Complex Electromagnetic Structures Research Articles

Artificial Microwave Volume Holograms Based on Printed Disk Media: Theory and Measurement of Single-Grating Holograms

A new type of complex electromagnetic structure, the artificial microwave volume hologram (AMVH), has been developed. The structure consists of cascaded planar lattices of metallic circular patches with varying size and can be designed to have an effective dielectric modulation that follows a holographic interference pattern. Under the illumination of certain electromagnetic waves, an AMVH can reproduce a required wave field pattern based on its design, just like an optical volume hologram. A theoretical model, namely the self-consistent dynamic-dipole interaction theory, has been presented to characterize AMVHs for wave scattering and beam reconstruction. It can be used for designing and optimizing AMVHs. Comparisons with the coupled-wave theory (CWT) and a full-wave finite element method analysis have been made to validate the proposed theory. A prototype AMVH has been fabricated and measured, which has confirmed the AMVH concept as well as the theoretical model

Optimized ADI-FDTD analysis of circularly polarized microstrip and dielectric resonator antennas

A dispersion-optimized alternating-direction implicit finite-difference time-domain (ADI-FDTD) method is presented in this letter for the accurate modeling of complex electromagnetic structures. The analysis focuses on circularly polarized slot-coupled microstrip and dielectric resonator antennas. Introducing a class of three-dimensional spatial/temporal operators, the novel algorithm yields robust curvilinear grids which efficiently treat fine details and interfaces. Hence, the serious dispersion errors of the usual schemes, as time-steps surpass the Courant limit, are greatly reduced, enabling fast broad-band simulations. Numerical validation confirms the above merits via various realistic structures.

Computational model of solid-state, molecular, or atomic media for FDTD simulation based on a multi-level multi-electron system governed by Pauli exclusion and Fermi-Dirac thermalization with application to semiconductor photonics

We report a general computational model of complex material media for electrodynamics simulation using the Finite-Difference Time-Domain (FDTD) method. It is based on a multi-level multi-electron quantum system with electron dynamics governed by Pauli Exclusion Principle, state filling, and dynamical Fermi-Dirac Thermalization, enabling it to treat various solid-state, molecular, or atomic media. The formulation is valid at near or far off resonance as well as at high intensity. We show its FDTD application to a semiconductor in which the carriers' intraband and interband dynamics, energy band filling, and thermal processes were all incorporated for the first time. The FDTD model is sufficiently complex and yet computationally efficient, enabling it to simulate nanophotonic devices with complex electromagnetic structures requiring simultaneous solution of the mediumfield dynamics in space and time. Applications to direct-gap semiconductors, ultrafast optical phenomena, and multimode microdisk lasers are illustrated.

TLM-G-a grid-enabled time-domain transmission-line-matrix system for the analysis of complex electromagnetic structures

A Grid-enabled time-domain transmission line matrix (TLM-G) system for full-wave analysis of complex electromagnetic (EM) structures is presented. The emerging Grid technology enables distributed EM simulations in a virtual organization. An introduction to Grid computing is given and a detailed description of the layout of the TLM-G system is made. Furthermore, the measured EM performance, scalability, and accuracy of the TLM-G system are shown.

P(MoM/MAS): an interactive environment, coupling WWW technology and parallel processing, to solve large-size electromagnetic problems

Parallel processing over the Internet is now becoming a realistic possibility. There are numerous of-the-shelf high-performance computing (HPC) platforms available with Internet access, on which to implement computationally intensive algorithms. HPC can be applied in the field of computational electromagnetics. The networking capabilities of the Internet now allow these computing resources to be used as a remote service. Additionally, the pragmatics of their utilization can be abstracted by adopting a World Wide Web (WWW) interface. A Web-based environment can provide the supportive tools for data entry, program initiation, result visualization, and even interactive modifications of the geometry and/or electromagnetic (EM) properties. For realistic interaction, the emerging question is which algorithm to use that supports the exploitation of parallelism. In order to exploit and utilize all the available performance of current and predicted HPC platforms, inherently-parallel-based algorithms have to be devised. One such algorithm is the parallel method of moments/method of auxiliary sources, P(MoM/MAS), introduced in this paper. The resulting algorithm parallelization enables the MoM/MAS method to be applied to solving electrically-large-in-size and complex EM structures on various computational platforms. This paper concentrates on the parallel-processing issues, and on the importance of adopting suitable algorithms, such as the MoM/MAS technique.