Stable modelling of arbitrary thin slots in the finite‐element time‐domain method

Abstract

SUMMARYA subcell model for arbitrarily located thin wires in the finite-element time-domain (FETD) method using modified telegraphers equations has been developed by Edelvik et al. Recently a dual set of equations has been proposed for modelling of thin slots. In this paper, we show that using a similar algorithm as for thin wires we can take thin slots of arbitrary location into account. Previous thin slot models have been susceptible for instabilities. We prove that a symmetric coupling between field and slot yields a stable time-continuous field-slot system and that the fully discrete field-slot system is unconditionally stable. The proposed method is demonstrated for scattering from straight and circular slots in an infinite conducting wall and for calculating the power delivered to a shielding enclosure including a slot. The results are in good agreement with published experimental data.