimization for transient response of photonic crystal structures

“…1). Interpreting the material behavior in ⍀ PML as anisotropic, dispersive, and lossy, the governing equation for r ⍀ = ⍀ S ഫ ⍀ PML takes the following general form [17]:…”

“…Additionally, time-domain methods can accommodate strongly nonlinear or active (time-varying) media, whereas frequency methods have difficulties with these physical regimes because the frequency is no longer preserved. Two of the major challenges of the FETD method are the computational cost associated with the computation of the sensitivities and the implementation of efficient absorbing boundary conditions (ABCs), such as the perfectly matched layer (PML) [17]. To the authors' knowledge, a topology optimization scheme based on the FETD method using PMLs as ABCs has not been reported before.…”

Efficient Time-Domain Analysis of Waveguide Discontinuities Using Higher Order Fem in Frequency Domain

“…For this purpose, time-domain FEM techniques have recently been developed [8,13,14], allowing electromagnetic phenomena to be modeled directly in the time domain. In [8], for instance, the spatially and temporally varying electric field is approximated using interpolatory spatial vector basis functions defined on tetrahedral elements, with time-dependent field-distribution coefficients, which are determined solving the corresponding second-order ordinary differential equation in time by a time-marching procedure. When compared to frequency-domain FEM solutions, time-domain FEM formulations enable effective modeling of time-varying and nonlinear problems and fast broadband simulations (provide broadband information in a single run), at the expense of the additional discretization -in time domain, and the associated numerical complexities, programming and implementation difficulties, and stability and other problems inherent for time-domain computational electromagnetic approaches.…”

“…However, timedomain analysis and characterization of such structures and evaluation of associated transient electromagnetic phenomena are also of great practical importance for a number of well-established and emerging areas of applied electromagnetics, including wideband communication, electromagnetic compatibility, electromagnetic interference, packaging, high-speed microwave electronics, signal integrity, material characterization, and other applications [11][12][13]. For this purpose, time-domain FEM techniques have recently been developed [8,13,14], allowing electromagnetic phenomena to be modeled directly in the time domain. In [8], for instance, the spatially and temporally varying electric field is approximated using interpolatory spatial vector basis functions defined on tetrahedral elements, with time-dependent field-distribution coefficients, which are determined solving the corresponding second-order ordinary differential equation in time by a time-marching procedure.…”

“…The finite element method (FEM), as one of the most powerful and versatile general numerical tools for electromagnetic-field computations [7][8][9][10], has been especially effectively used in full-wave three-dimensional (3-D) frequency-domain simulations of a broad range of multiport waveguide structures with arbitrary metallic and dielectric discontinuities, and the FEM is well established as a method of choice for such applications [1,2]. However, timedomain analysis and characterization of such structures and evaluation of associated transient electromagnetic phenomena are also of great practical importance for a number of well-established and emerging areas of applied electromagnetics, including wideband communication, electromagnetic compatibility, electromagnetic interference, packaging, high-speed microwave electronics, signal integrity, material characterization, and other applications [11][12][13].…”