Face-Centered Anisotropic Surface Impedance Boundary Conditions in FDTD

Abstract

Abstract-Thin-sheet models are essential to allow shielding effectiveness of composite enclosures and vehicles to be modeled. Thin dispersive sheets are often modeled using surface-impedance models in finite-difference time-domain (FDTD) codes in order to deal efficiently with the multiscale nature of the overall structure. Such boundary conditions must be applied to collocated tangential electric and magnetic fields on either side of the surface; this is usually done on the edges of the FDTD mesh cells at the electric field sampling points. However, these edge-based schemes are difficult to implement accurately on stair-cased surfaces. Here, we present a novel face-centered approach to the collocation of the fields for the application of the boundary condition. This approach naturally deals with the ambiguities in the surface normal that arise at the edges on stair-cased surfaces, allowing a simpler implementation. The accuracy of the new scheme is compared to edge-based and conformal approaches using both planar sheet and spherical shell canonical test cases. Staircasing effects are quantified and the new face-centered scheme is shown have up to 3-dB lower error than the edge-based approach in the cases considered, without the complexity and computational cost of conformal techniques.Index Terms-Finite-difference time domain (FDTD), impedance network boundary condition, surface-impedance boundary condition (SIBC).

A Conformal Thin Boundary Model for FDTD

“…Surface Impedance Boundary Conditions (SIBCs) are useful tools that can be used to model very thin materials [2], [3]. They allows a material that is much thinner than the size of the mesh to be simulated without having to simulate the field inside the material.…”

“…The algorithm is proposed in Section II and validated using different cavity models in Sections III, IV and V. Conclusions about the approach are presented in Section VI II. PROPOSED CONFORMAL ALGORITHM Here the adaptation of an existing SIBC [3] to a conformal mesh is described. Consider the cell in Fig.…”

Comments on “A New Conformal FDTD for Lossy Thin Panels”

“…Fig. 1 shows an example of results taken from [1], where a reasonably good agreement with analytical data exists at the resonant frequencies of the cavity, together with spiky anti-resonances at frequencies in between. The first four authors are with the Department of Electromagnetism and Matter Physics, University of Granada, 18071, Granada, Spain (email: {salva@ugr.es, mcabello@ugr.es, lmdiazangulo@ugr.es, antoniojema@correo.ugr.es}).…”

“…In previous papers [1]- [3], the authors employed a spherical cavity, with a conductive thin wall to validate novel lossy thin-panel treatments in the FDTD method. A set of spiky solutions, categorized as "spurious", appeared at frequencies between the "physical" ones.…”

Open-Source Software for Electromagnetic Scattering Simulation: The Case of Antenna Design

“…Vulture [69] implements a general-purpose FDTD algorithm, which has some interesting capabilities for electromagnetic engineering. At the moment the development seems to be stalled, although it continues on the front of research papers [93,94].…”