Face-Centered Anisotropic Surface Impedance Boundary Conditions in FDTD
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AuthorFlintoft, Ian; Bourke, Samuel; Dawson, John; Alvarez Gonzalez, Jesus; Ruiz Cabello, Miguel; Robinson, M. P.; Gonzalez Garcia, Salvador
Finite-difference time domainImpedance network boundary conditionSurface-impedance boundary condition
Flintoft, Ian; et. al. Face-Centered Anisotropic Surface Impedance Boundary Conditions in FDTD. IEEE Transactions on Microwave Theory and Techniques, vol. 66, no. 2, pp. 643-650, Feb. 2018 [http://hdl.handle.net/10481/50236]
SponsorshipThis work was supported by the U.K. Engineering and Physical Sciences Research Council through the Flapless Air Vehicle Integrated Industrial Research Programme under Grant GR/S71552/01, in part by the European Community’s Seventh Framework Programme under Grant FP7/2007-2013, in part by the High Intensity Radiated Field Synthetic Environment Research Project under Grant 205294, in part by the Spa nish MINECO, EU FEDER under Project TEC2013-48414-C3-01 and Project TEC2016-79214-C3-3-R, and in part by J. de Andalucia, Spain under Project P12-TIC-1442
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 tangen- tial 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.